Evaluation of Carifend®, an alpha-cypermethrin-coated polyester net, for the control of Lasioderma serricorne and Ephestia elutella in stored tobacco

The use of insecticide-treated nets has lately attracted scientific interest for the management of mosquitoes and related species, as well as for crop pest control and the protection of stored agricultural commodities. In our study, the effect of Carifend®, an alpha-cypermethrin-coated polyester net, on adults of the two most important stored-tobacco insect pests, Lasioderma serricorne and Ephestia elutella, was evaluated in laboratory bioassays. Carifend® was applied to the bottom of plastic Petri dishes, whereas an additional series of dishes with net material without insecticide was also prepared and served as control. Twenty beetles or moths of mixed sex were placed in each dish. Insects were exposed to the substrates for 1, 5, 15, 30, 60, 90, 120 and 240 min and for 12 and 24 h. Immediate mortality and knockdown effect were measured after each exposure. Afterward, all surviving individuals were placed in untreated plastic dishes and delayed mortality, as well as percentage of knocked down insects, were counted after 1, 3, 5 and 7 days. Immediate mortality was very low for both species tested, even after 24 h of exposure. In contrast, immediate knockdown was high, especially for exposure intervals longer than 60 min. After insect removal from dishes with Carifend®, the high knockdown percentages were gradually transformed in most cases to delayed mortality. Based on our results, Carifend® can provide a satisfactory level of protection for stored tobacco against these two major tobacco insect pests, at least at the conditions tested here.