浙江早稻谷中稻水象甲的存活研究

Survival of adult rice water weevils (Coleoptera: Curculionidae) during harvesti ng and storage of the first season rice crop in Zhejiang

研究了早稻收获和储藏期间稻水象甲LissorhoptrusoryzophilusKuschel一代成虫的数量动态及其存活时间与温湿度的关系。早稻收割时尚未迁离稻田的象甲中 ,仅 3～ 13%的个体随脱落操作落入稻谷中 ,且这些个体经太阳曝晒 2天后存活率不足 1% ;收割时残留于稻草中的虫量为稻谷中的 5 1～ 12 3倍。储藏 1个月的稻谷中所有成虫均死亡 ,但储藏相同时间的秕谷和稻草中存活成虫分别达到 2 5 0头 5 0kg秕谷和 17头 5 0kg稻草。成虫在≥ 90 %RH下的存活时间显著长于 35～ 75 %RH下 ,在玻璃管中的存活时间显著长于稻谷中。在稻谷中 ,温度对成虫存活时间的影响不明显 ,但在玻璃管中 ,2 0℃ (恒温 )下的存活时间显著长于 2 7 0～ 33 2℃ (室温 )下。利用生存分析的指数模型分析了成虫存活与湿度、温度和存放基质的关系 ,表明在 75～ 98%RH之间 ,湿度越低则成虫死亡风险越大 ,较高温度 ( 2 7 0～ 33 2℃ )和处于稻谷中其死亡风险亦高。这些结果为开展稻谷中稻水象甲的检疫提供了依据。

Numerical dynamics of adult rice water weevils, Lissorhoptrus oryzophilus Ku schel, during harvesting and subsequent storage of the first season rice crop, a s well as relationships between adult survival duration, temperature and humidit y, were examined. During harvesting, only 3-13% of weevil adults were transferre d to stored grain, and less than 1% of these could survive 2-days exposure to t he sun; however, the number of adults transferred to rice straw was 5.1-12.3 t imes more than that transferred to grain. One month after harvesting, no adult w eevils survived in stored grain, compared to 250 and 17 adults per 50 kg survivi ng in stored shrunken grain and straw, respectively. Survival duration of adults at ≥90% RH and in glass tubes was significantly longer than those at 35-75% RH and in rice grain. Survival duration was not evidently affected by temperature for adults in stored grain; however, survival duration at 20℃ (constant temperature ) was significantly longer than at 27.0-33.2℃ (room temperature) for adul ts in glass tubes. Analyses of relationships between survival and humidity, temp erature and substrate using the exponential model of survival analysis revealed that the risk of death increased significantly as humidity decreased in the rang e 75-98% RH, and that the risk of mortality was also higher under high temperatu res (27.0-33.2℃) and in stored grain. These results provide a basis for the quarantine of L. oryzophilus in stored rice grain.