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为了明确幼虫密度对草地螟Loxostege sticticalis种群增长的影响,对室内条件下(温度22±1℃,RH70%±5%,光周期16L∶8D)不同幼虫密度[1,10,20,30和40头/瓶(650mL)]饲养的草地螟生长发育及繁殖进行了研究。结果表明:幼虫密度对草地螟幼虫体色、发育历期和存活率,以及蛹重和成虫生殖等有显著影响。随着幼虫密度的增加,幼虫体色黑化程度呈增强趋势,幼虫密度大于10头/瓶时的体色黑化值均显著大于幼虫密度为1头/瓶时的体色黑化值(P<0.05)。20头/瓶的幼虫和蛹历期最短,且随幼虫密度的增加而显著延长(P<0.05)。幼虫存活率以10头/瓶最高,其他幼虫密度的幼虫存活率显著较低(P<0.05)。蛹重以1头/瓶的最重,并随幼虫密度增加而显著下降(P<0.05)。成虫产卵量和交配率分别以1和20头/瓶的幼虫密度最高,幼虫密度升高则产卵量、交配率逐渐降低。成虫产卵历期随着幼虫密度的增加逐渐缩短。雌、雄蛾寿命分别以10和20头/瓶幼虫密度时最长,幼虫密度过高时雌雄蛾寿命又显著缩短(P<0.05)。生命表分析表明,幼虫密度对草地螟种群增长指数有显著影响,以10头/瓶幼虫密度的种群增长指数最高,幼虫密度过高或过低时种群增长指数下降。据此认为,幼虫密度是影响草地螟种群增长的重要因子之一。
In order to clarify the effects of larval density on the population growth of Loxostege sticticalis, the larval density (1, 10, 20, 30 and 40) in laboratory conditions (temperature 22 ± 1 ℃, RH70% ± 5%, photoperiod 16L: 8D) Head / bottle (650mL)] feeding grassland borer growth and development were studied. The results showed that larval density had significant effects on the body color, developmental duration and survival rate of larvae of the larvae, as well as pupal weight and adult reproduction. With the increase of larval density, larvae showed an increasing tendency of body color blackening, and the body color blackening values at larval density of more than 10 heads / bottle were significantly greater than those at larval density of 1 head / bottle (P <0.05). The larvae and pupas of 20 heads / bottle had the shortest duration and significantly prolonged with the increase of larval density (P <0.05). The survival rate of larvae was the highest at 10 heads / bottle, while the larval survival rates of other larval densities were significantly lower (P <0.05). The pupal weight was the heaviest in 1 head / bottle and decreased significantly with the increase of larval density (P <0.05). The adult larvae had the highest fecundity and mating rate of 1 and 20 heads / bottle, respectively. Larval density increased the number of eggs and mating rate gradually decreased. The larvae ’s duration of ovulation gradually shortened as the density of larvae increased. The male and female moths had the longest life span of 10 and 20 heads per bottle, respectively, and the longevity of male and female moths was significantly shortened when the larval density was too high (P <0.05). The life table analysis showed that the density of larvae had a significant effect on the index of population growth of Meadow Stem Borer. The population growth index of larvae at a density of 10 heads / bottle was the highest, while the population growth index of larvae was too high or too low. Therefore, larval density is considered as one of the important factors that affect the population growth of Meadow Stem Borer.