Semiochemicals for green mirids and 'Helicoverpa': an update

Abstract

This presentation aims to provide an update on the potential applications of pheromones for mirids, Magnet® for 'Helicoverpa' and similar plant volatile-based formulations for attract and kill for mirids. Pheromone trapping trials for green mirids were done at eight sites on cotton, with the assistance of CRC extension officers and researchers. Mirid sampling using various methods (sweep nets, visuals, beat sheets and suction) was also done to determine correlation of trap catches and population dynamics during the trials. Results from the three sites so far analysed are variable. At Goondiwindi (Korolea), there was a good correlation between pheromone trap catches and mirid numbers in the field. However, at Narrabri (Auscott) and Boggabri (Brigadoon), there was a poor correlation, but catches were better correlated with the mated status of female mirids. This suggests that female competition might affect trap catches, and that there were some fundamental differences in the population dynamics of mirids between Korolea and the two more southerly sites. We have developed a bioassay technique to test plants and plant volatiles for attractiveness to female mirids in the laboratory. We have tested synthetic equivalents of volatiles from lucerne and native verbine ('Cullen cinereum'), and from other sources. At least five single volatiles appeared to be attractive in the olfactometer, but in contrast to what we found with Helicoverpa in the development of Magnet®, blends of these volatiles have not given additional attraction. Responses in the olfactometer are also somewhat unpredictable. Consequently, at this stage we are a long way off having a synthetic plant volatile attractant for mirids. The registration of Magnet® appears to be imminent. Further work on mirid semiochemicals will not be funded in the coming year. Future research will focus on using Magnet® in improving the efficiency of refuges as part of the resistance management program for Bollgard II. We will also be looking at developing attractants targeted at mated 'Helicoverpa' females.