부산대학교 도서관

In biological control programmes, it is very common to employ multiple species to manage a single insect pest. However, the beneficial effects of natural enemies are not always additive because of several factors, including interspecific competition between these biocontrol agents. For this reason, in the present study we assessed several biological parameters (percentage parasitism, fertility, induced mortality and population reduction) of the parasitoids Diachasmimorpha longicaudata and Aganaspis daci when used together against the medfly Ceratitis capitata under laboratory and greenhouse conditions. Our results showed that, under laboratory conditions, fertility and percentage parasitism corresponded to a different functional response for each species (D. longicaudata: type II; A. daci: type III), whilst under greenhouse conditions, and unlike what occurs with single releases, both parasitoids showed a type III functional response; this is the only response which may lead to direct density dependence when host densities are low. Our results also revealed that when both species acted together, they produced a very high total percentage parasitism compared to that reported for single releases under both laboratory (64–76%) and greenhouse (21–51%) conditions. The parasitism was also higher for A. daci except when medfly larvae were provided in an artificial diet. Furthermore, host mortality induced by the two parasitoids acting together was very high, especially at low‐host densities; medfly population was almost completely reduced under greenhouse conditions. In summary, the data reported here supports the combined use of these species in biological control programmes against the medfly and highlights the importance of several factors, such as climatic conditions and host density, when planning their field releases. The beneficial effects of natural enemies when used against a pest species are not always additive due to several factors, such as interspecific competition. In the present work, several biological parameters of the parasitoids Diachasmimorpha longicaudata and Aganaspis daci were assessed when used together against the medfly Ceratitis capitata under different conditions. Each species showed a different functional response under laboratory conditions (D. longicaudata: type II; A. daci: type III), whilst under greenhouse conditions both parasitoids showed a type III functional response, as shown in the figure (A: D. longicaudata; B: A. daci). Furthermore, the overall percentage parasitism and the host mortality produced by both species when acting together was higher than that reported for single releases. Thus, our results support the combined use of these species in IPM programmes against the medfly. [ABSTRACT FROM AUTHOR]