Thrips

Chaetanaphothrips signipennis (Banana rust thrips), Thrips imaginis (Plague thrips), Thrips tabaci (Onion thrips), Thrips safrus (Northern plague thrips), Frankliniella occidentalis (Western flower thrips), Frankliniella schultzei (Tomato thrips), Pezothrips kellyanus (Kelly’s citrus thrips)

While over 6000 species of thrips exist worldwide, only ten per cent are deemed to have an economic impact on crops. The most common group is Terebrantia, which includes many of the damaging species such as onion thrips, western flower thrips and plague thrips. Hosts include citrus, green beans, cotton, mungbeans, cereals, some vegetables, summer pulses, sunflowers, canola and peanuts. Thrips can be vectors for tobacco streak virus and tomato spotted wilt virus.

Refer to links below for a more detailed description on different thrips species.

Description

Thrips are small (2 mm), with a slender, cigar-shaped body with fringed wings. Colours range from pale to dark brown and sometimes black. The larvae are similar in appearance to adults however are smaller, pale and wingless.

Eggs are usually laid into plant tissue, although some species will lay eggs on the plant surface. Most species pupate in leaf litter whilst others pupate on protected parts of the plant, such as flowers.
Thrips have tiny needle-like mouthparts which puncture the outer layer of plant cells to suck the sap.

Affected leaves tend to have a silvery-white appearance and younger leaves can become distorted and growing points may die. Feeding damage to fruit can cause blemishes and fruit scarring, resulting in quality downgrades.

Control

As some thrips such as western flower thrips and onion thrips can develop resistance quickly, it is important not to rely on insecticides alone. Natural predators of thrips include pirate bugs, lacewing larvae and ladybird beetles, therefore encouraging these populations will assist in keeping thrips populations low. Avoiding applications of broad spectrum, residual chemicals is important in maintaining these beneficial insect populations.

Regularly monitoring plants for evidence of thrips damage, managing host weeds and planting resistant or tolerant crop varieties will assist in reducing economic losses. Also, turning in harvested residues in crops such as green beans, may assist in killing any thrips that may be present pupating in the soil.

Thrips often occupy protected areas such as flowers, growing tips and leaf curl galls. Consequently, systemic pesticides can be more reliable for control compared to contact pesticides which only control thrips present on the plant surface.

Movento® is ideal for controlling sucking pests which hide in protected parts of the plant and is also soft on most beneficial species when used as directed. Movento is registered for control of western flower thrips in beans (green), celery, rhubarb, eggplants, peppers, tomatoes, herbs, bulb vegetables (excluding bulb onions) and lettuces. It is also registered for control of tomato thrips in beans (green), celery, rhubarb, bulb vegetables (excluding bulb onions), and herbs. Registration for control of plague thrips exist in celery, rhubarb, herbs and provides suppression only in grapes. It is also registered for Kelly’s citrus thrips in citrus and for onion thrips in bulb onions and bulb vegetables. Lastly, it is also registered for suppression of northern plague thrips in grapes.

Movento® Energy and Confidor® Guard are both registered in bananas for the control of banana rust thrips.

Confidor 200 SC is registered for melon thrips control in eggplants and greenhouse thrips control in ornamental plants.

Related Pests

Banana rust thrips

Chaetanaphothrips signipennis

Banana rust thrips are a widespread problem in the coastal areas of Queensland and northern New South Wales. Predominantly affecting bananas, they have also been found in citrus and some native plants. In bananas they cause superficial damage to the skin which can result in the fruit being downgraded or rejected at market. Banana rust thrips are notably troublesome in areas with red soil and where bunch bagging is not used. Fruit that grows in the early warmer months tends to be more at risk.

Refer to the links below on different thrips species.

Plague thrips imaginis

Thrips imaginis

Plague thrips are native to Australia and are widespread across the southern mainland and Tasmania. Their main hosts are pome and stone fruit and will also feed on strawberries, legumes, tomatoes, Eucalyptus spp., grapes, ornamentals, grasses, weeds and a variety of native plants. They are frequently present in citrus trees but do not cause economic damage.

Refer to the links below on different thrips species.

Onion thrips

Thrips tabaci

Onion thrips infest a wide range of hosts, including onions, garlic, leek, beans, cabbage, cauliflower, broccoli, cotton, celery, tobacco, tomatoes, cucumber, strawberries, potatoes and a range of ornamentals. Onion thrips are known vectors of tomato spotted wilted virus (TSWV) and iris yellow spot virus (IYSV) which is a potentially destructive virus of onions.

Refer to the links below on different thrips species.

Western flower thrips

Frankliniella occidentalis

A more serious pest than other thrips species because it plays a major role in infecting tomato, potato, capsicum and lettuce crops with the tomato spotted wilt virus (TSWV).

Tomato Thrips

Frankliniella schultzei

Tomato thrips originate from South America and are widespread throughout Australia. They prefer to feed on flowers and have a wide range of hosts including tomatoes, tobacco, capsicums, lettuces, potatoes, grain legumes and several weed species. They are known vectors for tomato spotted wilt virus (TSWV) which can cause considerable yield losses in tomato, capsicum, potato and lettuce crops.

Kellys citrus thrips

Pezothrips kellyanus

Kelly’s citrus thrips (KCT) are a serious pest of citrus in inland Australia, where in the Riverland-Sunraysia region of South Australia alone, it is estimated to cost industry $10 million per annum in crop losses and control measures. KCT feed on the fruit, causing scurfing (or halo) damage at the stem end and rind blemish which results in quality downgrades and reduced pack-out rates. The most affected varieties are Navel and Valencia oranges, lemons and grapefruit.

Refer to the links below on different thrips species.

References

Broughton, S (2018), ‘Thrips in citrus’, Department of Primary Industries and Regional Development, https://www.agric.wa.gov.au/citrus/thrips-citrus

Duff, J (Viewed Oct 2019), ‘ Thrips in green beans’, Department of Employment, Economic Development and Innovation, Queensland Government, https://www.daf.qld.gov.au/__data/assets/pdf_file/0008/69740/trips-beansFS-web.pdf

Duff, J and Manners, A (2016), ‘Thrips: A pest management plant for productions nurseries’, Horticulture Innovation Australia, https://www.horticulture.com.au/growers/help-your-business-grow/research-reports-publications-fact-sheets-and-more/thrips-a-pest-management-plan-for-production-nurseries/

Duff, J and Manners, A (2017), ‘What are Thrips’, Horticulture Innovation Australia, https://www.horticulture.com.au/growers/help-your-business-grow/research-reports-publications-fact-sheets-and-more/thrips-fact-sheet/

Queensland Government (2018), ‘Thrips’, https://www.business.qld.gov.au/industries/farms-fishing-forestry/agriculture/crop-growing/pests-field-crops/thrips