Spider Mite Predators
Spider mite larvae, nymphs and adults feed on the underside of the leaves and cause yellow spots,later even yellow leaves. Plant cells turn yellow, which can be seen on the upper surface of the leaf as small yellow spots. This reduces the photosynthetic area of the leaf and the plant gets out of the physiological balance. This results in decreased plant growth and production. Finally the crop may die from the infestation. Nymphs and adults produce webbing that can cause cosmetic damage to the crop. If large numbers of spider mites are present, plants may be completely covered with webs.
Spider mites have many natural enemies, which limit their numbers in many landscapes and gardens, especially when undisturbed by pesticide sprays. Some of the most important are the predatory mites, including the Galendromus (=Metaseiulus) occidentalis, and persimilis species. Predatory mites are about the same size as plant-feeding mites but have longer legs and are more active. The purchase and release of predatory mites can be useful in establishing populations in large plantings or orchards, but the best results are obtained by creating favorable conditions for naturally occurring predators—for instance, by avoiding dusty conditions and pesticide sprays. The major predator mites commercially available for release are the western predatory mite and Phytoseiulus. The western predatory mite is more effective under hot, dry conditions. These predators do not feed on foliage or become pests; thus if pest mites are not available when predatory mites are released, the predators starve or migrate elsewhere. If you wish to establish predators in a heavily infested orchard or garden that has few predators, use a soap spray to bring pest mites to a lower level and then release predatory mites. A good guideline is that one predator is needed for every ten spider mites to provide control. More than one application of predatory mites may be required if you want to reduce pest populations rapidly. Concentrate releases in hot spots where spider mite numbers are highest. Once established on perennials, predatory mites may reproduce and provide biological control indefinitely without further augmentation unless nonselective insecticides are applied that kill the predators.
- For tomatoes and cucumbers, 10 predators per plant plus 1-2 per infested leaf.
- For other greenhouse crops, tropical plants, and outdoor gardens, 2,000 per 3,000 sq. ft.
- For bedding plants, 4,000-8,000 per 5,000 sq. ft.
- For large agri-business, 25,000 - 50,000 per acre depending on infestation.
Phytoseiulus persimilis This bright orange predator is native to the tropics of South America. It does best in a humid environment of 60 to 90% relative humidity. Does best where tempertures remain below 90 degrees F. Persimilis is sensitive to high tempertures and low relative humidity. A humidity of 60% or lower has a negative effet on the hatching of the eggs and the development of Persimilis. If spider mite problems occur in a hot and dry environment, Longipes or Californicus will provide better control than Persimilis. Persimilis can reduce spider mite population to very low numbers in two to three weeks. Since Persimilis are faster and stronger than their prey they easily catch and eat them. When released they smell their prey, then move quickly throughout the plant. Persimilis work best from tempertures of 50 t0 90 degrees F. They then die from lack of food. In situations where the pest reinfest the plants, we suggest introducing persimilis every 3 to 5 weeks or introducing either Occidentalis or Californicus in combination with Persimilis.
Amblyseius Swirski Predatory Mite, Amblyseius swirskii is an excellent biological control agent and has been used in controlling tiny pests such as whiteflies, thrips and spider mites that cause a serious damage to many economically important crops grown both in the greenhouses and fields. Effective against the following pests: Asian Citrus Psyllid, Broad mites, russet mites, two spotted spider mite, Western flower thrips, •Chilli thrips, Asian Citrus Psyllid, Greenhouse whitefly, and Tobacco whitefly.
Galendromus occidentalis is a very versatile mite predator and tolerates high temperatures low and high humidity (40-85%) well, both indoors and out. Does best in warm weather (80° to 110° F). Tolerates low humidity of inland valleys. Does not do well in cool coastal areas. Goes into diapause (hibernation) in colder temperatures. Recommended for greenhouses only if plants are maintained as low as 40% relative humidity. It is native to California and has been researched for spider mite control in almonds, grapes, and many other ornamentals and plants. This predator is well adapted for outdoor use and can perform in hot situations where humidity remains above 40%. Use G. occidentalis to control spider mites, two spotted mites, Russet mites, and others on gardens, greenhouses, and orchards of all types. Adults eat 1-3 pest adults or up to 6 pest eggs/day. Release rates indoors, 2-3/sq. ft. bi-weekly, 1-2 applications; outdoors, 5,000-20,000/acre, bi-weekly, 1-2 applications.
Neoseiulus Amblyseius californicus predatory mites consume their prey at a more leisurely pace than do their friends Mesoseiulus longipes and Phytoseiulus persimilis, one adult or a few eggs per day, they can survive longer under starvation conditions and can also live on a diet of pollen. In plants where it is very hard to detect the first spider mites, Californicus may be introduced preventatively, Completes a generation in one to two weeks depending on temperature (12 days at 50º F, 4 days at 95º F). The female lays about 3 eggs per day for two weeks and lives about 20 days. At 77º F the female can consume 5.3 spidermite eggs per day. Does best in warm humid conditions, but will also tolerate low humidity (40% - 80% RH at 50° - 105°F). Occurs along coast and inland valleys of California. Californicus is more resistant to chemical pesticide. Avoid using any pesticide one week prior or one week after releasing predators. STORAGE: Highly perishable, should be used immediately upon delivery. If storage is absolutely necessary, refrigerate at 40°-50° F. (6°-10° C). Not to exceed 2 days, to minimize mortality. They are not canabalistic and survive shipping very well. Release 1 - 4 per plant or 1 - 2 per square foot in greenhouses at the first sign of spidermites. Use 25,000 per acre in field. Later releases will require much higher numbers to be effective. Releases of californicus can be made when Spider mites are present and laying eggs. even if no spider mites have been found yet. N. californicus can tolerate low humidity and ideal temperatures 50-95 degrees F. Can tolerate temperatures up to 105 degrees F. Works great in gardens, greenhouses and indoor potted plants.The Amblyseius californicus will benefit many potted plants and trees. It can also be applied more plentiful to plants with a low damage threshold, such as pot plants, and clear up any early signs of mite infestation. It is very effective on various types of spider mites, broad mites and thrips are also on the menu. This predatory mite works well at both low (48-F) and high temperatures (98-F) and do not hibernate. The A. californicus is good resistance to drought and is more resistant to chemical pesticide.
Mesoseiulus longipes is similar to P. persimilis but can tolerate lower humidity 40% at 70 degrees F. but requires higher humidity as tempertures increase. M. longipes are effective in temperatures up to 100 degrees F, although a comparable increase in humidity is required. Apply these predators in warm greenhouses and interiorscapes with artificial lighting. The lifespan of the adults, the form in which they are shipped, is 34 days. Release rates indoors, 3/sq. ft. bi-weekly, 1-2 times; outdoors, 5,000-20,000/acre, bi-weekly, 1-2 times.
Neoseiulus fallacis - N. fallacis predator is similar to N. Californicus. Reproduces at lower temperatures than other predatory mites (P.persimilis)This predaceous mite has a strong preference for pest mite species and will travel from plant to plant searching for them.
- Resistant to more pesticides than most biological controls
- Survive in the absence of mite prey by feeding on other small arthropods and pollen
Neoseiulus fallacis are known to control the European Red Mite (Panonychus ulmi) below economic thresholds in fruit orchards. Also targets Two-Spotted Spider Mite (Tetranychus urticae), Spruce Spider Mite (Oligonychus ununguis) and Southern Red Mite (Oligonychus ilicis).
Neoseiulus fallacis is a native predatory mite that feeds on spider mites, rust mites and small insects. It is one of the most important biological control agents in North American berry and orchard crops. Adults have pear-shaped bodies, 0.l5mm long; they are tan to light orange in color, shiny, with long legs. Immature predators are cream colored and semi-transparent. Their eggs are oval and 0.3mm long.