Effects of Different Lethal Concentrations of Spirotetramat on the Pest Control Ability of Encarsia formosa Gahan
The sublethal effect of insecticides on Encarsia formosa Gahan is one of the main reasons affecting its parasitic ability.The aim of this study was to determine the sublethal effect of spirotetramat on the pest control ability of E.formosa.Population dynamics of E.formosa and parasitic ability of adults were observed and recorded in greenhouse cages with treatments of different lethal concentrations of spirotetramat to E.formosa using residue film method.After exposure to spirotetramat at LC50,the density of E.formosa pupae during vine stage-flowering stage dropped to 20.94 per 100 cm2 leaf,lower than that of the water-treated control.The density of eggs and high-instar nymphs Bemisia tabaci during vine stage-flowering stage reached 161.47 and 46.32 ind.per 100 cm2 leaf,higher than that of the water-treated control.After exposure to spirotetramat at LC10,the density of E.formosa pupae was only 38.14 per 100 cm2 leaf during vine stage-flowering stage,lower than that of the water-treated control.The parasitic rate of E.formosa on B.tabaci was about 60%on vine stage-flowering stage,significantly lower than that of the water-treated control.The temporal and spatial niche overlap indexes of E.formosa and high-instar nymphs B.tabaci were significantly reduced after exposure to different lethal concentrations of spirotetramat.These results show that pestcontrol potential of E.formosa is significantly inhibited when exposed to spirotetramat.
国家科技期刊平台
NSTL
万方数据
