Chilli Thirps Diagnostic Guide
Scirtothrips dorsalis Hood
The chilli thrips, Scirtothrips dorsalis Hood, is an important pest of various vegetable, ornamental and fruit crops. Thrips possess piercing and sucking mouthparts and cause damage by extracting the contents of individual epidermal cells leading to tissue necrosis. Chilli thrips create; damaging feeding scars, distortion of leaves, and discoloration of buds, flowers and young fruits by feeding on the meristems of the host plant’s terminals and on other newly developed plant parts.
Trees at Risk
Chilli thrips can effect over 100 different plant taxa. Common shrubs affected are; duranta, plumbeago, pittosporum, Indian hawthorn, snowbush, and rose.
Florida, Georgia, Hawaii, Louisiana, and Texas. Suggestions are this pest may spread further.
Signs of Damage
- Chilli thrips are pale colored and the lengths of their first and second instar larvae and the pupae are 0.37- 0.39, 0.68-0.71 and 0.78-0.80 mm, respectively.
- Adults are about 1.2 mm long with dark wings and dark spots forming incomplete stripes which appear dorsally on the abdomen (Seal et al. 2009a).
- Silvering of the leaf surface.
- Linear thickenings on the leaf surface.
- Brown frass markings on the leaves and fruits.
- Grey to black markings on fruits often forming a conspicuous ring of scarred tissue around the apex.
- Fruit distortion and early senescence of leaves.
Damage can be confused with lacebug or foliar diseases. Unlike other thrips, pupae of chilli thrips are generally found on leaves, leaf litter or on the axils of leaves, in curled leave.
- Lifcyce consists of egg, first and second instar larvae, pre-pupa, pupa, and adult. Females insert the eggs inside plant tissues above the soil surface.
- Eggs hatch between two to seven days, depending upon temperature.
- Larvae and adults tend to gather near the mid-vein or borders of the host leaf.
- The two larval stages are completed in eight to ten days and the pupal stage lasts for 2-4 days.
- The life span of chilli thrips is influenced by the host plant species. For example, at 28°C it takes 11 days for first instar larva to progress to adult stage on pepper plants and 13.3 days on squash plants. The chilli thrips adult’s life span lasts an average of 15.8 days on eggplant, but only 13.6 days on tomato plants (Seal et al. 2009a).
- 4-8 generations per year.
Field diagnosis of the insect and the host plant are usually sufficient.
Treatment Strategy Expectations
Systemics have been reported to work well. May need to combine with foliar sprays for faster control.
A Diagnostic Guide is designed to help you identify a pest issue and management solutions. Always refer to product label for all rates and approved uses. Some images courtesy forestryimages.org. Use of the images does not imply endorsement of treatments by forestryimages.org