棉铃虫蛹期在极端湿度下的失水动态

Water loss dynamics during the pupal stage of the cotton bollworm at extreme humidities

研究了极端相对湿度 (0 %、9%、2 2 5 %、80 %、90 %和 10 0 %)对棉铃虫Helicoverpaarmigera蛹期发育、存活和水分动态的影响。发育蛹在 2 5℃下 ,相对湿度≤ 9%时 ,不能羽化 ;湿度为2 2 5 %时 ,羽化率不足 2 0 %;高湿不影响它们的存活。在同样温度下 ,湿度≥ 9%时 ,滞育蛹在一个月内都极少死亡 ;在此期间 ,滞育终止率随湿度降低而升高。各湿度处理组发育蛹和滞育蛹从1日龄起的累计失水率都与其日龄呈线性相关。三个低湿处理组发育蛹中死亡个体在死亡前的平均累计失水率都在 32 %以上。滞育蛹经 0 %湿度处理一个月 ,平均仅失水 2 2 4 %;在湿度≥ 90 %时的同期失水率不超过 3 6 %。在 30℃下 ,发育蛹在 4h内测定的表皮渗透力最大 ,分别是 9 0(♀ )和 10 7(♂ ) μg (cm2 ·h·mmHg) ;滞育蛹的相应值出现在 2h内 ,分别为 4 7(♀ )和 5 4(♂ ) μg (cm2 ·h·mmHg)。

Performance and body water dynamics in the pupal stage of the cotton bollworm, Helicoverpa armigera, were investigated at 25℃ and relative humidities (RH) of 0%,9%,22 5%, 80%, 92%, and 100%. The non-diapause pupae failed to emerge at RH≤9% and about 20% of them succeeded in eclosion at 22 5% RH. The high humidities showed little influence on their survival. The diapausing individuals rarely died at all the humidities tested except 0% RH for 30 days, during which the diapause termination percent obviously increased with decreasing humidity. Significant linear relationships were found between the rate of cumulative water loss in both diapause and non-diapause pupae since one-day-old and their ages in day. The non-diapause pupae that died at each of the low RHs lost more than 32% of their body water on the day before death. The mean water loss in the diapausing specimens at 0% RH for one month averaged 22 4% and those at RH≥90% did not exceed 3 6% in the same period. The cuticular permeabilities of pupae determined with different specimens in 2,4, 8,12 and 24 hours respectively were always greater than that obtained with the identical specimens in the corresponding periods except in 2 hours. The maximum permeability of the non-diapause pupae, 9 0 and 10 7 μg·cm -2 ·h -1 ·mm Hg -1 for female and male respectively, occurred in 4 hours while that of the diapausing individuals, 4 7(♀) and 5 4(♂) μg·cm -2 ·h -1 ·mm Hg -1 , appeared in 2 hours.