Zetzellia mali–Predatory Mite

Biocontrol Agent Factsheet

Zetzellia mali is a small predatory mite that feeds on spider mites and rust mites. It does not consume as many prey per day as other mite predators but may aid them in keeping pest mite populations below damaging levels.

Common Names

None

Relative effectiveness

This predator primarily feeds on European red mite and rust mites, but will also feed on non-pest tarsonemids mites when prey are scarce. Unlike phytoseiid mites, which can only feed on motile stages of European red mite, Z. mali can penetrate the waxy surface of and consume European red mite eggs. Zetzellia mali is not as efficient of a predator as phytoseiid mites (such as Galendromus occidentalis), because it is a slow mover and does not consume many prey items per day. It also competes with phytoseiids and can feed on their eggs, so the overall benefit of this mite is somewhat limited.

Where to use

Fruit (especially apples, grapes) grown outside

This predator is naturally present in apple orchards in temperate North America and Europe.

About Zetzellia mali

Zetzellia mali is a small predatory mite that feeds on spider mites and rust mites. Although it can be found in grapes, it is best known from apples. It is a slow-moving predator and does not consume as many prey per day as other mite predators, such as phytoseiids (e.g., Galendromus occidentalisNeoseiulus fallacis). However, it may aid other predators in keeping pest mite populations below damaging levels.

  • Native/Non-native: Native
  • Preferred climate: Arid, humid, temperate, cold tolerant 
  • Region: Temperate North America and Europe
  • Established: Yes
  • Where established: Temperate North America and Europe

Zetzellia mali Appearance

These predatory mites are roughly football shaped, with a pointed head and rear. They are bright yellow and can develop a reddish blush as they feed on dark-colored prey; the color is especially prominent in adults. The eggs are spherical, bright yellow, and slightly smaller than spider mite eggs.

Close up picture of mite next to an egg on a leaf. The Z. mali has a yellow head area and yellow legs and a red body. The Z. mali eggs are spherical and lemon yellow.

A recently fed adult female Zetzellia mali (indicated by reddish coloring) on the surface of a leaf near three Z. mali eggs.

A close-up picture of a solid yellow Zetzellia mali mite. It is somewhat diamond shaped and has two pale red eyespots near the front of its head.

Zetzellia mali can also be solid yellow, especially if they have not fed on dark-colored prey recently.

How to Use Zetzellia mali

Biocontrol category: Conservation—attract and protect from the surrounding environment

When to use: Zetzellia mali can be found as early as spring on new apple foliage, with populations peaking in summer. Depending on temperature and leaf drop, Z. mali may be observed on foliage until late fall, when the females then move into overwintering locations on the bark. Population peaks of Z. mali tend to coincide with high rust mite populations.

Maximizing effectiveness: These predators are not commercially available. Maximizing effectiveness involves conservation, which is primarily driven by pesticide use (see relevant sections below).

Pest stage: All pest stages are attacked by this predator.

Mode of action: Predator

Conservation: The primary method for conserving Zetzellia mali is to avoid or limit harmful pesticide applications when possible. See Compatibility for pesticide selectivity information. The presence of rust mites can aid conservation of Z. mali. Pesticides that harm rust mites may reduce populations of predatory mites.

Compatibility: There is mixed evidence on whether Zetzellia mali is more or less pesticide tolerant than other mite natural enemies. There are some populations that are tolerant to pyrethroids and organophosphates. Fruit thinners such as naphthaleneacetic acid (NAA) and carbaryl can reduce populations of Z. mali. In general, follow recommendations for conserving the phytoseiid mites common in your apple system as opposed to specifically focusing on Z. mali. (Any time you use a pesticide, you must read and follow the label directions and comply with all applicable laws and regulations related to pesticide use. Also be sure that any pesticide used is approved for use in your country and state/province.)

Commercially available: No

About Pests Targeted by Zetzellia mali

Zetzellia mali primarily consumes non-web spinning spider mites and rust mites and has a strong preference for feeding on apple rust mites and European red mite eggs. It has been reported to eat brown mites and twospotted spider mites, but is not at all effective at controlling these pests. It can also feed on non-pest tarsonemid mites when other prey are scarce.

  • European red mite (Panonychus ulmi)
  • Brown mite (Bryobia rubrioculus)
  • Apple rust mite (Aculus schlechtendali)

Targeted Pest Damage

Damage by spider mites appears as small yellow or white spots on leaves, indicating where they have removed chlorophyll. Further damage can cause the leaves to turn brown (bronzing) or, on sensitive tree species like pears, cause the leaves to turn black, die, and fall off of the tree. Rust mite damage can appear somewhat similar, but rust mites may also feed on the skin of fruit, resulting in downgrading or unmarketability, especially in light-skinned varieties that show damage clearly.

Brown mite adult viewed top down. The mite has very long front legs and two red eyespots. Its general color is tannish-brown, with darker brown coloring on the abdomen.

Brown mite adult

Two spherical eggs on a leaf surface. The eggs are brick red.

Brown mite eggs

Author

Rebecca Schmidt-Jeffris
USDA-ARS

Date: January 2022

  • Zetzellia mali can also be solid yellow, especially if they have not fed on dark-colored prey recently. Image credit: R. Schmidt-Jeffris.
  • A recently fed adult female Zetzellia mali (indicated by reddish coloring) on the surface of a leaf near three Z. mali eggs. Image credit: R. Schmidt-Jeffris.
  • A Zetzellia mali mite tucked under a leaf midvein eating the egg of another predatory mite species (likely Galendromus occidentalis).
  • The life cycle of Zetzellia mali at typical summer temperatures. Image credit: R. Schmidt-Jeffris. Made with Biorender.com.
  • Brown mite adult. Image credit: R. Schmidt-Jeffris
  • Brown mite eggs. Image credit: R. Schmidt-Jeffris.