Insecticide resistance and its effects on the biological and reproductive outputs of two field collected populations of the houseflies Musca domestica L. (Diptera: Muscidae)

Abstract

The housefly (Musca domestica L., Diptera: Muscidae) is associated with economic losses by contaminating poultry products. Occurring cases of control failure and selection of resistant populations by synthetic insecticides misuse. Requiring studies of the physiological mechanisms of this resistance to determine the appropriate solutions to return the balance to that population, hence, the main objective of this work was to evaluate the effects of insecticide exposure in two populations of M. domestica to ten synthetic insecticides in their biological and reproductive parameters, to improve the integrated pest management for those populations. For this purpose, this dissertation was structured into two chapters. CHAPTER I consists of the comparative assessment of the susceptibility to insecticides by dose-response curves between a population of adult flies, one with no history of insecticides (POPUFLA) and another with a history of insecticide application (POPNEP), as well as analyzing the mortality of third-stage-larvae and pupae, at the maximum field recommended dose (MFRD). The results showed that the resistance ratios (LC50 POPNEP/ LC50 POPUFLA) were 20.5; 13.1; 12.4 and 12.2 folds for deltamethrin, thiamethoxam, lambda-cyhalothrin + thiamethoxam and lambda-cyhalothrin indicating potential insecticides’ resistance occurrence in POPNEP. Chlorfenapyr, imidacloprid, cyantraniliprole, chlorpyrifos, and spinetoram showed control effectiveness for the two populations. Larval and pupal mortalities ranged from 50 to 100% in the two populations for all the insecticides including azadirachtin. In CHAPTER II, an age-stage, two-sex, life table was used to evaluate insecticide resistance's potential effects on flies' biological parameters. Significant statistical differences were found for the egg, and third larval stage durations (H= 47.86; df =1; P <0.001), which prolonged the total development of POPNEP (15.71 ± 0.38 days) concerning POPUFLA (15.69 ± 0.25 days). Also, at the POPNEP females presented a higher intrinsic rate of increase (rm=0.197 females/ female/day) but, a longer mean generation time (T=33.21 days) compared to POPUFLA (rm=0192; T= 31.36). The overall findings suggest that the POPNEP is an insecticide-selected population that developed a fitness cost in terms of long development times but also has a reproductive advantage over the susceptible population POPUFLA. Both the encountered developmental cost and reproductive advantage linked to insecticide resistance should further be studied and verified under field conditions.