Reduced antennal sensitivity, behavioural response, and attraction of male codling moths, Cydia pomonella, to their pheromone (E,E)‐8,10‐dodecadien‐1‐ol following various pre‐exposure regimes

Abstract

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.

Orientational Behaviors and EAG Responses of Male Codling Moth After Exposure to Synthetic Sex Pheromone from Various Dispensers

“…Normal behavioral responses returned after >4 hr and EAG sensitivity after >1 hr. However, caging male codling moths for 30-34 hr in an orchard treated with 1000 Isomate-C dispensers per hectare had no measurable impact on behavioral responses to pheromone in a flight tunnel (Judd et al, 2005). Similar results were obtained by Schmitz et al (1997) and Rumbo and Vickers (1997) for the European grape moth, Lobesia botrana (Denis and Schiffermü ller), and the Oriental fruit moth, Grapholita molesta (Busck), respectively.…”

“…1-1.5 hr (Judd et al, 2005;Stelinski et al, 2005c). Similar Blong-lasting^adaptation has been reported for other moths, including polyphemus moth, Antheraea polyphemus (Cramer) (Kaissling, 1986), the obliquebanded leafroller, Choristoneura rosaceana (Harris) (Stelinski et al, 2003a), and the Pandemis leafroller, Pandemis pyrusana Kearfott (Stelinski et al, 2005c).…”

“…Similar Blong-lasting^adaptation has been reported for other moths, including polyphemus moth, Antheraea polyphemus (Cramer) (Kaissling, 1986), the obliquebanded leafroller, Choristoneura rosaceana (Harris) (Stelinski et al, 2003a), and the Pandemis leafroller, Pandemis pyrusana Kearfott (Stelinski et al, 2005c). In cases where the airborne concentration of pheromone has been quantified (Stelinski et al, 2003b;Judd et al, 2005), micrograms per liter of air are required to induce long-lasting adaptation. In field trials, long-lasting antennal adaptation in male obliquebanded leafrollers following 24 hr of exposure to Isomate dispensers was seen if males were held 1-2 cm from dispensers but not if the distance was increased to 2 m. Given that long-lasting adaptation was not recorded following any of the preexposure treatments in the current study, males probably did not receive the $ 355 mg min j1 l j1 dose required to induce long-lasting adaptation (Judd et al, 2005).…”

“…A 65% reduction of mating was observed when females were caged with males in 1.2-l containers with 1.0 mg of codlemone (Fluri et al, 1974), whereas by exposing males and females to air moving over one or three 1.0 mg lures of codlemone, there was only a 38% mating reduction (Charmillot et al, 1976). More recently, Judd et al (2005) established that exposures of male codling moths to ca. 35 mg codlemone/l of air in static air chambers for 10-30 min nearly eliminated response to otherwise attractive lures in a flight tunnel and reduced electroantennogram (EAG) responses.…”

“…Similar results were obtained by Schmitz et al (1997) and Rumbo and Vickers (1997) for the European grape moth, Lobesia botrana (Denis and Schiffermü ller), and the Oriental fruit moth, Grapholita molesta (Busck), respectively. Judd et al (2005) suggested that if male codling moths landed near Isomate-C Plus dispensers for several minutes, they might receive a sufficiently high dose of pheromone to reduce behavioral responses as seen in their preexposure laboratory experiment.…”