Studies On The Biological Character Of Cotton Bollworm Of The Cotton Field And Its Ecological Management In Jingyuan County

The biological character and the ecological management of the cotton bollworm of the cotton field in Jingyuan county was researched systematically between 2003 and 2004.The biological character of the cotton bollworm suggested that it had 3 generations a year, and hibernates with pupa, its larva did harm to the browse, group top, top, tip, flower and boll, the harmful period was about 70 days. The larva possessed 4 body colors, they wore green, light green, yellow and white, light red respectively, and green was the major color, the rate of the four body color was 10.81:3.66:3.25:l.The ova distributed on the browse, tip etc, 62.5% ova the first generation laid on the top of the browse of the cotton, 83.01% ova of the second generation on laid on the young tip 76.09% ova of the third laid on young tip and group top.The major ecological management of the cotton bollworm was that it could clean 65.33-74.60% ova by manual pinching during the full egg-laying period of the second generation of the cotton bollworm , and average clearance was 69.29%. Plonghing and irrigation in winter increased the mortality of the hibernating pupa to 43.05%, between it and the contrast had significance of difference, it lighten the occurrence degree of the population of the cotton bollworm of the next year .The using of disinsection light decreased 42.75% larva and 55.66% egg-laying and 7.48% harmful boll, and between the third generation and unlight district had significance of difference. Through investigating the selection and harmful degree of the egg-laying of the cotton bollworm of different variety, we found the new Luzao No.7 and the other variety had significance of difference in the egg number per one hundred plants, the rate of the harmed plants, and the rate of harmed boll, The new Luzao No.7and Zhong mian suo No39 which were suit for growing in the local were screened .The result of growing the maize trap strips (cotton: maize =6:1) was that the egg and larva number on the maize filaments was 4.37and 1.27 times the number of the cotton .The screening experiment of the pesticides showed that the 48% chlorpyrifos oil had the highest correction controlling effect after dealing 3d , its controlling effect was 98%, the next was 35% endosulfan oil ,its controlling effect was 94.8%, the variance analysis indicated that between 48% chlorpyrifos oil and 35% endosulfan oil and the other pesticides had significance of difference ,they were the effective pesticides to control the cotton bollworm .