DIMBOA GLUCOSIDE, A WHEAT CHEMICAL DEFENSE, AFFECTS HOST ACCEPTANCE AND SUITABILITY OF SITOBION-AVENAE TO THE CEREAL APHID PARASITOID APHIDIUS-RHOPALOSIPHI

The influence of hydroxamic acids (Hx), plant secondary metabolites as sociated with aphid resistance in wheat, on the host acceptance and su itability of the aphid Sitobion avenae to the cereal aphid parasitoid Aphidius rhopalosiphi was evaluated. Aphids showed a reduction in mean relative growth rate and in body size in the wheat cultivar with high er Hx level. Reduction in aphid size was related to a decreased succes s in avoiding parasitoid oviposition. A minor increase in A. rhopalosi phi developmental time was observed in aphids feeding on the higher Hx cultivar. Experiments with different concentrations of DIMBOA glucosi de, the main Hx in wheat, in artificial diets showed an increase in pa rasitoid developmental time at the highest concentration, with no chan ge in other performance variables. The evidence is discussed in relati on to the compatible utilization of host-plant resistance and biologic al control in integrated pest management.