Left: Phytoseiid adult before feeding. J.Ogrodnick
Center: Phytoseiid adult after feeding. Note coloration. J.Ogrodnick
Right: Mite eggs. From left, European red mite, phytoseiid, and Zetzellia mali. J.Ogrodnick

Galendromus (=Typhlodromus) pyri
(Acarina: Phytoseiidae)

Galendromus pyri is found in orchards throughout the world. It is particularly valuable as a natural enemy because of its ability to feed on many types of food when its primary prey is not available.

Appearance

Adults are pear-shaped and slightly smaller than European red mite adults, which are their primary prey. G. pyri adults are white until they feed when they take on the red or brown coloration of their prey. The eggs are pear shaped, almost transparent, but slightly larger than the round European red mite eggs. The larvae are also transparent and difficult to see without a microscope.

Of the five G. pyri life stages, only the larvae are six legged. All other post-egg stages have eight legs. In all stages, G. pyri is indistinguishable from Neoseiulus fallacis and Galendromus occidentalis, other phytoseiid predatory mites, without a compound microscope.

Habitat (Crops)

Many; this page deals only with orchard crops. G. pyri thrives in cool, humid climates, especially the orchards of the northeast, northern midwest, and early and late season in northwest orchards.

Pests Consumed

Galendromus pyri prefers European red mite and actively seeks this prey. It will also feed on the two-spotted spider mite and the apple rust mite.

Life Cycle

Mated adult females overwinter in crevices of the tree bark. They emerge on warm spring days, possibly before the tree buds. They live about 20 days, laying approximately 20-30 eggs. Eggs are laid on or in flower buds before flowers open, and afterwards along the ribs of the undersides of leaves. They hatch in 1-3 days, depending on the temperature. The life cycle, which is composed of five stages, egg, larva, protonymph, deutonymph, and adult, is completed three to four times a season. The low numbers in the spring, due to winter mortality, increase as summer progresses.

G. pyri move vigorously over plant surfaces in search of prey. When prey is scarce, they can survive and reproduce on a diet of pollen, fungi and plant fluids.

Relative Effectiveness

Unlike N. fallacis, G. pyri does not increase in population as quickly as an expanding pest mite population. However, G. pyri survives the winter in greater numbers than N. fallacis. In addition, it is able to thrive and will remain in the tree at low prey density, surviving on alternate foods whereas N. fallacis will leave. Thus, once the prey population is low, G. pyri will prevent its increasing. A mixed population of G. pyri and N. fallacis is desirable in northeast orchards and northern midwest orchards.

In northwest orchards, G. pyri works well with Galendromus occidentalis. In early and late season when it is cool, G. pyri is more efficient, whereas G. occidentalis is more efficient during the hot, dry summers.

Pesticide Susceptibility

Predatory mites are susceptible to many of the chemicals used to combat herbaceous mite infestations. A single application of a chemical considered highly toxic to G. pyri at any time during the season, will have a large negative impact on its abundance.

A strain of G. pyri that is resistant to pyrethroids has been patented in New Zealand.

The habit of G. pyri to overwinter in crevices can be used to advantage in the early spring with a pre-bloom horticultural oil application. This greatly reduces the number of European red mite eggs while not affecting predatory mite populations.

Conservation

It may take up to three years to establish a population of predators high enough to control pest mites. Integrated pest management strategies, as outlined in the tutorial of this guide, can help establish colonies of predatory mites.

Commercial Availability

G. pyri is a common inhabitant of commercial apple orchards in the northeastern United States. In addition, it can be obtained commercially (see the off-site publication, Suppliers of Beneficial Organisms in North America).

Acknowledgment

Thanks to Jan Nyrop for reviewing an earlier version of this section.

Adapted from:

Kain, D. and Nyrop, J. (1995) Predatory Mites. Insect Identification Fact Sheet No. 23. Cooperative Extension, Cornell University, Ithaca, NY.

Additional References

Beers, E.H., Brunner, J.F., Willett, M.J., and Warner, G.M. (Eds.) (1993) Orchard Pest Management: A Resource Book for the Pacific Northwest. Good Fruit Grower, Yakima, WA. 276 pp.

Helle, W. and Sabelis, M.W. (Eds.) (1985) Spider mites: Their Biology, Natural Enemies and Control. Vol. 1B. Elsevier, Amsterdam. 458 pp.

• Orchard mites
  • Galendromus occidentalis
  • Neoseiulus fallacis
  • Zetzellia mali
• Predators Table of Contents
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