两种表面活性剂对玫烟色棒束孢PF904菌株侵染小菜蛾幼虫的影响

目的]在前期筛选试验的基础上,比较表面活性剂对玫烟色棒束孢Isaria fumosoroseus PF904菌株侵染小菜蛾Plutella xylostella 3龄幼虫的增效作用,获得可提高玫烟色棒束孢PF904防治效果的助剂.方法]通过扫描电镜观察和室内致病力试验,测定喷施分别添加表面活性剂聚二甲基硅氧烷(OF...

Influence of two surfactants on the infection of Isaria fumosoroseus strain PF904 onPlutella xylostella(Lepidoptera: Plutellidae) larvae#br#

【Aim】 Based on our previous screening tests, this study aims to compare the synergism of surfactants on the infection ofIsaria fumosoroseusstrain PF904 on the 3rd instar larvae ofPlutella xylostella， and to screen the suitable adjuvant to improve the control efficacy ofI. fumosoroseusPF904. 【Methods】 After the 3rd instar larvae ofP. xylostellawere sprayed with the spore suspension ofI. fumosoroseusPF904 added with the surfactants PEG-12 dimethicone (OFX-0193) (final concentration 125 mg/L) and naphthalenesulfonicacid, dibutyl-, sodium salt (Nekal) (final concentration 250 mg/L), respectively, the number of attached conidia ofI. fumosoroseusPF904 on the larval body surface and the infection rate and pathogenicity ofI. fumosoroseusPF904 against the larvae were determined by observation with scanning electron microscopy and laboratory pathogenicity test. 【Results】 Adding 250 mg/L Nekal and 125 mg/L OFX-0193, significantly increased the number of attached conidia ofI. fumosoroseusPF904 at various structural areas on the body surface of the 3rd instar larvae ofP. xylostella. The numbers of conidia attached to spinous structural area, gentle structural area and acanthoid structural area on the body surface of the 3rd instar larvae of P. xylostella exposed to the spore suspension ofI. fumosoroseusPF904 with 250 mg/L Nekal were 2.19, 1.78 and 1.94 times as high as that of the control (spore suspension added with water), respectively, indicating that Nekal increases the adhesion rate ofI. fumosoroseusPF904 spores. Adding 250 mg/L Nekal and 125 mg/L OFX-0193, significantly reduced the conidial germination time, promoted the formation of appressorium and increased the infection rate ofI. fumosoroseusPF904. The results of laboratory pathogenicity test showed that adding 250 mg/L Nekal and 125 mg/L OFX-0193, significantly increased the pathogenicity of the spore suspension ofI. fumosoroseusPF904 against the 3rd instar larvae ofP. xylostella. After exposure to the spore suspension ofI. fumosoroseusPF904 with 250 mg/L Nekal, the corrected mortality rate of the 3rd instar larvae ofP. xylostellawas 79.2% and the median lethal time (LT₅₀) was reduced to 2.71 d, indicating that Nekal has a significant synergistic effect. 【Conclusion】 Nekal at the concentration of 250 mg/L is a suitable adjuvant forI. fumosoroseusPF904 to improve its control efficacy againstP. xylostellalarvae.