Diversity of coccinellid predators in upland rainfed rice ecosystem.

Abstract

The diversity of coccinellids and impact of pest population on coccinellids density has been studied in the upland rainfed rice agroecosystem in Bharathy variety cultivated in different rice establishment techniques at Hybrid Rice Evaluation Centre, Tamil Nadu Agricultural University, Gudalur. The Nilgiris for three years during Kharif 2010 to Kharif 2012. Three aspects, population of coccinellids and pests in different rice establishment techniques, diversity of coccinellids species in different rice establishment techniques and impact of pest density on the population of coccinellids were studied. A total of 13 species of coccinellids were observed from four different treatments of upland rice crop at different days after transplantation. Among the coccinellids, Cheilomenas sexmaculatus, Coccinella transversalis, B rumoides suturalis, Harmonia octomacula ta and Microspia discolour were predominant during crop season and they have significant positive correlation with the population of brown plant hopper and green leaf hopper. Regression analysis revealed that 71 percent of C. sexmaculatua, 89 percent of C. transversalis, 62 percent of B. suturalis , 79 percent of H. octomaculata and 75 percent of M. discolour population depends on the incidence of BPH and GLH in the upland rainfed rice ecosystem. Diversity indices revealed that diversity of coccinellids was more in the direct sown without weeding operation method than other methods.