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A novel non-contact bioassay method for quantitative evaluation of vapour phase toxicity of insecticides against mosquitoes

Sarkar, Manas, Akulwad, Ambadas, Kshirsagar, Rajendra
Journal of Asia-Pacific entomology 2018 v.21 no.4 pp. 1315-1320
Culex quinquefasciatus, bioassays, glass, insecticides, insects, mortality, mosquito control, pests, pyrethrins, quantitative analysis, toxicity, vapors
The recent advancement in new generation fluorinated pyrethroids (e.g., transfluthrin, metofluthrin etc.), the use of semi-volatile vapour phase insecticides for control of mosquitoes and other domestic pests rises. Enabling the examination of the vapour toxicity profiles of these molecules and many other similar new generation molecules will provide new avenues for researchers for understanding the bio-potency in the spatial killing of pests. Hence, it is critical to establish a well-controlled portable vapour-phase bioassay method that can provide the desired precision, accuracy, linearity and robustness. In this respect, we have designed a vapour-toxicity apparatus comprising glass assemblies and developed a novel bioassay method. We found that KT50 and percentage knockdown at 60 min reflect the concentration dependency. This validates and confirms that the method is sensitive enough to distinguish between concentrations and suitable for concentration-response experiments. We found that KT50 and percentage knockdown at 60 min at a given concentration does not differ significantly between experiments. Hence, the method has repeatability and precision. Percentage mortality and total KT50 against Culex quinquefasciatus shows that percentage mortality increases and KT50 decreases linearly with the increasing concentration. This method provides an easy to operate tool to test the vapour toxicity profiles of any vapour phase insecticide molecules against mosquitoes and flying insects.