Effect of wheat resistance, the parasitoid Aphidius rhopalosiphi, and the entomopathogenic fungus Pandora neoaphidis, on population dynamics of the cereal aphid Sitobion avenae

The influence of wheat (Triticum aestivum L.) resistance, the parasitoid Ap hidius rhopalosiphi De Stephani-Perez (Hymenoptera: Braconidae) and the ent omopathogenic fungus Pandora neoaphidis (Remaudiere et Hennebert) Humber (Z ygomycetes: Entomophthorales) on the density and population growth rate of the cereal aphid Sitobion avenae (F.) (Hemiptera: Aphididae) was studied un der laboratory conditions. Partial wheat resistance was based on hydroxamic acids, a family of secondary metabolites characteristic of several cultiva ted cereals. The partial resistance of wheat cultivar Naofen, the action of the parasitoid and the joint action of the parasitoid and fungus, reduced aphid density. The lowest aphid densities were obtained with the combinatio n of the parasitoid and the fungus, but wheat resistance under these circum stances did not improve aphid control. Significant reductions of population growth rate (PGR) of aphids were obtained with the joint action of wheat r esistance and natural enemies. In particular, the combined effects of paras itoids and fungi showed significantly lower PGR than the control without na tural enemies in both wheat cultivars. Our results support the hypothesis t hat wheat resistance and the utilization of biological control agents could be complementary strategies in an integrated pest management program again st cereal aphids.