Based on the information in this article, one might be able to better choose a predatory mite what with knowing their expected behaviors.
There was an interesting article titled “Understanding Predatory Mites: Keys To Successful Biocontrol” in the Association of Educational and Research Greenhouse Curators (AERGC) Fall, 2007 newsletter written by Kansas State University (KSU) entomologist and AERGC member Dr. Raymond A. Cloyd. The article covered the basics, describing biocontrol in general, then it delved into the use of predatory mites explaining how an understanding of their individual characteristics is key to using them successfully — especially when understanding leads to strategic multi-species implementations.
Dr. Cloyd explained in the article that commercial available predatory mites (adult females, specifically) in the family Phytoseiidae can be categorized into three groups, as follows:
Type I Mites
These are specialists mites feeding and surviving only on spider mites belonging to the Tetranychidae family. This is the family to which the well-known two-spotted mite, Tetranychus urticae, belongs. Dr. Cloyd noted that species belonging to this type have strong aggregation behaviors, commonly remaining among pest groupings for extended periods and can respond quickly to rising numbers. Conversely, Type I mites can also peter out quickly when prey isn’t available because they lack the ability to adapt to other food sources such as pollen and other mites. A classic example of a Type I mite is Phytoseiulus persimilis.
Type II Mites
These are still selective, but easily adapt to other species of pests mites and can also feed on pollen. For general mite control, management, and prevention, due to this adaptability, Type II mites are often a desirable choice for growers. Examples of Type II mites include Neoseiulus californicus, Galendromus occidentalis (see mite trio), N. cucumeris (which feeds primarily on thrips) and N. fallacis.
Type III Mites
These, according to the article, are “generalist” predatory mites. Since the term generalist isn’t one I feel comfortable using — because I feel it leads to possible confusion and disappointment — I will substitute it for extremely opportunistic. Terminology aside, Type III mites will feed on other non-mite prey, plus pollen, honeydew, and plant juices if need be. In the article it was noted that Amblyseius swirskii belong to this category. Also mentioned was that N. californicus was a hybrid Type II/Type III mite because of its ability to cross lines in the name of adaptation (being both selective and extremely opportunistic), as are most Phytoseiids it was noted. To quote:
The classifications discussed above may be simple generalizations because there are exceptions, particularly with Types II and III. — Dr. Cloyd
Based on my own observations, I also think of N. cucumeris and N. fallacis being Type II and II hybrids due to some of the pests I’ve seen them eat. Case in point, it was written that Type III mites will feed on eriophyid and tarsonemid mites (broad and cyclamen mites, respectively). I have witnessed this behavior from N. cucumeris and N. fallacis.
A Quick Overview
Based on the information in this article, one might be able to better choose a predatory mite what with knowing their expected behaviors. In summary:
- Spot infestations of two-spotted mites might be best controlled with the fast-acting and prey-specific Type I P. persimilis, but once the food is gone, they will be too.
- Smaller pest numbers, or sparser groupings might warrant the use of the Type II/III N. fallacis or one of our Mite Trio mite species. Do expect limited, and mostly inconsequential cannibalization.
- If all else fails try Type III, but do so with care. Cannibalization potential is greater so be forewarned. In such cases, it might be a good idea to try the mite-predatory beetle Stethorus punctillum, which can also be viewed as an extremely opportunistic predator, as most beetles are.
