BIOLOGY OF NEOSCONA DOENITZI AND ITS ROLE IN COTTON PEST CONTROL
ZHAO JIKGZHAO JIU FENGXIANG (Laboratory of Pest Natural Enemies, Department u; Biology, Hubei university)
Neoscona doenitzi is one kind of spiders with large population disturbitioa in cotton field as well as in other farm fields, fruit, gardens and forests in Hubei province.Neoscona doenitzi starts to breed inside its egg cocoons as newly hatching spiders in November and moves freely in late March next year. It has three generations per year in Wuhan district. The duration of each generation varies: about 238 days for the overwintering generation, about 45 days for first, and about 33 days for second generations respectively.Under natural condition the duration of generation for female spiders is longer than that of the male ones. After mating once, the female can lay fertilized eggs throughout its life. One female can lay as many as 9 egg cocoons. Each egg cocoon contains 80-90 eggs. The man of eggs laid per female is 475 eggs, the amount of egg laid is influenced by foods. The mean of the hatching rate of eggs is about 90%. Under normal conditions, the life-span of adult spiders is 50 days. The resistance of spiders to unfavorable environment is very strong.The spider preys mainly on cotton pests such as Heliothis 'armigera, Anomis flava, Agrotis ipsilon, Cicadula fasciifrons, Syllepta derogata, Tettigoniella mridis, Ostrinia pa-lustalia, Pectinophora gossypiella et al. and it is good in pest control.