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Multiple Thrips Species

Change in distribution of multiple thrips pests

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Name: Multiple Thrips Species
Taxonomic Position:
Animalia: Arthropoda: Insecta: Thysanoptera:
Common Names: Thrips

Many thrips species are important economic pests of plants. Not only can these insect pests do direct damage to plants, they are increasingly being found to vector plant diseases, such as the tomato spotted wilt virus. These insects can easily be introduced into new areas on cut flowers (especially in the flower head), ornamentals, fruits, and vegetables. Increased resistance against insecticides is probably the main factor involved in the spread of thrips pests along man-made routes. Also, the recent huge increase in international exchange of plant material greatly increases the likelihood of spread of formerly unimportant species. Once intercepted or established, thrips are extremely difficult to control with chemical pesticides.

Issues of Concern: There has been a recent change in the distribution of two thrips species and a new country of origin for one species:

*Stenchaetothrips biformis (Oriental rice thrips): This significant pest of rice was detected for the first time in the New World in 1994 in Guyana (Munroe, 1995). Since then, it has been detected in Venezuala in 1995 (Cermeli et al., 1995) and Trinidad in 1997 (White, 2000). Hence, this species is on the move within the New World. In the past, this insect has been intercepted by APHIS PPQ on Cymbopogon from the Philippines.
*Frankliniella panamensis: This species until recently was believed to be present in the US, and therefore it was not regulated by APHIS PPQ. However, it has been determined that, in fact, this species is not present in the US. It was originally described from Panama, and has been found in Costa Rica and Colombia on flowers. However, APHIS PPQ interceptions of this thrips are typically on cut flowers from further south in South America, especially from Peru and Ecuador. This species can potentially be introduced into new areas especially on cut flowers, as the adults are pollen feeders.
*Frankliniella bruneri: This species is a very common, abundant general flower feeder with a very large host range, including ornamental and crop plants. It was recently (February 7, 2000) intercepted on roses from Colombia for the first time. Hence, Columbia represents a new country of origin for this quarantine significant species. This species has long been known to be common among cut flowers imported from Mexico to the US.

In addition, see pest alert for palm thrips.

Vector(s)/Dispersal: Over sixteen virus diseases are spread by thrips, and an increasing number of thrips species are being found to carry viruses. It is mainly the genera Thrips and Frankliniella that are found to transmit plant diseases.

Quarantines: Thrips in general are of quarantine significance to NAPPO countries. A decision to limit the risk of spreading exotic thrips species to the US by adopting measures similar to those now used in Australia may be considered by the USDA-APHIS-PPQ in the near future. In Australia, "all plants and cuttings imported into Australia are subjected to mandatory treatments which kill any thrips which may be present" (Australian Quarantine and Inspection Service, 2000), which is not the case for the US at the present.

Detection Strategies
Thrips in general are difficult to detect at low densities in consignments. They are fast moving, slender-bodied, minute (0.5-5.0 mm in length) insects. Some thrips are light colored, while others are dark colored. Dark species are best seen on a light paper, and light species on a dark paper. Detections on cut flowers can be made by "banging" flowers on a well-lit appropriately colored surface. Inspectors should collect specimens from the sampling surface using a paint brush moistened with alcohol from the vial into which they will be placed. Since thrips are rapidly driven off fresh commodities by heat, a Berlese funnel technique may be an additional useful tool for detecting thrips. One can also inspect for characteristic silvering or streaking damage caused by thrips on the surface of leaves, fruits and vegetables (see photos in this alert).

Source: USDA-APHIS-PPQ, Miami, Florida and Baltimore, Maryland (USA)

Australian Quarantine and Inspection Service. 2000. Fact Sheet: Thrips. Commonwealth of Australia.
Cermeli, M., Garcia, E., and Gamboa, M. 1995. Stenchaetothrips biformis (Bagnall) (Thysanoptera: Thripidae) nueva plaga del arroz (Oryza sativa L.) en Venezuela. Boletin de Entomologia Venezolana N.S. 10(2):209-210.
Munroe, L. 1995. A new pest in Guyana's rice fields. Caraphin News No. 11 pp. 1-2.
White, G. 2000. First record of rice thrips (Thysanoptera: Thripidae) in Trinidad, West Indies. Florida Entomologist 83(2):188.

Warning: The information in this archived item was not confirmed with the appropriate National Plant Protection Organization and is provided solely for informational purposes. Please use this information with caution.

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