Phenyl Propionate and Sex Pheromone for Monitoring Navel Orangeworm (Lepidoptera: Pyralidae) in the Presence of Mating Disruption.

The recent availability of sex pheromone lures for the navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae), improves options for monitoring this key pest in conventionally managed almonds. These lures are, however, minimally effective in the presence of mating disruption. Experiments were conducted to determine if phenyl propionate (PPO), an attractant for the navel orangeworm, acts in an additive or synergistic manner when presented together with the pheromone. In the absence of mating disruption, traps baited with PPO captured significantly fewer adults than traps baited with a sex pheromone lure. There was no difference in the number of adults captured in traps with both attractants when mating disruption was not used. In the presence of mating disruption, pheromone traps were completely suppressed, yet traps with both pheromone and PPO captured significantly more adults than traps baited with only PPO. Traps with only PPO captured equal numbers of both sexes, whereas traps with both attractants had significantly more males. These findings demonstrate that PPO is likely to be useful for monitoring navel orangeworm in fields treated with mating disruption.

Variable development rate and survival of navel orangeworm (Lepidoptera: Pyralidae) on wheat bran diet and almonds.

A series of laboratory and field studies were conducted using three lines of navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae), reared on wheat bran diet and almonds, Prunus dulcis (Mill.) D.A.Webb, at constant and fluctuating temperature. The duration of development on wheat bran diet at constant temperature differed significantly among the three lines. Development was as much as 40% faster at constant temperature than at fluctuating temperatures, consequently the developmental duration determined at constant temperature was not an absolute measure. When the maximum temperature in fluctuating regimes exceeded 43 degrees C, survival decreased by 50% compared with the constant temperature control. In almonds held at constant temperature, the developmental rate on new-crop nuts was variety-dependent and was fastest on 'Nonpareil' almonds and slowest on the experimental selection '23-122'. Development and survival were also variety-dependent on unharvested (mummy) almonds, and navel orangeworm average emergence was earliest from Nonpareil and latest from 'Carmel' nuts, differing by 529 degree-days, whereas survival was the highest on 'Butte', 35.7%, and the lowest on Carmel nuts, 7.2%. In our trials, both the speed of development and survival depended on host age, variety and quality, indicating that almonds were a dynamic rather than a static nutrient source for navel orangeworm. Identifying the factors responsible for variation in development and survival will give insight into improving control strategies.