Project Number: 5352-22000-017-41
Project Type: Trust

Start Date: Jun 01, 2007
End Date: May 31, 2009

Objective:
1) Determine the critical duration of chilling (at temperatures likely encountered in Taiwan) needed for diapause-destined larvae needed to break diapause. 2) Determine the fate of diapause-destined larvae under tropical environments (short photoperiod, elevated temperatures, high chilling temperatures, short chilling period). 3) Determine the proportion of field codling moth population entering diapause at each harvest date. 4) Determine the proportion of both field and laboratory codling moth diapause-destined larvae surviving cold storage.

Approach:
Two separate series of experiments are proposed; one involving laboratory reared-diapausing codling moth and the other field collected diapausing codling moths. Fresh batches of laboratory reared codling moth eggs will be exposed to organic thinning apples every week and subjected to 3 different rearing regimes. The rearing regimes will consist of a 12:12 L:D photoperiod at 20°C (68°F), 8:16 L:D at 20°C, and 15:9 L:D at 20°C (68°F). Infested apples containing immature codling moths will be taken at 0 to 28d after planting (on a weekly basis) and stored at 1.1°C(34°F) for 0 to 126d (on a weekly basis). Following cold storage, infested, apples will be placed at 10°C (50°F) for 0 to 63d (on a weekly basis) at a 12:12 L:D photoperiod. Larvae will be assessed for survivorship after the first cold storage period. Any survivors will be re-introduced to thinning apples prior to placement at the 10°C (50°F) chilling temperature. Following the 10°C (50°F) storage period, infested apples will be returned to a 12:12 L:D photoperiod at 20°C (68°F)and monitored daily for cocooning. Cocooned larvae will be held at 12:12 L:D photoperiod at 20°C (68°F)for up to 6 months and monitored daily for pupation and adult emergence. Following the 6 months holding period, strips will be dissected and cocoons assessed for stage of development and survivorship. Field collected codling moths will be obtained from infested, unsprayed abandoned orchards on a bi-weekly basis beginning on August 1 and ending November 21 (if fruit is still available). Trees will be banded 2 weeks prior to the first harvest date and replaced at each harvest date. Harvested, infested fruit will be held at 1.1°C (34°F)for 0 to 119d (on a weekly basis). The 0d storage period will be used to assess stages of insects in fruit at time of harvest. Recovered bands will also be examined for number of cocoons and physiological state of larvae. Following cold storage period, samples will be handled in the same manner as in previous experiment. Infested fruit will be stored at 10°C (50°F) for 0 to 63d (on a weekly basis) at a 12:12 L:D photoperiod. Following storage, infested fruits will be placed at a 12:12 L:D photoperiod at 20°C (68°F) and monitored on a daily basis for cocooning. Cocooned larvae will be held at 12:12 L:D photoperiod at 20°C (68°F) for up to 6 months and monitored daily for pupation and adult emergence. Following the 6 months holding period, strips will be dissected and cocoons assessed for stage of development and survivorship. We will need to replicate these experiments at least 3 times (1 per year) to account for natural variation in response to environment and other endogenous factors. Documents Trust with WA Tree Fruit Research Commission. Log 32722. Formerly 5352-43000-010-05T (4/08).