Studies On Biological Control Of Tobacco Insect Pests In Linyi

Myzus persicae and Helicoverpa assulta are the two most important tobacco pest insects in Linyi, Shandong Province, resulting in serious effect to tobacco yields and quality. This paper mainly aims on the occurrence dynamics of the key tobacco pest insects in Linyi, the control effect of natural enemies and biopesticides on Myzus persicae and Helicoverpa assulta, the screening of effective biological management, to meet the requirement of IPM in Linyi tobacco fields. The results are showed as followings.The occurrence dynamics of main pest insects and their natural enemies were found out. The results indicated that the population dynamics of Myzus persicae in tobacco fields appeared as single peak curve, with peak period in late May or early June. With time increasing, the population of Myzus persicae delined. The larva in mixed population of Helicoverpa assulta and Helicoverpa armigera damaged tobacco after middle June, and two peak appeared including the first in late June or early July, and the second in late July or early August, with the greater population in the second than the first. The natural enemies of insect pests in tobacco fields mainly include predator (ladybird beetle, lacewings, hover flies) parasitoid (Aphidius gifuensis, Campoletis chlorideae).The effect of different ratio of ladybird to Myzus persicae on the control of Myzus persicae were studied with heterochromatic ladybirds. The results showed that the increased ratio of ladybird to Myzus persicae might result in the better control effect to Myzus persicae. The control effect of 90% would be achieved in five days in different ratio of ladybird to Myzus persicae.The control effects of ricinoleic acid, nicotine and pyrethrins on Myzus persicae, Matrine, emamectin-benzoate and abamectin on Helicoverpa assulta were also tested in tobacco fields. The results showed that the five biopesticides exhibited preferable control effect with persistent period over seven days. The operation key of the above biopesticides were put forward.The trapping effect of three traps on Helicoverpa armigera in tobacco fields were compared. The maximum pheromone trap catch and relatively stable trap effect were foud in the cone trap. No significant difference appeared between the pheromone trap catches of tray trap and water tray trap. The cone trap was more favorable for large area trap and insect pest forecast.