1a. Objectives (from AD-416)
Objective 1: Determine the comparative efficacy of alternative chemicals to methyl bromide and develop methods that keep alternative fumigants as well as methyl bromide out of the atmosphere following postharvest fumigation. • Sub-objective 1.A. Determine efficacy, practicality, and product quality (phytotoxicity) of alternative fumigants such as phosphine, sulfuryl fluoride, propylene oxide, ozone, and others to control postharvest commodity pests. • Sub-objective 1.B. Determine the efficacy of sulfuryl fluoride as an alternative to methyl bromide for use in flour/rice mills by direct comparison in laboratory and field experiments. • Sub-objective 1.C. Test absorbent materials to find more efficient materials than coconut-based activated carbon to recapture methyl bromide and other fumigants. • Sub-objective 1.D. Develop stacking and airflow techniques to maximize the efficiency of capturing methyl bromide from airstreams following commodity fumigation. Objective 2: Electrophysiological and behavioral responses of pests to host compounds • Sub-objective 2.A. Cigarette beetle host attractant identification and behavioral evaluation. • Sub-objective 2.B. Navel Orangeworm host attractant identification and behavioral evaluation. Objective 3: Develop combination quarantine treatments for foreign and domestic hay exports including timothy, alfalfa, oat, Bermuda, and Sudan grass hays and rye straw that utilize hay harvesting and postharvest handling procedures, and apply chemical fumigants to minimize human exposure. Objective 4: Develop models to accurately predict damage to nuts by navel orangeworm and determine the feasibility, accuracy, and precision of these predictions. • Sub-objective 4.A. Develop models for damage in Nonpareil and pollenizer almonds in Kern County based on previous year’s damage, harvest date and/or sanitation efficacy and then determine if these models can be extended to the entire almond belt • Sub-objective 4.B. Determine if the methodologies or models developed for almonds can be used to predict navel orangeworm damage in pistachios • Sub-objective 4.C. Develop models for almonds relating navel orangeworm damage to males captured in pheromone traps within the same year
1b. Approach (from AD-416)
Develop alternative chemical controls and quarantine fumigations for stored product insects. Develop equipment and investigate the feasibility of controlling fumigant emission to the atmosphere by trapping and destruction. Develop combinations of fumigants with other technologies to reduce the dosage of fumigant required to control or eradicate stored product and quarantine insects in durable and perishable commodities. Develop non-chemical control approaches for stored product pests of commodities to reduce the use of methyl bromide. Develop methods to detect infestations by detecting volatile emissions from insects and/or commodity. Develop methods to enhance or maintain quality of perishable commodities and ensure that treatments developed do not reduce quality of persihable commodities or shorten shelf-life. Formerly 5302-43000-030-00D and 5302-43000-028-00D (12/07)
3. Progress Report
Field drying harvested hay in windrows and compression of hay in modern compressors to produce compact export bales were found to cause high levels of mortality of Hessian fly, a pest of regulatory concern in hay exported from the western states to Asia. New volatile collection devices and procedures have been instituted for collecting host volatiles from nut trees and nut clusters. Two methods were adapted to assess pheromone component release ratios from moths and prospective lure formulations and these methods will be applied to volatile collections from individual nuts. Bioassay methods to assess attractiveness of host volatiles were improved for faster discrimination among actual hosts and host volatiles, by test insects. A multi-year study examining trapping and subsequent damage in almonds revealed a low, but statistically significant, association between navel orangeworm males trapped and damage later in the same season. The navel orangeworm is the primary pest of almonds and pistachios in California. The role played by sanitation in reducing the overwintering population of navel orangeworm in these two nut crops was evaluated in Madera and Fresno Counties. Studies continued on the combined ovicidal and neonate larvicidal activity of newly registered insecticides in almonds and pistachios. New studies were begun on the duration of control provided by pyrethroid, growth regulator and anthranilic diamide insecticides in pistachios as well as insecticide coverage in almonds and pistachios. Novel chemical and non-chemical techniques were developed to rapidly disinfest raw products of field pests, control storage pests in processed products amenable to re-infestation and microbial infection, reduce reliance on fumigation as a stand-alone measure for postharvest disinfestations, and minimize the environmental and ecological impact of postharvest processing.
1. Development of quarantine strategies to control hessian fly in exported hay. Hessian fly is a pest of regulatory concern in the western states and new methods are needed to assure trade partners that the pest is not accidentally introduced through hay imports. Hessian fly was shown by ARS researchers at Parlier, California, to be controlled in hay by field drying in windrows and compression in modern compressors that produce compact export bales. The work supports the concept that the occurrence of Hessian fly in harvested, processed, and fumigated hay bales is negligible. This research helps protect a $660 million annual foreign market.
2. Improved monitoring for navel orangeworm using egg traps. The navel orangeworm is the principal insect pest of almonds in the United States. Egg traps, the current method of monitoring navel orangeworm, are expensive and considered unreliable. ARS researchers at Parlier, California, with University of California and private industry collaborators, found pistachio meal to be as effective as the currently favored bait and determined the number of traps needed to reliably detect egg-laying. Monitoring with pistachio meal has been adapted on tens of thousands of acres of almonds, and will help prevent navel orangeworm damage to almonds, worth >$2.3 billion per year and planted on >800,000 acres.
3. Assessing ovicidal/neonate toxicity of insect growth regulators and anthranilic diamide insecticides. Recently, three new insecticides, as well as generic versions of current insecticides, have become available for use in almonds and pistachios and the relative toxicity of these chemicals to navel orangeworm eggs was unknown. Studies were undertaken in the field by ARS researchers at Parlier, California, using navel orangeworm eggs, to assess the relative toxicity of these materials. Pyrethroid insecticides were the most toxic, followed by insect growth regulators and anthranilic diamides. These data will be used to optimize control of this insect pest, thereby reducing the need to fumigate nuts.
4. The duration of control of insecticides in pistachios. Considerable uncertainty exists about the duration of navel orangeworm control provided by newly registered insecticides in pistachios. Pistachios are a valuable crop (500+ million pounds) and are increasing in importance. ARS researchers at Parlier evaluated 3 classes of newly registered insecticides for 8 weeks after application. Several insecticide classes alone or in combination provided control for more than 5 weeks. This information was provided to the Pistachio Research Board and will enable growers to revise their control strategies in order to optimize timing and reduce damage.
5. Optimizing insecticide applications. Many insecticide applications in tree nuts are conducted at speeds > 2.5 mph, although it has been previously shown that the application speed of the sprayer should not exceed 2 mph. Demonstration trials were conducted by ARS researchers from Parlier in Madera County and Paramount researchers in Kern County to reinforce the importance of spraying at 2 mph. Both studies demonstrated that spray coverage decreased by 30% when speed of the sprayer was increased to 2.3 mph. This research will help enable growers to achieve the most effective insecticide application and reduce crop damage.
6. Impact of the citrus commercial packing process on the Asian citrus psyllid. The possibility of occurrence of the Asian citrus psyllid in loads of citrus arriving in Australia threatens the ability of California to export citrus into that market. ARS researchers in Parlier, California, demonstrated that Asian citrus psyllids are completely washed from fruit that are submerged, flooded, or sprayed at high temperatures using soak tanks and wash lines consistent with commercial practices in California. Nearly 99% of the insects remain trapped by the solution until they drown. This research showed that Asian citrus psyllids will very likely not be present in commercially packed fruit and will help maintain access of California citrus to Australia, a market valued at $60 million annually.
7. Optimization of postharvest methyl bromide fumigation. Methyl bromide is an important fumigant, but the actual dosage received by different commodities is often poorly known. ARS researchers in Parlier, California, developed a kinetic model of methyl bromide sorption to facilitate comparison of insecticidal efficacy data obtained for a variety of different fruit and packaging types with varying load factors. This model ensures that a fumigant is applied at doses sufficient to maintain toxic exposures during fumigations. Results from the research are being utilized by USDA-APHIS and industry to design new efficacious treatment schedules.
8. Postharvest methyl bromide alternatives research. Methyl bromide is extensively used as a fumigant for quarantine disinfestation but its use is threatened by legislative action. ARS researchers in Parlier, California, demonstrated the insecticidal efficacy of sulfuryl fluoride and “Horn” phosphine toward species endemic to California. These fumigants could be used on both perishable and durable commodities. This research provides the basis for the eventual adoption of these fumigant technologies by United States agriculture.
Higbee, B.S., Burks, C.S. 2011. Effect of bait formulation and number of traps on detection of navel orangeworm (Lepidoptera: Pyralidae) oviposition using egg traps. Journal of Economic Entomology. 104(1):211-219.