Biologia e controle químico de Drosophila suzukii (Diptera: Drosophilidae), e toxicidade aos seus parasitoides

Abstract

Drosophila suzukii (Matsumura) (Spotted Wing Drosophila - SWD) is a pest of small fruit with thin skin that has been causing great damage to commercial crops and native fruits. The females have a robust and serrated ovipositor, which allows oviposition inside healthy fruits. SWD also presents high biotic potential under favorable environmental conditions, with temperature being one of the main abiotic factors determining its establishment and development. The main way of handling this pest is chemical control, but studies show that natural biological control can help with population suppression. Within this context, the present study aimed to test the efficiency of three artificial diets, based on biological parameters and life table of D. suzukii, to evaluate the effect of seven constant temperatures on the biology and thermal requirements of D. suzukii, to evaluate the effect of pesticides on adults and eggs of SWD, and to evaluate the toxicity of pesticides on parasitoids Trichopria anastrephae and Pachycrepoideus vindemmiae. The diets A (cornmeal, glucose and yeast) and C (cornmeal, molasses and yeast) are suitable for laboratory rearing of D. suzukii, since they provided the highest net rates of reproduction (Ro) (257.32 and 210.29, respectively) and the shortest periods between generations (T = 35 days), in relation to diet B (cornmeal, sugar and yeast) (Ro = 116.12; T = 37 days).The best temperatures for the development of D. suzukii were 23 and 25°C, since they provided the greatest viabilities of the biological cycle (egg-adult) (81% and 69%, respectively), the shortest period between generations (T = 28.91 and 28.76, respectively), better reproduction rate (Ro = 245.48 at 23°C) and finite rate of increase (rm = 0.190 and 0.166 days, respectively). There was no development at 30 and 33°C. The lower temperature threshold (TT) was 7.85°C, the thermal constant (K) 185.87 GD, and the estimation of annual generations ranged from 17.18 to 27.20, between cold and hot regions, respectively. The pesticides deltamethrin, dimethoate, spinosad, fenitrothion, phosmet, malathion, methidathion and zeta-cypermethrin resulted in 100% mortality of adults of SWD three days after treatment (DAT). Fenitrothion, malathion and methidathion have made 100% of the eggs unviable, followed by phosmet and diflubenzuron, which also caused a high reduction in larvae hatching, at two DAT. The species P. vindemmiae was more susceptible to the action of pesticides in relation to T. anastrephae, and the pesticides abamectin, spinosad and spinetoram caused high mortality and reduced parasitism of P. vindemmiae, however did not affect T. anastrephae. The results of the present study are of great importance for the design of field control strategies and the development of laboratory rearing for study purposes.