[Effect of plumular axis-cutted cotton on growth and development of cotton bollworm]

The method of plumular axis cutting was used to induce the resistance of cotton plants to cotton bollworms(Heliothis armigera). The bollworm was cultured in the laboratory, and the effect of induced cotton on the duration of larval development and weights of larvae and pupae was studied. In the treatments of infection and control, the lengths of larval period were delayed by 3 days and 0.5 days, the weights of larvae were decreased by 19.60% and 11.45%, and the pupae weights were decreased by 10.81% and 6.54%, respectively. After the 8 days old larvae were reared with induced cotton leaves for 3 days, the infected and uninfected cutted plants resulted in a decrease of the relative growth rates of larvae by 22.9% and 17.2% respectively, and in a decrease of the relative feeding rates by 26.1% and 21.4% respectively. It is suggested that plumular axis cutting could induce the resistance of cotton plants to bollworm, and influence the growth and development speed of bollworms through retarding their feeding and digestion. Combining with the treatment of Pseudomona gladioli D-2251 strain could obviously increase the insect-resistance of cotton plants.