Water content in diet affects growth and timing of female first mating, but not coloration, in the admirable grasshopper (Syrbula admirabilis)

Abstract

Understanding how water limitation affects the performance of herbivorous insects is relevant in a context of worldwide alterations of rainfall regimes due to climate change. Apart from its influence on insect growth and development, water availability has also been considered a cue for color polyphenism in some species. This is the case of the grassland-inhabiting admirable grasshopper (Syrbula admirabilis), for which water content in plant tissues, a potentially reliable cue to predict future vegetation conditions, has been proposed to determine the frequency of green-brown color morphs. We performed an experiment that manipulated water content of the diet (dry/wet treatment) in a group of individually monitored admirable grasshoppers to explore the effects on imago size, timing of female first mating, and coloration. Our results showed that grasshoppers in the wet treatment achieved larger sizes, and females mated comparatively earlier, than their counterparts in the dry treatment.We also found that hue (the dominant color) in imagines was significantly lower (browner) than in nymphs, but the magnitude of this color shift did not differ between treatments. This study supports the idea that water limitation has a negative impact on grasshopper growth and development, but rules out dietary water content as a cue for color polyphenism. This result encourages additional research to assess the actual contribution of environmental and genetic factors to color determination in admirable grasshoppers. Such information could help to better understand how color polymorphism is maintained in natural populations and to predict how it could evolve in a future in which environmental conditions will become more unpredictable.

Dehydration and infection elicit increased feeding in the western flower thrips,Frankliniella occidentalis, likely triggered by glycogen depletion

“…In this study, we examined the water balance characteristics of adult western flower thrips in relation to infection with TSWV. As a globally invasive pest, it is critical to understand the dehydration tolerance of thrips, because dehydration is a significant abiotic stressor that impacts geographical distribution, reproductive capacity, longevity, growth rates, and feeding behavior (Chown et al 2011, Albers and Bradley 2006, Finch et al 2020, Benoit et al 2010, Hera and Reichert 2021, Hagan et al 2018). Various viruses are known to influence the physiology and behavior of insects; thus, surveying the potential interplay between dehydration tolerance and TSWV infection may reveal a critical host-virus interaction leading to increased insect vector fitness and/or likelihood to spread disease.…”

Dehydration yields distinct transcriptional shifts associated with glycogen metabolism and increases feeding in the western flower thrips, Frankliniella occidentalis

“…In this study, we examined the water balance characteristics of adult western flower thrips. As a globally invasive pest, it is critical to understand the dehydration tolerance of thrips; dehydration is a significant abiotic stressor for insects that impacts geographical distribution, reproductive capacity, longevity, growth rates, and feeding behavior (Gray & Bradley, 2005;Chown et al, 2011;Hagan et al, 2018;Finch et al, 2020;Hera & Reichert, 2021). To examine water balance requirements of F. occidentalis, we determined water content, water loss rates, and survival, as well as the effect of dehydration on gene expression, nutrient allocation, and feeding avidity.…”