Influences Of The Host Plant To The Population Dynamics Of Tetranychus Turkestani Ugarove & Nikolski

The strawberry spider mite: Tetranychus turkestani Ugarove & Nikolski is the dominant species in thespider mite population, which.not only damages cotton and vegetables, but also"Special local products"such as Kourle pear and apple. Experiments were conducted to study the population characteristics of T.turkestani on the host plant, damage distributions on different Cotton species and population dynamics of T.turkestani and its natural enemies .The research results are as follows:1. Life tables of T. turkestani on different species of host plantThe life table of experimental population of T. turkestani was established at constant temperature of26±1℃, illumination time of 16 hours per day and humidity of 60±10%. The experiment result indicatedthat the value of the innate capacity of increase was 0.2243, 0.1956, 0.1776, 0.1763, 0.1233 on the soybean,upland cotton, kidney bean, eggplant, island Cotton. When the age distribution of experimental populationwas steady, the amounts of the immature age were 86.8428%, 88.3895%, 82.5008%, 85.6257% and77.2806% on five host plants respectively and the amounts of the adult 13.1572%, 11.6105%, 19.2892%,14.7138% and 22.7194% correspondingly. The reaction time to the adverse environment causing 99%death rate of T.turkestani was less than 30 days on the host plants except the island cotton.2. The population dynamics of T. turkestani and its natural enemies on different species of CottonA field survey of strawberry spider mite, T. turkestani and its natural enemies was conducted in thesummer 2005 in the experimental station in Kourle Xinjiang (86.12o E；41.45oN). The population of T.turkestani increased in June and July,reached its peakon l24th July (34.3±22.9 spider mite per plant) on theupland Cotton.The population of spider mite increased with the less number on the Island cotton, andreached its peak in first week of August, and the mean population number was 6.13±0.92 spider mite perplant. The population number was significantly more in upland cotton than that in island cotton.Thepopulation remained static up to first week of August and then decreased gradually．However,thepopulation of natural enemies was at par in upland and island cotton．Among the natural enemiesThripadae (R=0.63699,P=0.0003) on upland cotton and Chrysopedae (R=0.48681, P=0.0295) on islandcotton were negatively correlated with the population dynamics of this pest．The population of natural...