Mating competitiveness and pheromone trap catches of mass-reared, male codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), from the Osoyoos, British Columbia, Canada, massrearing facility operated by the Okanagan-Kootenay Sterile Insect Release Board, were compared to wild males using mark-release-recapture field experiments in spring, summer, and autumn at Summerland, British Columbia. In spring, significantly more wild diapause males mated with tethered, wild females than did non-irradiated (0 Gy) or irradiated (100 or 250 Gy) non-diapause, mass-reared males. A lower dose of radiation did not improve mating competitiveness, nor catches of mass-reared males released in spring. Median mating time for wild males was approximately 45 min earlier than mass-reared males with most wild males (70.5%) mating before sunset and mass-reared males mating at or shortly after sunset in spring. Superior mating competitiveness of wild males in spring was mirrored by greater recapture rates in pheromone-baited traps. In summer, mating competitiveness of mass-reared moths improved relative to wild males and there was a significant inverse relationship between radiation dose (0, 100, and 250 Gy) and competitiveness of mass-reared males. In autumn, untreated, wild males were significantly more responsive to pheromone traps than non-diapausing mass-reared males receiving 250 Gy of radiation. Mass-reared males, subjected to diapause-inducing conditions as larvae and emerged from diapause before this irradiation treatment, were recaptured significantly more often than similarly irradiated, non-diapause, mass-reared males, but not more than untreated, diapause wild males. We hypothesize that differences between wild and mass-reared males in daily timing or speed of responses to natural or synthetic pheromone sources under montane weather patterns typical of spring in British Columbia may partially explain poor activity of sterile males, and low sterile : wild overflooding ratios during spring when measured using pheromone traps by the sterile insect release programme in British Columbia.

The effects of pre‐exposing male codling moths, Cydia pomonella (L.) (Lepidoptera: Tortricidae), to their pheromone (E,E)‐8,10‐dodecadien‐1‐ol (codlemone), in static and moving air, under laboratory and field conditions, on subsequent antennal sensitivity, behavioural responsiveness, and attraction to codlemone were investigated. In flight tunnel experiments, the percentage of moths wing fanning and taking flight were mostly unaffected, but upwind flight to, and contact with, pheromone sources known to elicit responses of both were shown to depend on the intensity and duration of previous exposure to codlemone and recovery time between exposure and assessment. Ten to 30‐min pre‐exposures to codlemone in static air (≈ 35 µg l−1) not only caused a 99% reduction in attraction, but also significantly reduced electroantennogram response to codlemone. Recovery of full antennal sensitivity to codlemone took more than 1 h, but recovery of attraction took over 4 h, suggesting that habituation is also partially involved in reduced behavioural responsiveness following pre‐exposure. Seventy‐five min exposures to codlemone in moving air (5–10 cm s−1) at rates of 0.9, 4.5, and 18 µg h−1 from Celcon fibres caused 75, 86, and 99% disruption, respectively. However, 30–34‐h exposure of caged moths to air moving through an orchard treated with 1000 Isomate‐C® dispensers ha−1 releasing approximately 20 µg h−1 per dispenser during tests, had no impact on moth response in flight‐tunnel assays 30 min after removal from the orchard. In this treated orchard, catches of free‐flying moths in pheromone‐baited traps were completely inhibited. If observed mechanisms such as long‐lasting antennal adaptation or habituation of the central nervous system contribute to the disruption of pheromone communication among codling moths under field conditions, it seems unlikely that they occur following exposure to the average atmospheric concentrations of codlemone. For these effects to be important, codling moths may require close contact with pheromone sources for extended periods, or repeated close encounters.

No abstract

Pheromone trap catches and mating activity of sterile, mass-reared, diapaused and non-diapaused male codling moths, Cydia pomonella (L.) (Lepidoptera: Tortricidae), were compared with those of wild diapaused males using mark–release–recapture field experiments in springtime. Sterile moths were provided by the Okanagan–Kootenay Sterile Insect Release (SIR) Program mass-rearing facility, in Osoyoos, British Columbia, Canada. Nondiapause-reared (SIR-standard) and diapause-reared (SIR-diapaused) sterile males were recaptured in similar frequencies. Both types of sterile males were recaptured significantly less often than similarly released wild diapaused males, and ratios of recaptured sterile to wild males were similar with either sterile male. Ratios of sterile to wild males, using the combined catches of SIR-standard and SIR-diapaused males, were significantly lower when measured with traps baited with wild-females (21:1) than with traps baited with 10 μg pheromone (48:1). Both trapping ratios were markedly lower than the 80:1 ratio at which sterile and wild males were released. In mating studies, SIR-standard and SIR-diapaused males exhibited equivalent mating frequencies and both were recaptured in copula with tethered wild females significantly less often than released wild males. In the same mating studies, sterile mass-reared, diapaused males that had been chilled for 3 h at the Pacific Agri-Food Research Centre (PARC) before release (PARC-diapaused) were significantly more competitive than SIR-standard or SIR-diapaused males that averaged 24 h of chilling as part of normal SIR Program operations. PARC-diapaused males and released wild males mated with tethered females with equal frequency. We hypothesize that the length of time SIR males were chilled before being released may have caused SIR-diapaused males to be less mobile, and therefore less competitive with wild males in field mating assays, than were PARC-diapaused males. Based on these results, introduction of a diapause phase into the mass-rearing system used at the Osoyoos facility cannot currently be recommended as a means of improving trap-measured ratios of sterile to wild males, or increasing sterile × wild matings.

An integrated programme of pheromone‐mediated mating disruption using Isomate‐C®, post‐harvest removal of fruit, and trapping overwintering larvae with cardboard tree bands, was used to control codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), in four commercial ‘organic’ apple orchards in Cawston, British Columbia during 1989–1992. One application of 1000 dispensers ha−1 on May 1 delivered estimated seasonal totals of 16.6, 16.5 and 19.9 g of E,E‐8,10‐dodecadien‐1‐ol [=codlemone] ha−1 in 1990, 1991 and 1992, respectively, at median rates of 8.4, 8.3, and 13.3 mg · ha−1· h−1 during dusk flight periods of first brood and 5.3, 4.7 and 4.6 mg · ha−1· h−1 in second brood, respectively. Over this 3‐year period damage from codling moth at harvest ranged from 0.08 to 2.4%, and averaged <0.7% in these four organic orchards, while damage in five conventional orchards receiving sprays of azinphosmethyl ranged from 0.02 to 1.85%, and averaged 0.5%. Damage in an experimental orchard that was banded only, ranged from 43.5 to 56.7%, and averaged 48.9%. Between 1990 and 1992 cumulative male catches in Pherocon 1‐CP wing traps baited with 10 mg of codlemone declined by 52% and densities of overwintering codling moth larvae declined an average of 49.5% in all organic orchards. Overwintering populations in the banded experimental orchard showed an increase of 57.7% during this study period. We conclude that an integrated programme of pheromone‐mediated mating disruption, post‐harvest fruit removal and tree banding, controls codling moth effectively enough to make organic apple production viable in British Columbia.