US: Oxygenated phosphine may be replacement for methyl bromide

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USDA Agricultural Research Scientists have found that an oxygen-phosphine combination could be an alternative to methyl bromide to control a number of insects pests like the western flower thrip on harvested fruits and vegetables.

Phosphine is effective at controlling insects once combined with oxygen, the researchers say.

Entomologist Yong-Biao Liu with USDA’s Agricultural Research Service (ARS) in Salinas, Calif., found that oxygenated phosphine fumigation effectively controlled several insect pests during laboratory studies.

He tested phosphine fumigation under hih oxygen levels against four different pests – western flower thrips, leafminer purpae, grape mealybug eggs and Indianmeal moth, eggs and purpae.

In 5-hour fumigations with 1,000 parts per million of phosphine at 41 degrees Fahrenheit, control of western flower thrips on lettuce increased from 80 percent to 98 percent when oxygen was increased from 21 percent to 40 percent. When the oxygen level was increased to 80 percent, 99 percent of the western flower thrips were killed.

Liu used varying concentrations of oxygen at 41 degrees F and 50 degrees F and found that oxygenated phosphine fumigation was also effective in controlling leafminer pupae, grape mealybug eggs, and Indianmeal moth eggs and pupae.

Phosphine has been used for more than 80 years as a fumigant to control pests in stored products. It acts slowly against insects. Many insects, especially at egg and pupal stages, are very tolerant of phosphine, and it may take more than 10 days of fumigation treatment to control them. The new treatment would help speed up this process and control insects more quickly.

Source: phys.org