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.

Description

Onion thrips are slender and small (1.0-1.2 mm long), adults are pale yellow to light brown becoming darker in winter, with wings that are fringed with long hairs. Nearly all onion thrips are females, males are very rare if present at all, and the larvae are similar in shape to adults but are wingless and paler in colour.

Prevalent during mid-summer, adult and nymph stages feed on plants by piercing the leaf surface and sucking sap. Damage produces silvery patches on the leaves and in severe cases, leaves may wither and the whole plant may appear silvery, causing the crop to ripen prematurely and reduce yields. In onions, thrips can enter harvested bulbs and breed, reducing the marketability of bulbs.

Control

Practising good crop hygiene through the removal of potential host plants around crops is important to reduce onion thrips populations.

Crops should be monitored regularly for onion thrips and control measures should be implemented before numbers peak.

Onion thrips may develop resistance to insecticides quickly, therefore reliance on insecticides alone should be minimised.

At present there are few insecticide control options for onion thrips in onions. Movento ® is an effective option, including where resistant populations have developed to other compounds. Given the systemic nature of Movento® it is effective at controlling hidden thrips and is best applied to juvenile stages of onion thrips.

Related Pests

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.

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.

Northern Plague Thrips

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

Atlas of Living Australia (viewed Oct 2019), ‘Thrips tabaci’, https://bie.ala.org.au/species/urn:lsid:biodiversity.org.au:afd.taxon:ecc99341-8246-4f00-a951-a16fb8483269#overview

Bayer CropScience (Viewed Oct 2019), ‘Users guide for onions: Controlling onion thrips with Movento®’, file:///C:/Users/User/Downloads/Movento%20users%20guide%20for%20onions.pdf

Mo, J (2006), ‘Onion thrips in onion – identification and monitoring’, NSW Department of Primary Industries, Primefact 228, https://www.dpi.nsw.gov.au/__data/assets/pdf_file/0003/75720/Onion-thrips-in-onion-identification-and-monitoring.pdf

Mo, J (2006), ‘Pesticide resistance in onion thrips’, NSW Department of Primary Industries, Primefact 260, https://www.dpi.nsw.gov.au/__data/assets/pdf_file/0011/97742/Pesticide-resistance-in-onion-thrips.pdf

Mo, J (2006), ‘Seasonal patterns of onion thrips in onion – mass invasions or gradual population build up’, NSW Department of Primary Industries, Primefact 248, https://www.dpi.nsw.gov.au/__data/assets/pdf_file/0010/92935/Seasonal-patterns-of-onion-thrips-in-onions.pdf

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