Influence of visual cues on oviposition site searching and learning behavior in the parasitic beetle Dastarcus helophoroides (Fairmaire) (Coleoptera: Bothrideridae)

Abstract

Color cues play a key role in the location of hosts and host habitats; learning behavior can allow parasitoids to explore different hosts and reduce environmental uncertainty. However, it remains unclear whether the parasitic beetle Dastarcus helophoroides (Fairmaire) uses and learns visual cues to locate oviposition sites. In this study, we investigated the ability of females to respond to colors and associate the presence of a simulated oviposition site—wood with a trough—with colored substrates after training. Two sets of experiments were conducted: (i) investigating the innate preference for substrate coloration and (ii) investigating the ability to learn to associate substrate color with the presence of simulated oviposition sites, with the beetles being trained to respond to different substrate colors with simulated oviposition sites in sessions on 10 consecutive days. The parasitic beetles displayed an innate preference for the black substrate, but this preference changed after the beetles were trained on substrates of different colors. In the associative learning tests, these beetles laid more eggs on the reward-conditioned substrates than on the black substrate after being trained. Our results suggest that visual cues are learned and used by D. helophoroides during their search for and selection of oviposition sites.