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Aerial Application of Predatory Mites
several species
Order: Acari
Family: Phytoseiidae
One of the more effective methods of controlling spider mites in large scale commercial greenhouse operations, both vegetable and ornamental crops, is to purchase and release predatory mites that feed on the pest mites. Several species of predatory mites are used in this way, and there are a quite a few biological control companies that specialize in selling these and many other biological control agents. Worldwide, this type of biological control is fast becoming the stardard method of controlling insect and mite pests in large commercial greenhouse crops, and the biological control industry is constantly making advances in the diversity, production and effectiveness of biological control agents, as well as improving methods of delivery and application.
Today it is possible for a grower to place an order for a few hundred thousand predatory mites on Monday and have them delivered to his greenhouse on Thursday of the same week. The mites are usually shipped in a bottle filled with a granular media such as corn grits or vermiculite, and for small scale applications, they are released by simply sprinkling this mixture of mites and media over the plants—much like salting a steak. For larger scale releases, there are handheld applicators that dribble the mite/media mixture into the airstream of a small fan and blow the mites onto the crop.
Although this method of spider mite control is not cost effective for field-grown agronomic crops like cotton and soybeans, it is becoming more common in high value specialty crops such as strawberries and vegetables, especially in situations where miticide resistance, worker exposure and pesticide residue concerns limit use of standard miticides. Depending on release rates and frequency, cost for predatory mites can range into the hundreds of dollars per acre, and only crops with high per acre value can support such use. Cost of application is also a major consideration when using predatory mites in such situations, especially when applications have to be made by hand with workers walking every row.
One California company has developed an innovative method for releasing predatory mites, as well as other beneficial insects, onto outdoor specialty crops using a specially adapted GPS-controlled drone. Although we are not likely to see much use of this new application method here in Mississippi in the near future, simply because we don’t have much acreage of the kinds of high value crops on which this method of mite control is cost effective, it is interesting to know such methods exist and to see how pest control methods continue to adapt and evolve.
Thanks to Mr. Chandler Bennett of Parabug for providing this photo of one of their drones in action.
Blake Layton, Extension Entomology Specialist, Mississippi State University Extension Service.
The information given here is for educational purposes only. Always read and follow current label directions. Specific commercial products are mentioned as examples only and reference to specific products or trade names is made with the understanding that no discrimination is intended to other products that may also be suitable and appropriately labeled.
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