Intraspecific maternal competition induces summer diapause in insect parasitoids

AbstractOrganisms often live in unpredictable environments and have to adopt life history strategies that optimize their fitness under these conditions. According to bet ‐hedging theory, individuals can reduce variation in fitness outcomes by investing in different strategies at the same time. For arthropods, facultative summer diapause enables survival during dry and hot periods of the year, and can be triggered by a decrease in resource abundance. However, the e ffect of resource depletion on diapause induction has never been disentangled from the effect of the perception of the presence of competitors. Using two solitary parasitoid species of cereal aphids as a model system,Aphidius avenae (Haliday) andAphidius rhopalosiphi (De Stefani ‐Perez) (Hymenoptera: Braconidae), we tested whether (i) low absolute host density and/or (ii) high levels of parasitoid females’ competition lead to maternal‐induced summer diapause in parasitoid offspring. Under summer‐like climatic conditions, emerging parasitoid females were (i) reared a lone and exposed to different host densities (from 5 to 130 aphids), or (ii) reared together with competing females (from 2 to 20 females) and then exposed individually to 50 aphids. For both parasitoid species, low aphid densities did not induce summer diapause. However, the incidence of summer dia pause increased up to a maximum of 11% with increasing levels of competition experienced by female parasitoids. More than 60% of the females produc...
Source: Insect Science - Category: Biology Authors: Tags: ORIGINAL ARTICLE Source Type: research