Abstract
Since the discovery of the benzoylphenylurea (BPU) insect growth regulator (IGR) diflubenzuron, several new BPU analogs inhibiting chitin synthesis have been successfully tested against a variety of dipterous vector and nuisance insects, particularly mosquitoes and chironomid midges. One of these, UC-84572, was applied at different rates to assess control of natural populations of chironomid midges in outdoor ponds. The impact of UC-84572 on selected nontarget invertebrates coexisting with the midges was studied. Diflubenzuron (Dimilin 25% wettable powder) was also applied to the ponds as a standard in this study for comparison. Test ponds at the University of Florida were treated with 1, 5, and 10 ppb of UC-84572, while Dimilin was applied at 10 ppb active ingredient (AI). At predetermined intervals after the treatments and on the day of treatments, samples of zooplankton and of free-swimming invertebrates were collected. It is concluded that field applications of UC-84572 at rates up to 10 ppb AI or higher would cause adverse effects on some nontarget aquatic invertebrates, such as nymphal Ephemeroptera, larval and adult Coleoptera, Cladocera, and Copepoda. These adverse effects, however, are temporary and usually short-lived as shown in the present study and in other previous studies. No displacement or replacement of any animal group was noted in the ponds, indicating that UC-84572 did not cause any long-term or permanent alterations in the aquatic food-chain. Thus the superior activity of UC-84572 over diflubenzuron against target nuisance and vector Diptera (mosquitoes and midges) merits its further development and this new IGR has an excellent potential for their control. (VerNooy-PTT)