Anticipated host availability increases parasitoid host attack behaviour

Host feeding is common among synovigenic parasitoid wasps and is the mechanism through which they obtain nutrients for egg production. Upon host discovery, female wasps make a series of decisions that influence their host feeding and oviposition activities. Theoretical and empirical studies have shown that host availability is one of the factors that may affect these decisions. Diglyphus isaea, a synovigenic ectoparasitic wasp, parasitizes and kills (by feeding on or stinging) larval stages of agromyzid leafminer flies. We found that in the presence of large populations of adult leafminer flies, Liriomyza trifolii, the parasitoid wasp increased its host-killing behaviour, which appeared to be associated with a trend for increased protein uptake. Our study suggests that anticipated future host availability, which is based on a ‘host cue detour’ (sensu ‘infochemical detour’), affects the host-killing and host-feeding behaviour of this parasitoid wasp.