五种昆虫生长调节剂对韭菜迟眼蕈蚊的致毒作用

为明确昆虫生长调节剂对韭菜迟眼蕈蚊幼虫的毒力差异、作用特点和田间控制效果,采用药液定量滴加法比较了5种昆虫生长调节剂对其不同龄期幼虫的毒力、LC50对4龄幼虫生长发育和繁殖的影响,以及药剂致毒的温度效应和盆栽防效。结果表明:5种昆虫生长调节剂对韭菜迟眼蕈蚊2龄和4龄幼虫的毒力均以虱螨脲最高,LC50分别为0.173 mg/L和0.295 mg/L,氟铃脲和氟啶脲次之,均高于对照药剂辛硫磷;而吡丙醚和灭蝇胺低于辛硫磷。5种昆虫生长调节剂以LC50处理4龄幼虫后,虱螨脲、氟铃脲和氟啶脲对其存活幼虫后续发育历期、成虫羽化率和繁殖力的影响较大,尤其是单雌产卵量较清水对照分别降低72.6%、57.8%和58.1%;灭蝇胺也可使成虫产卵量降低;吡丙醚可引起卵孵化率下降。该类药剂对其幼虫的毒力基本不受环境温度的影响;虱螨脲、氟铃脲和氟啶脲7.5、15 g a.i./667 m2处理对当代4龄幼虫的防效较低,但对下一代幼虫的防效可达93%以上;虱螨脲、氟铃脲和灭蝇胺与新烟碱类的噻虫胺混用,可显著提高药剂的速效性,且持续控制作用好。

Toxic effects of five insect growth regulators on chive gnat Bradysia odoriphaga

Pot tests were conducted by using the dripping ration liquid methods to determine the toxicity and control efficacy of five insect growth regulators (IGRs) to chive gnat Bradysia odoriphaga larvae at different stages. Meantime, the effects of LC₅₀ on the development and fecundity of 4th instar larvae and temperature on the toxicity of the IGRs to B. odoriphaga were also studied. The results showed that the lufenuron had the highest toxicity to the 2nd and 4th instar larvae with a LC₅₀ of 0.173 and 0.295 mg/L, respectively. Based on LC₅₀ values, the order of toxicity levels of the five IGRs tested against B. odoriphaga was as follows: lufenuron >hexaflumuron >chlorfluazuron >phoxim >pyriproxyfen >cyromazine. There were distinctly differences in the individuals that survived the LC₅₀ dose of different IGRs. Lufenuron, hexaflumur and chlorfluazuron could significantly reduce the growth rate, adult emergence rate and fecundity of the B. odoriphaga, especially the fecundity; there were 72.6%, 57.8% and 58.1% reduction rates compared with the control, respectively. Cyromazine could suppress the adult fecundity, while pyriproxyfen had negative effect on egg hatching. On the other hand, the temperature had little influence on the toxicity of all these IGRs. In pot control test, lufenuron, hexaflumuron and chlorfluazuron at a dose of 7.5, 15 g a.i./667 m² had no ideal control effect against the 4th instar chive gnat treated; however, the control of the next generation larvae reached more than 93%. Lufenuron, hexaflumuron and cyromazine mixed with clothianidin could significantly improve their control effects and had lasting effects.