Field efficacy and nontarget effects of the mosquito Larvicides temephos, methoprene, and Bacillus thuringiensis var. israelensis in Florida mangroveswamps

We compared the efficacy and nontarget effects of temephos, Bacillus thurin giensis var. israelensis (B.t.i.), and methoprene applied by helicopter to control mosquito larvae in mangrove swamps on Sanibel Island, FL, in May 19 97. Three sites per treatment and 3 untreated sites were used. Temephos (Ab ate(TM)) was applied at 37 ml/ha (43% active ingredient [AI]), B.t.i. granu les (Vectobac G(TM)) were applied at 5.606 kg/ha (200 International Toxic U nits/mg), and methoprene (Altosid(TM) ALL) was applied at 213 ml/ha (5% AI) . Efficacy was quantified by monitoring the survival of caged and uncaged l arval Aedes taeniorhynchus. We quantified mortality of sentinel nontarget a mphipods (Talitridae) at all sites, monitored the effect of temephos on fly ing arthropods using light traps, and collected dead insects in tarps suspe nded under mangroves in areas treated with either temephos or methoprene. E ach pesticide showed good overall efficacy but occasional failures occurred . No detectable mortality of amphipods or Eying insects attributable to pes ticides was found. The inconsistent field efficacies of the pesticides indi cate a need for reinspection of treated sites in this habitat.