Postharvest Pest Control Research Articles

Nitric oxide as a new fumigant for postharvest pest control on fresh commodities

Nitric oxide as a new fumigant for postharvest pest control on fresh commodities

Oxygenated phosphine fumigation for control of Epiphyas postvittana (Lepidoptera: Tortricidae) eggs on lettuce.

Light brown apple moth, Epiphyas postvittana (Walker), is a quarantined pest in most countries. Its establishment in California and potential spread to other parts of the state and beyond make it urgent to develop effective postharvest treatments to control the pest on fresh commodities. Fumigation with cylindered phosphine at low temperature has emerged to be a practical methyl bromide alternative treatment for postharvest pest control on fresh commodities. However, its use to control E. postvittana eggs on sensitive commodities such as lettuce is problematic. E. postvittana eggs are tolerant of phosphine and long phosphine treatment also injures lettuce. In the current study, E. postvittana eggs were subjected to oxygenated phosphine fumigations to develop an effective treatment at a low storage temperature of 2 degrees C. In addition, soda lime as a CO2 absorbent was tested to determine its effects in reducing and preventing injuries to lettuce associated with phosphine fumigations. Three-day fumigation with 1,000 ppm phosphine under 60% O2 achieved 100% mortality of E. postvittana eggs in small-scale laboratory tests. In the presence of the CO2 absorbent, a 3-d large-scale fumigation of lettuce with 1,700 ppm phosphine under 60% O2 resulted in a relative egg mortality of 99.96% without any negative effect on lettuce quality. The 3-d fumigation treatment without the CO2 absorbent, however, resulted in significant injuries to lettuce and consequential quality reductions. The study demonstrated that oxygenated phosphine fumigation has the potential to control E. postvittana eggs and the CO2 absorbent has the potential to prevent injuries and quality reductions of lettuce associated with long-term oxygenated phosphine fumigation.

Nitric Oxide as a Potent Fumigant for Postharvest Pest Control

There is a great demand for safe and effective alternative fumigants to replace methyl bromide and other toxic fumigants for postharvest pest control. Nitric oxide, a common signal molecule in biological systems, was found to be effective and safe to control insects under ultralow oxygen conditions. Four insect species including western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera Thripidae); aphid, Nasonovia ribisnigri (Mosley) (Homoptera: Aphididae); confused flour beetle, Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae); and rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae), at various life stages were fumigated with 0.1-2.0% nitric oxide under ultralow oxygen levels of < or = 50 ppm in 1.9-liter glass jars at 2-25 degrees C depending on insect species. Fumigations were effective against all four insect species. Efficacy of nitric oxide fumigation increased with nitric oxide concentration, treatment time, and temperature. There were also considerable variations among insect species as well as life stages in susceptibility to nitric oxide fumigation. Complete control of thrips was achieved in 2 and 8 h with 2.0 and 0.2% nitric oxide, respectively, at 2 degrees C. At the same temperature, complete control of the aphid was achieved in 3, 9, and 12 h with 1.0, 0.5, and 0.2% nitric oxide, respectively. Larvae, pupae, and adults of confused flour beetle were effectively controlled in 24 h with 0.5% nitric oxide at 20 degrees C. Complete mortality of confused flour beetle eggs was achieved in 24 h with 2.0% nitric oxide at 10 degrees C. Rice weevil adults and eggs were effectively controlled with 1.0% nitric oxide in 24 and 48 h, respectively, at 25 degrees C. These results indicate that nitric oxide has potential as a fumigant for postharvest pest control.

Postharvest management of insects in horticultural products by conventional and organic means, primarily for quarantine purposes

Purpose of review: The presence of arthropod pests in or on horticultural commodities has caused major disruptions in the storage, processing and shipment of these products. Management of these pests has posed a problem to humans for thousands of years. Current technology has led to the development of numerous means (chemical, mechanical or procedural) to control these pests. For the most part, postharvest pest control is focused on trade and exports. The accidental introduction of a pest into a place where it is not known to be present has resulted in the establishment of quarantine restrictions and export treatment requirements. This review focuses on the most current state of postharvest and quarantine treatments in development and currently in use on horticultural products. The current implementation and acceptance of these treatments is also addressed. Findings: Conventional postharvest pest control measures include treatments with chemical fumigants and topical pesticides. Concerns over environmental pollution and human health have obstructed the use of conventional chemicals and fumigants and further development of new chemicals for postharvest treatments. Irradiation is considered a conventional treatment, however, it does not use chemicals nor does it result in detectible residues in the commodity. Improvements in engineering commercial irradiators such as restricting source exposure, and the development of more powerful X-ray converters of electron beams, as well as refinement of generic treatments for groups of pests, had led to the expansion of this treatment to achieve quarantine goals. Directions for future research: Organic compliant postharvest treatments have received much attention and are the area of the most research. These treatments can include topical treatments with organic, natural pesticides and biologically derived fumigants, temperature extremes, modified atmospheres, and other novel physical treatments. The status of postharvest treatments for the control of arthropod pests both approved and in development is discussed.

Recent advances in development of ultralow oxygen treatment for postharvest pest control on perishable commodities

Purpose of review: This review summarises and discusses recent research progress in controlled atmosphere (CA) treatment with ultralow oxygen (ULO) for postharvest pest control on perishable commodities. Findings: In the last 10 years few studies have been conducted on ULO treatment for postharvest pest control. However, significant progress has been made and several ULO treatments were developed for postharvest pest control on different types of perishable prod� ucts. Complete control of green peach aphid, sweetpotato whitefly, twopotted spider mite and western flower thrips was achieved with 18 h fumigation using >99% nitrogen without injury to begonia seedlings. Lettuce aphid, western flower thrips and black widow spi� ders were successfully controlled on head lettuce, broccoli and table grapes, respectively, without negative impact on product quality. Vine mealybug was successfully controlled without reducing the vitality of grape benchgrafts. The tolerance of lettuce to ULO treat� ment was increased through postharvest storage to improve the safety of ULO treatment. ULO treatment is promising for controlling selected pests on selected fresh commodities, especially on those that are evaluated for their vitality rather than appearance. Directions for future research: More research efforts should be directed towards identifying suitable pests and fresh commodities for ULO treatment. Emphasis should also be given to pest control on products such as rootstocks, bulbs and tubers, which are evaluated by vitality rather than appearance. Research should also be directed at enhancing the tolerance of commodities to CA treatment in order to make ULO and other CA treatments safer to product quality. Large scale studies and collaboration with industry are also vital for in� dustrial adaptation of ULO treatment.

Dielectric heating as a potential post-harvest treatment of disinfesting mangoes, Part I: Relation between dielectric properties and ripening

Rapid heating by microwave (MW) and radio frequency (RF) energy offers the possibility to reduce thermal treatment times in post-harvest pest control of mangoes. In order to understand interaction between the fruit and electromagnetic energy, dielectric properties (DPs) of mangoes were measured using an open-ended coaxial-line probe with an impedance analyzer. The influence of frequency (1–1800 MHz), temperature (20–60 °C) and ripening (16 days storage at 21 °C) on dielectric constant ( ɛ ′ ) and loss factor ( ɛ ″ ) was evaluated. Additionally, moisture content, soluble solids, acidity, pH, maturity index and electrical conductivity of the mango fruit after 0, 4, 8 and 16 days of storage were determined. DP values decreased with increasing frequency, but this reduction was larger for the loss factor than for the dielectric constant. Loss factor increased but dielectric constant decreased with increasing temperature. Both ɛ ′ and ɛ ″ values decreased with storage time, caused mainly by reduced moisture content and increased pH. According to calculations, RF energy at 27.12 MHz has a six times greater penetration depth in mangoes compared to MW energy at 1800 MHz at 20 °C. Values of ɛ ″ calculated from measured electrical conductivities in mango tissues matched well with the experimental ɛ ″ values at frequencies lower than 300 MHz, indicating a dominant ionic conduction effect at these frequencies. DP measurements of mangoes in storage can be useful in selecting the optimal ripening stage at which dielectric heating is suited for postharvest pest control.

Dielectric heating as a potential post-harvest treatment of disinfesting mangoes, Part II: Development of RF-based protocols and quality evaluation of treated fruits

With knowledge of frequency and storage dependent dielectric properties of mangoes, we studied a possible treatment that used radio frequency (RF) heating to reduce thermal treatment times in post-harvest pest control of immature mangoes. In this study, surface heating by hot water (HW) was combined with RF core heating of fruit against Mexican fruit fly ( Anastrepha ludens ) in mangoes ( Mangifera indica cv . Tommy Atkins). Mangoes were first heated in water at 45 °C for 50 min followed by RF heating in a 27.12 MHz, 12 kW RF system for 1 min to reach 48 °C over the whole volume of the fruit. Fruit was then held in water at 48 °C for 4, 6 or 8 min, which corresponded to one level at, one above and another below the time needed to achieve 100% killing of third-instar larvae of Anastrepha ludens at this temperature. The controls were treated in HW at 46.1 °C for 90 min, which is a commercial disinfestation treatment approved by the U.S. Department of Agriculture's Animal and Plant Health Inspection Service (USDA-APHIS) for mangoes before shipping to the USA. After 12 days of storage at 21 °C and 90% relative humidity, RF-treated mangoes were firmer than those treated at 46.1 °C in HW ( p

Considerations in design of commercial radio frequency treatments for postharvest pest control in in-shell walnuts

Scaling-up radio frequency (RF) treatment protocols to control insect pests in in-shell walnuts is an essential step to transfer laboratory results to industrial applications. Practical considerations in this effort should include walnut orientation, differential heating between open and closed shell walnuts after bleaching, intermittent mixing to improve heating uniformity, nut quality after storage, and energy costs. A pilot-scale 27 MHz, 6 kW/12 kW RF system was used to determine the effect of process parameters on walnut temperature distribution. Temperatures of vertically oriented walnuts were 7.4 °C higher than those of horizontally oriented walnuts. The open shell walnuts heated much faster in RF systems than closed shell walnuts after 1.5 min of bleaching. Mixing the walnuts twice during 3 min of RF treatment improved the heating uniformity of final walnut temperatures by reducing non-uniformity of the electromagnetic field in the RF system. The accelerated shelf life tests at 35 °C for 10 and 20 days provided accurate simulations of actual storage at 4 °C for 1- and 2-year periods, respectively, based on similar peroxide and free fatty acid values. The energy costs of treating 4540 kg/h was only $0.23 cents/kg. This study should provide useful information for designing an industrial scale quarantine security process against insect pests in walnuts as an alternative to chemical fumigation.

United States Department of Agriculture-Agricultural Research Service research on alternatives to methyl bromide: pre-plant and post-harvest.

Methyl bromide is a widely used fumigant for both pre-plant and post-harvest pest and pathogen control. The Montreal Protocol and the US Clean Air Act mandate a phase-out of the import and manufacture of methyl bromide, beginning in 2001 and culminating with a complete ban, except for quarantine and certain pre-shipment uses and exempted critical uses, in January 2005. In 1995, ARS built on its existing programs in soil-borne plant pathology and post-harvest entomology and plant pathology to initiate a national research program to develop alternatives to methyl bromide. The focus has been on strawberry, pepper, tomato, perennial and nursery cropping systems for pre-plant methyl bromide use and fresh and durable commodities for post-harvest use. Recently the program has been expanded to include research on alternatives for the ornamental and cut flower cropping systems. An overview of the national research program is presented. Results from four specific research trials are presented, ranging from organic to conventional systems. Good progress on short-term alternatives is being made. These will be used as the foundation of integrated management systems which begin with pre-plant management decisions and continue through post-harvest processing.

"There were nosusin the old days:" Post-Harvest Pest Management in an Egyptian Oasis Village

Over the past three decades, a new pest management paradigm has been introduced into the oasian farming system of the Egyptian Western Desert. This western, scientifically-based system supplants the traditional practices developed by the farmers over the millennia. This article documents the indigenous post-harvest pest control and storage practices, discusses how current pest control methods were introduced, examines the socioeconomic factors and reasons for adoption of new technologies, and presents the farmers' perceptions of the impacts these changes have made. In conclusion, I discuss how the indigenous pest management methods may be compared and integrated with western scientific methods towards the development of an environmentally safe integrated pest management (IPM) program. These observations can have important consequences for the development, implementation, and research of pest management practices in other traditional systems.