Species Diversity of Rice Insect Pests and Natural Enemies in Organic Rice Paddy Field

Abstract

Natural control of insect pest plays key role in organic rice production. Many species of insect pests and natural enemies have been involved. Species diversity of rice insect pests and natural enemies were carried out in organic rice paddy field at Environmental Entomology Research and Development Center, Kasetsart University, Kampaengsaen Campus during January – May 2009. Rice insect pests and natural enemies were collected from organic rice paddy field every 14 days from planting through harvesting period based on simple random sampling method using sweeping net at 10 times/sampling spot. The total of 3 sampling spots were randomized at each time of the sampling. All insect pests and natural enemies were identified, species diversity was calculated and the relationship to biotic factor: natural enemies and abiotic factors: temperature, relative humidity and rainfall were performed. The total of 52 species of insects and spiders composed of 20 species for insect pests, 25 species of insect natural enemies and 7 species of spiders were found. The highest species number of insects and spiders (46 species) was found during seed filling stage of rice and the lowest number (22 species) was found during seedling stage. Species diversity and species evenness of insect pests were 2.28 and 0.76 whereas those of natural enemies were 2.94 and 0.85 respectively. The species number of insect pests was not related to abiotic factors but it was related to the species number of natural enemies (r = 88.5) (P value ≤ 0.05).