Status of Insect Pests and Natural Enemies in MID Hill Rainfed Rice Agroecosystem

摘要

A study was conducted at Hybrid Rice Evaluation Centre, Tamil Nadu Agricultural University, Gudalur during Kharif 2010 - 2012 for documentation of seasonal incidence of pest and natural enemy spectra in the high altitude rice ecosystem. Results revealed that, there were 12 pests belonging to 6 orders and 7 natural enemies belonging to 4 orders. A total of 11 species of spiders from 7 families, 13 species of coccinellids ; one species each of rove beetle and ground beetle were also noticed in the ricefields. A total of 19 species of Odonata belonging to 16 genera representing five families and two suborders were collected from the mid hill high rainfall region of Tamil Nadu. Data on the seasonal incidence revealed that the population of GLH and BPHstarted from the first fortnight of September, the leaf folder and stem borer damage was observed from the third week of September and continued till harvest. Spiders were observed in the field from September first week till the harvest. Peak populationof spiders (4.00 per ten hills) was observed during third week of December. Peak population of coccinellids (2.44 per ten hills) and rove beetles (1.44 per ten hills) were observed during the third week of November and first week of December, respectively. The correlation and multiple regression analysis revealed that, the pest species such as GLH, BPH, leaf folder and yellow stem borer, showed significant positive impact on natural enemy incidence. The results of correlation analysis showed R2 values of 0.98, 0.95 and 0.93 for spider, coccinellid and rove beetle population with respect to availability of pest species.