Optimizing the release of Neoseiulus bicaudus to control Tetranychus turkestani on string beans
Author of the article:FU Zhen-Shi；SU Jie；DONG Fang；HAN Guo-Dong；ZHANG Jian-Ping
Author's Workplace：Key Laboratory at Universities of Xinjiang Uygur Autonomous Region for Oasis Agricultural Pest Management and Plant Protection Resource Utilization, The Key Laboratory of Oasis Eco-agriculture, Xinjiang Production and Construction Group, College of Agriculture, Shihezi University, Shihezi 832000, China；Key Laboratory at Universities of Xinjiang Uygur Autonomous Region for Oasis Agricultural Pest Management and Plant Protection Resource Utilization, The Key Laboratory of Oasis Eco-agriculture, Xinjiang Production and Construction Group, College of Agriculture, Shihezi University, Shihezi 832000, China；Key Laboratory at Universities of Xinjiang Uygur Autonomous Region for Oasis Agricultural Pest Management and Plant Protection Resource Utilization, The Key Laboratory of Oasis Eco-agriculture, Xinjiang Production and Construction Group, College of Agriculture, Shihezi University, Shihezi 832000, China；Key Laboratory at Universities of Xinjiang Uygur Autonomous Region for Oasis Agricultural Pest Management and Plant Protection Resource Utilization, The Key Laboratory of Oasis Eco-agriculture, Xinjiang Production and Construction Group, College of Agriculture, Shihezi University, Shihezi 832000, China
Key Words：Neoseiulus bicaudus; Tetranychus turkestani; biological control; release ratio
Abstract：[Objectives] To evaluate the optimal release ratio, release period and release frequency of the predatory mite Neoseiulus bicaudus to control the spider mite Tetranychus turkestani on string beans. [Methods] The number of T. turkestani on potted string beans and outdoor string bean crops was counted at fixed times and locations under different initial mite densities, different release ratios and different release frequencies. [Results] In the indoor experiment, the difference in control between different release ratios (predator: prey) of 1︰1, 1︰5 and 1︰10 was small, with control above 50% in all treatments. However, control following release ratios of 1︰15 and 1︰30 was less than 50%. In the field experiment, a predator prey: ratio of 1︰5 achieved control of above 81.65%, reaching 95.16% on the 28th day after release. Predator prey： ratios of 1︰10 and 1︰20 achieved 64.01% control for 28 days, and a predator prey: ratio of 1︰20 (two releases) was 64.27% the second day after the first release, and above 91.72% on the fourth day after the second release. At an initial high density (60 individuals/plant), the control effect of N. bicaudus on T. turkestani was less than 26%, but at moderate to low initial prey densities control was above 48.44%. [Conclusion] N. bicaudusis is an effective biological control agent for T. turkestani on string beans. To ensure the best results we suggest that N. bicaudus should be released at a ratio of 1︰10 or 1︰20 (two releases) when the spider mite population is relatively low.