Comparative toxicity of selected larvicides and insect growth regulators to a Florida laboratory population of Aedes albopictus.

Five organophosphates (OPs) (chlorpyrifos, chlorpyrifos methyl, fenthion, malathion, and temephos), 3 pyrethroids (bifenthrin, cypermethrin, and permethrin), and 2 microbial pesticides (Bacillus thuringiensis serovar.israelensis [B.t.i.] and Bacillus sphaericus) were tested as larvicides against a Florida Aedes albopictus population colonized in the laboratory. In addition, 3 insect growth regulators (IGRS) (diflubenzuron, methoprene, and pyriproxyfen) were evaluated. All OPs, except for malathion, were highly effective as indicated by low LC90s ranging from 0.0069 ppm (chlorpyrifos) to 0.026 ppm (fenthion); the larvae were considered tolerant to malathion (LC90 = 1.043 ppm). LC90 values of pyrethroids were: 0.0175 ppm (bifenthrin), 0.0079 ppm (cypermethrin), and 0.0031 ppm (permethrin). Commercial products of B.t.i., Vectobac and Bactimos were considered economically effective against Ae. albopictus larvae but products of B. sphaericus were ineffective (LC90s > 28 ppm). The IGRs showed exceptional activity. Pyriproxyfen (LC90 = 0.000376 ppm), was 2.23 and 21.5 times more toxic than diflubenzuron and methoprene, respectively. In general, toxicity ranking of chemicals and microbials tested was: IGRs > pyrethroids > OPs > microbials.