Gene silencing through RNA interference (RNAi) has revolutionized the study of gene 98 function, particularly in non-model insects. However, in Lepidoptera (moths and butterflies) 99 RNAi has many times proven to be difficult to achieve. Most of the negative results have been 100 anecdotal and the positive experiments have not been collected in such a way that they are 101 possible to analyze. In this review, we have collected detailed data from more than 150 102 experiments including all to date published and many unpublished experiments. Despite a 103 large variation in the data, trends that are found are that RNAi is particularly successful in the 104 family Saturniidae and in genes involved in immunity. On the contrary, gene expression in 105 epidermal tissues seems to be most difficult to silence. In addition, gene silencing by feeding 106 dsRNA requires high concentrations for success. Possible causes for the variability of success 107 in RNAi experiments in Lepidoptera are discussed. The review also points to a need to further 108 investigate the mechanism of RNAi in lepidopteran insects and its possible connection to the 109 innate immune response. Our general understanding of RNAi in Lepidoptera will be further 110 aided in the future as our public database at http://insectacentral.org/RNAi will continue to 111 gather information on RNAi experiments.

Our results suggest that signaling from the focus induces nested rings of regulatory gene expression that subsequently control the final color pattern. Furthermore, the remarkably plastic regulatory interactions downstream of focal signaling have facilitated the evolution of eyespot diversity.

HSP90 proteins are important molecular chaperones. Transcriptome and genome analyses revealed that the human HSP90 family includes 17 genes that fall into four classes. A standardized nomenclature for each of these genes is presented here. Classes HSP90AA, HSP90AB, HSP90B, and TRAP contain 7, 6, 3, and 1 genes, respectively. HSP90AA genes mapped onto chromosomes 1, 3, 4, and 11; HSP90AB genes mapped onto 3, 4, 6, 13 and 15; HSP90B genes mapped onto 1, 12, and 15; and the TRAP1 gene mapped onto 16. Six genes, HSP90AA1, HSP90AA2, HSP90N, HSP90AB1, HSP90B1 and TRAP1, were recognized as functional, and the remaining 11 genes were considered putative pseudogenes. Amino acid polymorphic variants were detected for genes HSP90AA1, HSP90AA2, HSP90AB1, HSP90B1, and TRAP1. The structures of these genes and the functional motifs and polymorphic variants of their proteins were documented and the features and functions of their proteins were discussed. Phylogenetic analyses based on both nucleotide and protein data demonstrated that HSP90(AA+AB+B) formed a monophyletic clade, whereas TRAP is a relatively distant paralogue of this clade.

Background: HSP90 proteins are essential molecular chaperones involved in signal transduction, cell cycle control, stress management, and folding, degradation, and transport of proteins. HSP90 proteins have been found in a variety of organisms suggesting that they are ancient and conserved. In this study we investigate the nuclear genomes of 32 species across all kingdoms of organisms, and all sequences available in GenBank, and address the diversity, evolution, gene structure, conservation and nomenclature of the HSP90 family of genes across all organisms.

Current explanations for why sexual ornaments are found in both sexes include genetic correlation, same sex competition, and mutual mate choice. In this study, we report developmental plasticity in mating behavior as induced by temperature during development in the butterfly Bicyclus anynana. Males and females reciprocally change their sexual roles depending on their larval rearing temperatures. This switch is correlated with a change in mating benefits to females and costs to males. The discrete seasonal environments, wet season and dry season, are known to produce the two developmental forms and as a consequence impose alternating, symmetrical patterns of sexual selection, one season on male ornaments, the following season on female ornaments. Thus, reciprocal selection through time may result in mutual sexual ornamentation.

Sexual and natural selection pressures are thought to shape the characteristic wing patterns of butterfly species. Here we test whether sexual selection by female choice plays a role in the maintenance of the male wing pattern in the butterfly Bicyclus anynana. We perform one of the most extensive series of wing pattern manipulations in butterflies, dissecting every component of the 'bulls-eye' eyespot patterns in both ventral and dorsal wing surfaces of males to test the trait's appeal to females. We conclude that females select males on the basis of the size and brightness of the dorsal eyespot's ultraviolet reflecting pupils. Pupil absence is strongly selected against, as are artificially enlarged pupils. Small to intermediate (normal sized) pupils seem to function equally well. This work contradicts earlier experiments that suggest that the size of dorsal eyespots plays a role in female choice and explains why male dorsal eyespots are very variable in size and often have indistinct rings of coloration, as the only feature under selection by females seems to be the central white pupil. We propose that sexual selection by female choice, rather than predator avoidance, may have been an important selective factor in the early stages of eyespot evolution in ancestral Lepidopteran lineages.

Investigating the relative importance of multiple cues for mate choice within a species may highlight possible mechanisms that led to the diversification of closely related species in the past. Here, we investigate the importance of close-range pheromones produced by male Bicyclus anynana butterflies and determine the relative importance of these chemical cues versus visual cues in sexual selection by female choice. We first blocked putative androconial organs on the fore- and hindwings of males, while also manipulating the ability of females to perceive chemical signals via their antenna. We found that male chemical signals were emitted by both fore- and hindwing pairs and that they play an important role in female choice. We subsequently tested the relative importance of these chemical cues versus visual cues, previously identified for this species, and found that they play an equally important role in female choice in our laboratory setting. In addition, females will mate with males with only one signal present and blocking both androconial organs on males seems to interfere with male to male recognition. We discuss the possible functions of these signals and how this bimodal system may be used in intra- and interspecific mate evaluation.

Visual patterns in animals may serve different functions, such as attracting mates and deceiving predators. If a signal is used for multiple functions, the opportunity arises for conflict among the different functions, preventing optimization for any one visual signal. Here we investigate the hypothesis that spatial separation of different visual signal functions has occurred in Bicyclus butterflies. Using phylogenetic reconstructions of character evolution and comparisons of evolutionary rates, we found dorsal surface characters to evolve at higher rates than ventral characters. Dorsal characters also displayed sex-based differences in evolutionary rates more often than did ventral characters. Thus, dorsal characters corresponded to our predictions of mate signalling while ventral characters appear to play an important role in predator avoidance. Forewing characters also fit a model of mate signalling, and displayed higher rates of evolution than hindwing characters. Our results, as well as the behavioural and developmental data from previous studies of Bicyclus species, support the hypothesis that spatial separation of visual signal functions has occurred in Bicyclus butterflies. This study is the first to demonstrate, in a phylogenetic framework, that spatial separation of signals used for mate signalling and those used for predator avoidance is a viable strategy to accommodate multiple signal functions. This signalling strategy has important ramifications on the developmental evolution of wing pattern elements and diversification of butterfly species.