Mantises exchange angular momentum between three rotating body parts to jump precisely to targets.

Flightless animals have evolved diverse mechanisms to control their movements in air, whether falling with gravity or propelling against it. Many insects jump as a primary mode of locomotion and must therefore precisely control the large torques generated during takeoff. For example, to minimize spin (angular momentum of the body) at takeoff, plant-sucking bugs apply large equal and opposite torques from two propulsive legs [1]. Interacting gear wheels have evolved in some to give precise synchronization of these legs [2, 3]. Once airborne, as a result of either jumping or falling, further adjustments may be needed to control trajectory and orient the body for landing. Tails are used by geckos to control pitch [4, 5] and by Anolis lizards to alter direction [6, 7]. When falling, cats rotate their body [8], while aphids [9] and ants [10, 11] manipulate wind resistance against their legs and thorax. Falling is always downward, but targeted jumping must achieve many possible desired trajectories. We show that when making targeted jumps, juvenile wingless mantises first rotated their abdomen about the thorax to adjust the center of mass and thus regulate spin at takeoff. Once airborne, they then smoothly and sequentially transferred angular momentum in four stages between the jointed abdomen, the two raptorial front legs, and the two propulsive hind legs to produce a controlled jump with a precise landing. Experimentally impairing abdominal movements reduced the overall rotation so that the mantis either failed to grasp the target or crashed into it head first.GPS was supported by HFSP grant LT00422/2006-C. DAC was funded by a Leverhulme Trust grant F/09 364/K to S.R. Ott, University of Leicester, whom we thank for his support.This is the accepted manuscript. The final version is available at http://www.cell.com/current-biology/abstract/S0960-9822%2815%2900086-X

Pollen feeding proteomics: Salivary proteins of the passion flower butterfly, Heliconius melpomene.

While most adult Lepidoptera use flower nectar as their primary food source, butterflies in the genus Heliconius have evolved the novel ability to acquire amino acids from consuming pollen. Heliconius butterflies collect pollen on their proboscis, moisten the pollen with saliva, and use a combination of mechanical disruption and chemical degradation to release free amino acids that are subsequently re-ingested in the saliva. Little is known about the molecular mechanisms of this complex pollen feeding adaptation. Here we report an initial shotgun proteomic analysis of saliva from Heliconius melpomene. Results from liquid-chromatography tandem mass-spectrometry confidently identified 31 salivary proteins, most of which contained predicted signal peptides, consistent with extracellular secretion. Further bioinformatic annotation of these salivary proteins indicated the presence of four distinct functional classes: proteolysis (10 proteins), carbohydrate hydrolysis (5), immunity (6), and "housekeeping" (4). Additionally, six proteins could not be functionally annotated beyond containing a predicted signal sequence. The presence of several salivary proteases is consistent with previous demonstrations that Heliconius saliva has proteolytic capacity. It is likely that these proteins play a key role in generating free amino acids during pollen digestion. The identification of proteins functioning in carbohydrate hydrolysis is consistent with Heliconius butterflies consuming nectar, like other lepidopterans, as well as pollen. Immune-related proteins in saliva are also expected, given that ingestion of pathogens is a likely route to infection. The few "housekeeping" proteins are likely not true salivary proteins and reflect a modest level of contamination that occurred during saliva collection. Among the unannotated proteins were two sets of paralogs, each seemingly the result of a relatively recent tandem duplication. These results offer a first glimpse into the molecular foundation of Heliconius pollen feeding and provide a substantial advance towards comprehensively understanding this striking evolutionary novelty.This work was supported by the Balfour-Browne Fund administered by the Department of Zoology at the University of Cambridge. Additional support came from the University of Kansas.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.ibmb.2015.04.00

Ear pinnae in a neotropical katydid (Orthoptera: Tettigoniidae) function as ultrasound guides for bat detection

Early predator detection is a key component of the predator-prey arms race, and has driven the evolution of multiple animal hearing systems. Katydids (Insecta) have sophisticated ears, each consisting of paired tympana on each foreleg that receive sound both externally, through the air, and internally via a narrowing ear canal running through the leg from an acoustic spiracle on the thorax. These ears are pressure-time difference receivers capable of sensitive and accurate directional hearing across a wide frequency range. Many katydid species have cuticular pinnae which form cavities around the outer tympanal surfaces, but their function is unknown. We investigated pinnal function in the katydid Copiphora gorgonensis by combining experimental biophysics and numerical modelling using 3D ear geometries. We found that the pinnae in C. gorgonensis do not assist in directional hearing for specific call frequencies, but instead act as ultrasound detectors. Pinnae induced large sound pressure gains (20–30 dB) that enhanced sound detection at high ultrasonic frequencies (> 60 kHz), matching the echolocation range of co-occurring insectivorous bats. These findings were supported by behavioural and neural audiograms and tympanal cavity resonances from live specimens, and comparisons with the pinnal mechanics of sympatric katydid species, which together suggest that katydid pinnae primarily evolved for the enhanced detection of predatory bats

Assessment and validation of a suite of reverse transcription-quantitative PCR reference genes for analyses of density-dependent behavioural plasticity in the Australian plague locust

<p>Abstract</p> <p>Background</p> <p>The Australian plague locust, <it>Chortoicetes terminifera</it>, is among the most promising species to unravel the suites of genes underling the density-dependent shift from shy and cryptic solitarious behaviour to the highly active and aggregating gregarious behaviour that is characteristic of locusts. This is because it lacks many of the major phenotypic changes in colour and morphology that accompany phase change in other locust species. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) is the most sensitive method available for determining changes in gene expression. However, to accurately monitor the expression of target genes, it is essential to select an appropriate normalization strategy to control for non-specific variation between samples. Here we identify eight potential reference genes and examine their expression stability at different rearing density treatments in neural tissue of the Australian plague locust.</p> <p>Results</p> <p>Taking advantage of the new orthologous DNA sequences available in locusts, we developed primers for genes encoding 18SrRNA, ribosomal protein L32 (RpL32), armadillo (Arm), actin 5C (Actin), succinate dehydrogenase (SDHa), glyceraldehyde-3P-dehydrogenase (GAPDH), elongation factor 1 alpha (EF1a) and annexin IX (AnnIX). The relative transcription levels of these eight genes were then analyzed in three treatment groups differing in rearing density (isolated, short- and long-term crowded), each made up of five pools of four neural tissue samples from 5^thinstar nymphs. SDHa and GAPDH, which are both involved in metabolic pathways, were identified as the least stable in expression levels, challenging their usefulness in normalization. Based on calculations performed with the geNorm and NormFinder programs, the best combination of two genes for normalization of gene expression data following crowding in the Australian plague locust was EF1a and Arm. We applied their use to studying a target gene that encodes a Ca²⁺binding glycoprotein, <it>SPARC</it>, which was previously found to be up-regulated in brains of gregarious desert locusts, <it>Schistocerca gregaria</it>. Interestingly, expression of this gene did not vary with rearing density in the same way in brains of the two locust species. Unlike <it>S. gregaria</it>, there was no effect of any crowding treatment in the Australian plague locust.</p> <p>Conclusion</p> <p>Arm and EF1a is the most stably expressed combination of two reference genes of the eight examined for reliable normalization of RT-qPCR assays studying density-dependent behavioural change in the Australian plague locust. Such normalization allowed us to show that <it>C. terminifera </it>crowding did not change the neuronal expression of the <it>SPARC </it>gene, a gregarious phase-specific gene identified in brains of the desert locust, <it>S. gregaria</it>. Such comparative results on density-dependent gene regulation provide insights into the evolution of gregarious behaviour and mass migration of locusts. The eight identified genes we evaluated are also candidates as normalization genes for use in experiments involving other Oedipodinae species, but the rank order of gene stability must necessarily be determined on a case-by-case basis.</p

Optimizing multivariate behavioural syndrome models in locusts using automated video tracking

Locusts exhibit a behavioural syndrome known as 'behavioural phase polyphenism', in which a number of behavioural traits change markedly in response to local population density. 'Solitarious' phase individuals, which are typical of low-density populations, change within hours from being relatively sedentary and repelled by other locusts to congregating actively with conspecifics and becoming more active (the 'gregarious' phase). In wild populations, this behavioural plasticity can lead to the emergence of mass marching bands of nymphs and winged adult swarms. Much of our understanding of behavioural phase transition comes from laboratory experiments, which routinely employ an arena-based assay to measure a suite of behavioural variables encompassing aspects of activity, movement pattern and responses towards a stimulus group of other locusts. Individuals are then quantitatively phenotyped along a linear scale from solitarious to gregarious, by entering their returned measurements for several behavioural characters into a logistic regression model. Recently, automated video tracking has enabled multiple experimenters to use a single behavioural model, rather than each having to construct their own. Here, we have taken advantage of another powerful feature of automated tracking systems: the opportunity to use stored data to conduct a rigorous optimization process, which both ensures that the derived statistical model encapsulates the multidimensional nature of locust behavioural phase to best effect, and also provides a new understanding of the relationship between different behaviours. © 2012 The Association for the Study of Animal Behaviour.status: publishe

Optimizing multivariate behavioural syndrome models in locusts using automated video tracking

Locusts exhibit a behavioural syndrome known as 'behavioural phase polyphenism', in which a number of behavioural traits change markedly in response to local population density. 'Solitarious' phase individuals, which are typical of low-density populations, change within hours from being relatively sedentary and repelled by other locusts to congregating actively with conspecifics and becoming more active (the 'gregarious' phase). In wild populations, this behavioural plasticity can lead to the emergence of mass marching bands of nymphs and winged adult swarms. Much of our understanding of behavioural phase transition comes from laboratory experiments, which routinely employ an arena-based assay to measure a suite of behavioural variables encompassing aspects of activity, movement pattern and responses towards a stimulus group of other locusts. Individuals are then quantitatively phenotyped along a linear scale from solitarious to gregarious, by entering their returned measurements for several behavioural characters into a logistic regression model. Recently, automated video tracking has enabled multiple experimenters to use a single behavioural model, rather than each having to construct their own. Here, we have taken advantage of another powerful feature of automated tracking systems: the opportunity to use stored data to conduct a rigorous optimization process, which both ensures that the derived statistical model encapsulates the multidimensional nature of locust behavioural phase to best effect, and also provides a new understanding of the relationship between different behaviours. © 2012 The Association for the Study of Animal Behaviour

Extracellular nutrient digestion and absorption in the insect gut.

Insects are the most abundant and diverse class of animals on the planet. One explanation for their success is their extraordinary ability to successfully consume a wide range of foods. Like all heterotrophic organisms, insects need to acquire vital nutrients from their diet. The central organ for food digestion and absorption of nutrients is the gastrointestinal tract. This organ's principal functions are mediating the efficient digestion of the diet and protecting the organism against harmful chemicals, microorganisms, and mechanical damage from the food. These functions are achieved through regional differentiation of the alimentary canal as well as highly flexible adaptations to the consumed diets, both at anatomical and molecular levels. Numerous studies describing the general gut morphology and associated digestive mechanisms of various insects exist. Nevertheless, the molecular patterns underlying digestion and nutrient uptake in insects are still poorly characterized. This review aims to provide an overview of the general strategies of extracellular macronutrient digestion and consequent nutrient absorption found among different orders of insects.status: publishe

Extracellular nutrient digestion and absorption in the insect gut

Insects are the most abundant and diverse class of animals on the planet. One explanation for their success is their extraordinary ability to successfully consume a wide range of foods. Like all heterotrophic organisms, insects need to acquire vital nutrients from their diet. The central organ for food digestion and absorption of nutrients is the gastrointestinal tract. This organ’s principal functions are mediating the efficient digestion of the diet and protecting the organism against harmful chemicals, microorganisms, and mechanical damage from the food. These functions are achieved through regional differentiation of the alimentary canal as well as highly flexible adaptations to the consumed diets, both at anatomical and molecular levels. Numerous studies describing the general gut morphology and associated digestive mechanisms of various insects exist. Nevertheless, the molecular patterns underlying digestion and nutrient uptake in insects are still poorly characterized. This review aims to provide an overview of the general strategies of extracellular macronutrient digestion and consequent nutrient absorption found among different orders of insects

Behavioural phase change in the Australian plague locust, Chortoicetes terminifera, is triggered by tactile stimulation of the antennae

Density-dependent phase polyphenism is a defining characteristic of the paraphyletic group of acridid grasshoppers known as locusts. The cues and mechanisms associated with crowding that induce behavioural gregarization are best understood in the desert locust, Schistocerca gregaria, and involve a combination of sensory inputs from the head (visual and olfactory) and mechanostimulation of the hind legs, acting via a transient increase in serotonin in the thoracic ganglia. Since behavioural gregarization has apparently arisen independently multiple times within the Acrididae, the important question arises as to whether the same mechanisms have been recruited each time. Here we explored the roles of visual, olfactory and tactile stimulation in the induction of behavioural gregarization in the Australian plague locust, Chortoicetes terminifera. We show that the primary gregarizing input is tactile stimulation of the antennae, with no evidence for an effect of visual and olfactory stimulation or tactile stimulation of the hind legs. Our results show that convergent behavioural responses to crowding have evolved employing different sites of sensory input in the Australian plague locust and the desert locust.status: publishe

Born to win or bred to lose: aggressive and submissive behavioural profiles in crickets

Aggression between conspecific males is widespread in the animal kingdom, as is the fact that some individuals are far more aggressive than others. Consistent interindividual differences in behavioural profiles are generally regarded as a hallmark for animal ‘personality’ in both vertebrates and invertebrates, but their proximate causes are poorly understood. While the social experiences of winning and losing are known to lead to heightened and depressed aggressiveness, respectively, and that different fighting experiences can lead to changes in other behaviours, the extent to which interindividual variation in aggression and correlated behaviours are determined alone by fighting experience, environmental factors or inherited predisposition is unclear. In this study, we video tracked individual, virgin adult male crickets, Gryllus bimaculatus, to quantify their general motility, exploratory behaviour and attraction to conspecific males after 48 h of social isolation, and compared this with their performances 24 h later, immediately after a fighting tournament that yielded cohorts of aggressive winners and submissive losers. Although all known behavioural effects of previous social experience in crickets last only a few hours at most, we found significant behavioural differences between the 48 h isolated future winners and losers, i.e. before the fight tournament. However, the experiences of winning and losing led to more pronounced and some additional changes in behaviour. We discuss whether these different behavioural profiles associated with the chances of winning and losing (‘personalities’) could arise from factors other than fighting experience, or possibly from dominance and subjugation experiences gathered under crowded culture conditions before social isolation with cumulative effects that may persist longer than those presently known