幼虫期营养对甜菜夜蛾生殖力及卵巢发育的影响

幼虫期营养是影响昆虫生长发育及种群动态的重要因素,笔者以周期性和突发性饥饿处理4、5龄甜菜夜蛾幼虫,结果表明,饥饿处理后蛹重下降,蛹期延长,羽化率和成虫交配率降低。以5龄幼虫的突发性饥饿影响最为显著,5龄幼虫饥饿处理36h时,产卵量仅为对照的56.8%。幼虫营养缺乏,可使产卵前期延长,卵期和雌蛾寿命明显缩短。5龄幼虫饥饿处理24h、36h,雌蛾卵巢管长度比对照分别缩短29.1%和36.1%,卵巢鲜重下降28.4%和30.9%。周期性饥饿处理只有5龄处理12h的影响较明显。突发性饥饿处理可引起卵巢内卵黄蛋白含量明显下降。在不同的营养条件下,雌蛾的产卵量与卵巢中的卵黄蛋白含量、产卵量与蛹重之间均呈明显的正相关。

Effect of Larval Foods on Fecundity and Ovary Development of Beet Armyworm Spodoptera Exigua(Hübner)

Effects of larval foods on reproduction, female duration and Vt content of beet armyworm, Spodoptera exigua ,were investigated by stimulating larval feeding habits. The larvals at 4th,5th stadium were raised under the condition of starvation for 24,36 h, others for 4,8,12 h per day. The results indicated that pupal weights, emerging rates, mating rates, eggs laid and female duration decreased when foods decreased. Remarkable effects were found at 5th stadium larvals starved for 36 h at which eggs laid decreased 43.6%. Under the condition of starvation, preoviposition periods gradually lengthened and oviposition periods shortened as foods decreased.When larvals at 5th stadium were starved for 24,36 h,the length of ovary tubes decreased 29.1% and 36.1% than contrasted with controls, respectively. The wet weight of ovaries dropped 28.4% and 30.9%, respectively. The above results also indicated that eggs laid positively correlated with pupal weigh of female pupa. In a word, the effects of starvation on 5th stadium larvals were more significant than those on 4th stadium larvals.