Factors driving the within-plant patterns of resource exploitation in a herbivore

1. Selective pressures exerted on the feeding behavior of animals have been extensively studied to understand their foraging patterns. In herbivores, specific within-plant patterns of resource exploitation have been reported, but their determinants remain poorly understood. 2. Here, we describe and decipher the determinants of the foraging pattern of the pollen beetle, Brassicogethes aeneus, a pollinivorous insect that is a pest of oilseed rape (Brassica napus). This insect feeds from flowers for almost all of its life cycle, except for a couple of weeks preceding blossoming. During this period, only flower buds are available and the insect destroys them to feed from the pollen they contain, causing serious yield losses. 3. We found that during this critical period, pollen beetles exhibit a stereotypic intra-inflorescence feeding pattern that depends on flower bud maturity. To explain this pattern, we first deciphered the selective pressures driving pollen beetles’ feeding behavior. Us...