Outlooks on Pest Management
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OUTLOOKS ON PEST MANAGEMENT INSECT PEST MANAGEMENT IN POSTHARVEST ECOSYSTEMS IN THE UNITED STATES OF AMERICA Frank H.Arthur,Judy A. Johnson, Lisa G. Neven, Guy J. Hallman and Peter A. Follett1 Considerthe problems and solutions to insect postharvest pest management of the kernel. Acomplete list of potential insect pests, as well Keywords: Post-harvest, insects, control, management, quarantine as information on the biology and range, can be found in Rees (2004). Insect pests in postharvest systems in the United States of Actual monetary losses due to stored-grain insectsare America (USA), which can include bulk grains in storage, generally consideredtobeinthe range of 5to10% of the and also the milling, processing, storage, and retail bulk commodities stored in the USA or about $1.25 to 2.5 industries, account for millions of dollars of losses each year billion (Flinn et al.2007). Management strategies for in direct and indirect costs. Insect pests in harvested fresh controlling insectsinbulk grains include cleaning and commodities can lead to huge economic losses due to sanitation of empty bins, use of aresidual grain protectant rejections of shipments, restrictions on shipments, reduction insecticide as grains are loaded into storage, samplingthe of market quality,and reduction of market price. Reduction bins by direct sampling or with the use of probe pitfall traps, in pest risk to exported fresh commodities as aphytosanitary aeration with low-volume ambient air to lower the internal measure involves some key postharvest steps. Some of the bulk temperature of agrain mass, and fumigation with major insect pests are common to different postharvest phosphine when needed (Hagstrum et al.1999). systems while others are unique to one particular system. In As bulk grains are milled, processed, and distributed, the this article, the major postharvest insect pests and their insect pest complex changes and shifts as well. In millingand impacts will be discussed for grains and processed grain processing facilities, Tribolium castaneum,the red flour products, tree nuts, and fresh fruit crops. beetle, and T. confusum,the confused flour beetle, are major pests. Perhaps the most important economic pest of processed foods products is Plodia interpunctella,the Indian Insect pest managementinbulk grains and meal moth, which can exist on awide variety of food processed grain products products (Mohandass et al.2007). Other beetle species can In the USA, the most economically-damaging insect pests are cause economic damage as well (Throne et al.2003). the lesser grain borer, Rhyzopertha dominica, Economic losses caused by insects in the processing, distribution, and storage system are estimated as millions of dollars resulting from contamination issues, product returns, legal issues associated with infestations, pest control applications, and consumer complaints (Throne et al.2003). However,actual quantificationofsuch losses is extremely difficult to assess because they are largely borne by private industry.Control of insects in this system is usually accomplished through fumigations of facilities or applications of aerosol insecticides and residual surface treatments (Arthur 2008). Sampling and monitoring is also emphasized as part of management programs, and there are anumber of recent studies that document extensive insect pest populations in and around milling, processing, and storage facilities (Campbell &Mullen 2004), and interpreting the data obtained from trapping and monitoring Figure1. Adult lesser grain borer (Rhyzopertha dominica) programs (Nansen et al.2008). on wheat. Footnote 1 and Sitophilusoryzae and S. zeamais,the rice weevil and the All of the authors areresearch entomologists with the USDA-Agricultural Research Service (ARS). Frank H. Arthur is with the Grain Marketing and maize weevil, respectively.These species feedinternally, cause Production Research Center in Manhattan, KS. Judy A. Johnson is with the San product damage,and when the mature adult exits the kernel, Joaquin ValleyAgricultural Sciences Center in Parlier,CA. Lisa G. Neveniswith it creates alarge hole. There are anumber of beetle pests that the Yakima Agricultural Research LaboratoryinWapato,WA. Guy J. Hallman is with the Kika de la Garza Subtropical Agricultural Research Center in Weslaco, are external feeders and spend their entire life cycle outside TX. Peter A. Follett is aresearch entomologist with US Pacific Basin Agricultural Research Center in Hilo,HI. DOI: 10.1564/20oct00 Outlooks on Pest Management–October 2009 1 ©2009. Research Information Ltd. All rights reserved INSECT PEST MANAGEMENT IN POSTHARVEST ECOSYSTEMSINTHE UNITED STATES OF AMERICA Insectpest managementintreenuts and dried 2002). fruit Before allowing entrance of productinto their markets, Dried fruits and tree nuts are used in baked goods and other importing countriesmay require phytosanitary certification confectionaries, and as snack foods. after inspection for live insects, therefore processors often ensure passing inspection by applying adisinfestation treatment, usually fumigation. For time-sensitive markets, such as inshell walnuts for the valuable European Union holiday market, methyl bromide has been preferred because of its rapid treatment times. Restrictions on the useofmethyl bromide imposed by the Montreal Protocol (Fields &White 2003) have limited its availabilitytodried fruitand nut processors, who are moving to phosphine or sulfuryl fluoride when possible. However, recentfindings have implicated sulfuryl fluoride as being apotentially important greenhouse gas (Mühle et al.2009), and Californiahas begun regulating field fumigations in an attempt to reduce volatile organic compounds (CDPR 2008). Suggested non-chemical alternatives for phytosanitary treatmentsinclude radio frequency (Wang et al.2007a; 2007b), low temperatures (Johnson 2007), controlledatmospheres(Soderstrom& Brandl 1990), combination treatments (Soderstrom et al. Figure2. Almond orchardinbloom. 1996; Johnson et al.1998; 2002), and vacuum treatments (Mbata &Phillips 2001). Both taste and appearance are extremely important to the As with grain products, it is difficult to estimate the actual perceived quality of these products and there is no tolerance economic loss due to insects in dried fruits and nuts. Aegerter for live insects. The discovery of live insects may result in &Folwell (2001) estimated fumigation costs for almond customer returns, loss of consumer confidence,rejection of processors to be $5.01-5.03/ton for methyl bromide and shipments, and loss of entire markets. Driedfruits and tree $5.47-5.88/ton for phosphine, whileestimates forwalnut nuts may be kept for many months in storage and as such processors were $8.11-9.47/ton for methyl bromide. Other they have several storage pests in common with stored grains control costs may include sanitation and aerosol fogging, but and processed food products, particularly P. interpunctella, the cost of customer returns and the resulting loss of T. castaneum,and Oryzaephilus surinamensis,sawtoothed customer confidence and legal costs must be considered as grain beetle. These pests may infest the product at any time well. during processing and storage, and, if undetected and uncontrolled, populations may build up rapidly.Inaddition, these commoditiesoften have field pests such as Amyelois transitella,the navel orangeworm, Cydia pomonella,the codling moth, Cadra figuliella,the raisin moth, and Carpophilus spp., dried fruit beetles. Any of these species or acombinationmay be present in harvested product and survive processing stages.Although field pests rarely reproduce or persist under commercial storage conditions, their presence poses aserious phytosanitary risk in exported Insect pest managementand quarantine in raw product. postharvest fruitand vegetables Marketing of these products for both foreign and domestic Rhagoletis indifferens,the western cherry fruit fly,isthe markets requires careful attention to sanitation, packaging, major pest of sweet cherries in the western USA. Although and storage to prevent insect infestation. As with storedgrain C. pomonella is listed as aquarantine pest in cherries facilities andmills,monitoring insect populations with destined to Japan, recent research indicates that sweet pheromone trapping programs can help in making cherries are not ahost for this pest (Wearing 2001; Hansen management decisions. Entire warehouses may be fumigated, &Rehmke 2003; Johnson &Hansen 2008). Although C. either on acalendar basis or in response to changes in trap pomonella has rarely been positivelyidentified in sweet numbers, to reduce storage pest populations. Processors may cherries within the past twenty years, fruit exported to Japan limit the introductionofinsects into processing facilitiesby muststill be fumigated with methyl bromide to meet fumigating all incoming product, and finished product may quarantine requirements. In thefield, thereisazero receive afinal fumigation before shipment.With some tolerance level for R. indifferens,and fruit from any orchards products, particularlytree nuts with high oil content like with positive trap catches, or harvested cherries that test walnuts, refrigerated storage (0-5°C) maybeusedto positive for the presence of R. indifferens are ineligible for maintain productquality.Thesetemperatures are also export (Hass 2001). The cherries are then usually diverted to effective at reducing insect infestations (Johnson et al.1998; processing. 2Outlooks on Pest Management–October 2009 INSECT PEST