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Deimatic behaviours, also referred to as startle behaviours, are used against predators and rivals. Although many are spectacular, their proximate and ultimate causes remain unclear. In this review we aim to synthesise what is known about deimatic behaviour and identify knowledge gaps. We propose a working hypothesis for deimatic behaviour, and discuss the available evidence for the evolution, ontogeny, causation, and survival value of deimatic behaviour using Tinbergen's Four Questions as a framework. Our overarching aim is to direct future research by suggesting ways to address the most pressing questions in this field. peerReviewed

Butterflies are a diverse and charismatic insect group that are thought to have evolved with plants and dispersed throughout the world in response to key geological events. However, these hypotheses have not been extensively tested because a comprehensive phylogenetic framework and datasets for butterfly larval hosts and global distributions are lacking. We sequenced 391 genes from nearly 2,300 butterfly species, sampled from 90 countries and 28 specimen collections, to reconstruct a new phylogenomic tree of butterflies representing 92% of all genera. Our phylogeny has strong support for nearly all nodes and demonstrates that at least 36 butterfly tribes require reclassification. Divergence time analyses imply an origin ~100 million years ago for butterflies and indicate that all but one family were present before the K/Pg extinction event. We aggregated larval host datasets and global distribution records and found that butterflies are likely to have first fed on Fabaceae and originated in what is now the Americas. Soon after the Cretaceous Thermal Maximum, butterflies crossed Beringia and diversified in the Palaeotropics. Our results also reveal that most butterfly species are specialists that feed on only one larval host plant family. However, generalist butterflies that consume two or more plant families usually feed on closely related plants., Funding came from the US National Science Foundation (NSF) GoLife ‘ButterflyNet’ collaborative grant (DEB-1541500, 1541557, 1541560) to A.Y.K., R.P.G., D.J.L. and N.E.P. Specimen collection and preservation was funded by NSF DBI-1349345, 1601369, DEB-1557007 and IOS-1920895 (A.Y.K.), NSF DEB-1120380 (D.J.L.), grants 9285-13 and WW-227R-17 from the National Geographic Society (D.J.L.), NSF DBI-1256742 (A.Y.K. and K.R.W.), NSF DEB-0639861 (K.R.W.) and NSF SES-0750480, DEB-0447244 and DEB-9615760 (N.E.P.). M.E. was supported by the Research Council of Norway (no. 204308) and the Hintelmann Scientific Award for Zoological Systematics. F.L.C. was supported by the European Research Council under the European Union’s Horizon 2020 research and innovation programme (project GAIA, no. 851188). M.P.B. was supported by the Swedish Research Council (IPG no. 2020‐06422). R.V. was supported by the Spanish Ministry of Science and Innovation grant PID2019-107078GB-I00/AEI/10.13039/501100011033. G.T. was supported by the Spanish Ministry of Science and Innovation (grants PID2020-117739GA-I00/AEI/10.13039/501100011033 and RYC2018-025335-I). V.L. was supported by the Russian Science Foundation (grant 19-14-00202) and by the Ministry of Science and Higher Education of the Russian Federation (grant 075-15-2021-1069). M.Y. was supported by MEXT KAKENHI no. 19916010 and JSPS KAKENHI grants 13010131, 23570111, 26440207, 17K07528 and 21H02215. A.B.B.M., H.P.R. and N.O.M. were supported by CNPQ grants proc 563332/2010-7 and 304273/2014-7., Main Results and discussion Methods Data availability Code availability References Acknowledgements Author information Ethics declarations Peer review Additional information Supplementary information Rights and permissions About this article

Temperature is thought to be a key variable explaining global patterns of species richness. However, to investigate this relationship carefully, it is necessary to study clades with broad geographic ranges that are comprised of species inhabiting diverse biomes with well- characterized species ranges. In the present study, we investigate the link between temperature and diversification in the butterfly family Pieridae (sulfurs and whites) by combining Next Generation sequences and published molecular data with fine-grained distribution information. After building the most comprehensive phylogeny of the group, with almost 600 species and all higher taxa (subfamilies, tribes and subtribes), we found strong support for the following relationships within the family: Dismorphiinae + (Coliadinae + (Pseudopontiinae + Pierinae)). With a curated distribution dataset of over 800,000 occurrences, we conducted multiple comparative phylogenetic analyses that provided strong evidence that species in environments with more stable daily temperatures or with cooler maximum temperatures in the warm seasons have higher diversification rates. We also found a positive correlation between speciation and extinction with paleotemperature: as global temperature decreased through geological time, so did diversification rates. Although many studies demonstrate higher diversity in the tropics, we have been able to identify specific climate variables associated with changes in diversification, while also inferring the most robust and well sampled phylogenomic framework for Pieridae to date.

Warning signals are well known in the visual system, but rare in other modalities. Some moths produce ultrasonic sounds to warn bats of noxious taste or to mimic unpalatable models. Here, we report results from a long-term study across the globe, assaying moth response to playback of bat echolocation. We tested 252 genera, spanning most families of large-bodied moths, and document anti-bat ultrasound production in 52 genera, with eight subfamily origins described. Based on acoustic analysis of ultrasonic emissions and palatability experiments with bats, it seems that acoustic warning and mimicry are the raison d'être for sound production in most moths. However, some moths use high-duty-cycle ultrasound capable of jamming bat sonar. In fact, we find preliminary evidence of independent origins of sonar jamming in at least six subfamilies. Palatability data indicate that jamming and warning are not mutually exclusive strategies. To explore the possible organization of anti-bat warning sounds into acoustic mimicry rings, we intensively studied a community of moths in Ecuador and, using machine-learning approaches, found five distinct acoustic clusters. While these data represent an early understanding of acoustic aposematism and mimicry across this megadiverse insect order, it is likely that ultrasonically signaling moths comprise one of the largest mimicry complexes on earth.

Butterflies are a diverse and charismatic insect group that are thought to have diversified via coevolution with plants and in response to dispersals following key geological events. These hypotheses have been poorly tested at the macroevolutionary scale because a comprehensive phylogenetic framework and datasets on global distributions and larval hosts of butterflies are lacking. We sequenced 391 genes from nearly 2,000 butterfly species to construct a new, phylogenomic tree of butterflies representing 92% of all genera and aggregated global distribution records and larval host datasets. We found that butterflies likely originated in what is now the Americas, ∼100 Ma, shortly before the Cretaceous Thermal Maximum, then crossed Beringia and diversified in the Paleotropics. The ancestor of modern butterflies likely fed on Fabaceae, and most extant families were present before the K/Pg extinction. The majority of butterfly dispersals occurred from the tropics (especially the Neotropics) to temperate zones, largely supporting a “cradle” pattern of diversification. Surprisingly, host breadth changes and shifts to novel host plants had only modest impacts.

Lepidoptera (butterflies and moths) are one of the most taxonomically diverse insect orders with nearly 160,000 described species. They have been studied extensively for centuries and are found on nearly all continents and in many environments. It is often assumed that adult butterflies are strictly diurnal and adult moths are strictly nocturnal, but there are many exceptions. Despite the broad interest in butterflies and moths, a comprehensive review of diel (day-night) activity has not been conducted. Here, we synthesize existing data on diel activity in Lepidoptera, trace its evolutionary history on a phylogeny, and show where gaps lie in our knowledge. Diurnality was likely the ancestral condition in Lepidoptera, the ancestral heteroneuran was likely nocturnal, and more than 40 transitions to diurnality subsequently occurred. Using species diversity estimates across the order, we predict that roughly 75-85% of Lepidoptera are nocturnal. We also define the three frequently used terms for activity in animals (diurnal, nocturnal, crepuscular), and show that literature on the activity of micro-moths is significantly lacking. Ecological factors leading to nocturnality/diurnality is a compelling area of research and should be the focus of future studies.

The subfamily Erebinae (Lepidoptera, Erebidae) includes approximately 10,000 species with many still undescribed. It is one of the most diverse clades within the moth superfamily Noctuoidea and encompasses a diversity of ecological habits. Erebine caterpillars feed on a broad range of host plants including several economically important crops. Adults possess a unique array of adaptations for predator defense, including some of the most sensitive hearing organs (tympana) across the Lepidoptera and striking wing coloration to startle visual predators. Despite the relevance of these moths to agriculture and ecological research, a robust phylogenetic framework is lacking. Here we used anchored hybrid enrichment, a relatively new approach in phylogenomics, to resolve relationships among the subfamily. Using the recently developed Lep1 anchored hybrid enrichment probe set, 658 gene fragments with an average length of 320 bp were captured from an exemplar set of 75 erebine species, representing 73 genera and 23 tribes. While the total number of erebine tribes is not firmly established, this represents at least 75% of known tribal level diversity. Anchored hybrid enrichment data were partitioned by locus and by codon position for maximum likelihood phylogenetic analysis and coalescent-based species-tree approaches. Results from our study provided strong nodal support (BP ≥ 95) for nearly all nodes in the partitioned ML tree, solidifying many relationships that were previously uncertain or moderately supported based on morphology or a smaller number of gene fragments. Likelihood analyses confidently resolved the placement of Acantholipini as a sister tribe to Sypnini and all other Erebinae. The remaining tribes were placed in a single, strongly supported clade split into two major subclades. Additionally, 25 tropical species that did not have previous tribal assignments are confidently placed on the phylogeny. Statistical comparisons with Shimodaira-Hasegawa (SH) tests found that our maximum likelihood trees were significantly more likely than alternative hypotheses. This study demonstrates the utility of anchored phylogenomics for resolving relationships within subfamilies of Lepidoptera.

Heteranassa Smith (Erebidae, Omopterini), native to the southwestern United States and Mexico, includes two recognized species, namely Heteranassa mima (Harvey) and Heteranassa fraterna Smith. These are separated mainly by subtle differences in wing color and pattern, leading to speculation about the validity of the described species. This study examines variation in external and internal morphology across the geographic range of the genus, aiming to clarify species limits, describe morphology, and provide a comprehensive assessment of variation within the genus. Results indicate that Heteranassa fraterna syn. n., is a junior synonym of Heteranassa mima.

Erebidae is one of the most diverse families within the order Lepidoptera (butterflies and moths), with nearly 25,000 described species. The nominal subfamily Erebinae is among the most species rich and taxonomically complex. It reaches its highest diversity in the tropics, where much of the fauna remains undescribed. Species in this subfamily feed on a broad range of host plants, with associated radiations on grasses and legumes, and some species are pests of agriculture and forestry. The Erebinae, as defined today, comprises a large portion of the former noctuid subfamily Catocalinae. However, many lineages have tenuous or uncertain systematic placement. Here, we review the complex historical classification of Erebinae, and discuss the possible placement of some of these lineages in light of traditional morphological groupings and recent molecular phylogenetic analyses. We present an updated list of named erebine tribes and their relationships, and identify morphological traits from literature used to group genera within these tribes.

We report the first record of the citrus pest Papilio demoleus Linnaeus collected near Guanica in the United States, Commonwealth of Puerto Rico, in March 2006.

The natural history of Pseudochrysops bornoi, native to Santo Domingo, Puerto Rico and Cuba, is poorly known. Based on observations of a population of P. b. escobioi made in March 2006 and March 2007 near Guanica, Puerto Rico, we describe likely host plants, flight behavior, mating flight and oviposition. On multiple occasions P. b. escobioi laid eggs in the developing inflorescences of acacia (Acacia farnesiana) and cinazo Pithecellobium circinale.