Effects Of Tobacco And Other Host Plants On Development And Susceptibility To Pesticide Of Spodoptera Litura (Fabricius)

Spodoptera litura Fabricius (Lepidoptera: Noctuidae) was a kind of worldwide insect pest and broke out intermittently in china. By rearing of the S. litura on Chinese cabbage, tobacco and sweet potato in the laboratory, the development and production of S. litura was studied on the four different host plants. Toxicity of S. litura fed on different host plants to five kinds of insecticides were measured. And the susceptibility mechanism was studied by means of synergist and enzyme dynamics. Effect of nicotine on development and susceptibility to pesticides were also studied. At the same time, many kinds of pesticides were filtered by topical application method. The main results were as follows:1.The effect of host plants on development and production to S. litura were different. It was showed in the choice trials that the order of adults oviposition preference on different host plants was Chinese cabbage>cowpea >sweet potato>tobacco, and the order of distribution of newly hatched larvae was cowpea>sweet potato>Chinese cabbage>tobacco. The larval duration sequence was tobacco>sweet potato>cowpea>Chinese cabbage, the sequence of larval survival percentage was cowpea>Chinese cabbage>sweet potato> tobacco, and the adults fecundity sequence was sweet potato>cowpea> Chinese cabbage>tobacco. Larvae fed on tobacco showed the highest efficien- cy of conversation of ingestied food (ECI) and efficiency of conversation of digestied food (ECD), but relative consumption rate (RCR) and approximate digestibility (AD) descended. It demonstrated that S. litura had definite adaptability to tobacco.2.Host plants significantly affected the susceptibility of larve to pesticides. Larvae fed on sweet potato showed highest susceptibility to pesticides, while the susceptibility of larvae fed on tobacco to phoxim and emamectin benzoate decreased significantly, and the toxicity of 5th larvae decreased 11.92 folds and 8.24 folds respectively compared with the larvae fed on sweet potato. The susceptibility of larvae fed on tobacco to chlorfenapyr and fenvalerate also...