Diversity of entomogenous fungi and their hosts and population dynamics of the fungi in a Masson′s pine plantation ecosystem
Ten plots were selected from bottom to top in Mt.Jingtingshan,Xuancheng,southern Anhui Province for detailed investigation of insect cadavers infected by entomogenous fungi.The population dynamics of Beauveria bassiana and Paecilomyces spp.from February 2005 through May 2006 were studied with isolate numbers as the estimate.The result showed that B.bassiana dominated within 16 months of observation,accounting for 54.17% of the total 611 isolates,followed by 3 Paecilomyces spp.which took 43.04%,while B.amorpha,B.brongniartii and Metarhizium anisopliae took only 0.33%,0.98% and 0.49%,respectively.Based on the investigation of diversity of insect hosts of the entomogenous fungi,B.bassiana and P.cateniannulatus had a Brillouin diversity indices are 1.89 and 1.23,respectively,with their respective evenness indices are 0.61 and 0.52,respectively.The diversity indices and evenness indices for P.farinosus and P.fumosoroseus are 1.19 and 0.78,0.49 and 0.32,respectively;the two indices for B.amorpha,B.brongniartii,and M.anisopliae were all very low.The diversity indices of host insects infected by B.bassiana in different seasons displayed a trend of high in summer and low in spring and fall,with the highest index appearing in July(1.77);that of the hosts infected by P.cateniannulatus displayed a trend of low in summer and high in fall,with the highest index in October(1.82);those infected by P.farinosus and P.fumosoroseus displayed a trend of high in spring.Their diversity indices are 1.18 and 1.54,respectively.Therefore,hot and humid summer is suitable for epizootics of B.bassiana,while lower temperatures are suitable for epizootics of the 3 Paecilomyces spp.Their population dynamics varies differently as season changes,suggesting a benefit of sustainable forest pest control in a complementary way.