Effects of aerial applications of naled on nontarget insects at Parris Island, South Carolina.

Testing impacts of large-scale aerial spraying to control public health pests under realistic field conditions are needed to understand impacts on natural populations of nontarget insects. Responses of terrestrial insects to aerial applications of an organophosphate insecticide, naled, used for mosquito and biting midge control were studied on Parris Island Marine Corps Recruit Depot, Parris Island, SC. Aerial applications were made with C-130 aircraft at dusk in 2003 and in 2005. In 2003, we sampled two locations on Parris Island with Malaise traps before and after spraying, and used Before-After analyses to examine changes in terrestrial insect diversity and abundance. In 2005, we sampled insects with yellow pan traps at three locations on Parris Island and at an untreated control site. A Before-After Control-Impact analysis at each location was conducted to compare changes. In 2003, numbers of four of 12 common taxa (Dolichopodidae, Sarcophagidae, Syrphidae, Tachinidae) were lower after sprays. However, there were no significant changes in numbers of common taxa or total numbers in 2005. Shannon diversities (H') were not different in either year indicating that sprays had minimal impact on overall community biodiversity. In contrast, populations of pestiferous biting midges (Culicoides spp.) collected in CDC-style traps were reduced by 94-99% after spraying in both years; mosquito numbers declined by 88.2% in 2003 and 92.5% in 2005, after sprays.