温度对小菜蛾(Plutella xylostella L.)发育和繁殖影响的研究

EFFECT OF TEMPERATURE ON THE DEVELOPMENT AND FECUNDITY OF PLUTELLA XYLOSTELLA

小菜蛾为长春、公主岭一带春甘蓝夏甘蓝的主要害虫。本研究测定了其各虫态的发育历期,存活率,成虫产卵量及寿命。得出发育起点温度,有效积温和内禀增长率等参数,并测定了小菜蛾的过冷却点和高温下的存活率。结果:全世代发育历期21℃,26.5天;24℃,20.4天;27℃,16.2天;30℃,14.8天;33℃,13.2天。发育起点温度9.54℃,有效积温298.7日度。温度升高,幼虫存活率下降;卵和蛹的存活率高于幼虫。产卵最适温度24℃～27℃,平均产卵量400粒/雌,最多596粒/雌。产卵开始后的3～5天内为产卵高峰。内禀增长率较高,30℃时高达0.2711,属r型生态对策。过冷却点:四龄幼虫—13.5℃,蛹—20.1℃。预蛹—11.3℃。35℃以上高温对幼虫化蛹极为不利;40℃高温对成虫羽化极为不利,35℃以上高温下饲养低龄幼虫可产生小形蛾。

Diamondback moth, Plutella xylostella L. have caused much serious damage on spring and summer cabbage field in Changchun, Gongzhuling and other regions in northeast of China in recent years. The experiments on effect of temperature on the developnent, fecundity and longevity of adult were carried out in 1988 and 1989. The durations of one generation are 26.5, 20. 4, 16.2, 14.8 and 13.2 days at 21, 24, 27, 30 and 33℃, respectively. Threshold temperature of development is 9.54℃and thermal constants is 298.7 daydegree. Survival rate of the larvae decreases with temperature increasing, and is less than that of eggs and pupae. The suitable temperature for adult deposting is at 24—27℃and the fecundity is 400 eggs/female, the maximum is 596 eggs/female. Most of the eggs ks laied in 3—5 days after begining of deposit.Based on above results, the intrinsic rate of increase(r)and other parameters of populations at different temperatures were calculated. The intrinsic rate of increase was 0.1472, 0.2232, 0.2684,0.2711and 0.2670 at 21, 24, 27, 30 and 33℃, respectively. The results show that diamondback moth is one of r—organisms on ecological strategy.The super cooling points of 4th instar, pupa and prepupa are —13.5, —20.1 and—11.3℃, respectively. The survival rates of larvae and pupae at high temperature were tested and the results indicated that the temperature over 37℃had harmful effect on pupae, and over 40℃ on emergence of adult. The small moth, which did not have reproductive ability, was produced by rearing the young instar at high temperature conditions.