Studies On The Interaction Regularity Among Tetranychus Cinnabarinus, Its Predator Enemies And Bt Cotton

Tetranychus cinnabarinus (Boisduval) is a major pest of cotton in China, and it is the dominant species of the cotton field in Hubei province, causing more or less damage every year. The number of Tetranychus cinnabarinus was reported to increase as the transgenic Bt cotton was extended in large area due to the less effective control of its ?predatory enemies. The population dynamics of Tetranychus cinnabarinus has recently been reported in Bt transgenic cotton, however, few systematic research has been conducted with regard to the interaction regularity among Tetranychus cinnabarinus, its predators and Bt transgenic cotton. In order to perfect the safety evaluation and provide technical support for planting of Bt transgenic cotton in the middle reaches of Yangtse River, the interaction regularity among Tetranychus cinnabarinus, its predators and transgenic cotton are systematically studied, and Results are shown as follows:Developmental duration of Tetranychus cinnabarinus fed on different cotton varieties was studied at different stages and temperatures inside the laboratory. The results showed that compared with that fed on non-transgenic cotton, there was no significant difference in the survival rate, development duration and the fecundity of the female adult of Tetranychus cinnabarinus fed on transgenic cotton in different generations at different stages and temperatures(20-35℃). It is revealed that Bt transgenic cotton has no significant impact on the growth and reproduction rate and other life parameters of Tetranychus cinnabarinus. The colony, average life span and form of Tetranychus cinnabarinus fed on different cotton varieties in 12 generations were also studied. Results showed little difference in the net reproductive rate, intrinsic growth rate, average life span, the finite increase rate and the doubling time of population between Tetranychus cinnabarinus fed on transgenic cotton and that fed on non-transgenic cotton in different generations. The predating functional response of propylaea japonica was compared using the Tetranychus cinnabarinus eggs that were reared on the transgenic Bt cotton in laboratory. Results showed that the number of predation increased as the age increased, and the daily maximum predation increased as well. The predating number of propylaea japonica to the preys was far more than that of conventional cotton and the predating functional response was in accord with the Holling II response. Variance analysis showed no distinctive difference in propylaea japonica's prey on Tetranychus cinnabarinus fed either on Bt cotton leaves or on conventional ones.The temporal and spatial niche of Tetranychus cinnabarinus and its predatory enemies in transgenic Bt cotton and conventional cotton field in Mid-Yangtse River...