Sex Attractant-based Monitoring of a Biological Control Agent of Gorse

Abstract

Cydia succedana (Denis & Schiffermuller) has been introduced into New Zealand for the biological control of gorse seeds (Ulex europaeus). Traps baited with a sex attractant were developed for monitoring the flight timing and number of adult male moths, and were used as a new tool for monitoring the establishment, phenology and efficacy of the agent. The best lure tested was (E,E)-8,10-dodecadien-1-yl acetate, although high catches were also made with the E,Z isomer. There was no difference in the total catch across a range of doses from 1 to 300 mug/lure (7151 insects caught). Male flight was recorded at the bottom, middle and top of a hillside between 280 and 370 m altitude, along with the percentages of plants at each site bearing flowers and seed pods. There was an initial seasonal linkage between the catch of males and plant phenology, but a lack of synchrony was evident between the insect and the plant in the second generation, indicating a potentially important limitation for biological control at this site. The prospects for using sex attractants in traps as an aid for monitoring populations of weed biological control agents are excellent. Other potential applications include the costeffective detection of establishment and the determination of the optimal size of founding populations to ensure establishment of control agents.