用昆虫病原线虫防治韭菜蛆

Using entomopathogenic nematodes for control of chive maggot,Bradysia odoriphaga Yang et Zhang

在15±O.5℃和25±0.5℃下,测定了8个线虫品系对韭菜蛆的致死率和LT_(50),并用筛选出的高毒力线虫品系进行了田间小区试验。结果表明,在15℃下,各线虫品系的 LT_(50)范围为5.31～22.08天,其中PS4线虫对韭菜蛆的毒力最大,LT_(50)为5.31天;在25℃下,供试的线虫对韭菜蛆的毒力明显比在15℃下高,其中PS4品系的LT_(50)为 2.71天。综合在15℃和25℃下对韭菜蛆的毒力,认为PS4是防治韭菜蛆最适宜的线虫品系。在15℃下,120条/ml的线虫剂量侵染韭菜蛆12天的致死率达85.7％,在25℃下,60条/ml侵染8天能达到82.3％的致死率。田间施用线虫后30天,韭菜蛆的防治效果达55.32％,受害株率减少71.37％,防治效果略低于化学农药辛硫磷。

Eight strains of Steinernema and Heterorhabditis were tested for selecting high virulence to chive maggot at 15±0.5℃ and 25±0.5℃.Results showed that S.feltiae PS4 was a potential biocontrol agent against the chive maggot based on LT50 at 25±0.5℃and at 15±0.5℃ The LT50 of the pest larvae exposed to S.feltiae PS4 strain was 5.31 at 15±0.5℃ and 2.71 at 15±0.5℃,respectively.The nematode dose of 120IJs/ml killed 85.7% pest larvae at 15±0.5℃ in 12d after treatment.At 25±0.5℃,the larval mortality caused by 60IJs/ml dosage was 82.3%.Field efficacy of 5.feltiae PS4 strain was examined against chive maggot in Hebei Province,Northern China.The effect was 55.32% and damaged plant decreased by 71.37% at doses of 25IJs/cm2 of S.feltiae PS4 in 30d after treatment.The effect was lower than that of the treatment with phoxin.