Insect personality depends on environmental conditions

Increasing evidence has accumulated within the last decade that individuals of different animal species show consistent behavior both across various contexts and through time, that is, they do have personality. However, little is known in how far the environment an individual is facing may influence the personality of insects, whereas it is well established that the environment can have profound influences on performance parameters. The development of personality may be closely linked to different expectations in future fitness leading to contrasting life-history strategies. We investigated in how far the environmental food conditions experienced during lifetime influence the life-history and shape the personality of the mustard leaf beetle, Phaedon cochleariae, a pest of crucifers. Beetles reared on low-quality food developed slower and gained lower body masses than insects reared on high-quality food. By performing behavioral tests analogous to vertebrate assays repeatedly during adult life, we identified 3 personality dimensions, boldness, activity, and nontargeted explorativeness. Comparing food-dependent differences of the personality dimensions with state-dependent differences of the expected future prospects, we found that beetles feeding low-quality food were bolder, thereby potentially increasing their capabilities to succeed in foraging. In contrast, animals feeding high-quality food were more active. Changes in boldness may be highly adaptive to increase future reproductive output, whereas activity is likely constrained by the energy uptake. Our results demonstrate that the environment does not only affect life-history traits but has also a consistent impact on an individual's behavior, which is likely highly adaptive.