การสร้างระบบนิเวศน์ของนาข้าวให้มีความสมดุลอย่างยั่งยืน เพื่อลดการระบาดของเพลี้ยกระโดดสีน้ำตาล

Abstract

Ecological engineering of rice agro-ecosystem was to sustain the balance of biotic organisms both flora and fauna in the whole rice agro-ecosystem. Biodiversity of flora and fauna in both numbers of species and populations could regulate outbreaks of any kind of organisms. For example outbreaks of brown planthoppers (Nilaparvata lugens) which was the most important insect pest in many rice growing countries. The purpose of research was to diversify and increase numbers of populations of natural enemies of rice insect pests by planting vegetables and flowers on rice bunds, in order to provide and increase food, nectars, pollens and shelters for natural enemies. And ultimately, the circle of preys (insect pests) and natural enemies (predators and parasitoids) would sustainable regulate each other in the system. Rice bunds of 20 ha of rice fields were planted with pumpkin, angled gourd, vegetable marrow, wax gourd, okra and sesame. 5 ha of rice fields were monitored for populations of rice insect pests and natural enemies by methods of direct insect count, yellow pan trap and weeping net. Each method was taken at 7 days interval during rice plants were 15-78 days old. A light trap was installed near rice fields. Data were compared between 5 ecological engineering fields (E-E) and 5 farmer practiced fields (control). Results indicated that numbers of BPH in the E-E and control were not significant different. Damage of rice plant by leaf folders and thrips in the E-E fields were lower. In the contrary, number of BPH in E-E fields was 3.4 folds higher by sweeping net, and leaf folder was 2.3 folds higher. Similarly, numbers of predators, spiders and dragonflies were higher in E-E fields. The highest peak of BPH population and the mirid bug (Cyrtorhinus lividipennis) which was the efficient predator also showed on the same period of early September. For chemical insecticide application, E-E fields applied 1.8 times lesser and the net income was not significant different to the control. This shown the ecological rice fields could sustain and balance the system if the ecological services in rice fields could be continue enhanced.