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United States Department of Agriculture

Agricultural Research Service


Location: Commodity Protection and Quality Research

2008 Annual Report

1a. Objectives (from AD-416)
The overall objective is to develop practical and economical non-chemical insect control and disinfestation treatments that are safe and environmentally acceptable to replace methyl bromide for fresh and durable commodities. Objective 1: Develop a biologically-based management program using biological agents and cultural controls. • Sub-objective 1.A. Develop a biological control program for olive fruit fly using imported parasitoids • Sub-objective 1.B. Develop cultural control methods for olive fruit fly • Sub-objective 1.C. Develop a laboratory diet for olive fruit fly • Sub-objective 1.D. Improve control of navel orangeworm in orchards by using entomopathogenic nematodes that target over-wintering larvae • Sub-objective 1.E. Develop information for obtaining approval to release insect parasitoids into bulk-stored dried fruits and nuts. • Sub-objective 1.F. Determine the potential of commercially available or novel pathogens to control stored product Coleoptera. Objective 2: Develop a sex pheromone based program for use in the integrated management of navel orangeworm. • Sub-objective 2.A. Develop a stable formulation for the recently identified female sex pheromone • Sub-objective 2.B. Develop trapping data to calculate realistic navel orangeworm numbers based on standard sticky trap catch data. • Sub-objective 2.C. Determine the size of mating disruption treatment block necessary for reduction of navel orangeworm damage in almonds • Sub-objective 2.D. Determine fitness of females and potential impact of mating disruption at times of first and second flight. Objective 3: Develop alternative physical treatments for dried fruits, nuts, and fresh fruits • Sub-objective 3.A. Determine whether forced hot air combined with controlled atmospheres (CATTS) for stone fruit or forced hot air for oranges are viable quarantine treatments. • Sub-objective 3.B. Develop and field test low and high temperature treatments for dried fruit and nut insect pests. • Sub-objective 3.C. Develop and field test vacuum treatments using low cost, flexible storage containers for dried fruit and nut insect pests.

1b. Approach (from AD-416)
Postharvest insects cause significant economic loss to the agricultural sector, both through direct damage by feeding or product contamination, and by the cost of control programs. The export trade of certain horticultural products may be affected as well, with importing countries requiring quarantine treatments to prevent the introduction of exotic pests. Of particular concern to agriculture in the Western U.S. are field pests such as the olive fruit fly (Bactrocera oleae), navel orangeworm (Amyelois transitella), and codling moth (Cydia pomonella), and storage pests such as the Indianmeal moth (Plodia interpunctella). Processors rely largely on chemical fumigants such as methyl bromide for insect disinfestation, but regulatory, environmental and safety concerns mandate the development of non-chemical alternatives. In addition, with the elimination of methyl bromide as a fumigant because of its ozone depletion, the development of alternatives is an immediate concern. This project addresses this problem with a broad collaborative approach, examining both preharvest, biologically based control strategies as well as physical postharvest disinfestation treatments. Areas of investigation will include the development of biological and cultural control practices for olive fruit fly, improved field control of navel orangeworm with mating disruption and entomopathogenic nematodes, improved sex pheromone of navel orangeworm, new microbial controls for stored product beetles, commercial-scale forced hot air control atmosphere treatment for stone fruits, volatile markers to identify suitable hot forced air treatments for citrus, and radio frequency heating, low temperature storage, vacuum treatments, and parasitoid releases for control of postharvest dried fruit and nut insects. New, non-chemical methods for control of these economically important pests will be the outcome of this research. Formerly 5302-43000-031-00D (03/08).

3. Progress Report
A parasitoid imported from Guatemala was shown to be an effective biological control agent for olive fruit fly in California. The late larval stage of olive fruit fly was found to be highly mobile increasing the distribution of the pest in orchards. Olive fruit fly was reared on a laboratory diet and methods to increase insect production were evaluated. Release ratios of pheromone components for the navel orangeworm (NOW) were assessed from filter paper used in laboratory assays and from rubber septa (a proposed release substrate for the field). Adjustments to septa loadings are in progress to align release ratios with the lab active filter paper ratios. Field tests are anticipated to determine final loading ratios for the pheromone components. Data were collected quantifying the effect of sugar and hydration on NOW longevity and fecundity under normal constant rearing temperatures and conditions of variable temperature similar to that found during first (mid-April) and second flight (mid-June). NOW infestation was examined using an ELISA mark-capture technique in almonds but, because too few females were caught in traps baited with almond meal, NOW damage patterns were also directly analyzed. Damage was higher in the first 200-400 feet from the edge, and was lower in interior samples, indicating that the outer 300 feet of a mating disruption block might need additional protection. Large scale (20 acre) trials were conducted in Madera and Tulare counties during February. Nematodes were efficacious when distributed by chemigation and reduced overwintering NOW by 55%. Nematodes did not work when there was insufficient moisture or the ground was tilled 24 hours after application. Heat treatments targeted toward disinfestation of fruit flies from oranges were conducted and the fruit tested for taste differences using a sensory panel after a period of cold storage. Taste was found to be negatively affected by heat treatment, especially when the fruit were waxed following treatment. Testing of a large semi-commercial heat treatment chamber used to treat boxed/palletized peaches and nectarines was done, with the focus being on improving the heat distribution within individual boxes by the use of different box designs. The effect of product moisture on mortality of diapausing and non-diapausing Indianmeal moth larvae under vacuum was examined at 25 and 30C. Diapausing larvae were more tolerant of vacuum than non-diapausing larvae. During vacuum treatments 100% insect mortality was reached when larval weight loss was about 50%. Using a heat block system, the most heat tolerant stage of peach twig borer was identified as the pupal stage. Working with the rearing specialist, a culture of bean weevil was obtained for radio frequency heat treatment studies. The above research seeks to reduce postharvest use of methyl bromide, and relates to National Program 308: Methyl Bromide Alternatives, Component II, Postharvest Alternatives.

4. Accomplishments
1. Biological and Cultural Control of Olive Fruit Fly. Economical methods are needed to control olive fruit fly in California to protect the U.S. domestic supply of canned olives and olive oil. A parasitoid imported from the USDA-APHIS-PPQ facilities in Guatemala was evaluated by scientists at the USDA, ARS San Joaquin Valley Agricultural Sciences Center, Parlier, CA, for longevity after release in California based on availability of food for adults, and presence of insecticidal bait sprays. The effect of field mulches and plant volatile compounds were evaluated for control of larval movement in orchards and adult egg production in a lab colony, respectively. This work supports the California olive industry valued at $75 million annually. This research addresses National Program 308, Component 2, Problem Statement C.

2. Efficacy of nematode application by chemigation. Chemigation is a cost effective method to apply nematodes but refinements are necessary to optimize the success of this treatment. In February 2008 an ARS entomologist at the USDA, ARS San Joaquin Valley Agricultural Sciences Center, Parlier, CA, evaluated microsprinkler coverage and its impact on success in Tulare county. Treatment was most successful when microsprinklers covered 80% of the plot area. This research demonstrated that sprinkler coverage plays an important role in treatment success and also provides additional evidence that nematodes can play a role in managing navel orangeworm. This research addresses National Program 308, Component 2, Problem Statement B.

3. Effect of product moisture on efficacy of vacuum treatments. Non-chemical alternatives to methyl bromide and other fumigants are needed for postharvest insect disinfestation of California tree nuts. Scientists at the USDA, ARS San Joaquin Valley Agricultural Sciences Center, Parlier, CA, showed that at 25 and 30C high moisture (9%), walnuts require longer vacuum treatment times than low moisture (6%) walnuts to completely disinfest product of Indianmeal moth, and that diapausing Indianmeal moth were more tolerant of vacuum treatments than non-diapausing larvae. This information will be used to develop more accurate treatment schedules and improve the adoption of vacuum treatments as a non-chemical alternative, thereby reducing industry reliance on environmentally harmful chemical fumigants. This research addresses National Program 308, Component 2, Problem Statement B.

5. Significant Activities that Support Special Target Populations

Review Publications
Yokoyama, V.Y., Rendon, P., Sivinski, J.M. 2008. Psyttalia cf. concolor (Hymenoptera: Braconidae) for Biological Control of Olive Fruit fly (Diptera: Tephritidae) in California. Journal of Economic Entomology. 37: 764-773

Last Modified: 2/23/2016
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