黄绿绿僵菌对褐飞虱和白背飞虱不同发育阶段的病原性的研究

本文报道了不同孢子浓度下黄绿绿僵菌对褐飞虱和白背飞虱不同发育阶段的易感性和毒力的研究。实验设10.5孢子/mm2,116.7孢子/mm2和1027.1孢子/mm2三种孢子剂量,两种飞虱分为幼龄若虫(1龄和2龄若虫)、高龄若虫(3、4、5龄若虫)和成虫三个发育阶段。实验发现褐飞虱与白背飞虱的三个发育阶段对黄绿绿僵菌的不同浓度的孢子液有不同程度的易感性。黄绿绿僵菌对褐飞虱幼龄若虫的毒力指标LT50在三种孢子剂量下依次为>21、20.82和16.55;对高龄若虫的LT50在三种孢子剂量下依次为17.68、15.49和13.98;而对成虫的LT50在三种孢子剂量下依次为17.10、12.57和9.14。黄绿绿僵菌对白背飞虱幼龄若虫的毒力指标LT50在三种孢子剂量下依次为>21、17.29和13.13;对高龄若虫的LT50在三种孢子剂量下依次为16.94、15.02和13.03;而对白背飞虱成虫的LT50在三种孢子剂量下依次为12.78、10.16和7.64。二者的成虫的易感性比若虫的易感性强,高龄若虫的易感性比幼龄若虫的强。白背飞虱比褐飞虱对黄绿绿僵菌更加敏感。二者的死亡率随孢子浓度的增大而增大。

PATHOGENICITY OF METARHIZIUM ANISOPLIAE VAR.ACRIDU TO THE DEVEOLPMENTAL STAGES OF BROWN PLANTHOPPER NILAPARVATA LUGENS STAL AND SOGATELLA FURCIFERA(HORVATH)

The susceptibility and virulence of entomopathogenic fungus Metarhizium aniso pliae var. acridum to the stages of brown planthopper (BPH), Nilaparvata lugens (Stal) and whitebacked planthopper (WBPH), Sogatella furcifera (Horvath) were investigated under laboratory conditions. Three dosages of M. anisopliae var. acridum ranging from 10.5, 116.3 and 1027.1 conidial/mm2 were used in the experiment. The tested stages of host included three developmental stages, young nymphs (1-2 instars), old nymphs (3-5 instars) and adults. It was found that all tested stages of the planthoppers were susceptible to the fungal infection. The degree of virulence LT50 of M. anisopliae var. acridum against young nymphs of N. lugens are >21, 20.82 and 16.55, respectively with the 3 dosages, the LT50 of the fungus against the old nymphs are 17.68, 15.49 and 13.98, respectively with the 3 dosages; the LT50 of the fungus against the adults are 17.10, 12.57 and 9.14 respectively with the 3 dosages. The degree of virulence LT50of M. anisopliae var. acridum on young nymphs of S. furcifera are >21, 17.29 and 13.13, respectively with the 3 dosages ; the LT50 of the fungus against the old nymphs are 16.94, 15.02 and 13.03, respectively with the 3 dosages; the LT50 of the fungus against the adults are 12.78, 10.16 and 7.64, respectively with the 3 dosages. Adults were more susceptible to M. anisopliae var. acridum infection than their nymphs and the young nymphs were most resistant to the fungal infection. The cumulative mortality of each stage was dosage-dependent. Of all the developmental stages, WBPH was more susceptible than BPH to M. anisopliae var. acridum infection with the same dosages.