INTEGRATION OF CHEMICAL AND BIOLOGICAL-CONTROL SYSTEMS FOR ARTHROPODS- EVALUATION IN A MULTITROPHIC CONTEXT

The methods used to evaluate and categorise the effects of pesticides on beneficial arthropods are reviewed, including the potential signifi cance of indirect, 'sub-lethal' activity and the importance of bioavai lability of pesticides under semi-field or field conditions. Interspec ific and intraspecific differences in the susceptibility of natural en emies (parasitoids and predators) to pesticides are considered, includ ing the use of resistant strains in Integrated Pest Management (IPM) s ystems. The potential impact of pesticide resistance in the target pes t on its natural enemies is also discussed. The need to assess the inf luence of the host plant/cultivar on the efficacy of pesticides for us e in integrated control programmes (ditrophic effects) and of the poss ible effects of such chemicals on host plant/cultivar-pest-parasitoid systems (tritrophic effects) are then described with specific referenc e to the diamondback moth and key endolarval parasitoids. Finally, the potential for manipulation of tritrophic interactions to enhance para sitism by application of low doses of toxicants is demonstrated.