绿僵菌在蝗虫种群中传播流行与其持续控制作用

Epidemic and Sustainable Control of Metarhizium Anisopliae in Grasshopper Populations.

绿僵菌(Metarhizium anisopliae)为蝗虫病原真菌,可在蝗虫种群中流行传播,实现多年持续控制。以亚洲小车蝗3龄蝗蝻为试虫,油剂处理后3天与野外网捕相同虫龄亚洲小车蝗混合饲养,试虫病、健比(单位:头)10∶50、20∶40、30∶30、40∶20,结果显示:病虫可以将绿僵菌疾病传播给健虫,疾病传播几率分别可达24.6%、31.0%、39.0%和52.0%。与健康短星翅蝗蝗蝻混合饲养,疾病传播几率分别可达15.6%、23.5%、32.7%和40.0%。野外圆心处理试验,结果表明:施药区外疾病感染率随时间的推移逐渐上升,处理后40 d施药区外400 m疾病感染率八个方向均值可达8.95%。不同方向疾病感染水平无显著差异,绿僵菌传播主要与草原蝗虫的活动、顺风风向显著相关。野外间隔施药试验结果表明:蝗虫移动扩散的习性可以有效地将病原传播到未施药区域,距离30 m、60m、120m间隔区域,药后49d校正虫口减退率分别达到58.39%、63.41%、57.17%,因此30m、60m间隔施药方式在应用绿僵菌防治蝗虫中有一定应用价值。以2006年绿僵菌油剂处理区为基础,2007年调查411头蝗虫混合种群,39头感染绿僵菌,感染率9.49%;2008年调查532头蝗虫混合种群,8头感染绿僵菌,感染率1.5%。进一步利用绿僵菌M189菌株特异性SCAR标记技术,调查不同年份处理区绿僵菌土壤宿存能力,油剂处理区3年、4年、5年、6年后绿僵菌土壤检出率分别为6.36%、7.69%、9.15%、9.05%;饵剂处理区3年、4年、5年、6年后绿僵菌土壤检出率分别为17.78%、17.54%、16.13%、14.88%。

The entomopathogenic fungus, M. anisopliae, which destroys organization organs of grasshopper, releases toxin causing death and grows, reproduces in the body, can cause epidemic and sustainable control of grasshopper populations. We have studied epidemic of grasshopper with M. anisopliae by cage experiment, results showed that affected grasshopper could spread disease of M. anisopliae to health. When the proportion of affected and health grasshopper was 10：50, 20：40, 30：30 and 40：20, the transmission rate between individuals within same species was 24.6%, 31.0%, 39.0% and 52.0% respectively, while the transmission rate from species occurring early in the season to those occurring late was 15.6%, 23.5%, 32.7% and 40.0% respectively. Disease of M. anisopliae can spread 400 meters far away from spraying area, and the average of infection rates from 8 directions around treatment area was 8.95%. This result indicated that there was no significant difference of infection with fungus from 8 directions, and the epidemic efficiency was correlated with grasshopper activities and downwind. M. anisopliae oil formulation was sprayed on band pattern, and the results showed that moving and feeding behavior of grasshopper could spread disease, an effective control was obtained in non-spraying insecticide area between sprayed bands. Correction population decline rates was 58.39%, 63.41% and 57.17 at 30m, 60m and 120m interval areas after 49 days, therefore, it was valuable for spraying with the fungus on band pattern. The epidemic with the fungus at different years had been studied, result showed that the infection rate of grasshopper were 9.49% and 1.5% after oil spraying one and two years later. Further studies by M. anisopliae M189 strains SCAR specific markers indicated, the detection rate of M. anisopliae in the soil was 6.36%, 7.69%, 9.15% and 9.05% at oil spraying area, while the rate was 17.78%, 17.54%, 16.13% and 14.88% at bait feeding area after 3, 4, 5 and 6 years later.