Body temperature differences between green and brown grasshoppers do not result from thermal physiology or thermal preferences

Colour polymorphisms correspond to the co-occurrence of several distinct colour morphs that vary in hue and/or brightness, independently of sex, age or any other state-dependent modifiers. Colour morphs could represent different life-history strategies, maximising their fitness locally in the trait space through trade-offs between all their biological functions. This mechanism could play a role in the maintenance of the green-brown polymorphism in Orthoptera.
Grasshoppers are characterized by a widespread green-brown polymorphism and continuous variability in brightness within colour morphs. It has previously been found that brown individuals are warmer in the field than green conspecifics, but it is unclear if these differences are related to thermal physiology and/or thermal preferences. Therefore, we experimentally tested the thermal physiology and thermal preferences of three green-brown polymorphic species of acridid grasshoppers.
We found no differences between green and brown gra..., Sampling
We studied the colour morphs of Acrida ungarica, Pseudochorthippus parallelus, and Gomphocerus sibiricus (hereafter simply referred as to ungarica, sibiricus, and parallelus, respectively). Individuals were collected in the field during the 2023 summer season (in mid to late June in east-central Germany for parallelus; in mid-July and mid-august in northern Italy for ungarica; in mid-July in the French Alps for sibiricus). Ungarica were collected as nymphs, parallelus and sibiricus were collected mostly as nymphs. The first sampling of ungarica led to an over-representation of males because field sex ratios were highly unbalanced (17:2, males:females). We, therefore, oversampled females to compensate for missing individuals during the second sampling campaign.
All three species are green-brown polymorphic (Figure 1). Ungarica features two colour morphs: green and brown. Sibiricus presents green and brown individuals. Brown sibiricus can be subdivided into a plain-brown morph an..., , # Body temperature differences between green and brown grasshoppers do not result from thermal physiology or thermal preferences

Short summary:

Colour polymorphisms correspond to the co-occurrence of several distinct colour morphs that vary in hue and/or brightness, independently of sex, age or any other state-dependent modifiers. Colour morphs could represent different life-history strategies, maximising their fitness locally in the trait space through trade-offs between all their biological functions. This mechanism could play a role in the maintenance of the green-brown polymorphism in Orthoptera.

Grasshoppers are characterized by a widespread green-brown polymorphism and continuous variability in brightness within colour morphs. It has previously been found that brown individuals are warmer in the field than green conspecifics, but it is unclear if these differences are related to thermal physiology and/or thermal preferences. Therefore, we experimentally tested the thermal physi...,