The Polyphagous Character Of Spodoptera Exigua (Hübner) And The Evaluation Of Effect Of Different Monitoring And Controlling Techniques

The beet armyworm Spodoptera exigua (Hübner) is a kind of polyphagous insect pest which could cause crop calamity and distributed in the worldwide. In the recent years it has endangered many kinds of vegetables and industrial crops in China. So improvement of its predicting and controlling techniques are demanded urgently. The authors have done a series of experiments in the lab and much more investigation in the fields in order to explore the relationship between beet armyworm and hosts, solve the existed gaps on its forecasting and controlling technique. We want to explain the influence of different host species on the growth and reproduction of the beet armyworm. The effects of predicting and controlling with sex pheromone, the resistance level of different varieties of transgenic Bt cotton and the toxicity and controlling effect of pesticide to the beet armyworm had been tested. The main results were as follows:1. There were the selective taxis difference of laying eggs and larva feed of the beet armyworm among different host species. The order of taxis of laying eggs among host species was: tomato, romaine lettuce, celery, lettuce, spinach, turnip, Chinese cabbage, green vegetables, bud dish. The amount of laying eggs in tomato had occupied 22% of the total amount at the hosts. The larva liked romaine lettuce and lettuce occupied 25% and 20% respectively. The amount of larva liking celery and tomato was very small and only occupied 3% and 1%.2. The larva of beet armyworm feed on different hosts result in the difference of the period of insect growth and development. The population's quality and the influence of reproduction were different, too. The period of growth on lettuce and romaine lettuce was the shorter, only 23.96 days and 24.30 days respectively. But in the celery the period was 29.9 days. The egg stage, pupa stage and moth stage among different host species were similar. But there was big difference in larva stage. In romaine lettuce, the rate of larva survival, pupation and emergence was high to 77.8%, 75.56%, 67.78%, respectively. But in the celery the larva survival rate, pupation rate and emergence rate was only 20%, 15.56%, 12.22%, respectively. There were significant difference on the pupa weight and the amount of single female's eggs among the different host species the larva feed on. The pupa weight in the lettuce was 90.11mg, but the pupa weight in the celery was only 55.33mg. The amount of single female's eggs in the romaine lettuce reached 440, in the celery it only reached 108.74. The results showed the romaine lettuce and the lettuce were the more suitable hosts. The life span of beet armyworm in the romaine lettuce and lettuce was both short, but their population quality and the...