Effects Of Six Kinds Of Fungicides Commonly Used In Rice Fields On The Toxicity And Growth Of Trichogramma Chilonis

The use of natural enemies to control pests is an important issue in China's current and future biological control.Trichogramma is an important egg parasitic wasp of a variety of agricultural lepidopteran pests,and is the most widely used and most successful parasitoid.Does the large-scale use of fungicide adversely affect the survival,development,and reproduction of parasitoid ? In order to provide a scientific basis for the rational use of fungicide in production and the coordination of biological control and chemical control,the effect of prothioconazole,difenoconazole,thifenamide,azoxystrobin,prochloraz and tebuconazole commonly used in paddy fields on Trichogramma chilonis are evaluated indoors in this paper.First,the effect of six fungicides on T.chilonis was determined by the drug film method,and the toxic effect of the fungicide mixture on T.chilonis was determined.Secondly,the effects of six fungicides on the growth and development toxicity of T.chilonis and their offspring were determined by the dipping method and the drug film method.Finally,using Glutathione S-transferases?GSTs?and Carboxylesterase?Car E?detoxification enzymes as indicators,the effect of six fungicides on their activities were determined.The main research results of this article are as follows:1.Prochloraz shows the highest toxicity,with an LC₅₀ of 116.25 mg/L,followed by tebuconazole,and an LC₅₀ of 225.90 mg/L,all of which are medium-risk agents;.Prothioconazole,difenoconazole,thifenamide,and azoxystrobin are relatively safe against T.chilonis,with an LC₅₀ value greater than 2000 mg/L,which are a low-risk agent.The lethal time of prochloraz and tebuconazole was LT₅₀ of 0.27 d and 0.35 d,and which significantly reduced the life span of T.chilonis.The life span of T.chilonis treated with prothioconazole,difenoconazole,thifenamide and azoxystrobin was not significantly different from that of the control.2.The six fungicides have significant differences on the growth and development of T.chilonis indicators and progeny.Both prochloraz and tebuconazole significantly reduced the emergence rate of T.chilonis and caused a significant increase in the rate of deformities.Moreover,prochloraz has a significant reduction effect on the parasitism of F0 and F1 generation of T.chilonis.Thifenamide and azoxystrobin significantly increased the malformation rate of various insect states during development,in addition,the pupal stage treatment reduced the parasitism of its emergent bees.Different treatment methods of difenoconazole and prothioconazole have no growth and development toxicity to T.chilonis and there is no significant difference between the indicators with the control.In terms of sex ratio,the six fungicides had no significant effect on T.chilonis.3.The effect of prochloraz mixed with prothioconazole and thiofuran on T.chilonis 8-24 h were not significantly different from the control,tebuconazole mixed with prothioconazole,azoxystrobin and thiofuran respectively were no significant difference between the survival performance and the control at a specific time period,it indicates that the toxicity of the corresponding mixture has decreased in different stages.4.Further tests showed that prothioconazole,azoxystrobin,and thiofuran induced the activity of GSTs or Car E of T.chilonis increased to some degree.The GSTs and Car E activities of parasitoid were mainly inhibited by prochloraz and tebuconazole during 24 hours,the effect of difenoconazole on the activity of two detoxification enzymes in T.chilonis was not significantly different from that of the control.In summary,this article systematically analyzes the acute toxicity,development,and sex-to-male ratio,teratogenicity,and detoxification enzymes of six fungicides such as prothioconazole on T.chilonis,at the same time,it provides a scientific basis for the rational use of fungicides.Based on this,put forward actual production suggestions,prochloraz and tebuconazole have a greater lethal effect on T.chilonis and growth and development toxicity,and should be avoided during the bee release period;Azoxystrobin and thiafuramide should be used with caution,although it has no lethal effect but has an impact on growth and development;prothioconazole and difenoconazole have good compatibility with T.chilonis.