Toxicity and effects of mosquito larvicides methoprene and surface film (Agnique® MMF) on the development and fecundity of the tadpole shrimp Triops newberryi (Packard) (Notostraca: Triopsidae).

Abstract

We investigated the interactions of tadpole shrimp, a mosquito biological control agent, with the juvenile hormone analog methoprene and a monomolecular surface film. In laboratory assays, the tadpole shrimp (TPS) Triops newberryi (Packard) was able to tolerate high concentrations of methoprene without negative impacts on its growth, longevity, and fecundity when exposed to 1 to 10 mg/liter, or 90-900 fold, of the IE(90) levels against a laboratory colony of Culex quinquefasciatus Say. The same held true in field trials when the habitats were treated with Altosid(®) Liquid Larvicide (Altosid(®) LL, 5% methoprene) at 0.3-1.2 liters/ha. or 1-4 fold of the label rates for mosquito control. However, some significant impacts on the TPS occurred when they were exposed to Agnique(®) Monomolecular Film (Agnique(®) MMF) at the label rates for mosquito control ranging from 1.89-9.45 liters/ha. under laboratory and field conditions. To avoid the negative impact of Agnique MMF on tadpole shrimp, it appears that 1.89 liters/ha. would be the maximum rate when Agnique MMF is used to control mosquitoes in the habitats where the TPS is employed as a biological control agent, or prevailing in the aquatic habitats with potential for suppressing mosquito larval populations.