Lady bugs and killer mites!!
Spider Mite Predator Phytoseiulus persimilis
Description
Phytoseiulus persimilis, also known as the fast-action mite predator, is used for the control and management of various spider mites. “Killers.” That’s what they are. They can’t go long without food. These mites, like tiny spiders, eight legs and all, are voracious predators of most of the spider mite pest Tetranychus spp.
P. persimilis are shipped as adults and immatures in corn grit or as adults and immatures, with a bonus of some eggs, on bean leaves.
The corn grit product is flowable and easy to distribute. The leaves, however, are also an excellent distribution medium, and seem to go a little further for some folks. Moreover, the predatory mites are more comfy during their travels on the leaves. These are the same leaves upon which they’re reared.
P. persimilis can control a number Tetranychus spp. mites. Some of the species they can impact include: the two-spotted mite (T. urticae), the carmine red mite (T. cinnabarinus), and the Pacific mite (T. pacificus).
Life-style
The tiny 0.5 mm. hunter-orange female mites lay eggs amongst spider mite concentrations and their webbing (which is produced by the two-spotted mite), if present. They can lay up to 60 eggs! They hatch into minuscule larvae which develop into nymphal forms before reaching adulthood. These, too, are fierce predators, consuming many spider mites eggs and young.
The life-span of these predators is roughly 8 days in their immature stages, then around 36 days as adults. The conditions for optimum performance will be between 70-85°F (extended to 60-90°F) with a relative humidity of between 60-90%. Please note, however, cooler temperatures will hamper reproduction and development a certain degree.
Benefits
These mites are gluttonous, there’s no other way to look at it. And their gluttony is to your advantage. If you put P. persimilis in a suitable environment with nearly any crop to clean up two-spotted mites, that’s exactly what they’ll do. Very fast, very active, very thorough.
P. persimilis are very cost-effective — not the most cost-effective, but worthwhile anyway. And at the recommended rates, they can be a very loud bang for the buck! These predators are an excellent curative agent.
Drawbacks
If there are no spider mites suitable to the tastes of P. persimilis available, they’ll quickly starve to death. Unlike Neoseiulus fallacis which can support its needs with pollen, or N. californicus which can walk around as a wafer-thin disk endlessly eating nothing, P. persimilis must have fresh meat. Its preventive skills amount to none.
This predatory mite species will not do very well in cold climates (see N. fallacis for that).
Scouting
Uninfested and damage/webbing-free new growth is a good sign. So is empty webbing, in interiorscapes and some greenhouses, or missing webbing, outdoors (if it was there to begin with).
Unless your scouting is really top-notch, you’ll probably miss most of the predators present on the leaves. However, if you see some orange, long-legged agile-looking mites running quickly across the leaf’s undersurface, they are probably these predators.
Advisories
Be certain of your pest species. P. persimilis are not as flexible as some other available species. These guys like Tetranychus species only. And not all of them, either.
Low-growing crops like strawberries allow these mites to work all summer long, in the hottest of conditions (this is true in California where these mites are often used in strawberries and other like-crops). The reason, we feel, is the more humid microclimate close to the ground and under the canopy of the plants’ leaves. To artificially recreate these conditions, try a little foliar misting. Most pernicious varieties of mites prefer hot, dry conditions. Consequentially, between the coolness and humidity increase registered when misting, you will be hampering the pests as well as helping the good guys.
The P. persimilis leaf product will often contain a little surprise for its users at no extra cost: Feltiella acarisuga, a predatory spider mite midge similar to Aphidoletes aphidimyza.
Usages
Where can’t they be used would be a more appropriate question. We’ve seen the successful implementation of these species in just about every conceivable situation, except tomatoes where they don’t perform as well. If you have the appropriate species and number of mites, and if the conditions are right, control is virtually inevitable.
Release Rates for Phytoseiulus persimilis
Classification
Release Information
Comments Spring release are par for the course, but fall releases should be considered. They are effective in a preventive capacity.
Prevent 5-9/yd, mnthly, as needed.
Low 10-18/yd, tri-wkly, 2-3 times.
Med 18-26/yd, bi-wkly, 2-4 times.
High 26-32/yd, weekly, 3-4 times.
Maint 3-6/yd, mnthly, indef.
Garden 25-45% of rates listed.
Acre+ 5-30% of rates listed.
Note: one yard equals 9 square feet; rates are per beneficial insect.
I notice that my plant is covered in many white spots and there are small clusters of webs near the bottom! Turns out I have spider mites. I really want to get rid of these pesky suckers so is there any help I could receive from you guys!? Help!
