Effects of systemic imidacloprid on Coleomegilla maculata (Coleoptera : Coccinellidae)

The coccinellid predator Coleomegilla maculata (DeGeer) is found throughout the central and eastern United States and is a potential biological contro l agent for interiorscapes. Currently, the systemic insecticide imidaclopri d is widely used in interiorscape and landscape integrated pest management. Effects of imidacloprid on the fitness and behavior of C. maculata were ex amined by confining groups of adults with inflorescences of treated sunflow er, Helianthus annus L. 'Big Smile'; chrysanthemum, Chrysanthemum morifoliu m Ramat. 'Pelee'; and dandelion, Taraxacum officinale Wiggers. Confinement with inflorescences from imidacloprid-treated plants significantly decrease d the general mobility of C. maculata in each plant system. The magnitude o f the reduction in mobility varied with plant species. In the sunflower bio assay, survivorship was lower for beetles exposed to imidacloprid at the la bel rate and twice the label rate (38.3 +/- 6.60 and 20.0 +/- 6.71% surviva l, respectively) than for beetles confined to untreated controls (97.5 +/- 2.50% survival). Also, in the sunflower bioassay, beetles exposed to the la bel rate and twice the label rate of imidacloprid took longer to produce th eir Ist eggs (9.78 +/- 2.01 and 14.00 +/- 2.10 d after bioassay respectivel y) than beetles from untreated controls (2.56 +/- 0.50 d after bioassay). T he results reported here indicate that the use of imidacloprid may not be c ompatible with the coccinellid predator C. maculata.