The behavioural basis of a pheromone monitoring system for pea moth, Cydia nigricana

The flight and mating behaviour of the pea moth (Cydia nigricana) was studied at overwintering sites and in pea fields to see whether it could be exploited to provide early warning of adult immigration into pea crops. The field threshold temperature for take-off is 18 ^CC. Most flight activity-occurred in June and July between 16.00 and 18.00 B.S.T. with peak activity at 17.04 h. Moths were not caught in suction traps at heights above 0–4 m, but they can probably travel several km by fluttering above vegetation in winds of up to 10 km/h. Female moths produce a sex pheromone(s) highly attractive to males; ‘calling’ by females and mating occur during the period of maximum flight activity. Suction traps and egg counts detected the presence of moths in crops at about the same time. On average, sticky and water traps containing live virgin females as a lure caught respectively 17 and 130 times more males than suction traps and, on occasions, 25 and 300 times more; these attractive traps should detect the arrival of immigrants sooner than suction traps or egg counts. Extracts of virgin females dispensed from filter paper at doses of one and five female-equivalents (FE) attracted males rapidly but temporarily. Rubber dispensers with extracts of twenty FE remained attractive for 6 days. Several synthetic attractants were screened using doses of o-i mg on rubber dispensers in sticky traps. CYs-8-dodecenyl acetate and erans-8, frans-io-dodeca-dienol at doses of o-i mg were slightly attractive; the latter at doses of 1 -o mg was more attractive than twenty FE doses of extract and could be used for experimental monitoring of pea moth until its own synthetic sex pheromone(s) is available.