Boletín de la AeE

Adult parasitic wasps generally require food both as an energy source for host searching and for the production and maturation of eggs. The availability of sugar sources can increase the parasitoid´s longevity, fecundity, and overall activity. The introduction of (artificial) sugar sources, consequently, provides a promising strategy to increase the effectiveness of natural enemies, during both crop cultivation and storage. Despite the fact that many authors have speculated on the potential of applying food sources as a strategy to raise parasitoid fítness and (as a direct consequence) increasing biológica! control efficacy, the actual validity of this basic concept remains to be proven.

In this study a storage system was chosen to address the question how food supplements (honey) affect parasitoid-host dynamics. The fact that migratory effects can be excluded in closed storages, makes this system particularly suitable to investigate how the nutritional quality of food supplements contributes to hostnatural enemy interactions. Further advantages of the storage system are its simplicity and the fact that the presence of accidental sugar sources, as they commonly occur in field crops (honeydew, flowering weeds), can be excluded.

The effects of food supplements are generally not limited to beneficiáis. Therefore, in the present study, the effect of artificial food sources on the longevity and fecundity of both the cowpea weevil Callosobruchus chinensis and its parasitoid Anisopteromalus calandrae was investigated. Weevils and parasitoids were either provided with water only, oí exposed to water in combination with either honey, uninfested beans, C. chinensis infested beans (host feeding), or infested beans plus honey.

Néctar feeding was found to increase both longevity and lifetime fecundity of ( while the weevil´s lifespan was not affected by the other treatments. Both honey and weevil infested beans increased the parasitoid´s longevity dramatically. Parasitoid lifetime fecundity was found to be primarily affected by host feeding.

The implications of these findings for biological control of storage pests will be discussed along with possible strategies for making food application selective.