Biological Control Of Pests In Organic Late Season Rice-An Experimental Study Conducted In The Tobacco-rice Rotation Area Of Chenzhou City

This paper reports on the findings of an experimental study in regard to the biological control of pests in organic late reason rice, which taken place at the tobacco-rice rotation area in Qiaoshi town, Guiyang county of Chenzhou City, in the year of2011and2012. The following conclusions can be drawn from the study.The investigation on insect species feeding on rice crops in both organic late reason rice and conventional rice paddy fields were conducted at this production base, through a combined method of field examination and insect trapping lamp.46species, belonging to19families and7orders, were identified.39species found in the organic late season rice filed;28recorded in conventional field and21associated with both. Among which, Nilaparvata lugens Stal, Chilo suppressalis Walker, Cnaphalocrocis medinalis Guenee, Nezara viridulavar.smaragduta Fabri, were recognized as the major pests of the area. On the other hand, natural enemies were examined as well,63species of29families and8orders were documented.52observed in the organic late season rice fields, which considerably outnumbered the41species spotted at the conventional rice fields. Natural enemies found from the fields including Crocothemis servillia Drur, Chrysopa sinica Tjeder, Propylaea japonica Thunbery, T. nitensAudouin Audouin, T. japonicaBoes. Et Str., Rana limnocharis Boie.It is proved that weather conditions had a significant effect on the trapping result according to the experiment carried out onto major pests such as Nilaparvata lugens Stal, Chilo suppressalis Walker, Cnaphalocrocis medinalis Guenee, using frequency oscillation solar energy insect-trapping lamps. The number of affected rice plants contracted with either stem/sheath blight diseases caused by Chilo suppressalis Walker ranged from2.38,2.63and3.88per100crops at various distances of30meters,50meters and70meters away from the lamp, in the study to determine the effective trapping range of the lamps. Slightly different result was obtained when sampling the leaf rolling rice crops induced by Cnaphalocrocis medinalis Guenee, they were2.94,3.47and3.91. Nonetheless, both statistics further supported the conclusion that the lamp should be installed in a range no more than70meters for a desired outcome.The study of Cnaphalocrocis medinalis Guenee’reaction to sex hormones confirmed placing one lure in one single trap is the most effective practice in production. In terms of height, hanging the trap in a position slightly higher up to15cm atop the plant trapped the best. The effectiveness was considerably reduced when the trap was positioned15cm below or30cm above the plant top. The controlled trial of traps located at distance of15meters,20meters and25meters verified the conclusion that the farther the distance was, the fewer insects were destroyed. Among the three, the15m lamp was the one that killed the most adult insects.The rice-duck integrated farming affirmed the effectiveness of pests control through breeding ducks in rice fields. Major insects including Nilaparvata lugens Stal and Chilo suppressalis Walker were significantly reduced, however, the control effect on Cnaphalocrocis medinalis Guenee was not prominent.It’s hoped this report provides some scientific basis in pests ecological control in the organic rice production and has a certain practical value.