1Andhra Pradesh Agricultural University, Rajendranagar, Hyderabad-500 030 (India).
2Directorate of Rice Research, Rajendranagar, Hyderabad-500 030 (India).
3Natural Resources Institute, Chatam Maritime, Kent, U.K.
During 1991–92 wet and dry seasons, a controlled release formulation comprising (z)-9-hexadecenal and (z)-11-hexadecenal in 1:3 proportion with PVC matrix as base was evaluated for its potentiality to disrupt pheromone mediated communication in yellow stem borer, Scirpophaga incertulas Walker, infesting rice. The pheromone dispensers stapled on top of 1.0 m bamboo sticks were fixed in rice field at 20 days after transplanting. On the basis of trapping depression index, high levels of communication disruption of 97 and 86 per cent were achieved in the first season with dispensers spaced at 4 and 5 m apart with pheromone application @ 40 m 50 g a.i/ha, respectively. Later, at a constant spacing of 4 m (625 dipensers/ha) communication disruption indices at 10, 20 and 40 g a.i/ha were 85, 100 and 98 per cent, respectively. Evidently, at as low as 10 g.i/ha, the potentiality suggests the possibility to achieve mating disruption of S. incertulas through this controlled release formulation.
