Cypermethrin (CP), cypermethrinϩtrans-tetramethrin (CT), prallethrin (PR) and diazinon (DI) were applied to wallpaper or glass to evaluate the control of adult houseflies of up to 60 days; immediate mortality from direct spraying and dry residues was also determined. Mortality from fresh residues was greater on glass for all pyrethroids. CP was toxic by direct spraying, but its effect on glass was brief. Adding trans-tetramethrin extended CP activity up to 60 days (mortality Ͼ77%). Negligible activity on wallpaper was probably due to insecticide absorption. PR and DI had little effect on wallpaper. The results recommend CT applied to glass windows to achieve extended control. © Pesticide Science Society of Japan Keywords: housefly control, cypermethrin, diazinon, Musca domestica, prallethrin, trans-tetramethrin.The housefly, Musca domestica L. (Diptera: Muscidae), is a cosmopolitan pest that affects the quality of life of people by invading homes, particularly in areas near livestock. 1-3) Indoors, insecticide use against houseflies is restricted to chemicals with a low effect on humans and pets. Pyrethroids are a logical choice as they are broad-spectrum pesticides with minor toxicity to mammals; however, there have been many reports of the development of resistance to pyrethroids and other insecticide groups by houseflies. 4-7) Thus, there is a need to develop methods for housefly control indoors, including new pyrethroids. The objective of this study was to evaluate the efficacy of four commercial insecticides in Chile, Cyperkill Plus (cypermethrin 25%, CP), Cyperkill 25 EC (a 5 : 3 mixture of cypermethrin 25% and transtetramethrin 15%, CT), Anasect 2.5 EC (prallethrin 2,5%, PR), and Greenline conchuelas (diazinon 50%, DI) (ANASAC, Chile) on adult houseflies, and to determine immediate mortality from direct spraying and dry residues on two surfaces, wallpaper and glass, as well as residual action up to 60 days after application.
Short-term effect of residuesAdult house flies were collected in several locations of the Metropolitan Region of central Chile to start a colony, as in Khalequzzaman et al. 8) Flies were collected from small farms without any insecticide management; thus, they had not been exposed and were reared for three generations before using them for the study. Insecticides were diluted in water at the maximum dosages recommended on the labels (30, 30, 50, and 60 mL commercial products in 5 L water, for CP, CT, PR, and DI, respectively), and were sprayed with an ST-4 Potter Tower (2 mL solution each time) onto both the lid and bottom of Petri dishes lined with or without vinyl-coated wallpaper. The treated dishes were kept at 25°C and under a 14 : 10 light:dark regime. Prior to exposure, the caged flies were anesthetized with chloroform in a cotton wick for 5-10 min. Then, groups of 30 flies were placed in untreated and covered Petri dishes for 24 h with sugar water embedded in a cotton wick to allow them to recover, or to remove them if they seemed affected. They were then exposed to 0°C for 6...