David G. Brandl

High temperature combined with carbon dioxide enriched or reduced oxygen atmospheres for control of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae)

Abstract Heat combined with controlled atmospheres increased mortality of Tribolium castaneum (Herbst) larvae when temperatures of ≥38°C were combined with carbon dioxide enriched or oxygen deficient atmospheres. Preconditioning of larvae to treatment temperature for 24 or 48 hr prior to controlled atmosphere treatments at 38°C significantly reduced larval mortality relative to a 1 hr preconditioning. Heat combined with controlled atmospheres can significantly reduce treatment time. However, if heat is applied prior to the application of controlled atmospheres, the time of treatment must be extended.

Sampling and pheromone trapping for comparison of abundance of Amyelois transitella in almonds and pistachios

The navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae), is the primary insect pest of almonds, Prunus amygdalus Batsch (Rosaceae), and pistachios, Pistacia vera L. (Anacardiaceae), in California, USA. Abundance of A. transitella was compared between these crops by examining total and infested mummy nuts collected in trees and on the ground between January and March in 2003 and 2004, and by examining the number of males captured in sticky traps baited with virgin females as a pheromone source during the subsequent growing seasons. There was an 8–9‐fold greater density of total mummies (potential hosts) in pistachios compared to almonds. The proportion of mummies infested was not significantly different between the crops in 2003, but significantly more almond than pistachio mummies were infested in 2004. In 2003, the average density of infested mummies per hectare was greater in pistachios than in almonds, but in 2004 the converse was true. Examination of meteorological data did not suggest an explanation for more live A. transitella per infested mummy in almonds in 2004. The number of males captured in pistachios was consistently greater than the number captured in almonds, particularly during the second flight in June and July. The number of males captured in sticky traps in the summer was more strongly associated with the total mummy density in the sanitation survey of the previous winter than with the density of infested mummies. We conclude that the overall density of mummy nuts serving as potential oviposition sites prior to the next years crop has a greater impact on the abundance of A. transitella during the growing season and subsequent harvest than does the density of infested mummies. The implications for the ecology and management of this pest species are discussed.

Responses of Cydia pomonella (L.) (Lepidoptera: Tortricidae) adults and eggs to oxygen deficient or carbon dioxide enriched atmospheres

Abstract The mortality of 2–24 hr old Cydia pomonella (L.) eggs treated with oxygen (O 2 ) deficient or carbon dioxide (CO 2 ) enriched atmospheres is exposure time dependent. At 25°C and 95% r.h., O 2 concentrations of 0, 0.5, 1, 2, and 5% (in nitrogen) produced LT 95 s of 1.2, 1.7, 1.6, 1.7, and 24.4 days, respectively. Pure nitrogen was significantly more effective than the other O 2 deficient atmospheres. Carbon dioxide concentrations of 20, 40, 60, 80, and 100% (in air) produced LT 95 s of 3.6, 1.3, 1.4, 1.6, and 1.4 days, respectively. Only 20% CO 2 induced significantly less mortality than the higher concentrations. Regression parameters for each atmosphere are given. Combining O 2 deficient with CO 2 enriched atmospheres did not increase C. pomonella egg mortality over that of the atmospheres used alone. Sublethal concentrations of CO 2 enriched atmospheres altered C. pomonella reproductive capacity. Carbon dioxide concentrations of 40% or more reduced adult survival and reduced surviving adults ability to mate.

Monitoring Amyelois transitella males and females with phenyl propionate traps in almonds and pistachios

We examined phenyl propionate as an attractant for trapping navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae) adults, with the objective of developing a method of trapping both sexes more effectively than with almond meal. Two initial experiments maximized the total number of adults captured using phenyl propionate released from glass vials with cotton wicks. A third experiment compared the numbers of males and females captured using these glass dispensers in either bucket or sticky traps. The glass vial dispensers captured more adults than 0.1% phenyl propionate in water (as both attractant and killing agent), and far more adults were captured with glass vial phenyl propionate dispensers than with almond meal. On rare occasion, the glass vial dispensers captured as many adults as traps baited with virgin females, but usually phenyl propionate in glass vials captured fewer adults than virgin‐baited traps. Glass vial phenyl propionate dispensers were equally effective in sticky traps or bucket traps. The majority of females captured were mated, and the proportion of males captured increased over time within flights (generations). We conclude that phenyl propionate released from glass vials captured A. transitella adults more effectively than currently available options, and will be useful in research projects where capturing intact adults and comparing mating status are important. Developing a cost‐effective phenyl propionate‐based alternative to the egg traps currently used for commercial monitoring will be more difficult.

Effect of natural and artificial photoperiods and fluctuating temperature on age of first mating and mating frequency in the navel orangeworm, Amyelois transitella.

Abstract The effect of weak illumination during part or all of the scotophase on mating frequency of navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae), was examined in environmental chambers under long photoperiods and constant warm temperature (colony conditions) or shorter photoperiods and a cooler thermoperiod intended to mimic spring conditions in our region. These data were compared to mating frequencies in sentinel females placed in the field during the first three weeks of May. Under colony conditions weak illumination in the final hour of the scotophase resulted in ∼90% mating on the first day after eclosion; significantly greater mating compared to complete darkness throughout the scotophase, weak illumination throughout the scotophase, or weak illumination for both the first and last hour of the scotophase. In an environmental chamber programmed to simulate spring conditions, little mating occurred on the first night after eclosion and three nights were required for more than 50% of the females to mate. There was no difference in mating frequency with between moths exposed to complete darkness throughout the scotophase and those provided with weak illumination in the last half hour of the scotophase or throughout the scotophase. This delay in age of first mating was consistent with field observations with sentinel females at May in the central San Joaquin Valley. The authors conclude that, along with greater longevity and later oviposition, first mating occurs at a later age in spring conditions compared to summer conditions in this species. Planned studies of the effect of delayed mating in first and second flights will need to take these factors into account.