青海省门源草原毛虫取食特性及其防控经济阈值

Studies on feeding characteristics of grassland caterpillar Gynaephora menyuanensis and its economic threshold for control in Qinghai

中文关键词:门源草原毛虫  取食能力  产量损失  防治效果  经济阈值

keywords:Gynaephora menyuanensis  feeding capacity  production loss  control effect  economic threshold

中文摘要:为明确青海省门源草原毛虫Gynaephora menyuanensis的取食特性及其防控经济阈值，在室内条件下观察门源草原毛虫对8种植物的取食偏好及其取食能力；并按照不同虫口密度进行室外笼罩试验，测定不同虫口密度下门源草原毛虫造成的牧草产量损失以及不同生物药剂对门源草原毛虫的防治效果，并根据当年牧草价格、产量水平及防治费用等计算门源草原毛虫的经济阈值。结果表明：在供试的8种植物中，门源草原毛虫较喜食针茅Stipa capillata和垂穗披碱草Elymus nutans，相对取食频数分别为0.33和0.26；4龄幼虫日取食量最高，为40.67 mg/d，5龄幼虫对针茅的利用率和转化率均最高，分别为6.61%和93.94%。将门源草原毛虫虫口密度x与牧草产量损失率y进行回归模型拟合结果显示，线性函数y=0.051x+0.083（R²=0.940）的拟合最好。田间防治结果表明，施药10 d后，球孢白僵菌Beauveria bassiana与金龟子绿僵菌Metarhizium anisopliae混合施用对门源草原毛虫的防治效果最高，为98.92%；其次为金龟子绿僵菌单独施用，防治效果达97.33%。仅用苏云金芽胞杆菌Bacillus thuringiensis Ps3防治门源草原毛虫时的经济阈值为49.35~57.00头/m²，仅用金龟子绿僵菌防治时的经济阈值为45.43头/m²，仅用球孢白僵菌防治草原毛虫时经济阈值为54.25头/m²，金龟子绿僵菌与球孢白僵菌混合施用防治时的经济阈值为90.92头/m²。门源草原毛虫3龄幼虫取食量最小，根据使用药剂造成防治成本及防治效果产生差异性，建议在门源草原毛虫3龄前使用金龟子绿僵菌进行田间防治。

Abstract:In order to elucidate the feeding habits of grassland caterpillar Gynaephora menyuanensis in Qinghai and establish its economic threshold for prevention and control, the G. menyuanensis feeding preferences and its feeding ability on eight plant species were observed under indoor conditions. Cages enveloping tests were conducted using different population densities, and the control effects of different biological agents against G. menyuanensis were also analyzed. We calculated the economic threshold of G. menyuanensis by considering factors such as the price of pasture, level of yield, and prevention cost, providing theoretical basis for the prevention and control of G. menyuanensis. The results showed that among the eight selected plant species, G. menyuanensis preferred for needle fescue Stipa capillata and pendulous lancelet Elymus nutans, with relative feeding frequencies of 0.33 and 0.26, respectively. The highest daily feeding amount (40.67 mg/d) was recorded for the 4th instar larvae, and the 5th instar larvae showed the highest utilization and conversion rates on needle fescue, at 6.61% and 93.94%, respectively. A regression model relating density (x) and forage yield loss (y) yielded the linear function y= 0.051x+0.083 (R²=0.940), which was the best fit. The results of field control showed that, 10 d post-application, a mixed treatment of Beauveria bassiana and Metarhizium anisopliae achieved the highest control effect at 98.92%, followed by the application of M. anisopliae alone at 97.33%. The economic thresholds for the control of G. menyuanensis were 49.35-57.00 individuals/m² for Bacillus thuringiensis Ps3 alone, 45.43 individuals/m² for B. thuringiensis alone, 54.25 individuals/m² for C. albicans, and 90.92 individuals/m² for a mixed treatment of M. anisopliae and B. bassiana. Since the 3rd instar larvae had the lowest feeding rates, considering the cost of control and control effect, it is recommended to apply M. anisopliae for field control before the larvae reach the 3rd instar.