Epidemiological determinants of Chrysomya (Diptera: calliphoridae) infestation in layer farms of Minas Gerais, Brazil

Abstract

Aspects related to the epidemiology of Diptera belonging to genus Chrysomya were studied in order to determine predisposing factors for their occurrence in commercial laying hens farms from the state of Minas Gerais, Brazil. An observational, analytical and sectional survey was conducted to verify the main epidemiological determinants of infestations by Chrysomya spp. Forty-three farms were visited in 2012 and these 13 (30,23%) were infested by Chrysomya putoria, 4 (9,30%) by Chrysomya megacephala and 2 (4,65%) by Chrysomya albiceps and in 2 farms (4,65%) was not possible to identify the species of Chrysomya. The epidemiological determinants for the occurrence of infestations by Chrysomya spp. were investigated using multiple logistic regression models. Housing clustering type and its conditions were important factors involved in epidemiology of these species (OR=5.05, 95% CI = 2.66 to 9.58, p = 0.000). It was also observed that the increase of the humidity of manure leads to increase chances of infestations (OR = 1.81, 95% CI = 1.36 to 2.40, p = 0.000). The presence of the beetle “lesser mealworm” (Alphitobius diaperinus) (OR = 0.15, 95% CI = 0.067 to 0.36, p = 0.000) was characterized as a protective factor against infestations, probably due to predation behavior of the beetle. Some regions of the state were characterized as lower risk areas for Chrysomya spp. infestation as compared to other regions. Management measures, such as constant monitoring of water leaks on manure, adequate composting of dead poultry and periodic removal of manure could assist in decreasing the presence of Chrysomya spp. inside the laying houses.