Stenchaetothrips biformisBagnall

Old World pest of rice poised to enter North America

Click here for the enlargement of
this photo or for additional images

Name: Stenchaetothrips biformis Bagnall
Taxonomic Position:
Animalia: Arthropoda: Insecta: Thysanoptera: Thripidae
Common Names: Oriental rice thrips; paddy thrips; trips del arroz (Spanish); thrips du riz (French)

In July 1997, specimens of oriental rice thrips, Stenchaetothrips biformis, were found damaging seedling rice (Oryza sativa) near Caroni, Trinidad. The affected field was sprayed with insecticide and no more thrips were found during future monitoring exercises. Prior to this observation, the first detections of S. biformis in the New World were in Guyana in 1994 and Venezuela in 1995. It should be noted that the location in Venezuela, Calabozo, is approximately 700 km west-southwest of Trinidad.

Issues of Concern: The oriental rice thrips is an economically important pest of rice crops in the Old World, and is especially damaging to young rice plants sown late in the season. Wilting and scorching of the leaf tips is produced by larval and adult feeding, occasionally leading to stunting or death of the affected plants, particularly during prolonged dry periods. According to Mound (1997), S. biformis ranks fifth out of 35 thrips pests worldwide. In addition to rice, S. biformis is known to be polyphagous on other grass species, greatly increasing its chances of spread from South America and the Caribbean basin to the rice producing regions of the US and Mexico.

Hosts: The primary host is rice (Oryza sativa), and secondary hosts are Zea mays (maize) and Saccharum spontaneum (wild sugarcane). Wild grass hosts include species in the genera Agropyron (wheatgrass), Festuca (fescues), and Pennisetum (feathergrass).

Asia (Afghanistan, Bangladesh, Bhutan, Cambodia, China, India, Indonesia, Japan, Korea, Laos, Malaysia, Myanmar, Nepal, Pakistan, Philippines, Sri Lanka, Thailand, United Arab Emirates, Vietnam); Europe (Czech Republic, Italy, Romania); Oceania (Australia, Guam, Papua New Guinea); South America (Guyana, Venezuela).

Detection Strategies
The larvae and adults of this species feed on the growing tips of seedling rice, causing the tip to silver and show translucent to yellow-brown streaking. To form a protective chamber for feeding, both larvae and adult fold the leaf longitudinally. Eggs are laid singly in slits, with the upper half of the egg exposed on the leaf surface.

The genus Stenchaetothrips is often confused with the genus Thrips, the critical difference being the length of the Ocellar setae. As opposed to to Thrips, the Ocellar II and III setae are more elongate and shorter, respectively, in the Stenchaetothrips. In general, adult thrips are dark brown, slender insects with very slightly projecting eyes and seven-segmented antennae. Adults are winged or wingless. Stenchaetothrips biformis has a more darkened body color than typical thrips, with shaded forewings and a large gap in the forevein setae.

The oriental rice thrips may be controlled with flooding, however, if this species were to become economically important in North America it could interfere with the current practice of draining fields for control of Hydrellia spp. (rice leaf miners).

Source: Broda, S. In press. The oriental rice thrips, Stenchaetothrips biformis Bagnall (Thripidae: Thysanoptera), and its potential risk to US agriculture.

Mound, L.A., and R. Marullo. 1996. The Thrips of Central and South America: An Introduction (Insecta: Thysanoptera). Associated Publishers, Gainesville, FL. p. 195.

Mound, L.A. 1997. Biological Diversity. In: Lewis, T. (ed.) Thrips as Crop Pests. CAB International, New York, N.Y. pp. 197-215.

White, G. 2000. First record of rice thrips (Thysanoptera: Thripidae) in Trinidad, West Indies. Florida Entomologist 83(2): p. 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.