单双季稻混栽地区第三代螟虫的发生特点及防治

Characteristics and control of the third generation of rice stem borers in single and double rice cropping areas:

比较了单双季稻混栽地区第三代水稻螟虫在中稻、单晚稻和连晚稻上的发生特点和防治。结果表明，第三代螟虫的发生以二化螟为主，三化螟和大螟数量较少，为害状主要是虫伤株和白穗，枯孕穗极少，中稻、单晚稻的发生量和为害程度显著高于连晚稻，且中稻田最早，连晚田最迟。卵孵高峰期基本上与各稻作的破口至齐穗期相吻合，在破口至齐穗期施用２０ ％ 三唑磷 Ｅ Ｃ 和５ ％锐劲特 Ｓ Ｃ，防效可达８８６ ％ ～１００ ％ 。二化螟幼虫的残留量和分布位置以中稻最高，单晚稻次之，连晚稻最低；二化螟的卵寄生蜂只有１ 种，寄生率７ ％ 左右，幼虫寄生蜂有６ 种，寄生率１５ ％ 左右。并提出了第三代螟虫的防治策略。

The paper compares occurrence characteristics and control of the third generation of rice borers in mid single rice,late single rice and late double rice cropping fields (M SPR,L SRF and L DRF) in areas with single as well as double rice cropping.The results showed that,striped stem borer Chilo suppressalis was the dominant species in all surveyed rice fields,whereas the other two species Scirpophage incertulas and Sesamia inferans only occurred in low population.Injury symptoms were mainly injured rice plant stems and white heads,and relatively few empty heads were observed.Occurrence of stem borers in M SRF and L SRF was significantly higher than that in L DRF. The population occurred the earliest in M SRF and the latest in L DRF,and hatching peak of egg masses were nearly synchronized to the heading period of all kinds of rice.Application of such insecticides as 20% triazophos and 5% fitroni during the heading stage led to control effects of 88.6%～100%, and the remained larval individuals number as well as their distribution position in the rice stems were highest in M SRF and the lowest in L DRF.During the egg and larval stages of C.suppressalis ,one and six parasitoids were found respectively,parasitizing 7% egg masses and 15% larvae.Baseed on these results,we put forward control strategies of the third generation rice stem borers.