核型多角体病毒对草原毛虫的毒力测定

BIOASSAY ON VIRULENCE OF THE NUCLEAR POLYHEDROSIS VIRUS AGAINST GRNAEPHORA QINGHAIENS1S LARVAE

从青海草原毛虫自然罹病死亡的幼虫体分离出多株核型多角体病毒，选出毒力较强的ＧｑＮＰＶ－８７株，并进行生物学特性测定，方差分析表明，１．２５×１０＾２￣１．２５×１０＾８ＰＩＢ／虫间７种剂量感染３龄幼虫，不同剂量间的校正死亡率差异极显著，而各处理死亡均数差异显著性测定中，１．２５×１０＾７￣１．２５ ×１０＾８ＰＩＢ／虫差异不显著，剂量和死亡率回归方程为Ｙ＝２．３２７９＋０．

Bioassay of an isolate of Gynaephora qinghaiensis nuclear polyhedrosis virus G_qNPV-87 was conducted in natural Qinghai grassland on the third instar lavae of grassland caterpillar which in- dividually reared on wheat leaf contaminated with the polyhedra.The regression equation be- tween dosage and mortality was Y=2.3279+0.5492X(on the seventh day).The LD_(50)value and 95% fiducial limits were 7.3357×10~4PIB/larva and 6.2399×10~4～8.6239×10~4PIB/larva.The LT_(50)values for 1.25×10~5,1.25×10~6 and 1.25×10~7PIB/larva treatments were 9.8,6.5 and 4.1 days,respectively.Larvae mortality was rising with the increase of concentration of polyhedra, whereas the relationship of the concentration-time and mortality was reversed. The median lethal time(LT_(50))of the G_qNPV was shortened with the increase of the virus concentration and the decrease of the larvae instar,during whith the G_qNPV was fed.The most favorable temperature for the G_qNPV inlection was about 20～25℃.In this range of temperature, the LT_(50)was shortened obviously.