ANALYSIS AND INTERPRETATION OF LONG-TERM LIGHT TRAP DATA FOR HELICOVERPA-PUNCTIGERA (LEPIDOPTERA, NOCTUIDAE) IN AUSTRALIA - POPULATION-CHANGES AND FORECASTING PEST PRESSURE

Using regression analysis the early season dynamics of Helicoverpa pun ctigera (Wallengren) were determined from long series of light trap ca tches (10-19 years) from three sites in Australia (Narrabri and Trangi e in New South Wales, and Turretfield in South Australia). The size of the second spring generation (G(2), the one causing major pest proble ms in summer cropping regions) was strongly related to the size of the first spring generation (G(1)). In most cases, rainfall in early wint er had a positive influence on the size of G(2), whereas rainfall in s pring had a negative effect. Regressions were found to account for 49 to 93% of the annual variation in G(2), depending on site. The use of light trap catches ana weather data to forecast pest levels from a few months to a few weeks in advance is discussed, along with the improve d understanding of early season H. punctigera dynamics.