Habitat-conditioned feeding behaviour in Barbitistes constrictus (Orthoptera: Tettigoniidae)

Abstract

Some insect herbivores can regulate their nourishment intake by different feeding behaviour. This mechanism allows them to persist with utilising different food resources according to the composition of the vegetation within their habitats. Using a two-choice experiment, we analysed foraging behaviour in females of the tree-dwelling bush-cricket Barbitistes constrictus (Orthoptera), which originated from two different forest habitats, spruce and beech forest. We found that individuals from the spruce forest mainly foraged on needle tips, and thus they nibbled more needles per day than individuals from the beech forest (medians 106.0 vs. 42.5; p < 0.0001). However, when the contents of droppings were dissected, the volume of consumed spruce was similar in both groups of bush-crickets (median > 90%), which is explained by the different feeding techniques of bush-crickets from different habitats. We propose possible scenarios for bush-cricket feeding adaptations to the deleterious effects of the host plant chemical compounds serving as a plant defence against herbivores.