利用4种因子预测小地老虎的发生趋势

Prediction of Agrotis ypsilon( Rottemberg )Occurrence Tendency by Using 4 Factors

山西省忻定盆地的小地老虎一年发生3代,以第1代幼虫为害为主。第1代幼虫的发生为害程度与当年越冬代成虫始见期和4月份的降水、气温等有着密切的关系,总的趋向是在成虫始见期早、成虫量大、4月份降水量多、气温高的情况下,小地老虎发生的几率较大。将利于小地老虎发生的影响因子与其为害程度一一对应,把1 a中具备3个以上有利因子的年份界定为偏重或大发生年,把具备2个有利因子的年份界定为中度发生年,把出现0～1个有利因子的年份界定为偏轻或轻度发生年,于5月上旬初即可做出比较准确的发生趋势预报。在实际操作中,以4个因子为基础,结合耕作环境等全面考虑,还可进一步提高小地老虎预测预报的准确性。

Agrotis ypsilon has 3 generations annually in Xinding basin, and damages caused by larve of the first generation are the most serious. Occurrence period and damage degree of the first generation larva are closely related to early dates of overwintering adults, rainfall and temperature in April, and so on. The main trend is that A. ypsilon is more likely to occur under the condition of earlier dates of overwintering adults, larger population of adults, more rainfall and higher temperature in April. One-to-one correspondence between impact factors and occurrence degree were established. Year with 3 or more, 2 and 1 or less favourable factors was defined as severe, moderate and mild occurrence year, respectively. In practice, the accuracy of prediction could be further improved based on the 4 factors as well as cultivation environment.