嗜菌异小杆线虫H06品系对红棕象甲各虫态的致病力及侵染行为

Pathogenicity and Infection Behavior of Heterorhabditis bacteriophora H06 Strain to Different States of Rhynchophorus ferrugineus Oliver

为阐明昆虫病原线虫(entomopathogenic nematodes, EPNs)对红棕象甲(Rhynchophorus ferrugineus)的防控潜力,采用室内生物测定法研究了嗜菌异小杆线虫H06品系对红棕象甲各虫态的致病力及其侵染行为学特性。结果表明,各虫态红棕象甲被EPNs侵染后,卵的死亡率最高,LC_(50)为104.85 IJs/mL,其次为1~2龄幼虫、3~4龄幼虫和5~6龄幼虫,其LC_(50)分别为165.34、215.31、292.26IJs/mL;7~10龄幼虫和蛹对EPNs的敏感性无显著差异;不同接种部位对不同龄期幼虫死亡率的影响中,3龄幼虫处理以气孔和肛门接种的死亡率较高,分别为91.11%和78.89%,而6龄和8龄幼虫处理中均以口器接种致死率最高;在肛门接种处理中,各龄期的红棕象甲幼虫死亡率无显著差异。经EPNs侵染后,红棕象甲各虫态体色均变成红色或红褐色,轻触虫体无自主反应,同时幼虫伴随体壁皱缩;线虫接近供试虫体表气孔后,会在气孔周围停留片刻,最后从气孔处进入虫体,成功侵入的EPNs个体数量约占33.33%。

In order to clearify the potential of entomopathogenic nemotodes(EPNs)on the control of Rhynchophorus ferrugineus,the pathogenucity of Heterorhabditis bacteriophora H06 against all stages of R.ferrugineus and the be-havior of the invading red palm weevil larvae was studied using laboratory bioassay methods.The results showed that the mortality of eggs was the highest in all stages after R.ferrugineus was infected by EPNs,and LC_(50)was 104.85 IJs/mL,followed by 1‒2 instar larvae,3‒4 instar larvae and 5‒6 instar larvae,LC_(50)was 165.34 IJs/mL,215.31 IJs/mL and 292.26 IJs/mL respectively;No significant differences were observed in the sensitivity between 7‒10 instar larvae and pupae to EPNs.Among the effects of inoculation site on the mortality of different instar larvae,the mortality of the 3rd instar larvae was the highest when inoculated with spiracle and anus,which was 91.11%and 78.89%respectively,while the lethal rate of inoculation with mouthparts was the highest in the treatment of the 6th and 8th instar larvae.No significant difference presented in the mortality of different instar R.ferrugineus larvae when treated with vent inocula-tion.The R.ferrugineus body color changed to red or reddish brown,no spontaneous response when touching,and the body wall of R.ferrugineus shrinked after treated by EPNs.When the nematode approached the spiracle of R.ferrugi-neus larval,it stayed around the spiracle for a moment,and finally entered the insect body,and the number of EPNs successfully invaded was about 33.33%.