Cognitive decline in aging parasitoid wasps

Aging induces cognitive decline in humans and some other animals. For species that rely on learning and memory for reproduction, impaired cognitive functions may incur severe fitness costs. Here we report age-related cognitive decline in a solitary parasitoid wasp, Venturia canescens , that uses olfactory memories for host seeking and selection. We trained individual wasps to associate an odour with an oviposition reward, and compared their learning and memory performances at different stages of the reproductive life. Wasps between 6- and 14-day-old showed consistently poorer learning and reduced memory retention than young conspecifics, and this tendency increased with age. In this parasitoid insect, aging induces a precocious cognitive decline in reproductive females, which could severely impact their fitness through altered abilities to identify high quality hosts.