Safety Evaluation Of Three Insecticides On Eretmocerus Hayati

Bemisia tabaci Gennadius is one of the main invasive pests in China,which leads to serious economic losses in agriculture and forestry production every year.At present,the control of B.tabaci mainly relies on chemical control.However,the use of insecticides not only has caused serious resistance in B.tabaci,but also caused serious biological and environmental safety problems,such as the toxicity to natural enemies.Eretmocerus hayati Zolnerowich&Rose is the dominant parasitoid of B.tabaci.In this study,the safety evaluation of thiamethoxam,abamectin and sulfoxaflor on Er.hayati was conducted.The main results and conclusions were as follows:The laboratory toxicity of thiamethoxam,abamectin and sulfoxaflor to the pupae and adults of Er.hayati were determined by leaf dipping method.The toxicity of the three insecticides to the pupae of Er.hayati were slightly harmful.According to the risk quotient analysis,it was found that abamectin was safe to Er.hayati adults,while thiamethoxam and sulfoxaflor were slightly to moderately toxic to Er.hayati adults.All the three insecticides showed negative selectivity to the parasitoid adults.The sublethal effects of thiamethoxam,abamectin and sulfoxaflor at the maximum recommended concentration in the field on the pupae and F₁ generation parasitoids were studied by building age-stage,two-sex life table.The longevity and host control efficiency of adults emerged from pupae were significantly decreased after the pupae treated with the three insecticides.After thiamethoxam treatment,the egg-larval stage（9.73 d）,pre-pupa-pupa stage（7.15 d）,pre-adult stage（16.88 d）,mean generation time（19.35 d）,female longevity（6.82 d）and the oviposition period（6.75 d）were statistically shortened,the number of eggs laid per female（65.40 eggs/female）,the net reproductive rate（R₀）,and the host control efficiency of F₁ generation parasitoids were significantly decreased;After abamectin treatment,the egg-larva stage（10.21 d）was shortened,the pre-pupa-pupa stage（7.90 d）and pre-adult stage stage（18.11 d）were significantly prolonged,the number of host-fed and the host control efficiency of F₁ generation parasitoids were significantly decreased;After sulfoxaflor treatment,the egg-larval stage（10.26 d）was shortened,and the pre-pupa-pupa stage（7.23 d）was prolonged,and there was no significant effect on host control efficiency of F₁ generation parasitoids.In general,thiamethoxam had the most adverse effect on the pupae of Er.Hayati,followed by abamectin and sulfoxaflor.The sublethal effects of thiamethoxam,abamectin and sulfoxaflor at sublethal concentrations LC₂₀0 on the adults and F₁ generation parasitoids were studied by building age-stage,two-sex life table.The longevity and host control efficiency of parental adults were significantly reduced and the longevity and oviposition period of F₁ generation were significantly shortened after the parental adults treated with the three insecticides.After thiamethoxam treatment,the pre-pupa-pupa stage（7.45 d）and the preadult stage（17.27 d）was significantly prolonged;After abamectin treatment,the pre-pupa-pupa stage（7.32 d）,the pre-adult stage（17.48 d）,the mean generation time（20.98 d）,and the total preoviposition period（17.75 d）were significantly prolonged,the number of eggs laid per female（98.16eggs/female）and the host control efficiency of F₁ generation were significantly decreased;After sulfoxaflor treatment,the egg-larval stage（9.74 d）and the mean generation time（19.54d）were significantly shortened.The number of eggs laid per female（92.69 eggs/female）,the number of parasitism and the host control efficiency of F₁ generation were significantly decreased.In general,abamectin and sulfoxaflor showed more adverse effects on the adults of Er.hayati,relative to thiamethoxam.