Some factors affecting the reliability of pheromone traps for measurement of the relative abundance of Helicoverpa punctigera (Wallengren) and H. armigera (Hübner) (Lepidoptera: Noctuidae)

Abstract

AbstractExperiments were conducted in a cotton field in north-western New South Wales to determine the effect of pheromone trap design and placement on the catch of Helicoverpa punctigera (Wallengren) and H. armigera (Hübner) adults in paired traps. A cone trap design was found to give consistently larger catches of moths than two funnel trap designs. Furthermore, lower efficiency of catch of H. punctigera tended to bias relative catches in the funnel traps towards H. armigera. In comparison to the ratios of the two species in egg samples from the field, the cone trap did not show much bias to either species of moth. Traps located 40 m inside a cotton field showed larger catches and reduced variation compared with egg species ratios than traps placed at the edge of the field. Wind speed and direction and insecticide application also affected the catch in the traps. The catch data tended to become unreliable after the end of February, possibly due to changes in crop attractiveness for oviposition. It was found that the less numerous moth species at a given time still tended to be over-represented in pheromone traps in comparison to the ratios in egg counts. A linear time trend was introduced to compensate for the bias. The use of the traps shows promise in determining the relative abundance of the two species for use in resistance management strategies and other purposes.