Control of salt marsh Culicoides and Tabanus larvae in small plots with granular organophosphorus pesticides, and the direct effect on other fauna

In further field tests at Cape Cod, Massachusetts [cf. RAE/B 60, 587], granular formulations of Dursban applied to salt-marshes at 0.2 and 0.05 lb/acre and of diazinon applied at 0.2 lb/acre reduced the numbers of larvae of Culicoides furens (Poey) and C. hollensis (Melander & Brues) by over 80% in the course of 7-9 days after application. Fenthion (Baytex) at 0.2 and Abate [O,O,O’,O’-tetramethyl O,O’-thiodi-p-phenylene diphosphorothioate] at 0.3 lb/acre gave poor control. Few non-target organisms were killed by these treatments. Those observed included fiddler crabs (Uca sp.), killifish (Fundulus sp.), prawns (Palaemonetes sp.) and ribbed mussels (Modiolus demissus). In other tests, granular formulations of Dursban at 0.05 lb/acre, Abate at 0.4 and diazinon at 0.3 did not appear to control the larvae of Tabanus lineola F. and T. nigrovittatus Macq., and only diazinon reduced the invertebrate fauna in the treated plots.