Insecticides resistance and its effects on the biology outputs of field collected populations of the house flies Musca domestica L. (Diptera: Muscidae)
Synthetic insecticides, dose-response, susceptibility, life table, toxicology
The ethology of houseflies (Musca domestica L., Diptera: Muscidae) and their proximity to human environments make it an important biological vector of diseases among humans and animals, being associated with economic losses by contaminating poultry products, workers' food and environment. The selection of resistant populations by misuse of insecticides, makes its control becomes increasingly difficult, requiring further studies on the biological mechanism of this resistance in order to elucidate the appropriate solutions to return the ecological balance to that population. Hence, the main objective of this work was to evaluate the exposure effect of two populations of M. domestica to some synthetic insecticides, to improve the integrated pest management in Nepomuceno city. For this purpose, this dissertation was structured in two chapters. The first consists to assessed and compared the susceptibility 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), also was analyzed the mortality of third-stage-larvae and then the mortality to one-day-old pupae, at the maximum field recommended dose (MFRD) of synthetic insecticides. The main finding of this first chapter was that the results showed that the RR was 20,46; 13,03; 12,40; 12,24; 2,69; 2,34; 1,25; 1,06 and 0,92 folds for Deltamax, Actara, Engeo Pleno, Termimax, Pirate, Evidence, Benevia, Capataz and Delegate respectively. Demonstrating differences in susceptibility between the two populations (Diff of Means= 9.374; t=3.193; p=0.002) and a risk of insecticide resistance occurring in POPNEPO. On larvae bioassays, resulted as the best controllers the chlorpyrifos and imidacloprid treatments, reaching 100% mortality in POPNEP, and the Anova-2 analysis showed statistically significant differences for population (df=1; F= 5.215; p= 0.026), and also for the insecticidal factor (df= 9; f= 4.552; p=0.001), and for the toxicity bioassays on pupae, the better results were reached by imidacloprid with 100% mortality in POPNEP. The Anova-2 analysis showed statistically significant differences for the insecticidal factor (df= 9; f= 4.530; p<0.001) and for the Population x insecticidal factor (df= 9; f= 3.357; p<0.002). The second chapter was about to evaluate the effect of exposure to insecticides on the biological parameters of houseflies, using a life table for the two populations. The main finding of this second chapter was that there were significative differences between populations development at the parameters egg duration, and third instar duration, which prolongs the total development of POPNEP (15,71 ± 0,38 days) respect to POPUFLA (15,69 ± 0,25 days) (H = 47,857, df =1, p <0,001). As well as differences between the ratio of females (H = 6.062, df =1, p = 0.014). Which leads us to think that the physical cost of POPNEP is quite relevant respect the development duration, but not about the amount of adult population and in turn its detrimental to chemical control since it highlights the need to create new control methods with the correct synthetic insecticides for its control. Thus, these insecticides Delegate, Capataz and Benevia are promising for use in the development of safer formulations for health and the environment against adult flies, making it possible to include them in Integrated Pest Management strategies in Nepomuceno City.