Population Ecology of Ostertagia sp

Zhao Kaiyuan Cai Xuepeng Lu Wenshun Wang Peiya Huang Zhenjia Duan ZhiqinJing Zhizhong Chen Juan Jin Jiashen (Lanzhou Vet Res Inst, CAAS, Lanzhou 730046)Yuan Zhenpu Li Anmin (Gannan Husbandry and Veterinary Institute)

Ostertagia; larvae; population ecology

Under natural conditions, effects of temperature and humidity on the development of larvae of Ostertagia, and their development rules and distribution features under different ecological conditions, were investigated. The results demonstrated that eggs and larvae of Ostertagia did not develop in Gahai districts from December through March, when the mean temperature were 8℃, 11.4℃, 4.7℃ and 2.2℃ respectively. The eggs began to develop in the late of April and only a small number of them developed into first or second stage larvae. During May, the maximum and minimum temperature were 22.2℃ and 4.5℃ and a few third stage larvae appeared. From June to October, a great number of third stage larvae emerged and sheep and cattle were infected. In November, as the temperature was getting down the development of eggs also slow down, and stop after the middle of the month. Thus the grazing time of the grassland can be divided into the safe period (December to April) and dangerous period(May to November). It showed that the development of eggs and larvae directly correlated to temperature and humidity, but the movement and distribution of larvae to humidity of air.