Feeding responses of adult seven-spotted ladybirds, Coccinella septempunctata (Coleoptera, Coccinellidae), to insecticide contaminated prey in laboratory arenas

Abstract

The behavioural responses previously reported from Coccinella septempunctata to the organophosphate, dimethoate, have implications for the effective development of integrated pest management (IPM) strategies. Through a series of simple tests, coccinellids’ consumption rates were measured from live pesticide-resistant aphids, treated with five insecticides from three chemical classes: carbamates, organophosphates and pyrethroids. This study quantifies for the first time the doses of ingested insecticide to which C. septempunctata responds, and demonstrates that a number of insecticides can cause C. septempunctata to change its feeding behaviour. Females were confirmed to eat more than males, and responses to insecticides were observed more frequently in females. Aphid consumption was reduced most in the pyrethroid treatment groups, but choice tests found no preference for either treated or untreated prey in any group. The results are discussed in terms of the mechanism by which coccinellids detect insecticides, and the consequences for IPM.

Keywords:

• Coccinellid
• predatory efficiency
• integrated pest management
• sub-lethal behavioural responses

Acknowledgements

We thank Alastair Murray and Carola Deppe of the Central Science Laboratory statistics team for their help and advice, Syngenta, United Phosphorous and Dow AgroSciences for supplying insecticides. DGT thanks Dr J.M. Smith for help and advice pertaining to the production of intelligible sentences. The work was supported by Defra Seedcorn funding to Central Science Laboratory.