Abstract

                                Three species of rice stem borers occurred in Tamil Nadu, of which yellow stem borer (YSB), Scirpophaga incertulas (Walker) was more predominant than pink stem borer (PSB). Sesamia inferens, (Walker) dark-headed borer (DSB), Chilo polychrysus (Meyrick) in both Kar (June-September) and Pishanum (Oct-Jan) seasons. The PSB was second most numerous (35.21%) in Kar and was relatively as abundant as YSB in Pishanum (48.43%). The DSB was less common during either season (4.29-7.18%). Varieties had variable compostion of stem borer infestation. The YSB infestation was more from early tillering to maximum tillering stage, decreasing gradually with increasing PSB infestation from flowering stage. YSB was the most common species in all districts. PSB was more abundant than DSB in Coimbatore, Tanjore, Tuticorin, Madurai and Dharmapuri districts, whereas DSB was more numerous in Tirunelveli, Kanyakumari and Vellore districts.

Key words : Stem borer, Rice, Species composition, Relative abundance