海南省撩荒地生态系统飞蝗的持续控制

ON THE SUSTAINABLE MANAGEMENT OF ORIENTAL MIGRATORY LOCUST DWELLING IN ABANDONED LAND ECOSYSTEM IN HAINAN PROVINCE

针对海南蝗区飞蝗每年发生4代、世代重叠、发生为害时间长等特点,提出了应用蝗虫微孢子虫持续控制海南蝗区飞蝗灾害的新技术。研究结果表明,在第2代飞蝗发生期应用蝗虫微孢子虫防治低、中密度蝗群和采用蝗虫微孢子虫与卡死克互补协调应用技术防治高密度蝗群,处理后5周,校正虫口减退率分别达76.6％～97.2％和79.8％～88.3％;且存活蝗虫感病率分别达33.6％～95.0％和23.3％～26.7％。蝗虫微孢子虫防治第3代高密度蝻群,处理后2周,校正虫口减退率达50％左右,群居型蝗虫占整个蝻群的比例下降了90％以上,存活蝗虫感病率也在10％以上。1998年蝗虫微孢子虫处理地区,1999年蝗虫的虫口密度仍在防治指标以下,且存活蝗虫感病率达10.5％～31.3％。初步认为,在低、中密度下,每hm^2施用30个单位的微孢子虫,在高密度下,每hm^2施用45个单位的微孢子虫及卡死克(105ml/hm^2)与微孢子虫(60单位/hm^2)协调应用技术治理蝗群,均能达到预期效果。

In the light of the occurrence characteristics of oriental migratory locust ( OML) Locusta migratoria manilensis (Meyen) in Hainan Island, namely, four (the most in China) generations a year, generation overlapping and long damage duration, etc. , a new set of techniques by mainly applying the microsporangium Nosema locustae and sometimes cascade (one of the acylurine chemicals having acdysis inhibition activity) in addition for sustainable management of the locust disaster originally from abandoned land was developed. In 2nd generation, to use N. locustae only against the lower and middle densities of OML population and combinedly use microsporangium and cascade for suppressing the high density OML population. Five weeks after the two treatments, the corrected population decrease rates attained to 76. 6% - 97.2% and 79. 8% - 88. 3% , respectively, and the infection rates of the survival locusts were 33.6% -95.0% and 23.3% - 26.7% , respectively. As to singly use N. locustae against high population OML nymphs in 3rd generation, the corrected population decrease rate at the time two weeks after treatment was around 50% , the proportion of aggregationtype nymphs to the whole of the nymphs was more than 90% reduced, and the infection rate of the survivals was more than 10% . In microsporangium treatment plot treated in 1998, the population density of OML one year later (1999) was still under the action threshold. It was indicated that, to use 3 billion spores/hm2 of N. locustae against lower/middle density OML and coor-dinately use 4.5 billion spores/hm2 of N. locustae or 6.0 billion N. locustae spores + 105 ml of cascade per hectare against higher density OML were good enough to keep the OML population under control in at least two years.