Impact of Zoophthora anhuiensis (Entomphthoraceae) on the fecundity of Myzus persicae apterae during the latent period of its infecti on
LI Huiping, FENG Mingguang
2001, (5):
749-753.
Asbtract
(
0 )
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 LD50 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 LT50 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 (r2=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 (R0) 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 (rm) 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.
