ASSOCIATION OF PHEROMONE TRAP CATCH OF S. LITURA AND H. ARMIGERA WITH FIELD INCIDENCE AND WEATHER PARAMETERS IN TOBACCO, COTTON AND CHICKPEA

Abstract

A study was conducted to understand the association of pheromone trap catch of S. litura and H. armigera with field incidence and weather parameters in tobacco, cotton and Bengalgram in CTRI Research Station, Guntur. It was observed that the peak catch of S. litura moths in pheromone traps in nursery was recorded during the third week of September followed by a decline. Maximum incidence of this pest was observed in tobacco nurseries after two weeks of peak catch of moths was recorded in traps. Thus a general lag period of two weeks was observed between the peak catch of moths in pheromone traps and maximum incidence of the pest in the nurseries. Similar lag period of two weeks was observed between peak moth catch and maximum incidence of this pest in the field crop also. A strong association of pheromone trap catch and field incidence of H. armigera was observed in case of non-Bt cotton when maximum incidence and pheromone trap catch were recorded during second week of November. It was observed that 78-87% variability in pheromone trap catch could be explained by weather parameters in case of S. litura. There was a significant positive association between pheromone trap catch and the rainfall. The variability in the field incidence of S. litura could be explained by weather parameters to an extent of 74-82% in tobacco nurseries and rainfall exhibited a strong positive association with field incidence. In the case of field crop 52- 74% of variability in the incidence of this pest could be explained by weather parameters and here too rainfall had a strong positive association. The variability in the incidence of H. armigera in non- Bt cotton could be influenced by weather parameters to an extent of 78-82% (except during 2008-09) and during these years rainfall had a significant positive influence whereas minimum temperature had a significant negative influence on the incidence of this pest.