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Locusts exhibit remarkable phenotypic plasticity changing their appearance and behavior from solitary to gregarious when population density increases. These changes include morphological differences in the size and shape of brain regions, but little is known about plasticity within individual neurons and alterations in behavior not directly related to aggregation or swarming. We investigated looming escape behavior and the properties of a well-studied collision-detection neuron in gregarious and solitarious animals of three closely related species, the desert locust (Schistocerca gregaria), the Central American locust (S. piceifrons) and the American bird grasshopper (S. americana). For this neuron, the lobula giant movement detector (LGMD), we examined dendritic morphology, membrane properties, gene expression, and looming responses. Gregarious animals reliably jumped in response to looming stimuli, but surprisingly solitarious desert locusts did not produce escape jumps. These solitarious animals also had smaller LGMD dendrites. This is the first study done on three different species of grasshoppers to observe the effects of phenotypic plasticity on the jump escape behavior, physiology and transcriptomics of these animals. Unexpectedly, there were little differences in these properties between the two phases except for behavior. For the three species, gregarious animals jumped more than solitarious animals, but no significant differences were found between the two phases of animals in the electrophysiological and transcriptomics studies of the LGMD. Our results suggest that phase change impacts mainly the motor system and that the physiological properties of motor neurons need to be characterized to understand fully the variation in jump escape behavior across phases. 

Based on past and expanded DNA sampling, the orthopteran families Stenopelmatidae and Anostostomatidae, as currently structured, are shown to be non-monophyletic. The splay-footed cricket genus Comicus is confirmed to be genetically distinct from all Stenopelmatidae. We add two specimens to our previously published phylogenetic tree for New World Stenopelmatus Jerusalem cricket species and report the first multilocus DNA recovery for S. ater from Costa Rica. Male internal genitalia may be of systematic value in Jerusalem crickets, but we believe they should be analyzed when in their unfolded, “physiologically functional” configuration, where morphological characters can be seen in more detail when compared to their preserved, folded state. We describe Stenopelmatus nuevoguatemalae n. sp. from Guatemala. 

The genusPterotiltusKarsch, 1893 currently contains 18 described species. The genus is distributed in West, Central, and East Africa from Ghana to the Congo basin as far as Western Uganda.Pterotiltus biokosp. nov.is described from specimens recently collected on Bioko Island in Equatorial Guinea. A key toPterotiltusspecies is provided. 

Abstract Cave crickets (Rhaphidophoridae) are insects of an ancient and wingless lineage within Orthoptera that are distributed worldwide except in Antarctica, and each subfamily has a high level of endemicity. Here, we show the comprehensive phylogeny of cave crickets using multi-gene datasets from mitochondrial and nuclear loci, including all extant subfamilies for the first time. We reveal phylogenetic relationships between subfamilies, including the sister relationship between Anoplophilinae and Gammarotettiginae, based on which we suggest new synapomorphies. Through biogeographic analyses based on divergence time estimations and ancestral range reconstruction, we propose novel hypotheses regarding the biogeographic history of cave crickets. We suggest that Gammarotettiginae in California originated from the Asian lineage when Asia and the Americas were connected by the Bering land bridge, and the opening of the western interior seaway affected the division of Ceuthophilinae from Tropidischiinae in North America. We estimate that Rhaphidophoridae originated at 138 Mya throughout Pangea. We further hypothesize that the loss of wings in Rhaphidophoridae could be the result of their adaptation to low temperatures in the Mesozoic era. 

Ensiferan orthopterans offer a key study system for acoustic communication and the process of insect hearing. Cyphoderris monstrosa (Hagloidea) belongs to a relict ensiferan family and is often used for evolutionary comparisons between bushcrickets (Tettigoniidae) and their ancestors. Understanding how this species processes sound is therefore vital to reconstructing the evolutionary history of ensiferan hearing. Previous investigations have found a mismatch in the ear of this species, whereby neurophysiological and tympanal tuning does not match the conspecific communication frequency. However, the role of the whole tympanum in signal reception remains unknown. Using laser Doppler vibrometry, we show that the tympana are tonotopic, with higher frequencies being received more distally. The tympana use two key modalities to mechanically separate sounds into two auditory receptor populations. Frequencies below approximately 8 kHz generate a basic resonant mode in the proximal end of the tympanum, whereas frequencies above approximately 8 kHz generate travelling waves in the distal region. Micro-CT imaging of the ear and the presented data suggest that this tonotopy of the tympana drive the tonotopic mechanotransduction of the crista acustica (CA). This mechanism represents a functional intermediate between simple tuned tympana and the complex tonotopy of the bushcricket CA.