Location: Crop Improvement and Protection Research
2017 Annual Report
Objectives
The long-term goal of this project is to develop alternative postharvest pest control treatments that are effective and safe for control of quarantine pests on a wide range of perishable agricultural commodities. This project builds upon our previous success with nitric oxide (NO) and oxygenated phoshine (PH3) fumigations as potential alternatives to methyl bromide fumigation for postharvest pest control on fresh fruits and vegetables. Nitric oxide was found to have higher efficacy than regular PH3 and may also enhance postharvest quality of fresh products. Oxygenated PH3 fumigation was found to control external pests with greater efficacy than regular PH3 fumigation. Successful completion of the project will result in specific NO fumigation and oxygenated PH3 fumigation treatments against four insect species on fresh fruit and vegetables including western flower thrips, light brown apple moth, codling moth, and the fruit fly spotted wing drosophila. Specific objectives are listed below:
Objective 1. Develop nitric oxide fumigation treatments for postharvest pest control.
Sub-objective 1.A. Develop an effective nitric oxide fumigation treatment to control western flower thrips on fresh fruit and vegetables.
Sub-objective 1.B. Develop an effective nitric oxide fumigation treatment to control light brown apple moth on fruit.
Sub-objective 1.C. Develop an effective nitric oxide fumigation treatment to control codling moth in apples.
Sub-objective 1.D. Develop an effective nitric oxide fumigation treatment to control spotted wing drosophila in sweet cherries and strawberries.
Objective 2. Develop oxygenated phosphine fumigation treatments for postharvest pest control.
Sub-objective 2.A. Determine feasibility of oxygenated phosphine fumigation to control codling moth in apples.
Sub-objective 2.B. Determine feasibility of oxygenated phosphine fumigation to control spotted wing drosophila in strawberries.
Approach
Objective 1. Nitric oxide fumigation under ultralow oxygen conditions will be studied for controlling insect pests including western flower thrips, light brown apple moth, codling moth, and spotted wing drosophila on harvested fresh commodities for their exports. Small scale laboratory fumigations will be conducted to determine effective treatments (concentration, time, and temperature) for different insects. Selected treatments will then be tested on specific fresh products to evaluate the impact of the treatments on postharvest quality.
Objective 2. Oxygenated phosphine fumigation under high oxygen conditions will be studied for controlling codling moth larvae in apples and spotted wing drosophila in sweet cherries and strawberries. Small scale laboratory fumigations will be conducted to determine effective treatments to control the most tolerant life stages of the pests in the fruits. Selected effective treatments will then be tested on fresh products to verify their efficacies and impact of postharvest quality of the fresh products.
Progress Report
Continuing to determine residues of nitric oxide fumigation in fresh and stored products to provide necessary data for eventual registration of nitric oxide as a pesticide for postharvest pest control. Understanding residues of nitric oxide fumigation is important to determine the potential impact on food safety and registration with the United States Environmental Protection Agency (EPA) for postharvest pest control. After completing residue analyses on over 20 fresh fruit and vegetables, research has started on residue analysis on stored products including grains, beans, and nuts. This research relates to the Objective 1 “Develop nitric oxide fumigation treatments for postharvest pest control” of the project plan.
Nitric oxide fumigation of packaged lettuce has been found to be problematic due to poor ventilation of plastic wraps that impedes air exchange. Research is in progress to develop a nitric oxide fumigation treatment to control lettuce aphid and western flower thrips on harvested lettuce through reduction of nitric oxide concentration and increased treatment time in order to achieve effective control of the insects but prevent injury to lettuce quality. This research relates to the Objective 1A “Develop an effective nitric oxide fumigation treatment to control western flower thrips on fresh fruit and vegetables” of the project plan.
Nitric oxide fumigation requires establishment of ultralow oxygen environment in fumigation chambers before injecting the fumigant. Nitrogen gas has been used to establish ultralow oxygen environment. Research is in progress to determine whether carbon dioxide can be used to establish ultralow oxygen environment for nitric oxide fumigation and its possible effects on efficacy of nitric oxide fumigation against stored product insects. The research is intended to provide another option for conducting nitric oxide fumigation. This research relates to the Objective 1 “Develop nitric oxide fumigation treatments for postharvest pest control” of the project plan.
Accomplishments
1. Nitric oxide fumigation treatment to control codling moth in apples. Codling moth is an important quarantine pest on exported apples and other fruits and is also difficult to control. An ARS researcher in Salinas, California in collaboration with two entomologists from APHIS and the University of California, Davis successfully developed an effective nitric oxide fumigation treatment for control of codling moth larvae in apples. A 24 hour fumigation treatment with five percent nitric oxide at a low storage temperature of 2 degrees Celsius not only provides complete control of codling moth larvae in apples but also enhances postharvest quality. Treated apples were firmer and retained color better than the controls two- and four-weeks after post-treatment cold storage. The study showed that nitric oxide fumigation has the potential for controlling codling moth in apples.
2. Nitric oxide fumigation leaves no harmful residues on fresh products. It is important to determine residues of nitric oxide fumigation to ensure its safety to human health and provide necessary data for eventual registration of nitric oxide for commercial use as a pesticide. An ARS researcher in Salinas, California in collaboration with an entomologist from University of California, Davis determined that nitric oxide fumigation does not leave toxic residues in fumigated fresh fruit and vegetables. Nitric oxide fumigation can result in increased nitrate and nitrite as residues. Nitric oxide fumigation when conducted properly with nitrogen flush at the end of fumigation to dilute nitric oxide did not cause significant increases in nitrate or nitrite as compared with controls on 20 fresh products. Nitrate and nitrite levels in fumigated products are within their normal ranges. This study shows that nitric oxide fumigation does not have residue concerns and therefore is safer for human health than most other fumigants, and therefore has good potential to be used for postharvest pest control.
Review Publications
Liu, Y.-B., Yang, X., Simmons, G. 2016. Efficacy and safety of nitric oxide fumigation for controlling codling moth in apples. Insects. 7:71. doi: 10.3390/insects7040071.
Yang, X., Liu, Y.-B. 2017. Residual analysis of nitric oxide fumigation on fresh fruit and vegetables. Postharvest Biology and Technology. 132:105-108.
