嗜线虫致病杆菌HB310菌株对家蚕的毒力及安全性评价

嗜线虫致病杆菌(Xenorhabdus nematophila)HB310菌株与小卷蛾斯氏线(Steinernema carpocapsae)互助共生,对多种寄生害虫具有杀灭作用。为了探讨该共生菌在蚕区大田农作物害虫防治上应用的可行性,研究了嗜线虫致病杆菌HB310菌液和蛋白毒素粗提物对家蚕的生物学安全性。结果表明:HB310菌液对家蚕的急性毒力很低,即使在处理后120h,仍然不能测定其LC50;家蚕对HB310菌液和蛋白毒素粗提物均表现出一定的拒食性,5龄幼虫对2.24×106CFU/mL HB310原菌液和0.57mg/mL杀虫蛋白粗提物的48h拒食率分别达到24.90%和23.05%;HB310菌液及蛋白毒素粗提物对家蚕各龄幼虫体重均有明显的抑制作用,并且随龄期而增大;从蚁蚕开始一直饲喂含HB310原菌液人工饲料的幼虫各龄历期均明显延长,存活率显著下降,到4龄全部死亡;幼虫取食含HB310原菌液人工饲料72h后改饲喂正常饲料,1龄和2龄的历期明显长于对照,但以后各龄历期、化蛹率、羽化率、蛹重和茧层量等各项生物学和经济性状指标均与对照无显著差异;1.12×104CFU/mL HB310菌液和0.11mg/mL蛋白毒素粗提物对家蚕的生长发育无显著影响。综合分析认为,HB310菌株对家蚕低毒性。

Evaluation of Toxicity and Safety of Xenorhabdus nematophila HB310 on the Silkworm, Bombyx mori

Xenorhabdus nematophila HB310 is highly oral virulent to many insects, and is symbiotic with Steinernema carpocapsae. The objective of study was to determine the biological safety of X. nematophila HB310 culture broth and crude insecticidal protein extract on the silkworm, Bombyx mori. The results indicated that acute toxicity of X. nematophila HB310 culture broth was very low, which LC50 could not be detected (LC50>2.24×106 CFU /mL) even at 120 h after toxin-treatment,but high concentration of HB310 culture broth and insecticidal protein crude extract all showed obvious antifeeding activities and growth inhibition to silkworm larvae. The antifeedant rates of culture broth(2.24×106 CFU/mL)and insecticidal protein crude extract(0.57 mg/mL)to 5th instar larvae was 24.90% and 23.05%, respectively. The larvae with toxin-feeding treatment in short time (just at 72 h) or the low concentration of HB310 culture broth (1.12×104 CFU/mL) and crude insecticidal protein extract (0.11 mg/mL) showed no effect on the growth and development of 3th-5th instar larvae, pupation rate, cocoon weight, pupa weight, cocoon shell weight, emergence rate and fecundity of adult. The above results indicated that HB310 was low toxicity to the silkworm.