Bryobia Mites

Bryobia species

Family: Tetranychidae

Order: Acarina

Class: - Arachnida

Other names:

Clover Bryobia mite, Clover mite.

Description:

Brown to grey body to 0.85 mm with 8 pale orange legs mainly on canola lupins and lucerne. Crushing the mites to kill them leaves a large reddish spot.

Female parthenogenic - lays unfertilised eggs.

Male unknown or very rare.

Adult female lead grey with front end of body and legs red or pink.

Body - flattened, oval shape, green brown to lead grey or reddish brown.

Body length - 0.7-0.85 mm long.

Abdomen - has feather like plates.

Legs - 4 pairs of legs (front pair of legs twice as long as any other pair and look like antennae).

Mouth Parts - Piercing stylet for piercing and sucking plant tissue.

Eggs - Spherical, bright red and can develop to an adult in 3 weeks from hatching under optimal conditions.

Larva -Bright red, disk shaped and 6 legged. It has distinctive dorsal body setae that are longer, slender, and serrate.

Nymphs - Two nymphal stages protonymph and deutonymph, which are eight-legged like the adults. Older nymphs are the same colour as the adults.

Biology:

They develop from unfertilised eggs (i.e. parthenogenic).

Life Cycle:

Depends on the particular species.

E.g. Apple and pear Bryobia - overwintering eggs are found in creases of bark and at base of twigs and shoots. They hatch in spring with bud burst and feed on leaves. Summer eggs are usually laid on bark and have an incubation of 3 weeks. Adults grow and mature 3 weeks after hatching.

E.g. Clover Bryobia Mite (Bryobia praetiosa Koch) feed on grass and other low herbage, particularly plants belonging to legume family. They have life cycle similar to Redlegged Earth Mites or Blue Oat Mite being active during cool, moist autumn to spring and producing dormant over summering eggs. Bryobia eggs hatch when rain occurs and don't have the same cool temperature requirement as Redlegged Earth Mite so they are often seen earlier in the season. They are active when temperatures are above 100C.

Habitats:

Origin and History:

Distribution:

Clover Bryobia Mite - Widespread. Asia, Africa, Australia, Europe, North and South America.

Damage Symptoms:

Clover Bryobia Mite -

Small, irregular silver to white streaks on the leaves.

In lawns, injured foliage usually turns yellow to brown and then wilts.

Feeds on many plant species including Clover, Alyssum, Capeweed, Daffodil, Dandelion, lawn grasses, ornamental flowers, Primrose, Shepherd's Purse, Salvia and Strawberry.

Significance:

They infest a wide range of plants including apple, pear, several Prunus species, gooseberry, walnut, hawthorn, ivy, clover, grass, herbaceous plants and occasionally cucumbers under glass. Bryobia mites are rarely an important pest but if present a fine speckling can develop on the foliage of their host. Damage results from the piercing of the leaves to extract plant sap. Leaves then lose their normal deep colour, becoming a pale and silvered or bronzed colour. Heavy infestation may cause yellowing, wilting and eventually defoliation of bushes.

Occasionally they may invade houses and are a nuisance and leave red stains when crushed. They are not known to be a threat to health, food or clothing.

Management and Control:

Bryobia mite is easily eradicated by most of acaricides.

In fruit trees some options for summer or spring are; oil, demeton-s-methyl, dicofol, tetradifon.

Clover Bryobia Mites are usually controlled by Redlegged Earth Mite control procedures.

For paddocks to be cropped, green weeds may be sprayed with Le Mat before seeding to achieve control.

Controlling weeds in previous crops and in the autumn before planting will control many Bryobia Mite infestations.

Related Species:

Similar Species:

Redlegged Earth Mite (Halotydeus destructor) has a dark or black body with red legs.

Blue Oat Mite (Penthaleus major) has a red spot on its back.

Balaustium Mite (Balaustium medicagoense) has short hairs on their body.

Clover Bryobia Mite (Bryobia praetiosa) has very long front legs.


References:

Ministry of Ag, Fisheries and Food (Publication). Willowburn Estate, Alnwick, Northumberland, Leaflet 305 revised 1985.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.