- Other names
- Glover mite, Tetranychus gloveri
Spider mites are so-called because they produce silk. Cotton red spider mite is a generalist species and has been recorded from over 100 different hosts throughout the Pacific and Americas.
In bananas, the mite is most likely to be found on the underside of older leaves, in dry weather and/or on stressed plants. This species is characterised by the red colour of female adult mites. Mites, eggs and webbing can be found along the midrib of the underside of the leaves.
Severe outbreaks could be associated with aerial or cover sprays of broad-spectrum insecticides. Outbreaks of spider mites are usually localised within a plantation.
Warm dry conditions favour mite populations and stressed plants can be more affected than others. Dry micro-climate conditions under plastic bunch covers could be particularly favourable for encouraging an increase in mite numbers.
Adult females are usually less than 0.5 mm in length, have 8 legs and are barely visible to the naked eye. They are bright crimson red when alive.
Adult males tend to have an orange tinge, and immature mites range from greenish to brownish as they mature.
Cotton red spider mites lay colourless eggs. The eggs of other spider mites found on banana (e.g. T. lambi and T. urticae) are also clear when first laid and often become yellow-orange before hatching.
These mites have been recorded on several hosts in the Northern Territory. To date, they have only been detected on bananas and some common weed species in the Wet Tropics region in North Queensland. The full extent of the distribution in Australia is unknown.
The small round colourless egg is followed by three immature stages. These are similar to the adult stage, though a different colour (see above).
The life cycle can be completed in 1-4 weeks, depending on temperature. There are many overlapping generations each year.
All stages of the life cycle plus cast skins, dead mites, and dark faecal droplets occur together, mostly near the veins of the underside of leaves. With high numbers, they can extend over the whole leaf and possibly the fruit.
Cotton red spider mites have been recorded on crop species including banana, cotton and papaya.
Host species include: banana, cotton, beans, eggplant, beetroot, peas, sweet potato palm trees, papaya and many other ornamental and weed species.
Spider mites repeatedly puncture plant cells and suck out the cell contents causing cell death and breakdown. In bananas:
Monitor crops at least fortnightly during hot dry conditions and every 3 weeks at other times. Apply a miticide treatment to prevent damage if mites are found on the young leaves and dry to hot conditions are expected. Miticides are most efficient if applied early in the infestation.
Mites are spread by wind, on clothing and equipment.
Populations increase rapidly in hot dry weather and favour dusty conditions.
Monitoring and action
Control is the same as other spider mites. In general, spider mite activity is mainly confined to dry periods, and specific miticides may be required during these times. High humidity does not favour spider mites and mite populations in north Queensland tend to reduce in the wet season.
The small, shiny black mite-eating ladybird beetle predator, Stethorus spp. is the most important predator of plant-feeding mites in bananas. Both larvae and adults feed on the mites. The black pupae of the ladybird may be seen as a line on either side of the midrib when mite populations are high.
Other predators include:
Spray with a miticide only when plants are not suffering heat/moisture stress. If leaves are wilted or plants are small, coverage of the mites on the under-surface of leaves is difficult. Do not exceed recommended rates and volumes or fruit 'burn' may result.
For good chemical mite control:
Chemical registrations and permits
Check the Australian Pesticides & Veterinary Medicines Authority chemical database and permit database for chemicals registered or approved under permit to treat this pest on the target crop in your state/location. Always read the label and observe withholding periods.
Avoid moving infested plants.