| Popis: |
In an anniversary investigation post inoculative release of Beauveria bassiana against Masson's pine caterpillars in a Masson's pine plantation, 119 strains were isolated from 30 host insects, soil, litter and air. Based on an esterase isozyme analysis, all these strains were assigned to 32 esterase types, suggesting abundant genetic diversity. The esterase type 2 was assigned including 18 other strains from 11 different host insects, indicating that the released strain had successfully survived in different insect populations and persisted in enzootic condition in 12 insect populations including pine caterpillars and grey pine weevils. Other host insects could maintain the food chain when the target insect population was low. The other esterase types included 1-23 strains. The anniversary host transfer dynamics further revealed that B. bassiana could transfer among different host insects in the pine ecosystem. The virulence of the strains of each esterase differed substantially, which suggested that B. bassiana persisted and dispersed along more than one route, and each esterase stood for at least one branch in the food web. Some hosts connected different esterase types at nodal points, making the food web very complicated. In addition, the strains isolated from soil, litter, forest crown and air belonged to different esterase types, suggesting that a complex of saprophytic food chains existed in the plantation, which made the food web more complicated, and benefited the sustainable control of the Masson's pine caterpillar and other pest insects in the ecosystem. |
