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大造桥虫是危害大豆的主要食叶性害虫之一。为了明确大造桥虫幼虫发育龄期及各龄期对大豆叶片的取食量,深入研究其取食危害规律,采用离体叶片单头饲养法,系统观测幼虫生长发育及各龄期取食量。结果显示,大造桥虫幼虫共6龄,在27～28℃条件下,幼虫发育历期平均需要19.05 d,其中1龄3.07 d,2龄2.00 d,3龄1.86 d,4龄2.24 d,5龄3.33 d,6龄6.38 d。各龄幼虫的头宽与体长均随着龄期的增长而增大,头宽与体长的生长模型分别为y1=0.178e0.489x(R2=0.997)和y2=1.671e0.519x(R2=0.994);大造桥虫幼虫发育阶段与取食量的关系模型为:叶面积,y1=6.387e1.202x(R2=0.976),鲜叶重,y2=0.467e1.319x(R2=0.949)。整个幼虫期可累计取食大豆叶片面积为17 218.88 mm2,重量为2 669.50 mg。其中4～6龄幼虫的取食量占整个幼虫期取食量的98%以上。因此,从有效控制大造桥虫幼虫危害的角度出发,防治宜在3龄前进行。
Damascus is one of the major leaf-eating pests that endanger soybean. In order to clarify the larvae ’s developmental age and feeding instinct on soybean leaves at various stages, the feeding habits of larvae were studied in depth. The single leaf feeding method was used to observe the growth and development of larvae and the feeding amount . The results showed that the Larvae larvae had a total of 6 instar larvae at 27-28 ℃. The average duration of larvae was 19.05 days. The first larvae 3.07 days, the second instar 2.00 days, the third instar 1.86 days, the fourth latrus 2.24 days 5 Age 3.33 d, age 6 6.38 d. The head width and body length of all larvae increased with age, and the growth models of head width and body length were y1 = 0.178e0.489x (R2 = 0.997) and y2 = 1.671e0.519x (R2 = 0.994). The model of the relationship between larvae ’s developmental stages and their food intake was: leaf area, y1 = 6.387e1.202x (R2 = 0.976), fresh leaf weight, y2 = 0.467e1.319x (R2 = 0.949). The total larvae could accumulate soybean leaves area of 17 218.88 mm2, weighing 6667.50 mg. Among them, the intake of 4 ~ 6th instar larvae accounted for more than 98% of the total larval feeding amount. Therefore, from the perspective of effective control of Dahashi larvae, prevention and control should be carried out before the third instar.