饲料含氮量对棉铃虫发育和繁殖的影响

分别用含氮量为1.48%、2.31%、2.89%和3.64%的人工饲料和嫩棉铃饲养棉铃虫(Heliotkls arraigera),测定6龄幼虫对食物和氮的利用效率,并研究饲料氮对棉铃虫发育和繁殖的影响.结果表明,随饲料含氮量的增加,幼虫发育历期减短,6龄幼虫的干重和食物利用率均有所增加,虫体和虫类的含氮量增高.当饲料含氮量从1.48%增加到2.89%时,氮累积速率(NAR)增长了45%,氮利用率(NUR)增加16%,种群增长指数增加65%.饲料氮从2.89%增至3.64%,NAR值不变,NUR值和种群增长指数分别下降25%和10%.饲料含氮量在1.48%和2.89%之间时,正是棉铃中含氮量变化的幅度,在这幅度间对棉铃虫发育繁殖的影晌最大.饲料含氮量在2.31%至2.89%时,是幼虫生长发育最适宜的范围,成虫繁殖力最强.这是它对寄主作物长期适应的结果.饲料含氮量过高或过低对棉铃虫的发育和繁殖都是不利的.

EFFECTS OF DIETARY NITROGEN ON DEVELOPMENT AND FECUNDITY OF THE COTTON BOLLWORM, HELIOTHIS ARMIGERA (HUBNER)

The utilization and effects of dietary nitrogen on development and fecundity of the cotton bollworm, Heliothis armigera (Hubner), were studied by rearing the larvae on either young cotton bolls or artificial diets in which the nitrogen content was adjusted to be 1.48%, 2.31%, 2.89% and 3.64%, respectively. The results indicated that approximate digestibility, total nitrogen content and dry weight in the sixth instar larvae increased with dietary nitrogen. When dietary nitrogen was increased from 1,48% to 2.31%, nitrogen accumulation rate (WAR), ni-trogen utilization efficiency (NUR) and index of population growth increased by 45%, 16% and 65%, respectively, and the larvae developed relatively fast. When nitrogen content was increased from 2.8.9% to 3.64%, NAR did not change while NUR and index of population growth decreased by 25% and 10%, respectively. Most favourable effect on fecundity of the cotton bollworm would be attained when nitrogen content of the dien was within range between 1.48% and 2.89%, which is just the nitrogen content trend in the cotton bolls. It is clear from these results that either too high or too low dietary nitrogen content will produce unfavorable ef fects on development and fecundity of the cotton bollworm.