Behaviour of the adult seven spot ladybird, Coccinella septempunctata (Coleoptera : Coccinellidae), in response to dimethoate residue on bean plants in the laboratory

The sub-lethal effects of dimethoate residue on the distribution and locomo tor activity of adults of Coccinella septempunctata Linnaeus on Vicia faba plants were investigated in the laboratory. The presence of dimethoate resi dues on the upper half of the plant caused C. septempunctata to spend signi ficantly less time on the plants overall. When given a choice of treated an d untreated surfaces, C. septempunctata spent proportionately more time on the untreated areas of the plant. The locomotor activity of C. septempuncta ta was also altered following encounter with dimethoate residues resulting in a significant increase in the proportion of time spent walking and a red uction in the proportion of time spent resting. The proportion of time spen t on plant parts was also affected, with a reduction in the time spent on t he apex and an increase in the proportion of time spent on the stem, indica ting a possible avoidance response. The proportion of time spent on the ada xial leaf surface was significantly increased following dimethoate treatmen t. The implications for integrated pest management are considered.