棘禾草螟生物学特性及其防治研究

棘禾草螟(Chilo hyrax Bleszynski)是蛀食荻芦茎秆的大害虫。近年来,在我省荻芦的被害株率为98％以上,对荻芦的产量与质量影响极大。通过系统调查研究,明确了棘禾草螟是湖南、湖北,江西、江苏等省荻芦最严重的害虫。棘禾草螟在湖南沅江1年发生2—3代,以老熟幼虫多数在荻芦蔸中、少数在残秆中越冬。影响其越冬虫量的因子,主要是收割芦苇时留蔸太高,放火烧苇田不适时或不放火烧苇田。防治棘禾草螟,主要采取“齐泥收割荻芦”;“适时放火烧苇田”;化学防治重点掌握第一代卵孵化高峰期,施用以杀虫双为主的农药。这一综合措施,对控制棘禾草螟的为害效果显著。

STUDIES ON THE BIONOMICS AND CONTROL OF THE AMUR SILVERGRASS STEM BORER, CHILO HYRAX BLESZYSKI

The Amur silvergrass stem borer, Chilo hyrax Bleszyski, is the most serious pest infesting the Amur silvergrass, Miscanthus sacchariflous (Maxim) and Common reed, phragmites commuis Trin in Hunan, Hubei and Jiangsi Provinces.It has two to three generations per year and passes the winter as a full-grown larva, most in the stubbles of Amur silvergrass and some in the stem.The emergence of overwintering Iarvae extends from the end of March to the end of May.The larvae of the first generation occur in the beginning of May. The larvae of the second generation appear in early July. Overlapping of generations occurs. The seasonal life cycle records are presented in Fig.2.Eggs are deposited on the leaf surface, 92.6% of the eggs are deposited on the under surface of the leaf, and 7.4% deposited on the upper surface of the leaf. Newly hatched larvae scattered away immediately and attacked the heart leaf of the host, after the 3rd instar they bored into the stem.When the larva becomes full-grown, it makes an exit passage to the surface of the stem and leaves only a thin membrane and pupates in the stem.Cultural methods, such as harvesting by cutting the reeds as close to the ground surface as possible, removing the reeds out to the field before March, destruction of infested stocks for the control of the Amur silvergrass stem borer are recommended.Several in secticides were tested. Results show that 25% dimehypo SL, 25% Chlordimeform SL, 4.5% parathion-methyl/Trichlorphon Combi. P. and 40% methamidophos EC are highly effective.