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Laboratory and field evaluation of the efficacy of four insecticides for Aedes vigilax (Diptera: Culicidae) and toxicity to the nontarget shrimp Leander tenuicornis (Decapoda: Palaemonidae)

Brown, M.D., Thomas, D., Mason, P., Greenwood, J.G., Kay, B.H.
Journal of economic entomology 1999 v.92 no.5 pp. 1045-1051
Aedes vigilax, Palaemonidae, insecticidal properties, toxicity, temephos, pirimiphos-methyl, methoprene, Bacillus thuringiensis subsp. israelensis, nontarget organisms, field experimentation, pH, turbidity, water quality, water temperature, salinity, bioassays, adverse effects, dissolved oxygen, Queensland
Laboratory and field evaluations were conducted in southeastern Queensland, Australia, to determine the toxicities of 2 organophosphate compounds (temephos and pirimiphosmethyl), an insect growth regulator (s-methoprene), and Bacillus thuringiensis variety israelensis de Barjac (Bti) to Aedes vigilax (Skuse), an Australian saltmarsh mosquito vector of Ross River virus. The toxicity of these compounds to Leander tenuicornis Say, a cohabiting nontarget shrimp species, was also assessed. s-Methoprene and Bti were found to be the most selective for Ae. vigilax, with selectivity ratios of (LC(95) nontarget/LC(95) target) of 255,000 and 38,000, respectively. In contrast, selectivity ratios of 13 and 0.01 were calculated for temephos and pirimiphos-methyl, respectively. As predicted by the laboratory studies, the field applications of s-methoprene and Bti were highly effective against Ae. vigilax, while not affecting L. tenuicornis survival. In contrast, although temephos and pirimiphos-methyl were both effective against Ae. vigilax, these products also killed 100% of caged L. tenuicornis, s-Methoprene and Bti did not affect water quality, whereas temephos and pirimiphos-methyl significantly influenced pH and turbidity. Accordingly, based on the high selectivity ratios, excellent field efficacy, and lack of influence on abiotic water characteristics, s-methoprene and Bti were ideal for insecticide control of Ae. vigilax in Australian saltmarsh pools.