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通过生物测定比较了9种昆虫病原线虫共生菌对东亚飞蝗Locusta migratoria manilensis4龄蝗蝻的杀虫活性,其中嗜线虫致病杆菌Xenorhabdus nematophila HB310菌株(以下简称Xn HB310)对4龄蝗蝻的活性最高;采用浸叶法进一步测定了Xn HB310菌液对不同虫态的东亚飞蝗的毒力。结果表明:在饲喂96 h后,Xn HB310菌液对2龄蝗蝻、4龄蝗蝻和成虫的致死中浓度(LC50)分别为2.97×105、4.90×105和6.24×105CFU/mL,致死中时间(LT50)分别为51.48、52.59和64.34 h。研究还发现该菌株对东亚飞蝗具有明显的拒食活性,处理48 h后Xn HB310菌液对2龄蝗蝻、4龄蝗蝻和成虫的拒食中浓度(AFC50)分别为1.15×105、2.36×105和3.16×105CFU/mL。通过点滴或剪除东亚飞蝗成虫感觉器官的方法,证实了Xn HB310菌液对东亚飞蝗产生拒食作用的器官是下颚须和下唇须,剪除下颚须和下唇须及两者均剪除的拒食率分别为37.36%、51.28%和100%。研究结果表明,嗜线虫致病杆菌Xn HB310菌液对东亚飞蝗的杀虫速度快且活性高,具有开发为防治东亚飞蝗杀虫剂的潜力。
The insecticidal activities of 9 species of entomopathogenic nematophagids against locusts of Locusta migratoria manilensis 4 were compared by bioassay. Xenorhabdus nematophila HB310 strain (Xn HB310 for short) had the highest activity on the 4th instar locusts, The leaf-decaying method was used to further determine the virulence of Xn HB310 bacterium to different oriental migratory locusts. The results showed that the LC50 of Xn HB310 strain on the 2nd instar, 4th instar 蝻 and adult adults after feeding 96 h were 2.97 × 105, 4.9 × 105 and 6.24 × 105 CFU / mL, respectively. The median lethal time (LT50) were 51.48, 52.59 and 64.34 h respectively. The study also found that the strain had significant antifeeding activity against Locusta migratoria manilensis. The concentrations of antifeedant dietary concentrations (AFC50) of Xn HB310 bacterium against 2nd and 3rd instar larvae and adult adults after 48 h of treatment were 1.15 × 105 and 2.36 × 105 and 3.16 × 10 5 CFU / mL. By spotting or cutting off the sensory organs of Locusta migratoria manilensis, it is confirmed that the organs that Xn HB310 bacterium liquid has antifeeding effect on Locusta migratoria manilensis are the jaws and the lower lip, the cut-off jaws and the lower lip and both the antifeedant Rates were 37.36%, 51.28% and 100% respectively. The results showed that Xn HB310 strain of Xanthomonas oryzae is fast and highly active against Locusta migratoria manilensis and has the potential to be developed as a control insecticide against Locusta migratoria manilensis.