Toxical Effects Of Insect Growth Regulators And Other Insecticides To Bradysia Odoriphaga

Bradysia odoriphaga Yang et Zhang, commonly called as chive maggot, belongs to Sciaridae Diptera. It is an important underground pest threatening greenhouses chives and difficult to prevent. Highly toxic insecticides are usded on production abusely and blandly, which leads to insecticides resistance, pesticide pollution and harm to human health, restrict leek production. Insect growth regulators (IGRs) were known as the "third generation pesticides’. It is safety to human and animal, and environment-friendly. This paper compared the toxicity of IGRs to the different stages of odoriphaga, observed the sublethal effects of insecticides on the growth, development and reproduction, and studied its characteristics. The purpose is to screen IGRs pesticide both efficient and secure for controlling odoriphaga, clear mode of action on the three types of IGRs and study on the temperature effect of different kinds of insecticides to odoriphaga, then to select the efficient combination. This objective of this paper is to reduce product pesticide residue and effectively control the pest to provide a theoretical basis and technical support through rational use of insecticides. The main results were as follows:1. In order to determine the pesticide toxicity,14different types of insecticides on2th and4th instar larvae of odoriphaga was detected using the dripping ration liquid methods, we can see that the toxicity of IGRs, neonicotinoids insecticides were higher, and botanical, insecticides relatively low toxicity. The toxicity of chitin synthesis inhibitor (CSI) are very high in the IGRs, which lufenuron LC50up to0.295mg/L; the toxicity of hexaflumuron and chlorfluazuron were similar, LC50was0.475mg/L and0.419mg/L respectively; juvenoids pyriproxyfen followed, LC50was3.874mg/L; while toxicity of cyromazine belongs to ecdysone hormone analogs (EHA) is relatively low, LC50was only12.249mg/L. The toxicity of lufenuron hexaflumuron and chlorfluazuron were also higer than methomyl. The results also show the toxicity tendency between2th instars and4th instars of odoriphaga was apparently, no significant difference. Virulence factor was froml.70to2.20. But the insect growth regulators’effect is slow,4th instar larvae need treatment observation period to pupation, in order to more fully demonstrate the toxicity of such insecticides. This has a greater theoretical and practical significance on biological specificity determination and application of pesticides.2. The effects of4IGRs were treated on sublethal dose to odoriphaga. All them have an adverse effect on development and fecundity. However, there were differences between the different types. When the4th instars were treated by sublethal dose of CSI lufenuron were greater than compared to control larvae, and larval developmental period prolonged0.57days, pupal emergence rate decreased by52.8%, male and female pupal weight decreased by26.3%and32.9%respectively, fecundity was only36.8,72.6%lower than the control, and egg hatchability29.2%lower; When the4th instars were treated by sublethal dose of hexaflumuron, compared to control larvae of larval developmental period prolonged2.39days, and larval developmental period prolonged0.76days, eggs laid per female reduced by50.3%, egg hatch rate reduced by44.2%. This showed the impact of CSI greatest fecundity. After the cyromazine to EHA treatment, mainly affecting its fecundity,43.2%lower than the control,, the difference was significantly better than lufenuron; after the pyriproxyfen to JHA treatment to, larval developmental period prolonged2.2days, and egg hatchability29.2%lower.3. In the Discussion on several IGRs’mechanism found, after lufenuron, hexaflumuron to LC50concentrations4th instar larvae, their metabolism enzyme carboxylesterase activity was significantly inhibited, but the apparent activation of acetylcholinesterase activity and phenol oxidase are. After juvenoids pyriproxyfen treated4th instar larvae, carboxylesterase activity of acetylcholinesterase inhibition significantly, but the phenol oxidase activation has a significant role.4. When hexaflumuronand lufenuron mixed with clothianidin, clothianidin mixed with nicotine, azadirachtin, matrine, garlic oil respectively, found that clothianidin and hexaflumuron1:1, clothianidin and lufenuron1:2; clothianidin and nicotine1:2,1:4, clothianidin and azadirachtin1:2,1:4,1:8, clothianidin1:2mix with garlic oil, both showed synergism. Which clothianidin and azadirachtin by co-toxicity coefficient1:2mix after the highest, CTC was162.6, the most significant synergies.5. Experimental of temperature effect results show that no significant effect on the temperature of the IGSs efficacy. Under three different given temperatures, the toxicity of was Just1.21to1.44times. While methomyl, clothianidin and imidacloprid, were showed the positive temperature effect, imidacloprid showed the most obviously positive temperature effect, the toxicity in24℃is only3.41times higher than in8℃.6. In pot test:insect growth regulators’larvae corrected mortality were lower to the contemporary of Bradysia odoriphaga, only18.9to34.5%. The corrected mortality can increase up to94%when were treated in the7.5mg/L15mg/L of hexaflumurona and30mg/Llufenuron. When clothianidin and its mix of contemporary significantly increased larval mortality correction to72.0to81.7%, the second generation of larvae reached the corrected mortality more than95%; Clothianidin halving the dose mixed with azadirachtin, the larvae corrected mortality were83.1%, no significant difference between the results of a single dose of clothianidin. After the mixing not only improve fast-acting and extend the effective, it is worth to be extending and applicating.