安徽虫瘟霉在侵染潜伏期内对桃蚜无翅成蚜生殖力的影响

Impact of Zoophthora anhuiensis (Entomphthoraceae) on the fecundity of Myzus persicae apterae during the latent period of its infecti on

在 8个剂量 (0 .48～ 61.15个孢子·mm-2 )下测定安徽虫瘟霉F970 2 9菌株对桃蚜 (Myzuspersicae(Sulzer) ) 2～ 3龄若蚜 (5 7～ 84头 /剂量 )的毒力 ,接种后第 3～ 7d的半致死剂量LD50 分别为 3 .0 9、1.88、1.3 3、1.2 8和 1.2 6个孢子 /mm2 ;致死中时LT50 为 2～ 6d ,随剂量增大而缩短 .将该菌株按 60个孢子·mm-2 的剂量接种桃蚜的无翅成蚜 ,在 10、15、2 0和 2 5℃下其侵染潜伏期分别为 7.2、5 .3、4.9和 3 .9d ,温度与潜伏期呈显著负相关 (r2 =0 .94) .在相同梯度温度下 ,接种成蚜在病害潜伏期内平均产若蚜 7.97头、11.2 0头、11.86头和 11.2 0头 ,与同期对照相比依次下降 5 6.45 %、41.5 8%、3 9.98%和 49.0 2 % .根据日观察数据建立接种后潜伏期内与对照蚜虫的生命生殖力表 ,获得各温度下接种桃蚜的净生殖率 (R0 )均低于对照 ,分别下降 5 8.3 2 % (10℃ )、45 5 4% (15℃ )、43 .11% (2 0℃ )和 5 0 .84% (2 5℃ ) ,内禀增长率 (rm)比对照分别下降 2 4.2 8%、16.98%、14 .12 %和 2 0 .13 % ,表明安徽虫瘟霉感染引发的真菌病害对桃蚜种群增长具有显著的抑制作用 .

An isolate (F97029) of the entomophthoraceous fungus, Zoophthora anhuiensis ( Li) Humber,was bioassayed on the nymphs (instars 2 and 3) of the green peach aph id, Myzus persicae (Sulzer),at the dosages of 0.48～61.15 spores·mm -2 with each dosage including 57～84 numphs. The values of LD 50 were estimate d as 3.09,1.88,1.33,1.28 and 1.26 spores·mm -2 on days 3～7 after inoculat ion,respectively. The LT 50 estimates ranged from 2～5d at 1.31～61 15 spo res·mm -2 ,decreasing with the increasing dosages. These indicate that the isolate was highly virulent to aphids. After M. persicae apterae were inocul ated at the dose of about 60 spores·mm -2 ,the period from inoculation to a phid death was on average 7.2d,5.3d,4.9d,and 3.9d at 10,15,20,and 25℃,respecti ve ly. The above latent periods were significantly correlated to the temperatures ( r 2=0.94abstract During the latent periods at the above temperatures,the fecundity of infected apterae was estimated as 7.97,11.20,11.86,and 11.20 nymphs per aptera. In contrast to those uninoculated,the fecundity decreased by 56.45%,41.58%,39 .98%,and 49.02%,respectively. Based on the life fecundity table established w it h daily observations during the latent periods,the net reproductive rate ( R 0) of the infected apterae dropped by 58.32%,45.54%,43.11%,and 50.84% at the temperatures considered. These contributed to decreases of their intrinsic incr ease rate ( r m) by 24.28 %,16.98%,14.12%,and 20.13%. The results show that Z. anhuiensis infection is of great potential for suppression of M. persicae population increase.