氟虫腈烷基化衍生物对柞蚕饰腹寄蝇的杀虫活性、结构与防效关系

Insecticidal Bioactivity and Structure-activity Research of Fipronil Alkylated Derivatives for Control of Blepharipa tibialis Chao

柞蚕饰腹寄蝇是危害柞蚕的主要寄生虫害之一,其两种传统防治方法(采取蝇毒磷溶液浸蚕和乐果溶液喷施柞树叶面由柞蚕取食)长期使用导致产生抗药性问题。为筛选柞蚕饰腹寄蝇防治新药剂,以氟虫腈为母体化合物合成5种氟虫烷基化衍生物(Fipronil Alkylated Derivatives,FAD),采用熔点测试、IR和1H-NMR确认其结构;以4龄春柞蚕为试虫测定衍生物对柞蚕的毒性,在此基础上设置4个浓度梯度,以5龄大批混养蚕测定了其柞蚕饰腹寄蝇的防治效果。毒性试验结果表明,所合成的化合物对4龄春柞蚕的LC_(50)高于1 300mg/L,毒性较氟虫腈(LC_(50)=182.2 mg/L)大幅下降。防治效果试验表明,编号为2和4的FAD化合物在1 000 mg/L处理后,其结茧率与空白对照结茧率相当,均约为70%,且对柞蚕饰腹寄蝇的防效高于80%。测定化合物的色谱容量因子(logK),计算其疏水参数(logP)、摩尔容积(MV)、拓扑极化表面积(TPSA)、最高占有轨道(HOMO)和最低空轨道(LUMO)的能量之差ΔELUMO-HOMO,进行构效关系分析,推断化合物的logK、logP和MV可能是影响防效活性的主要因素,且增加到一定阈值后,防效会降低。为进一步定量构效关系研究奠定了基础。

Blepharipa tibialis Chao（ B. tibialis Chao） is one of major pests does harm to tussah silkworm. The two traditional ways of control it,of which one is take coumaphos solution to dip silkworm and the other is spraying dimethoate on oak leaves that silkworm Antheraea pernyi feed on,have developed the drug resistance problems due to long-term using. For the seeking of new agents for B. tibialis Chao control,5 Fipronil Alkylated Derivatives（ FADs） were synthesized using Fipronil as the parent compound; their structures were confirmed by melting point test,IR and1 H-NMR. The toxicity of FADs to spring tussah in the 4 th instar larvae were evaluated. On the basis of toxicity results,the insecticidal bioactivity of FADs to B. tibialis Chao were determined by 4 gradient concentrations tests with polycultured spring tussah in the 5 th instar larvae. The toxicity test results showed that the LC50 of FAD compounds to the 4-instar-spring tussah silkworm were all〉 1 300 mg/L,and their toxicity were lower than that of Fipronil. The B. tibialis Chao control results indicated that after 1 000 mg/L treatment,FADs with compound No. 2 and 4 have high cocooning yield,which is equal to the rate of blank treatment（ ≈70%）,and the control effect for B. tibialis Chao are〉 80%. The chromatographic capacity factor（ logK） of FADs were determined,their hydrophobic parameter（ logP）,molar volume（ MV）,topological polar surface area（ TPSA）,the highest occupied molecular orbital（ HOMO）,the lowest unoccupied molecular orbital（ LUMO） and relevant energy difference ΔELUMO-HOMOwere also calculated to analyze the structure-activity relationship of compounds. It＇s inferred that logK,logP and MV are the main factors affect the control activity of FADs to B. tibialis Chao as they increased to a certain threshold,the control activity will decrease. This work lays a basis for further quantitative structure-activity relationship research.