绿僵菌粗毒素对竹织叶野螟幼虫血细胞的影响

Effects of Metarhizium anisopliae crude toxins on Algedonia coclesalis larvae hemocytes

通过测定不同浓度梯度(200、500、1000、2000、5000 mg·L^(-1))绿僵菌粗毒素对竹织叶野螟幼虫的杀虫活性,及竹织叶野螟幼虫取食绿僵菌粗毒素(浓度为5000 mg·L^(-1))后其血细胞浓度和形态的变化,研究绿僵菌粗毒素对织叶野螟幼虫血细胞的影响。结果表明:以浓度为5000 mg·L^(-1)的绿僵菌粗毒素,采用浸叶法喂食4~5龄竹织叶野螟幼虫9 d后,幼虫的累计校正死亡率达97.37%,致死中时为3.91 d。竹织叶野螟幼虫取食粗毒素后,随着处理时间的延长其体内总血细胞浓度先升高后下降,在处理时间为2 d时达到最大值,为5.92×10^(6)个·mL^(-1),极显著高于对照(P<0.01)。各血细胞中,粒血细胞浓度、浆血细胞浓度均随着处理时间的延长呈现先升高后降低的变化趋势,且均在处理时间为2.0 d时达到最高值,分别为26.99×10^(5)、22.85×10^(5)个·mL^(-1),极显著高于对照(P<0.01);原血细胞、珠血细胞浓度分别在处理时间为1.5、2.0 d时达到最高值,极显著高于对照(P<0.01),随后急速下降;而类绛色血细胞浓度随着处理时间的延长总体呈下降趋势。在对竹织叶野螟幼虫取食绿僵菌粗毒素后其各类血细胞比例分析中发现,粒血细胞比例较高,为42.1%~47.9%,浆血细胞随着处理时间的延长比例显著升高(P<0.05),在处理时间为3.5 d时比例升至最高,为39.9%。显微观察发现,幼虫取食绿僵菌粗毒素后,当处理时间为2 d时,血细胞出现破裂、空泡化、内含物外流等现象。可见,绿僵菌粗毒素对竹织叶野螟幼虫有较强的毒力,且2~3 d对其血细胞的浓度和形态有较大影响。

The effects of Metarhizium anisopliae crude toxins on Algedonia coclesalis larvae hemocytes were investigated by determining the insecticidal potency of different concentrations(200,500,1000,2000,and 5000 mg·L^(-1))of the crude toxins against A.coclesalis larvae.Changes in hemocyte counts and morphologies were then assessed in A.coclesalis larvae,which were fed M.anisopliae crude toxins at 5000 mg·L^(-1) concentration.Cumulative collective mortality after feeding 4 to 5 instar larvae for 9 days with 5000 mg·L^(-1) M.anisopliae crude toxins using the leaf dipping method was 97.37%,and the LT 50 was 3.91 days.After feeding on crude toxins,the total hemocyte concentration in A.coclesalis larvae first increased,then decreased with extended treatment time,displaying a maximum value of 5.92×10^(6) pcs·mL^(-1) when the duration of treatment reached 2.0 d,significantly higher than that of the control(P<0.01).Among the hemocytes,the concentrations of granulocytes and plasmatocytes showed increasing,followed by decreasing trends with prolonged treatment time.Both reached their respective maximum values(26.99×10^(5) pcs·mL^(-1) and 22.85×10^(5) pcs·mL^(-1))when the duration of treatment reached 2.0 d.These values were significantly higher than that of the control(P<0.01);prohaemocytes and spherulocytes reached their maximum densities when duration of treatment reached 1.5 d and 2.0 d,respectively significantly higher than that of the control(P<0.01)then rapidly decreased.Oenocytoid concentration showed a decreasing trend with prolonged treatment time.Our analyses of the proportions of various types of hemocytes in the larvae of A.coclesalis after feeding on M.anisopliae crude toxins revealed a rather high proportion of granulocytes,ranging from 42.1%to 47.9%.The proportion of plasmatocytes increased significantly with prolonged treatment time to 39.9%at 3.5 d(P<0.05).Microscopic observation revealed ruptured,vacuo lated hemocytes that exuded their contents when A.coclesalis larvae fed on the crude toxins for 2.0 d.Collectively,M.anisopliae crude toxins exhibited strong toxicity against A.coclesalis larvae,exerting a huge impact on hemocyte concentration and hemocyte morphology within 2-3 days.