Stimulating effects of the insecticide chlorpyrifos on host searching and infestation efficacy of a parasitoid wasp

• Published in: Pest management science 2002-04, Vol.58 (4), p.321-328
• Main Authors: Rafalimanana, Halitiana, Kaiser, Laure, Delpuech, Jean-Marie
• Format: Article
• Language: English
• Subjects: Agricultural sciences; Animals; associative learning; bananas; Biological and medical sciences; chlorpyrifos; Chlorpyrifos - toxicity; conditioning; Control; Drosophila; Drosophila - parasitology; Eucoilidae; Female; females; France; Fundamental and applied biological sciences. Psychology; host seeking; Host-Parasite Interactions; insect control; Insecticides - toxicity; Integrated pest control; Larva - parasitology; larvae; Leptopilina heterotoma; Life Sciences; memory; Neurons and Cognition; odors; organophosphorus; oviposition; ovipositor; Parasitic Diseases, Animal - parasitology; parasitic wasps; parasitism; Phytopathology. Animal pests. Plant and forest protection; population; Protozoa. Invertebrates; Smell; sub-lethal effects; sublethal effects; Toxicity Tests; Wasps - drug effects
• ISSN: 1526-498X; 1526-4998
• DOI: 10.1002/ps.454

Hymenopterous parasitoids play an important role in the control of insect populations. During oviposition, Hymenopterous parasitoids use cues such as odours from their environment to locate their specific host. Leptopilina heterotoma (parasitoid of Drosophila larvae) locate their host by probing the substrate with the ovipositor. This behaviour can be induced by the odour of the host substrate alone. We analysed the sub-lethal effects of chlorpyrifos at LD20 on the probing activity in response to a fruit odour (banana). The insecticide increased the percentage of females spontaneously probing in response to the odour. Parasitoid females were then conditioned to associate banana odour with the oviposition in host larvae. This conditioning enables parasitoids to memorise the odour and to increase their probing response to this odour. During the olfactory conditioning, females exposed to the insecticide found and oviposited in host larvae more quickly than control females. One hour after the olfactory conditioning, females exposed to the insecticide presented a higher increase of their probing response to the odour than controls. Twenty-four hours after conditioning, the stimulation produced by chlorpyrifos was no longer perceptible, but the level of response of conditioned females was still higher than that of non-conditioned females, showing that odour memory was not impaired by the insecticide treatment. These sub-lethal effects, that stimulate host searching by parasitoids without impairing odour memorisation, could increase their parasitic efficiency.