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 control agent for interiorscapes. Currently, the systemic insecticide imidacloprid is widely used in interiorscape and landscape integrated pest management. Effects of imidacloprid on the fitness and behavior of C. maculata were examined by confining groups of adults with inflorescences of treated sunflower, Helianthus annus L. 'Big Smile'; chrysanthemum, Chrysanthemum morifolium Ramat. 'Pelee'; and dandelion, Taraxacum officinale Wiggers. Confinement with inflorescences from imidacloprid-treated plants significantly decreased the general mobility of C. maculata in each plant system. The magnitude of the reduction in mobility varied with plant species. In the sunflower bioassay, survivorship was lower for beetles exposed to imidacloprid at the label rate and twice the label rate (38.3 ± 6.60 and 20.0 ± 6.71% survival, respectively) than for beetles confined to untreated controls (97.5 ± 2.50% survival). Also, in the sunflower bioassay, beetles exposed to the label rate and twice the label rate of imidacloprid took longer to produce their 1st eggs (9.78 ± 2.01 and 14.00 ± 2.10 d after bioassay respectively) than beetles from untreated controls (2.56 ± 0.50 d after bioassay). The results reported here indicate that the use of imidacloprid may not be compatible with the coccinellid predator C. maculata.