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Insect Frontiers, May 2010 Volume 2 Number 5 (PDF final)
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Insect Behavior
Genotype effect on regulation of behaviour by vitellogenin supports reproductive origin of honeybee foraging bias
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Kate E. Ihlea,
a
b Department of Chemistry, Biotechnology and Food Science,
Norwegian
In honeybee colonies, food collection is performed by a group of mostly sterile females called workers. After an initial nest phase, workers begin foraging for nectar and pollen, but tend to bias their collection towards one or the other. Although foraging choices of honeybees are influenced by vitellogenin, an egg-yolk precursor protein, workers typically do not lay eggs. The forager reproductive ground plan hypothesis (RGPH) proposes an evolutionary path in which the behavioural bias towards collecting nectar or pollen on foraging trips is influenced by variation in reproductive physiology, such as hormone levels and vitellogenin (vg) gene expression. Recently, the connections between vitellogenin and foraging behaviour were challenged by Oldroyd & Beekman (2008), who concluded from their study that the ovary, and especially vitellogenin, played no role in foraging behaviour of bees. We address their challenge directly by manipulating vg expression by RNA interference (RNAi) mediated gene knockdown in two honeybee genotypes with different foraging behaviour and reproductive physiology. We found that vg affected the food-loading decisions of the workers only in the genotype in which the timing of foraging onset (by age) was also sensitive to vitellogenin levels. In the second genotype, changing vitellogenin levels did not affect foraging onset or bias. The effect of vitellogenin on workers' age at foraging onset is explained by the well-supported double repressor hypothesis (DHR), which describes a mutually inhibitory relationship between vitellogenin and juvenile hormone (JH), an endocrine factor that influences development, reproduction and behaviour in many insects. These results support the RGPH and demonstrate how it intersects with an established mechanism of honeybee behavioural control.
Animal Behaviour Volume 79, Issue 5, May 2010, Pages 1001-1006
Relevance of resource-indicating key volatiles and habitat odour for insect orientation
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I. Beyaerta, N. Wäschkea, A. Scholza, M. Varamab, 1, A. Reineckec, 2 and M. Hilkera,
a
b Finnish Forest Research Institute,
c Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology,
Olfactory orientation by insects may be guided by specific volatile blends released from sites where resources are present. Such blends need to be recognized against the odorous background of the habitat. The egg parasitoid Closterocerus ruforum is known to be attracted to plant volatiles induced by egg deposition of its herbivorous host, the pine sawfly Diprion pini. The parasitoid has to detect this volatile signal against a background of other pine volatiles (i.e. odour from pine without host eggs). Previous studies have shown that attractive resource-indicating odour (pine with host eggs) and nonattractive habitat odour (pine without eggs) differ only by enhanced quantities of (E)-β-farnesene in the resource-indicating odour. However, (E)-β-farnesene per se was not attractive. We studied the relevance of quantitative ratios of (E)-β-farnesene and other pine volatiles present in the habitat for parasitoid orientation by electrophysiological methods (EAG) and behavioural (olfactometer) assays. Seven of 12 terpenoid pine volatiles elicited an EAG response. In tests of the parasitoid's behavioural response to EAG-active volatiles, a blend of five components (including (E)-β-farnesene) was sufficient to attract the parasitoid but only when the ratio of (E)-β-farnesene and the other compounds matched that in odour from egg-laden pine. Since the quantities of volatiles from egg-laden and egg-free pine are not significantly different except for (E)-β-farnesene, our results show that the quantity of a resource-indicating key compound (here (E)-β-farnesene) is validated by its ratio to quantities of background volatiles emitted by both the resource and the habitat.
Animal Behaviour Volume 79, Issue 5, May 2010, Pages 1077-1086
Is mate choice in Drosophila males guided by olfactory or gustatory pheromones?
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Claude Everaerts
a Centre des Sciences du Goût et de l'Alimentation, UMR6265 CNRS, UMR1324 INRA,
Drosophila melanogaster flies use both olfactory and taste systems to detect sex pheromones and select the most suitable mate for reproduction. In nature, flies often face multiple potential partners and should have an acute sensory ability to discriminate between different pheromonal bouquets. We investigated both the pheromones and the chemosensory neurons influencing Drosophila mate choice. We measured various courtship traits in single tester males simultaneously presented with two target male and/or female flies carrying different pheromonal bouquets (pairs of control flies of the same or different sex, same-sex target pairs of pheromonal variant strains). The courtship traits reflected the perception of either olfactory cues perceived before or gustatory cues perceived after the first physical taste contact. Our results suggest that male mate choice exists in D. melanogaster and that male discrimination between potential mates could be a two-step process involving chemical cues perceived before and after the first gustatory contact. In addition, when a male was simultaneously presented with two potential sexual partners, the olfactory and gustatory cues he used depended on the pheromonal patterns of both flies, but his response could also depend on additional effects resulting from the simultaneous perception of the two flies, leading to a nonlinear choice of a sexual partner. Moreover, some tester males with genetically altered gustatory receptor neurons strongly changed their partner preference, indicating that the fly's peripheral nervous system is essential for pheromonal detection and mate choice.
Animal Behaviour Volume 79, Issue 5, May 2010, Pages 1135-1146
Multimodal mate assessment by male praying mantids in a sexually cannibalistic mating system
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Katherine L. Barrya,
a Department of Biological Sciences,
b School of Biological Sciences,
The traditional view of sexual selection has been that of competing males and choosy females; however, more recently it has been recognized that males may exhibit mate choice when females vary in quality and when males suffer costs associated with mating. Sexually cannibalistic mating systems provide an opportunity to examine male mate choice further: the high costs potentially involved in the mating process for males, as well as variation in female quality, predict male mate choice. We used the praying mantid Pseudomantis albofimbriata to determine the effect of female body condition on male mate choice in a system with frequent precopulatory sexual cannibalism. Female body condition is positively correlated with fecundity and negatively correlated with the propensity to cannibalize, so we predicted males would strongly prefer females in good condition to maximize their reproductive potential. Results of our simultaneous choice tests showed that males use chemical and visual cues for mate location and assessment, and that they can use either of these sensory modalities to distinguish and choose between females differing in body condition, with a significant preference for good-condition females. However, surprisingly, males rarely rejected poor-condition females in the more ecologically relevant scenario of only one immediate potential mate and both sensory modes available to them, which may be explained by the strong scramble competition known for praying mantid systems. These results show that even when female quality varies and the cost of mating for males is substantial, male mate rejection does not always evolve.
Animal Behaviour Volume 79, Issue 5, May 2010, Pages 1165-1172
Properties of male ejaculates do not generate geographical variation in female mating tactics in a butterfly Pieris napi
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Panu Välimäki
a Department of Biology,
Polyandry brings about benefits for females but, from the males' perspective, if there is a possibility of females mating with multiple partners, male characteristics that prevent or delay remating of females are favoured, which may result in antagonistic coevolution between the sexes. The green-veined white butterfly, Pieris napi, is a predominantly polyandrous species with male nutrient donation transferred within the ejaculate at mating. Male ejaculates that are exaggerated in size or content can be interpreted as a means to reduce female remating. We explored whether geographical variation in the degree of polyandry among P. napi populations results from variation in the male's ability to manipulate females to mate at a suboptimal rate. Females that mated with a larger male capable of delivering a large spermatophore remated later than those that mated with a smaller male. However, we found no spatial variation in sexual size dimorphism or relative ejaculate size. Moreover, the mating frequency of females was not affected by the origin of males with which they mated. We argue that even if large male ejaculates evolved to ensure paternity of a given male with negative side-effects on female fitness, female counteradaptations conceal possible implications of antagonistic coevolution. Geographical variation in female mating frequency is probably maintained by selection acting upon female life history traits associated with the degree of polyandry.
Animal Behaviour Volume 79, Issue 5, May 2010, Pages 1173-1179
Acoustic Experience Shapes Alternative Mating Tactics and Reproductive Investment in Male Field Crickets
Nathan W. Bailey
Department of Biology, University of California, Riverside, Riverside, CA 92521, USA
Highlights Sexual signals provide information about the social environment to developing animals. Juvenile male field crickets use those signals to shape adult reproductive traits. Acoustic experience decreases the likelihood of adopting satellite mating tactics. However, acoustic experience increases condition and investment in reproductive tissues
Summary Developmental plasticity allows juvenile animals to assess environmental cues and adaptively shape behavioral and morphological traits to maximize fitness in their adult environment [1]. Sexual signals are particularly conspicuous cues, making them likely candidates for mediating such responses. Plasticity in male reproductive traits is a common phenomenon, but empirical evidence for signal-mediated plasticity in males is lacking. We tested whether experience of acoustic sexual signals during juvenile stages influences the development of three adult traits in the continuously breeding field cricket Teleogryllus oceanicus: male mating tactics, reproductive investment, and condition. All three traits were affected by juvenile acoustic experience. Males of this species produce a long-range calling song to attract receptive females, but they can also behave as satellites by parasitizing other males' calls [2]. Males reared in an environment mimicking a population with many calling males were less likely to exhibit satellite behavior, invested more in reproductive tissues, and attained higher condition than males reared in a silent environment. These results contrast with other studies [3] and demonstrate how the effects of juvenile social experience on adult male morphology, reproductive investment, and behavior may subsequently influence sexual selection and phenotypic evolution.
Current Biology, Volume 20, Issue 9, 845-849, 22 April 2010
http://www.cell.com/current-biology/abstract/S0960-9822%2810%2900348-9
Species of various insect orders possess specialised tarsal adhesive structures covered by a thin liquid film, which is deposited in the form of footprints. This adhesive liquid has been suggested to be chemically and physiologically related to the epicuticular lipid layer, which naturally covers the body of insects and acts as the prime barrier to environmental stresses, such as desiccation. The functional efficiency of the layer, however, is jeopardised by partial melting that may occur at physiological temperatures. In this study, light microscopic images of elytral prints show that the epicuticular lipid layer of the Colorado potato beetle Leptinotarsa decemlineata actually is partially liquid and chemical investigations reveal the high similarity of the epicuticular hydrocarbon pattern and the tarsal liquid. By means of chemical manipulation of the surface hydrocarbon composition of live beetles, the substance exchange between their tarsal adhesive hairs and the body surface is monitored. Histological sections of L. decemlineata tarsi, furthermore, reveal glandular cells connected to individual adhesive setae and departing from these results, an idea of a general mechanism of tarsal secretion is developed and discussed in a functional–ecological context.
Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology Volume 196, Number 5 / May, 2010 369-378
http://www.springerlink.com/content/8170h71552212g42/
Minimum viewing angle for visually guided ground speed control in bumblebees
Emily Baird*, Torill Kornfeldt and Marie Dacke emily.baird@cob.lu.se
To control flight, flying insects extract information from the pattern of visual motion generated during flight, known as optic flow. To regulate their ground speed, insects such as honeybees and Drosophila hold the rate of optic flow in the axial direction (front-to-back) constant. A consequence of this strategy is that its performance varies with the minimum viewing angle (the deviation from the frontal direction of the longitudinal axis of the insect) at which changes in axial optic flow are detected. The greater this angle, the later changes in the rate of optic flow, caused by changes in the density of the environment, will be detected. The aim of the present study is to examine the mechanisms of ground speed control in bumblebees and to identify the extent of the visual range over which optic flow for ground speed control is measured. Bumblebees were trained to fly through an experimental tunnel consisting of parallel vertical walls. Flights were recorded when (1) the distance between the tunnel walls was either 15 or 30 cm, (2) the visual texture on the tunnel walls provided either strong or weak optic flow cues and (3) the distance between the walls changed abruptly halfway along the tunnel's length. The results reveal that bumblebees regulate ground speed using optic flow cues and that changes in the rate of optic flow are detected at a minimum viewing angle of 23–30 deg., with a visual field that extends to approximately 155 deg. By measuring optic flow over a visual field that has a low minimum viewing angle, bumblebees are able to detect and respond to changes in the proximity of the environment well before they are encountered.
Journal of Experimental Biology 213, 1625-1632 (2010)
http://jeb.biologists.org/cgi/content/abstract/213/10/1625
The spatial frequency tuning of optic-flow-dependent behaviors in the bumblebee Bombus impatiens
Jonathan P. Dyhr1,2,* and Charles M. Higgins2,3 jdyhr@email.arizona.edu
1 Graduate Program in Neuroscience, The University of Arizona, 1040 E. 4th Street, Tucson, AZ 85721-0077, USA
2 Department of Neuroscience, The University of Arizona, 1040 E. 4th Street, Tucson, AZ 85721-0077, USA
3 Department of Electrical and Computer Engineering, The University of Arizona, 1040 E. 4th Street, Tucson, AZ 85721-0077, USA
Insects use visual estimates of flight speed for a variety of behaviors, including visual navigation, odometry, grazing landings and flight speed control, but the neuronal mechanisms underlying speed detection remain unknown. Although many models and theories have been proposed for how the brain extracts the angular speed of the retinal image, termed optic flow, we lack the detailed electrophysiological and behavioral data necessary to conclusively support any one model. One key property by which different models of motion detection can be differentiated is their spatiotemporal frequency tuning. Numerous studies have suggested that optic-flow-dependent behaviors are largely insensitive to the spatial frequency of a visual stimulus, but they have sampled only a narrow range of spatial frequencies, have not always used narrowband stimuli, and have yielded slightly different results between studies based on the behaviors being investigated. In this study, we present a detailed analysis of the spatial frequency dependence of the centering response in the bumblebee Bombus impatiens using sinusoidal and square wave patterns.
Journal of Experimental Biology 213, 1643-1650 (2010)
http://jeb.biologists.org/cgi/content/abstract/213/10/1643
Comb construction in mixed-species colonies of honeybees, Apis cerana and Apis mellifera
Ming-Xian Yang1,2, Ken Tan2,3, Sarah E. Radloff4,*, Mananya Phiancharoen5 and H. Randall Hepburn1,2 s.radloff@ru.ac.za
1 Department of Zoology and Entomology, Rhodes University, Grahamstown 6140, South Africa
2 Eastern Bee Research Institute, Yunnan Agricultural University, Heilongtan, Kunming, Yunnan Province 650201, People's Republic of China
3 Xishuangbanna Tropical Botanical Garden, Chinese Academy of Science, Kunming, Yunnan Province, 650223, People's Republic of China
4 Department of Statistics, Rhodes University, PO Box 94, Grahamstown 6140, South Africa
5 Rachaburi campus, King Mongkut's University of Technology Thonburi, 126 Prachautid Road, Bangkok 10140, Thailand
Comb building in mixed-species colonies of Apis cerana and Apis mellifera was studied. Two types of cell-size foundation were made from the waxes of these species and inserted into mixed colonies headed either by an A. cerana or an A. mellifera queen. The colonies did not discriminate between the waxes but the A. cerana cell-size foundation was modified during comb building by the workers of both species. In pure A. cerana colonies workers did not accept any foundation but secreted wax and built on foundation in mixed colonies. Comb building is performed by small groups of workers through a mechanism of self-organisation. The two species cooperate in comb building and construct nearly normal combs but they contain many irregular cells. In pure A. mellifera colonies, the A. cerana cell size was modified and the queens were reluctant to lay eggs on such combs. In pure A. cerana colonies, the A. mellifera cell size was built without any modification but these cells were used either for drone brood rearing or for food storing. The principal elements of comb-building behaviour are common to both species, which indicates that they evolved prior to and were conserved after speciation.
Journal of Experimental Biology 213, 1659-1664 (2010)
http://jeb.biologists.org/cgi/content/abstract/213/10/1659
Ant search strategies after interrupted tandem runs
Nigel R. Franks1,*, Thomas O. Richardson2,1, Samantha Keir1, Stephen J. Inge1, Frederic Bartumeus3 and Ana B. Sendova-Franks2 nigel.franks@bristol.ac.uk
1 School of Biological Sciences, University of Bristol, Woodland Road, Bristol, BS8 1UG, UK
2 Department of Mathematics and Statistics, BIT, University of the West of England, Frenchay Campus, Coldharbour Lane, Bristol, BS16 1QY, UK
3 Centre d'Estudis Avançats de Blanes (CEAB-CSIC) C/Accés Cala Sant Francesc, 14, 17300 Blanes, Girona, Spain
Tandem runs are a form of recruitment in ants. During a tandem run, a single leader teaches one follower the route to important resources such as sources of food or better nest sites. In the present study, we investigate what tandem leaders and followers do, in the context of nest emigration, if their partner goes missing. Our experiments involved removing either leaders or followers at set points during tandem runs. Former leaders first stand still and wait for their missing follower but then most often proceed alone to the new nest site. By contrast, former followers often first engage in a Brownian search, for almost exactly the time that their former leader should have waited for them, and then former followers switch to a superdiffusive search. In this way, former followers first search their immediate neighbourhood for their lost leader before becoming ever more wide ranging so that in the absence of their former leader they can often find the new nest, re-encounter the old one or meet a new leader. We also show that followers gain useful information even from incomplete tandem runs. These observations point to the important principle that sophisticated communication behaviours may have evolved as anytime algorithms, i.e. procedures that are beneficial even if they do not run to completion.
Journal of Experimental Biology 213, 1697-1708 (2010)
http://jeb.biologists.org/cgi/content/abstract/213/10/1697
Drosophila fly straight by fixating objects in the face of expanding optic flow
Michael B. Reiser1,* and Michael H. Dickinson1,2 reiserm@janelia.hhmi.org
1 Department of Computational and Neural Systems, California Institute of Technology,
2 Department of Biology,
Flies, like all animals that depend on vision to navigate through the world, must integrate the optic flow created by self-motion with the images generated by prominent features in their environment. Although much is known about the responses of Drosophila melanogaster to rotating flow fields, their reactions to the more complex patterns of motion that occur as they translate through the world are not well understood. In the present study we explore the interactions between two visual reflexes in Drosophila: object fixation and expansion avoidance. As a fly flies forward, it encounters an expanding visual flow field. However, recent results have demonstrated that Drosophila strongly turn away from patterns of expansion. Given the strength of this reflex, it is difficult to explain how flies make forward progress through a visual landscape. This paradox is partially resolved by the finding reported here that when undergoing flight directed towards a conspicuous object, Drosophila will tolerate a level of expansion that would otherwise induce avoidance. This navigation strategy allows flies to fly straight when orienting towards prominent visual features.
Journal of Experimental Biology 213, 1771-1781 (2010)
http://jeb.biologists.org/cgi/content/abstract/213/10/1771
The twilight zone: ambient light levels trigger activity in primitive ants
Ajay Narendra*, Samuel F. Reid and Jan M. Hemmi ajay.narendra@anu.edu.au
Many animals become active during twilight, a narrow time window where the properties of the visual environment are dramatically different from both day and night. Despite the fact that many animals including mammals, reptiles, birds and insects become active in this specific temporal niche, we do not know what cues trigger this activity. To identify the onset of specific temporal niches, animals could anticipate the timing of regular events or directly measure environmental variables. We show that the Australian bull ant, Myrmecia pyriformis, starts foraging only during evening twilight throughout the year. The onset occurs neither at a specific temperature nor at a specific time relative to sunset, but at a specific ambient light intensity. Foraging onset occurs later when light intensities at sunset are brighter than normal or earlier when light intensities at sunset are darker than normal. By modifying ambient light intensity experimentally, we provide clear evidence that ants indeed measure light levels and do not rely on an internal rhythm to begin foraging. We suggest that the reason for restricting the foraging onset to twilight and measuring light intensity to trigger activity is to optimize the trade-off between predation risk and ease of navigation.
Proc. R. Soc. B 22 May 2010 vol. 277 no. 1687 1531-1538
http://rspb.royalsocietypublishing.org/content/277/1687/1531.abstract
Insect Biology
Butterfly wing colors: glass scales of Graphium sarpedon cause polarized iridescence and enhance blue/green pigment coloration of the wing membrane
Doekele G. Stavenga1,*, Marco A. Giraldo1,2 and Hein L. Leertouwer1 d.g.stavenga@rug.nl
1 Department of Neurobiophysics, University of Groningen, Physics-Chemistry Building, Nijenborgh 4, Groningen, 9747 AG, The Netherlands
2 Institute of Physics, University of Antioquia, Medellín, AA 1226, Colombia
The wings of the swordtail butterfly Graphium sarpedon nipponum contain the bile pigment sarpedobilin, which causes blue/green colored wing patches. Locally the bile pigment is combined with the strongly blue-absorbing carotenoid lutein, resulting in green wing patches and thus improving camouflage. In the dorsal forewings, the colored patches lack the usual wing scales, but instead have bristles. We have found that on the ventral side most of these patches have very transparent scales that enhance, by reflection, the wing coloration when illuminated from the dorsal side. These glass scales furthermore create a strongly polarized iridescence when illuminated by obliquely incident light from the ventral side, presumably for intraspecific signaling. A few ventral forewing patches have diffusely scattering, white scales that also enhance the blue/green wing coloration when observed from the dorsal side.
Journal of Experimental Biology 213, 1731-1739 (2010)
http://jeb.biologists.org/cgi/content/abstract/213/10/1731
Insect Biochemistry
Light-dependent Phosphorylation of the Drosophila Transient Receptor Potential Ion Channel*
Olaf Voolstra‡,1, Katherina Beck‡,2, Claudia Oberegelsbacher‡, Jens Pfannstiel‡§ and Armin Huber‡§voolstra@uni-hohenheim.de
The Drosophila phototransduction cascade terminates in the opening of an ion channel, designated transient receptor potential (TRP). TRP has been shown to become phosphorylated in vitro, suggesting regulation of the ion channel through posttranslational modification. However, except for one phosphorylation site, Ser982, which was analyzed by functional in vivo studies (Popescu, D. C., Ham, A. J., and Shieh, B. H. (2006) J. Neurosci. 26, 8570–8577), nothing is known about the role of TRP phosphorylation in vivo. Here, we report the identification of 21 TRP phosphorylation sites by a mass spectrometry approach. 20 phosphorylation sites are located in the C-terminal portion of the channel, and one site is located near the N terminus. All 21 phosphorylation sites were also identified in the inaCP209 mutant, indicating that phosphorylation of TRP at these sites occurred independently from the eye-enriched protein kinase C. Relative quantification of phosphopeptides revealed that at least seven phosphorylation sites were predominantly phosphorylated in the light, whereas one site, Ser936, was predominantly phosphorylated in the dark. We show that TRP phosphorylated at Ser936 was located in the rhabomere. Light-dependent changes in the phosphorylation state of this site occurred within minutes. The dephosphorylation of TRP at Ser936 required activation of the phototransduction cascade.
The Journal of Biological Chemistry, 285, 14275-14284. May 7, 2010
http://www.jbc.org/content/285/19/14275.abstract
Crystal Structure of the Catalytic Domain of Drosophila β1,4-Galactosyltransferase-7*
Boopathy Ramakrishnan‡§ and Pradman K. Qasba‡,1qasba@helix.nih.gov
The β1,4-galactosyltransferase-7 (β4Gal-T7) enzyme, one of seven members of the β4Gal-T family, transfers in the presence of manganese Gal from UDP-Gal to an acceptor sugar (xylose) that is attached to a side chain hydroxyl group of Ser/Thr residues of proteoglycan proteins. It exhibits the least protein sequence similarity with the other family members, including the well studied family member β4Gal-T1, which, in the presence of manganese, transfers Gal from UDP-Gal to GlcNAc. We report here the crystal structure of the catalytic domain of β4Gal-T7 from Drosophila in the presence of manganese and UDP at 1.81 Å resolution. In the crystal structure, a new manganese ion-binding motif (HXH) has been observed. Superposition of the crystal structures of β4Gal-T7 and β4Gal-T1 shows that the catalytic pocket and the substrate-binding sites in these proteins are similar. Compared with GlcNAc, xylose has a hydroxyl group (instead of an N-acetyl group) at C2 and lacks the CH2OH group at C5; thus, these protein structures show significant differences in their acceptor-binding site. Modeling of xylose in the acceptor-binding site of the β4Gal-T7 crystal structure shows that the aromatic side chain of Tyr177 interacts strongly with the C5 atom of xylose, causing steric hindrance to any additional group at C5. Because Drosophila Cd7 has a 73% protein sequence similarity to human Cd7, the present crystal structure offers a structure-based explanation for the mutations in human Cd7 that have been linked to Ehlers-Danlos syndrome.
The Journal of Biological Chemistry, 285, 15619-15626 May 14, 2010
http://www.jbc.org/content/285/20/15619.abstract
Thermal sensitivity of mitochondrial metabolism in two distinct mitotypes of Drosophila simulans: evaluation of mitochondrial plasticity
Nicolas Pichaud1, Etienne Hébert Chatelain1, J. William O. Ballard2, Robert Tanguay3, Geneviève Morrow3 and Pierre U. Blier1,* pierre_blier@uqar.qc.ca
1 Laboratoire de biologie intégrative, Département de Biologie, Université du Québec à Rimouski, 300 Allée des Ursulines, Rimouski, Québec, Canada, G5L 3A1
2 School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney 2052, Australia
3 Laboratoire de Génétique Cellulaire et développementale, Département de Médecine, Institut de Biologie intégrative et des systèmes, 1030 ave de la Médecine, Université Laval, Québec, Canada, G1V 0A6
The overall aim of this study was to (1) evaluate the adaptive value of mitochondrial DNA by comparing mitochondrial performance in populations possessing different haplotypes and distribution, and to (2) evaluate the sensitivity of different enzymes of the electron transport system (ETS) during temperature-induced changes. We measured the impact of temperature of mitochondrial respiration and several key enzymes of mitochondrial metabolism in two mitotypes (siII and siIII) of Drosophila simulans. The temperature dependencies of oxygen consumption for mitochondria isolated from flight muscle was assessed with complex I substrates (pyruvate + malate + proline) and with sn glycerol-3-phosphate (to reduce complex III via glycerophosphate dehydrogenase) in both coupled and uncoupled states. Activities of citrate synthase, cytochrome c oxidase (COX), catalase and aconitase, and the excess capacity of COX at high convergent pathway flux were also measured as a function of temperature. Overall, our results showed that functional differences between the two mitotypes are few. Results suggest that differences between the two mitotypes could hardly explain the temperature-specific differences measured in mitochondria performances. It suggests that some other factor(s) may be driving the maintenance of mitotypes. We also show that the different enzymes of the ETS have different thermal sensitivities. The catalytic capacities of these enzymes vary with temperature changes, and the corresponding involvement of the different steps on mitochondrial regulation probably varies with temperature. For example, the excess COX capacity is low, even non-existent, at high and intermediate temperatures (18°C, 24°C and 28°C) whereas it is quite high at a lower temperature (12°C), suggesting release of respiration control by COX at low temperature.
Journal of Experimental Biology 213, 1665-1675 (2010)
http://jeb.biologists.org/cgi/content/abstract/213/10/1665
Single base–resolution methylome of the silkworm reveals a sparse epigenomic map
Hui Xiang, Jingde Zhu, Quan Chen, Fangyin Dai, Xin Li, Muwang Li, Hongyu Zhang, Guojie Zhang, Dong Li, Yang Dong, Li Zhao, Ying Lin, Daojun Cheng, Jian Yu, Jinfeng Sun,Xiaoyu Zhou, Kelong Ma, Yinghua He, Yangxing Zhao, Shicheng Guo, Mingzhi Ye, Guangwu Guo, Yingrui Li, Ruiqiang Li, Xiuqing Zhang, Lijia Ma, Karsten Kristiansen, Qiuhong Guo, Jianhao Jiang, Stephan Beck, Qingyou Xia, Wen Wang & Jun Wang
CAS-Max Planck Junior Research Group, State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, The Chinese Academy of Sciences, Kunming, China.
BGI-Shenzhen,
Cancer Epigenetics and Gene Therapy Program, The State-key Laboratory for Oncogenes and Related Genes, Shanghai Cancer Institute, Shanghai Jiaotong University, Shanghai, China.
Cancer Epigenetics Laboratory, Obstetrics and
The Key Sericultural Laboratory of Agricultural Ministry,
Sericultural Research Institute,
Department of Biology,
Shanghai
UCL Cancer Institute,
Epigenetic regulation in insects may have effects on diverse biological processes. Here we survey the methylome of a model insect, the silkworm Bombyx mori, at single-base resolution using Illumina high-throughput bisulfite sequencing (MethylC-Seq). We conservatively estimate that 0.11% of genomic cytosines are methylcytosines, all of which probably occur in CG dinucleotides. CG methylation is substantially enriched in gene bodies and is positively correlated with gene expression levels, suggesting it has a positive role in gene transcription. We find that transposable elements, promoters and ribosomal DNAs are hypomethylated, but in contrast, genomic loci matching small RNAs in gene bodies are densely methylated. This work contributes to our understanding of epigenetics in insects, and in contrast to previous studies of the highly methylated genomes of Arabidopsis1 and human2, demonstrates a strategy for sequencing the epigenomes of organisms such as insects that have low levels of methylation.
Nature BiotechnologyVolume: 28,Pages: 516–520Year published: (2010)
http://www.nature.com/nbt/journal/v28/n5/abs/nbt.1626.html?lang=en#/
Insect Cell Biology
Scarface, a secreted serine protease-like protein, regulates polarized localization of laminin A at the basement membrane of the Drosophila embryo
Georgina Sorrosal1, Lidia Pérez1, Héctor Herranz1 & Marco Milán1,2 marco.milan@irbbarcelona.org
Institute for Research in Biomedicine, Baldiri i Reixac 10, 08028
Institució Catalana de Recerca i Estudis Avançats, Baldiri i Reixac 10, 08028
Cell–matrix interactions brought about by the activity of integrins and laminins maintain the polarized architecture of epithelia and mediate morphogenetic interactions between apposing tissues. Although the polarized localization of laminins at the basement membrane is a crucial step in these processes, little is known about how this polarized distribution is achieved. Here, in Drosophila, we analyse the role of the secreted serine protease-like protein Scarface in germ-band retraction and dorsal closure—morphogenetic processes that rely on the activity of integrins and laminins. We present evidence that scarface is regulated by c-Jun amino-terminal kinase and that scarface mutant embryos show defects in these morphogenetic processes. Anomalous accumulation of laminin A on the apical surface of epithelial cells was observed in these embryos before a loss of epithelial polarity was induced. We propose that Scarface has a key role in regulating the polarized localization of laminin A in this developmental context.
EMBO reports (2010) 11, 373 - 379
http://www.nature.com/embor/journal/v11/n5/abs/embor201043.html
Insect Chemoreception
Behavioral insensitivity to DEET in Aedes aegypti is a genetically determined trait residing in changes in sensillum function
Nina M. Stanczyka,b, John F. Y. Brookfieldb, Rickard Ignellc, James G. Logana,1, and Linda M. Fieldajames.logan@bbsrc.ac.uk
N,N-Diethyl-m-toluamide (DEET) is one of the most effective and commonly used mosquito repellents. However, during laboratory trials a small proportion of mosquitoes are still attracted by human odors despite the presence of DEET. In this study behavioral assays identified Aedes aegypti females that were insensitive to DEET, and the selection of either sensitive or insensitive groups of females with males of unknown sensitivity over several generations resulted in two populations with different proportions of insensitive females. Crossing experiments showed the “insensitivity” trait to be dominant. Electroantennography showed a reduced response to DEET in the selected insensitive line compared with the selected sensitive line, and single sensillum recordings identified DEET-sensitive sensilla that were nonresponders in the insensitive line. This study suggests that behavioral insensitivity to DEET in A. aegypti is a genetically determined dominant trait and resides in changes in sensillum function.
PNAS May 11, 2010 vol. 107 no. 19 8575-8580
http://www.pnas.org/content/107/19/8575.abstract?etoc
Insect Ecology
A mathematical model of exposure of non-target Lepidoptera to Bt-maize pollen expressing Cry1Ab within
J. N. Perry1,*, Y. Devos2, S. Arpaia3, D. Bartsch4, A. Gathmann4, R. S. Hails5, J. Kiss6, K. Lheureux2, B. Manachini7, S. Mestdagh2, G. Neemann8, F. Ortego9, J. Schiemann10 and J. B. Sweet11 joe.perry@bbsrc.ac.uk
Genetically modified (GM) maize MON810 expresses a Cry1Ab insecticidal protein, derived from Bacillus thuringiensis (Bt), toxic to lepidopteran target pests such as Ostrinia nubilalis. An environmental risk to non-target Lepidoptera from this GM crop is exposure to harmful amounts of Bt-containing pollen deposited on host plants in or near MON810 fields. An 11-parameter mathematical model analysed exposure of larvae of three non-target species: the butterflies Inachis io (L.), Vanessa atalanta (L.) and moth Plutella xylostella (L.), in 11 representative maize cultivation regions in four European countries. A mortality–dose relationship was integrated with a dose–distance relationship to estimate mortality both within the maize MON810 crop and within the field margin at varying distances from the crop edge. Mortality estimates were adjusted to allow for physical effects; the lack of temporal coincidence between the susceptible larval stage concerned and the period over which maize MON810 pollen is shed; and seven further parameters concerned with maize agronomy and host-plant ecology. Sublethal effects were estimated and allowance made for aggregated pollen deposition. Estimated environmental impact was low: in all regions, the calculated mortality rate for worst-case scenarios was less than one individual in every 1572 for the butterflies and one in 392 for the moth.
Proc. R. Soc. B 7 May 2010 vol. 277 no. 1686 1417-1425
http://rspb.royalsocietypublishing.org/content/277/1686/1417.abstract?etoc
Induced niche shift as an anti-predator response for an endoparasitoid
Frédéric B. Muratori1,2,*, Sophie Borlee2 and Russell H. Messing2 frederic.muratori@uclouvain.be
When two developmental stages do not share the same ecological niche, the control of the niche shift through a change in developmental timing, referred to as ‘heterokairy’, can provide an adaptive advantage for the individual (e.g. if mortality risk is higher in the first niche). For endoparasitic species that develop inside another (host) species, mortality of the host may directly induce mortality risk for the parasite. Thus, endoparasitoid larvae should be selected for response to host predation. In this study, aphids previously parasitized by the endoparasitoid Endaphis fugitiva, Gagné and Muratori (Diptera: Cecidomyiidae), were experimentally exposed to increased mortality risks. Both simulated attack and actual predator attacks against aphid hosts induced early emergence of the parasitoid larvae. Parasitoid emergence from the aphids occurred several minutes before the predator finished feeding on the aphid, allowing enough time for the parasitoid larvae to avoid direct predation. Predator-induced emergence produced significantly smaller parasitoid larvae than controls, but, interestingly, no effect on Endaphis adult size was found. To our knowledge, this is the first evidence of induced emergence in an insect parasitoid, but we suggest that this mechanism might be at work in many other species where plasticity in development time allows the individual to perform an adaptive niche shift.
Proc. R. Soc. B 22 May 2010 vol. 277 no. 1687 1475-1480
http://rspb.royalsocietypublishing.org/content/277/1687/1475.abstract
Host sanctions and pollinator cheating in the fig tree–fig wasp mutualism
K. Charlotte Jandér1,2,3,* and Edward Allen Herre2kcj4@cornell.edu
Theory predicts that mutualisms should be vulnerable to invasion by cheaters, yet mutualistic interactions are both ancient and diverse. What prevents one partner from reaping the benefits of the interaction without paying the costs? Using field experiments and observations, we examined factors affecting mutualism stability in six fig tree–fig wasp species pairs. We experimentally compared the fitness of wasps that did or did not perform their most basic mutualistic service, pollination. We found host sanctions that reduced the fitness of non-pollinating wasps in all derived, actively pollinated fig species (where wasps expend time and energy pollinating), but not in the basal, passively pollinated fig species (where wasps do not). We further screened natural populations of pollinators for wasp individuals that did not carry pollen (‘cheaters’). Pollen-free wasps occurred only in actively pollinating wasp species, and their prevalence was negatively correlated with the sanction strength of their host species. Combined with previous studies, our findings suggest that (i) mutualisms can show coevolutionary dynamics analogous to those of ‘arms races’ in overtly antagonistic interactions; (ii) sanctions are critical for long-term mutualism stability when providing benefits to a host is costly, and (iii) there are general principles that help maintain cooperation both within and among species.
Proc. R. Soc. B 22 May 2010 vol. 277 no. 1687 1481-1488
http://rspb.royalsocietypublishing.org/content/277/1687/1481.abstract
Insect Evolution
MATERNAL EFFECTS, BUT NO GOOD OR COMPATIBLE GENES FOR SPERM COMPETITIVENESS IN AUSTRALIAN CRICKETS
Damian K. Dowling 1,2,3 ,
1 School of Biological Sciences, Monash University, Clayton, 3800, Victoria, Australia 2 Centre for Evolutionary Biology, School of Animal Biology (M092), University of Western Australia, Crawley, 6009, Western Australia, Australia 3 E-mail: damian.dowling@sci.monash.edu.au 4 E-mail: magdalena.nystrand@sci.monash.edu.au 5 E-mail: lsimmons@cyllene.uwa.edu.au
Explanations for the evolution of polyandry often center on the idea that females garner genetic benefits for their offspring by mating multiply. Furthermore, postcopulatory processes are thought to be fundamental to enabling polyandrous females to screen for genetic quality. Much attention has focused on the potential for polyandrous females to accrue such benefits via a sexy- or good-sperm mechanism, whereby additive variation exists among males in sperm competitiveness. Likewise, attention has focused on an alternative model, in which offspring quality (in this context, the sperm competitiveness of sons) hinges on an interaction between parental haplotypes (genetic compatibility). Sperm competitiveness that is contingent on parental compatibility will exhibit nonadditive genetic variation. We tested these models in the Australian cricket, Teleogryllus oceanicus, using a design that allowed us to partition additive, nonadditive genetic, and parental variance for sperm competitiveness. We found an absence of additive and nonadditive genetic variance in this species, challenging the direct relevance of either model to the evolution of sperm competitiveness in particular, and polyandry in general. Instead, we found maternal effects that were possibly sex-linked or cytoplasmically linked. We also found effects of focal male age on sperm competitiveness, with small increments in age conferring more competitive sperm.
Evolution 2010 Volume 64 Issue 5, Pages 1257 - 1266
http://www3.interscience.wiley.com/journal/123192458/abstract
Z LINKAGE OF FEMALE PROMISCUITY GENES IN THE MOTH UTETHEISA ORNATRIX: SUPPORT FOR THE SEXY-SPERM HYPOTHESIS?
Vikram K. Iyengar 1,2 and
1 Department of Biology,
Female preference genes for large males in the highly promiscuous moth Utetheisa ornatrix (Lepidoptera: Arctiidae) have previously been shown to be mostly Z-linked, in accordance with the hypothesis that ZZ–ZW sex chromosome systems should facilitate Fisherian sexual selection. We determined the heritability of both female and male promiscuity in the highly promiscuous
Evolution 2010 Volume 64 Issue 5, Pages 1267 - 1272
http://www3.interscience.wiley.com/journal/123192456/abstract
THE ROLES OF LIFE-HISTORY SELECTION AND SEXUAL SELECTION IN THE ADAPTIVE EVOLUTION OF MATING BEHAVIOR IN A BEETLE
Alexei A. Maklakov 1,2,3 , Luis Cayetano, Robert C. Brooks 1 , and Russell Bonduriansky 1
1 Evolution & Ecology Research Centre and
Although there is continuing debate about whether sexual selection promotes or impedes adaptation to novel environments, the role of mating behavior in such adaptation remains largely unexplored. We investigated the evolution of mating behavior (latency to mating, mating probability and duration) in replicate populations of seed beetles Callosobruchus maculatus subjected to selection on life-history ("Young" vs. "Old" reproduction) under contrasting regimes of sexual selection ("Monogamy" vs. "Polygamy"). Life-history selection is predicted to favor delayed mating in "Old" females, but sexual conflict under polygamy can potentially retard adaptive life-history evolution. We found that life-history selection yielded the predicted changes in mating behavior, but sexual selection regime had no net effect. In within-line crosses, populations selected for late reproduction showed equally reduced early-life mating probability regardless of mating system. In between-line crosses, however, the effect of life-history selection on early-life mating probability was stronger in polygamous lines than in monogamous ones. Thus, although mating system influenced male–female coevolution, removal of sexual selection did not affect the adaptive evolution of mating behavior. Importantly, our study shows that the interaction between sexual selection and life-history selection can result in either increased or decreased reproductive divergence depending on the ecological context.
Evolution 2010 Volume 64 Issue 5, Pages 1273 - 1282
http://www3.interscience.wiley.com/journal/123188423/abstract
Tom A. R. Price 1 , Zenobia Lewis 2 , Damian T. Smith 1 , Gregory D. D. Hurst 3 , and Nina Wedell 1,4
1 School of Biosciences,
Selfish genetic elements occur in all living organisms and often cause reduced fertility and sperm competitive ability in males. In the fruit fly Drosophila pseudoobscura, the presence of a sex-ratio distorting X-chromosome meiotic driver Sex Ratio (SR) has been shown to promote the evolution of increased female remating rates in laboratory populations. This is favored because it promotes sperm competition, which decreases the risk to females of producing highly female-biased broods and to their offspring of inheriting the selfish gene. Here, we show that non-SR males in these SR populations evolved an increased ability to suppress female remating in response to the higher female remating rates, indicating male–female coevolution. This occurred even though SR was rare in the populations. This was further supported by a correlation between females' remating propensity and males' ability to suppress female remating across populations. Thus SR can generate sexual conflict over female remating rate between females and the noncarrier males that make up the majority of the males, promoting evolution of increased ability of males to suppress female remating.
Evolution 2010 Volume 64 Issue 5, Pages 1504 – 1509
http://www3.interscience.wiley.com/journal/122685685/abstract
Sexual conflict and the gender load: correlated evolution between population fitness and sexual dimorphism in seed beetles
Göran Arnqvist1,* and Midori Tuda2 goran.arnqvist@ebc.uu.se
Although males and females share much of the same genome, selection is often distinct in the two sexes. Sexually antagonistic loci will in theory cause a gender load in populations, because sex-specific selection on a given trait in one sex will compromise the adaptive evolution of the same trait in the other sex. However, it is currently not clear whether such intralocus sexual conflict (ISC) represents a transient evolutionary state, where conflict is rapidly resolved by the evolution of sexual dimorphism (SD), or whether it is a more chronic impediment to adaptation. All else being equal, ISC should manifest itself as correlated evolution between population fitness and SD in traits expressed in both sexes. However, comparative tests of this prediction are problematic and have been unfeasible. Here, we assess the effects of ISC by comparing fitness and SD across distinct laboratory populations of seed beetles that should be well adapted to a shared environment. We show that SD in juvenile development time, a key life-history trait with a history of sexually antagonistic selection in this model system, is positively related to fitness. This effect is due to a correlated evolution between population fitness and development time that is positive in females but negative in males. Loosening the genetic bind between the sexes has evidently allowed the sexes to approach their distinct adaptive peaks.
Proc. R. Soc. B 7 May 2010 vol. 277 no. 1686 1345-1352
http://rspb.royalsocietypublishing.org/content/277/1686/1345.abstract?etoc
Insect Genetics
Sexual isolation of male moths explained by a single pheromone response QTL containing four receptor genes
Fred Goulda,1, Marie Estocka,2, N. Kirk Hillierb,3, Bekah Powella, Astrid T. Groota,4, Catherine M. Warda,5, Jennifer L. Emersona, Coby Schala, and Neil J. Vickersb fred_gould@ncsu.edu
bDepartment of Biology,
Long distance sexual communication in moths has fascinated biologists because of the complex, precise female pheromone signals and the extreme sensitivity of males to specific pheromone molecules. Progress has been made in identifying some genes involved in female pheromone production and in male response. However, we have lacked information on the genetic changes involved in evolutionary diversification of these mate-finding mechanisms that is critical to understanding speciation in moths and other taxa. We used a combined quantitative trait locus (QTL) and candidate gene approach to determine the genetic architecture of sexual isolation in males of two congeneric moths, Heliothis subflexa and Heliothis virescens. We report behavioral and neurophysiological evidence that differential male responses to three female-produced chemicals (Z9-14:Ald, Z9-16:Ald, Z11-16:OAc) that maintain sexual isolation of these species are all controlled by a single QTL containing at least four odorant receptor genes. It is not surprising that pheromone receptor differences could control H. subflexa and H. virescens responses to Z9-16:Ald and Z9-14:Ald, respectively. However, central rather than peripheral level control over the positive and negative responses of H. subflexa and H. virescens to Z11-16:OAc had been expected. Tight linkage of these receptor genes indicates that mutations altering male response to complex blends could be maintained in linkage disequilibrium and could affect the speciation process. Other candidate genes such as those coding for pheromone binding proteins did not map to this QTL, but there was some genetic evidence of a QTL for response to Z11-16:OH associated with a sensory neuron membrane protein gene.
PNAS May 11, 2010 vol. 107 no. 19 8660-8665
http://www.pnas.org/content/107/19/8660.abstract?etoc
Insect Learning
Electric Shock-Induced Associative Olfactory Learning in Drosophila Larvae
Dennis Pauls *, Johanna E.R. Pfitzenmaier *, Rebecca Krebs-Wheaton, Mareike Selcho, Reinhard F. Stocker and Andreas S. Thum andreas.thum@unifr.ch
Department of Biology,
Associative plasticity is a basic essential attribute of nervous systems. As shown by numerous reports, Drosophila is able to establish simple forms of appetitive and aversive olfactory associations at both larval and adult stages. Whereas most adult studies on aversive learning employed electric shock as a negative reinforcer, larval paradigms essentially utilized gustatory stimuli to create negative associations, a discrepancy that limits the comparison of data. To overcome this drawback, we critically revisited larval odor–electric shock conditioning. First, we show that lithium chloride (LiCl), which was used in all previous larval electric shock paradigms, is not required per se in larval odor–electric shock learning. This is of considerable practical advantage because beside its peculiar effects LiCl is attractive to larvae at low concentration that renders comparative learning studies on genetically manipulated larvae complicated. Second, we confirm that in both a 2-odor reciprocal and a 1-odor nonreciprocal conditioning regimen, larvae are able to associate an odor with electric shock. In the latter experiments, initial learning scores reach an asymptote after 5 training trials, and aversive memory is still detectable after 60 min. Our experiments provide a comprehensive basis for future comparisons of larval olfactory conditioning reinforced by different modalities, for studies aimed at analyzing odor–electric shock learning in the larva and the adult, and for investigations of the cellular and molecular substrate of aversive olfactory learning in the simple Drosophila model.
Chemical Senses 2010 35(4):335-346; doi:10.1093/chemse/bjq023’ http://chemse.oxfordjournals.org/cgi/content/abstract/35/4/335
Insect Molecular Biology
The molecular basis for water taste in Drosophila
Peter Cameron, Makoto Hiroi, John Ngai & Kristin Scott
Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, 16 Barker Hall
Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute and Functional Genomics Laboratory, 142 Life Sciences Addition
Journal name:
The detection of water and the regulation of water intake are essential for animals to maintain proper osmotic homeostasis1. Drosophila and other insects have gustatory sensory neurons that mediate the recognition of external water sources2, 3, 4, but little is known about the underlying molecular mechanism for water taste detection. Here we identify a member of the degenerin/epithelial sodium channel family5, PPK28, as an osmosensitive ion channel that mediates the cellular and behavioural response to water. We use molecular, cellular, calcium imaging and electrophysiological approaches to show that ppk28 is expressed in water-sensing neurons, and that loss of ppk28 abolishes water sensitivity. Moreover, ectopic expression of ppk28 confers water sensitivity to bitter-sensing gustatory neurons in the fly and sensitivity to hypo-osmotic solutions when expressed in heterologous cells. These studies link an osmosensitive ion channel to water taste detection and drinking behaviour, providing the framework for examining the molecular basis for water detection in other animals.
NatureVolume: 465,Pages:91–95Date published: (06 May 2010)DOI:
http://www.nature.com/nature/journal/v465/n7294/abs/nature09011.html?lang=en#/affil-auth
Insect Molecular Ecology
Wolbachia modulates Chikungunya replication in Aedes albopictus
L. MOUSSON*, E. MARTIN*, K. ZOUACHE‡, Y. MADEC†, P. MAVINGUI‡ and A. B. FAILLOUX* afaillou@pasteur.fr
*Institut Pasteur, Génétique moléculaire des Bunyavirus, 25-28 rue du Dr Roux, F-75724 Paris Cedex 15, France , †Institut Pasteur, Unité de Recherche et d'Expertise Epidémiologie des Maladies Emergentes, 25-28 rue du Dr Roux, F-75724 Paris Cedex 15, France , ‡Université Lyon, F-69022, Lyon, France, Université de Lyon 1, Villeurbanne, CNRS, UMR5557, Ecologie Microbienne, Lyon, France
The Aedes albopictus mosquito has been involved as the principal vector of recent major outbreaks due to the chikungunya virus (CHIKV). The species is naturally infected by two strains of Wolbachia (wAlbA and wAlbB). Wolbachia infections are thought to have spread by manipulating the reproduction of their hosts; cytoplasmic incompatibility is the mechanism used by Wolbachia to invade natural populations of many insects including Ae. albopictus. Here, we report a study on the effects of removing Wolbachia from Ae. albopictus on CHIKV replication and examine the consequences of CHIKV infection on some life-history traits (survival and reproduction) of Wolbachia-free Ae. albopictus. We found that Wolbachia-free mosquitoes maintained a highly heterogeneous CHIKV replication compared to Wolbachia-infected individuals. In Wolbachia-infected Ae. albopictus, the regular increase of CHIKV followed by a steady viral load from day 4 post-infection onwards was concomitant with a decline in Wolbachia density. This profile was also detected when examining the two key organs for viral transmission, the midgut and the salivary glands. Moreover, Wolbachia-free Ae. albopictus was not altered in life-history traits such as survival, oviposition and hatching characteristics whether infected or not with CHIKV. We found that Wolbachia is not essential for viral replication, its presence could lead to optimize replication from day 4 post-infection onwards, coinciding with a decrease in Wolbachia density. Wolbachia may regulate viral replication in Ae. albopictus, with consequences on survival and reproduction.
Molecular Ecology 2010 Volume 19 Issue 9, Pages 1953 - 1964
http://www3.interscience.wiley.com/journal/123327351/abstract?CRETRY=1&SRETRY=0
Differential introgression causes genealogical discordance in host races of Acrocercops transecta (Insecta: Lepidoptera)
ISSEI OHSHIMA*† and KAZUNORI YOSHIZAWA* issei@nibb.ac.jp
*Systematic Entomology, Department of Ecology and Systematics, Graduate School of Agriculture, Hokkaido University, Sapporo 060-8589, Japan , †Division of Evolutionary Biology, National Institute for Basic Biology, Okazaki 444-8585, Japan
Recently diverged populations often exhibit incomplete reproductive isolation, with a low level of gene flow continuing between populations. Previous studies have shown that, even under a low level of gene flow, genetic divergence between populations can proceed at the loci governing local adaptation and reproductive isolation but not at other neutral loci. A leaf-mining moth, Acrocercops transecta, consists of Juglans- and Lyonia-associated host races. The two host races differ in host preferences of ovipositing females and in larval adaptation to host plants but mate readily in the laboratory, producing fertile hybrids. The Juglans and Lyonia races are often sympatric in the wild, implying that gene introgression could occur in nature between the two host races. We tested this hypothesis by combining phylogenetic analyses with coalescent simulations, focusing on mitochondrial genes (COI and ND5) and the nuclear Tpi, Per and Ldh genes located on the Z-chromosome. The mitochondrial genes clearly distinguished the Lyonia race from the Juglnas race, whereas the Tpi, Per and Ldh genealogies did not reflect the two host races. Coalescent simulations indicated gene flow at the three Z-linked genes in both directions, whereas there was no introgression in the mitochondrial genes. The lack of introgression in mitochondrial genes suggests that female host preference is the primary force leading to the bifurcation of maternally inherited loci. Thus, the results show that a low level of gene flow coupled with the inflexible female host preference differentiates histories of divergence between maternally and biparentally inherited genes in this host race system.
Molecular Ecology 2010 Volume 19 Issue 10, Pages 2106 - 2119
http://www3.interscience.wiley.com/journal/123337844/abstract
Population genetic structure of two primary parasitoids of Spodoptera frugiperda (Lepidoptera), Chelonus insularis and Campoletis sonorensis (Hymenoptera): to what extent is the host plant important?
VIOLAINE JOURDIE*†, NADIR ALVAREZ*, JAIME MOLINA-OCHOA‡, TREVOR WILLIAMS§, DAVID BERGVINSON¶, BETTY BENREY*, TED C. J. TURLINGS* and PIERRE FRANCK** ted.turlings@unine.ch
*Université de Neuchâtel, Institut de Biologie, Case Postale 158, 2009 Neuchâtel, Switzerland , †University of Manchester, Faculty of Life Sciences, Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK , ‡Universidad de Colima, Facultad de Ciencias Biológicas y Agropecuarias, Apartado postal no. 36, Campus Tecomán, Colima 28100, Colima, México , §ECOSUR, Apdo Postal 36, Tapachula 30700, Chiapas, México , ¶CIMMYT Apdo. Postal 6-641, 06600 Mexico, D.F., Mexico , **INRA, UR1115 Plantes & Systèmes de culture Horticoles, AgroParc, Domaine St-Paul, 84914 AVIGNON Cedex 9, France
Plant chemistry can strongly influence interactions between herbivores and their natural enemies, either by providing volatile compounds that serve as foraging cues for parasitoids or predators, or by affecting the quality of herbivores as hosts or prey. Through these effects plants may influence parasitoid population genetic structure. We tested for a possible specialization on specific crop plants in Chelonus insularis and Campoletis sonorensis, two primary parasitoids of the fall armyworm, Spodoptera frugiperda. Throughout
Molecular Ecology 2010 Volume 19 Issue 10, Pages 2168 - 2179
http://www3.interscience.wiley.com/journal/123342770/abstract
Insect Morphology
Female germline stem cell niches of earwigs are structurally simple and different from those of Drosophila melanogaster
Waclaw Tworzydlo 1, Malgorzata Kloc 2 3, Szczepan M. Bilinski 1 *sbili@zuk.iz.uj.edu.pl
1Department of Systematic Zoology, Institute of Zoology, Jagiellonian University, Krakow, Poland
2The Methodist Hospital, The Methodist Hospital Research Institute, Houston, Texas
3The University of Texas M. D. Anderson Cancer Center, Houston, Texas
Stem cells function in niches, which consist of somatic cells that control the stem cells' self-renewal, proliferation, and differentiation. Drosophila ovary germline niche consists of the terminal filament (TF) cells, cap cells, and escort stem cells; signaling from the TF cells and the cap cells is essential for maintenance of germline stem cells (GSCs). Here, we show that in the earwig Opisthocosmia silvestris, the female GSC niche is morphologically simple and consist of the TF cells and several structurally uniform escort cells. The most posterior cell of the TF (the basal cell of the TF) differs from remaining TF cells and is separated from the anterior region of the germarium by the processes of the escort cells, and consequently, does not contact the GSCs directly. We also show that between somatic cells of earwig niche argosome-like vesicles and cytoneme-like extensions are present. J. Morphol., 2010. © 2009 Wiley-Liss, Inc.
Journal of Morphology 2010 Volume 271 Issue 5, Pages 634 - 640
http://www3.interscience.wiley.com/journal/123222114/abstract
Neotropical katydids (Orthoptera: Tettigoniidae) are preyed on by gleaning bats, which are known to use male calling songs to locate them. At least one katydid species has been reported to stop singing in response to bat echolocation calls. To investigate the relationship between this behavioural defence and ecological and sensory factors, we surveyed calling song characteristics, song cessation in response to the echolocation calls of a sympatric gleaning bat (Trachops cirrhosus), and T-cell responses (an auditory interneuron sensitive to ultrasound) in five katydid species from Panamá. The two katydid species that stopped singing in response to bat calls (Balboa tibialis and Ischnomela gracilis, Pseudophyllinae) also had the highest T-cell spike number and rate in response to these stimuli. The third pseudophylline species (Docidocercus gigliotosi) did not reliably cease singing and had low T-cell spiking activity. Neoconocephalus affinis (Copiphorinae) produced continuous calling song, possibly preventing males from hearing the bat during singing, and did not show a behavioural response despite high T-cell activity in response to bat calls. Steirodon rufolineatum (Phaneropterinae) did not cease singing and differed in T-cell activity compared to the other species. T-cell function might not be conserved in katydids, and evidence for this idea is discussed.
Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology Volume 196, Number 5 / May, 2010 349-358
http://www.springerlink.com/content/c8436816240755x3/
Mutation of the Drosophila vesicular GABA transporter disrupts visual figure detection
Hao Fei1,*,
1 Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
2 Howard Hughes Medical Institute, Department of Integrative Biology and Physiology, UCLA, Los Angeles, CA 90095, USA
3 Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
4 Howard Hughes Medical Institute Janelia Farm Research Campus, Ashburn, VA 20147, USA
The role of gamma amino butyric acid (GABA) release and inhibitory neurotransmission in regulating most behaviors remains unclear. The vesicular GABA transporter (VGAT) is required for the storage of GABA in synaptic vesicles and provides a potentially useful probe for inhibitory circuits. However, specific pharmacologic agents for VGAT are not available, and VGAT knockout mice are embryonically lethal, thus precluding behavioral studies. We have identified the Drosophila ortholog of the vesicular GABA transporter gene (which we refer to as dVGAT), immunocytologically mapped dVGAT protein expression in the larva and adult and characterized a dVGATminos mutant allele. dVGAT is embryonically lethal and we do not detect residual dVGAT expression, suggesting that it is either a strong hypomorph or a null. To investigate the function of VGAT and GABA signaling in adult visual flight behavior, we have selectively rescued the dVGAT mutant during development. We show that reduced GABA release does not compromise the active optomotor control of wide-field pattern motion. Conversely, reduced dVGAT expression disrupts normal object tracking and figure–ground discrimination. These results demonstrate that visual behaviors are segregated by the level of GABA signaling in flies, and more generally establish dVGAT as a model to study the contribution of GABA release to other complex behaviors.
Journal of Experimental Biology 213, 1717-1730 (2010)
http://jeb.biologists.org/cgi/content/abstract/213/10/1717
Insect Neuroscience
Response competition associated with right–left antennal asymmetries of new and old olfactory memory traces in honeybees
References and further reading may be available for this article. To view references and further reading you must purchase this article.
Elisa Frasnellia,
a CiMeC, Centre for Mind/Brain Sciences,
38068
b Centre for Neuroscience and Animal Behaviour,
Armidale, NSW 2351,
Lateralized recall of olfactory memory in honeybees was tested, following conditioning of the proboscis extension reflex (PER), at 1 or 6 h after training. After training with lemon (+)/vanilla (−) or cineol (+)/eugenol (−) recall at 1 h was better when the odour was presented to the right side of the bee than when it was presented to the left side. In contrast, recall at 6 h was better when the odour was presented to the left than to the right side. This confirmed previous evidence of shorter-term recall via the right antenna and long-term memory recall via the left antenna. However, when trained with either a familiar appetitive odour (rose) as a negative stimulus, or with a naturally aversive odour (isoamyl acetate, IAA) as a positive stimulus, bees showed suppression of the response from both the right and the left side at 1 h after training (likely due to retroactive inhibition) and at 6 h responded to both odours on both sides. We argued that at 6 h, when access to memory has completed the shift from the right to the left side, memory of these familiar odours in the left side of the brain would be present as both positive (rose)/negative (IAA) (as a result of long-term memory either biologically encoded or acquired well before testing) and negative (rose)/positive (IAA) (as a result of the long-term memory of training) stimuli, thus producing response competition. As a direct test of this hypothesis, bees were first trained with unfamiliar lemon (+)/vanilla (−) and then (16 h later) re-trained with vanilla (+)/lemon (−); as predicted, 6 h after re-training bees responded to both odours on both the left and right side.
Behavioural Brain Research Volume 209, Issue 1, 1 May 2010, Pages 36-41
Visual experience and age affect synaptic organization in the mushroom bodies of the desert ant Cataglyphis fortis
Sara Mae Stieb 1, Thomas Sebastian Muenz 1, Rüdiger Wehner 2, Wolfgang Rössler 1 *
1Department of Behavioral Physiology and Sociobiology, Biozentrum, University of Würzburg, Germany
2Brain Research Institute, University of Zürich, Switzerland
Desert ants of the genus Cataglyphis undergo an age-related polyethism from interior workers involved in brood care and food processing to short-lived outdoor foragers with remarkable visual navigation capabilities. The quick transition from dark to light suggests that visual centers in the ant's brain express a high degree of plasticity. To investigate structural synaptic plasticity in the mushroom bodies (MBs) - sensory integration centers supposed to be involved in learning and memory - we immunolabeled and quantified pre- and postsynaptic profiles of synaptic complexes (microglomeruli, MG) in the visual (collar) and olfactory (lip) input regions of the MB calyx. The results show that a volume increase of the MB calyx during behavioral transition is associated with a decrease in MG numbers in the collar and, less pronounced, in the lip. Analysis of tubulin-positive profiles indicates that presynaptic pruning of projection neurons and dendritic expansion in intrinsic Kenyon cells are involved. Light-exposure of dark-reared ants of different age classes revealed similar effects. The results indicate that this structural synaptic plasticity in the MB calyx is primarily driven by visual experience rather than by an internal program. This is supported by the fact that dark-reared ants age-matched to foragers had MG numbers comparable to those of interior workers. Ants aged artificially for up to 1 year expressed a similar plasticity. These results suggest that the high degree of neuronal plasticity in visual input regions of the MB calyx may be an important factor related to behavior transitions associated with division of labor. © 2010 Wiley Periodicals, Inc. Develop Neurobiol 70: 408-423, 2010
Developmental Neurobiology 2010 Volume 70 Issue 6, Pages 408 - 423
http://www3.interscience.wiley.com/journal/123271725/abstract
The Amiloride-Sensitive Epithelial Na+ Channel PPK28 Is Essential for Drosophila Gustatory Water Reception
Zijing Chen,1,2 Qingxiu Wang,1 and Zuoren Wang1 ZuorenWang@ion.ac.cn
1Institute of Neuroscience, State Key Laboratory of Neuroscience,
Water sensation is a specific taste modality in the fruit fly. Water-induced hypoosmolarity activates specific gustatory receptor neurons; however, the molecular identity of the putative osmolarity sensor in these neurons remains unknown. We found that amiloride and its analogs specifically antagonized the response of water gustatory receptor neurons and the behavior of flies toward water stimulation. Deletion of the gene that encodes the amiloride-sensitive PPK28 channel, a DEG/eNaC (degenerin/epithelial sodium channel) family member, abolished the water-induced activity of water gustatory receptor neurons and greatly diminished the behavioral response of flies to water. Ectopic expression of the PPK28 channel in the bitter cells within the intermediate-type sensilla renders these sensilla responsive to water stimuli. Thus, the amiloride-sensitive PPK28 channel may serve as the osmolarity sensor for gustatory water reception in the fruit fly.
The Journal of Neuroscience, May 5, 2010, 30(18):6247-6252
http://www.jneurosci.org/cgi/content/abstract/30/18/6247
Long-Term Memory Leads to Synaptic Reorganization in the Mushroom Bodies: A Memory Trace in the Insect Brain?
Benoît Hourcade,1 Thomas S. Muenz,2 Jean-Christophe Sandoz,1 Wolfgang Rössler,2 and Jean-Marc Devaud1 devaud@cict.fr
1Research Centre on Animal Cognition, Centre National de la Recherche Scientifique–Université Paul-Sabatier, Unité Mixte de Recherche 5169, 31062
The insect mushroom bodies (MBs) are paired brain centers which, like the mammalian hippocampus, have a prominent function in learning and memory. Despite convergent evidence for their crucial role in the formation and storage of associative memories, little is known about the mechanisms underlying such storage. In mammals and other species, the consolidation of stable memories is accompanied by structural plasticity involving variations in synapse number and/or size. Here, we address the question of whether the formation of olfactory long-term memory (LTM) could be associated with changes in the synaptic architecture of the MB networks. For this, we took advantage of the modular architecture of the honeybee MB neuropil, where synaptic contacts between olfactory input and MB neurons are segregated into discrete units (microglomeruli) which can be easily visualized and counted. We show that the density in microglomeruli increases as a specific olfactory LTM is formed, while the volume of the neuropil remains constant. Such variation is reproducible and is clearly correlated with memory consolidation, as it requires gene transcription. Thus stable structural synaptic rearrangements, including the growth of new synapses, seem to be a common property of insect and mammalian brain networks involved in the storage of stable memory traces.
The Journal of Neuroscience, May 5, 2010, 30(18):6461-6465;
http://www.jneurosci.org/cgi/content/abstract/30/18/6461
Calcium Activates a Chloride Conductance Likely Involved in Olfactory Receptor Neuron Repolarization in the Moth Spodoptera littoralis
Adeline Pézier, * Marta Grauso, * Adrien Acquistapace, Christelle Monsempes, Jean-Pierre Rospars, and Philippe Lucas phillipe.plucas@versailles.inra.fr
Unité Mixte de Recherche 1272 Physiologie de l'Insecte, Signalisation et Communication, Institut National de la Recherche Agronomique, F-78000 Versailles, France
The response of insect olfactory receptor neurons (ORNs) to odorants involves the opening of Ca2+-permeable channels, generating an increase in intracellular Ca2+ concentration. Here, we studied the downstream effect of this Ca2+ rise in cultured ORNs of the moth Spodoptera littoralis. Intracellular dialysis of Ca2+ from the patch pipette in whole-cell patch-clamp configuration activated a conductance with a K1/2 of 2.8 µM. Intracellular and extracellular anionic and cationic substitutions demonstrated that Cl– carries this current. The anion permeability sequence I– > NO
The Journal of Neuroscience, May 5, 2010, 30(18):6323-6333;
http://www.jneurosci.org/cgi/content/abstract/30/18/6323
Axonal Degeneration Is Regulated by the Apoptotic Machinery or a NAD+-Sensitive Pathway in Insects and Mammals
Zohar Schoenmann,1 Efrat Assa-Kunik,2 Sheila Tiomny,1 Adi Minis,1 Liat Haklai-Topper,1 Eli Arama,2 and Avraham Yaron1 eli.arama@weizmann.ac.il avraham.yaron@weizmann.ac.il
Departments of 1Biological Chemistry and 2Molecular Genetics, Weizmann Institute of Science,
Selective degeneration of neuronal projections and neurite pruning are critical for establishment and maintenance of functional neural circuits in both insects and mammals. However, the molecular mechanisms that govern developmental neurite pruning versus injury-induced neurite degeneration are still mostly unclear. Here, we show that the effector caspases 6 and 3 are both expressed within axons and that, on trophic deprivation, they exhibit distinct modes of activation. Surprisingly, inhibition of caspases is not sufficient for axonal protection and a parallel modulation of a NAD+-sensitive pathway is required. The proapoptotic protein BAX is a key element in both pathways as its genetic ablation protected sensory axons against developmental degeneration both in vitro and in vivo. Last, we demonstrate that both pathways are also involved in developmental dendritic pruning in Drosophila. More specifically, the mouse WldS (Wallerian degeneration slow) protein, which is mainly composed of the full-length sequence of the NAD+ biosynthetic Nmnat1 enzyme, can suppress dendritic pruning in C4da (class IV dendritic arborization) sensory neurons in parallel to the fly effector caspases. These findings indicate that two distinct autodestruction pathways act separately or in concert to regulate developmental neurite pruning.
The Journal of Neuroscience, May 5, 2010, 30(18):6375-6386;
http://www.jneurosci.org/cgi/content/abstract/30/18/6375
Sialyltransferase Regulates Nervous System Function in Drosophila
Elena Repnikova,1 * Kate Koles,1 * Michiko Nakamura,1 Jared Pitts,1 Haiwen Li,1 Apoorva Ambavane,1 Mark J. Zoran,2 and Vladislav M. Panin1 panin@tamu.edu
1Departments of Biochemistry and Biophysics and 2Biology,
In vertebrates, sialylated glycans participate in a wide range of biological processes and affect the development and function of the nervous system. While the complexity of glycosylation and the functional redundancy among sialyltransferases provide obstacles for revealing biological roles of sialylation in mammals, Drosophila possesses a sole vertebrate-type sialyltransferase, Drosophila sialyltransferase (DSiaT), with significant homology to its mammalian counterparts, suggesting that Drosophila could be a suitable model to investigate the function of sialylation. To explore this possibility and investigate the role of sialylation in Drosophila, we inactivated DSiaT in vivo by gene targeting and analyzed phenotypes of DSiaT mutants using a combination of behavioral, immunolabeling, electrophysiological, and pharmacological approaches. Our experiments demonstrated that DSiaT expression is restricted to a subset of CNS neurons throughout development. We found that DSiaT mutations result in significantly decreased life span, locomotor abnormalities, temperature-sensitive paralysis, and defects of neuromuscular junctions. Our results indicate that DSiaT regulates neuronal excitability and affects the function of a voltage-gated sodium channel. Finally, we showed that sialyltransferase activity is required for DSiaT function in vivo, which suggests that DSiaT mutant phenotypes result from a defect in sialylation of N-glycans. This work provided the first evidence that sialylation has an important biological function in protostomes, while also revealing a novel, nervous system-specific function of
The Journal of Neuroscience, May 5, 2010, 30(18):6466-6476;
http://www.jneurosci.org/cgi/content/abstract/30/18/6466
Light-Mediated TIM Degradation within Drosophila Pacemaker Neurons (s-LNvs) Is Neither Necessary nor Sufficient for Delay Zone Phase Shifts
References and further reading may be available for this article. To view references and further reading you must purchase this article.
Chih-Hang Anthony Tang1, Erica Hinteregger1, 2, Yuhua Shang1 and Michael Rosbash1,
1 Howard Hughes Medical Institute,
Department of Biology,
Circadian systems are entrained and phase shifted by light. In Drosophila, the model of light-mediated phase shifting begins with photon capture by CRYPTOCHROME (CRY) followed by rapid TIMELESS (TIM) degradation. In this study, we focused on phase delays and assayed TIM degradation within individual brain clock neurons in response to light pulses in the early night. Surprisingly, there was no detectable change in TIM staining intensity within the eight pacemaker s-LNvs. This indicates that TIM degradation within s-LNvs is not necessary for phase delays, and similar assays in other genotypes indicate that it is also not sufficient. In contrast, more dorsal circadian neurons appear light-sensitive in the early night. Because CRY is still necessary within the s-LNvs for phase shifting, the results challenge the canonical cell-autonomous molecular model and raise the question of how the pacemaker neuron transcription-translation clock is reset by light in the early night.
Highlights ? TIM degradation within s-LNvs is neither necessary nor sufficient for phase delays ? CRY within s-LNvs is necessary for phase delays ? Dorsal circadian neurons are light-sensitive in the early night ? Circadian phase shifting is a network property
Neuron Volume 66, Issue 3, 13 May 2010, Pages 378-385
Drosophila TRPA1 channel mediates chemical avoidance in gustatory receptor neurons
Sang Hoon Kima,1, Youngseok Leea,1, Bradley Akitakea, Owen M. Woodwardb, William B. Gugginob, and Craig Montella,2
Mammalian sweet, bitter, and umami taste is mediated by a single transduction pathway that includes a phospholipase C (PLC)β and one cation channel, TRPM5. However, in insects such as the fruit fly, Drosophila melanogaster, it is unclear whether different tastants, such as bitter compounds, are sensed in gustatory receptor neurons (GRNs) through one or multiple ion channels, as the cation channels required in insect GRNs are unknown. Here, we set out to explore additional sensory roles for the Drosophila TRPA1 channel, which was known to function in thermosensation. We found that TRPA1 was expressed in GRNs that respond to aversive compounds. Elimination of TRPA1 had no impact on the responses to nearly all bitter compounds tested, including caffeine, quinine, and strychnine. Rather, we found that TRPA1 was required in a subset of avoidance GRNs for the behavioral and electrophysiological responses to aristolochic acid. TRPA1 did not appear to be activated or inhibited directly by aristolochic acid. We found that elimination of the same PLC that leads to activation of TRPA1 in thermosensory neurons was also required in the TRPA1-expressing GRNs for avoiding aristolochic acid. Given that mammalian TRPA1 is required for responding to noxious chemicals, many of which cause pain and injury, our analysis underscores the evolutionarily conserved role for TRPA1 channels in chemical avoidance.
PNAS May 4, 2010 vol. 107 no. 18 8440-8445
http://www.pnas.org/content/107/18/8440.abstract?etoc
DOI:
Insect review
Short-term memories in Drosophila are governed by general and specific genetic systems
In a dynamic environment, there is an adaptive value in the ability of animals to acquire and express memories. That both simple and complex animals can learn is therefore not surprising. How animals have solved this problem genetically and anatomically probably lies somewhere in a range between a single molecular/anatomical mechanism that applies to all situations and a specialized mechanism for each learning situation. With an intermediate level of nervous system complexity, the fruit fly Drosophila has both general and specific resources to support different short-term memories. Some biochemical/cellular mechanisms are common between learning situations, indicating that flies do not have a dedicated system for each learning context. The opposite possible extreme does not apply to Drosophila either. Specialization in some biochemical and anatomical terms suggests that there is not a single learning mechanism that applies to all conditions. The distributed basis of learning in Drosophila implies that these systems were independently selected.
Learn. Mem. 2010. 17: 246-251
http://learnmem.cshlp.org/content/17/5/246.abstract
Nature versus nurture in social insect caste differentiation
References and further reading may be available for this article. To view references and further reading you must purchase this article.
Tanja Schwander1, 4,
and Laurent Keller3
1 Simon Fraser University, Biological Sciences,
2 Behaviour and Genetics of Social Insects Laboratory, School of Biological Sciences A12,
3 University of
Recent evidence for genetic effects on royal and worker caste differentiation from diverse social insect taxa has put an end to the view that these phenotypes stem solely from a developmental switch controlled by environmental factors. Instead, the relative influences of genotypic and environmental effects on caste vary among species, ranging from largely environmentally controlled phenotypes to almost purely genetic systems. Disentangling the selective forces that generate variation for caste predisposition will require characterizing the genetic mechanisms underlying this variation, and identifying particular life-history strategies and kin structures associated with strong genetic effects on caste.
Trends in Ecology & Evolution Volume 25, Issue 5, May 2010, Pages 275-282
Edited by
2010-05-16
https://blog.sciencenet.cn/blog-278346-325268.html
上一篇：Insect Frontiers, April 2010 Volume 2 Number 4
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