Differential pheromone trap efficiency in the mass trapping of yellow stem borer, Scirpophaga incertulas in rice ecosystem

Abstract

Factors affecting differential pheromone efficiency in the mass trapping of yellow stem borer, Scirpophaganincertulas (Walk.) were studied in rice ecosystem of eastern India. It was observed that trapping did not accurately indicate the overall pest pressure as trap catches were influenced by the efficiency of lure, trap location, population density of virgin female and bio-meteorological relation of that particular locality. Detection of the factors that affect the capturing efficiency of pheromone trap should be the primary concern in the development of mass trapping systems. Further study on replacement of lure at certain interval after installation of funnel trap in rice field showed that numerically pheromone lure (one to two replacements) are equally effective and significantly better than control. The assessment of optimum height/level of pheromone lure showed that the trap height at above crop canopy captures higher than the nearer to the ground level. At the initial stage of the crop growth, the trap should be at least one foot above crop canopy but gradually it should be almost at the canopy level for getting maximum trapping of adult moths in rice ecosystem. The effect of population density of virgin female showed that the pheromone trap efficiency was also lower in second and third generation as compared to first generation. Significant decline in pheromone trap catches with increasing female population densities, evaluated by light trap catches, was detected in three different generations. The studies on bio-meteorological relation showed that high temperature and maximum sunshine hour were directly or indirectly responsible for maximum trapping of adult male moth of rice yellow stem borer during the month of August to November in the eastern India.