Yan Chen, Ring, Dennis R., Owings, Allen D. | 8/4/2014 11:31:19 PM
Scientific name: Scirtothrips dorsalis (Hood)
Description: Chilli thrips adults are slender and pale brown with fringed wings that fold and form a darker band along their back. They are approximately half of the size of common flower thrips, i.e. 0.4 to 0.6 mm (0.016 to 0.024 inch) in length (Photo 1). Immature stages (larvae and pupae) are very small, yellow and difficult to distinguish from other thrips species.
Pest status: Chilli thrips are found throughout tropical and subtropical regions, attacking over 150 plant species among 40 different families, including many fruit, ornamental and vegetable crops. The first U.S. detection was in Hawaii in 1987. It became established in Florida in 2005 and has now been reported in Texas, Georgia, Alabama and Louisiana.
Biology: Its life cycle is similar to western flower thrips and is completed in 12 to 20 days depending on host plant and temperature. Chilli thrips have a low and high developmental threshold of ~51degrees F and 91 degrees F. Many overlapping generations may occur in suitable conditions. Eggs are laid in plant tissue near floral structures, leaf veins and terminal parts. Larvae emerge from eggs in 6-8 days when temperatures are optimal. The two larval instars take about 2-4 days and 3-6 days to complete. The pupal stage lasts 2-3 days and is spent on the plant or in the soil near the base of the plant. Females oviposit from 60 to 200 eggs during their life.
Ornamental plants as host: At least 46 nursery and landscape plant species have been identified as chilli thrips hosts. The most common hosts include shrubs such as roses, ligustrum, crape myrtle, cleyera, Indian hawthorn, duranta, viburnum and camellia and herbaceous plants such as begonia, coleus, snapdragon, zinnia, coreopsis, verbena and plumbago.
Feeding injury: Chilli thrips feeds on tender young growth (leaves, stem terminals and developing flowers buds and fruits) with rasping-sucking mouthparts. Feeding causes bronzing and curled and distorted leaves, with high infestations leading to leaf drop, dwarfed and stunted plants and bud shed. Photo 2 shows chilli thrips feeding injury on some ornamental plants.
Monitoring: Examine deformed and stunted foliar terminals with a hand lens for thrips life stages. Tapping plant parts over a sheet of white paper will dislodge thrips that can be seen and collected. In nursery production, thrips movements can be monitored with yellow or blue sticky cards near vents, doors and susceptible plants.
Management: Where feasible, reduce weeds that harbor thrips, install thrips-proof insect screens and inspect all new plants to prevent thrips infestations.
Products containing chlorfenapyr, spiromesifen, spinosad and imidacloprid can effectively control chilli thrips. An initial spray program can include a treatment with spinosad, followed 7 to 10 days later by a neonicotinoid and 7 to 10 days afterwards by the application of an organophosphate. Rotation among different classes of insecticides with different modes of actions is needed to reduce the risks of insecticide resistance in chilli thrips and outbreaks of secondary pests. The use of pyrethroids, organophosphate or other broad-spectrum insecticides in the landscape is not recommended, due to their negative impacts on beneficial species that help prevent thrips outbreaks. Contact your local extension agent for the latest pesticide recommendations.
Natural enemies including minute pirate bugs (Orius spp.), lacewings and some predatory mites, which help reduce chilli thrips outbreaks but alone may not provide satisfactory control on preferred hosts such as roses. Adult Orius insidiosus feeds on all life stages of thrips as well as aphids, mites, moth eggs and pollen; therefore, numbers of this bug do not decline strongly even if thrips numbers are drastically reduced. Conserving beneficial arthropods will assist in thrips management, especially in the landscape.
On-going research efforts:
A team of LSU AgCenter and University of Florida IFAS scientists are conducting research to better manage chilli thrips in nursery production by determining: economic thresholds for various management programs, fertilization rates to help plants avoid and recover from thrips injury, rotation and tank mixing programs with biopesticides as alternatives to broad-spectrum insecticides, and the economic feasibility of using economic thresholds and biopesticides.
Additional internet sources: http://entnemdept.ufl.edu; http://www.ldaf.louisiana.gov; http://www.lsuagcenter.com/
The chilli thrips USDA Pest Management Alternatives (PMAP) research team:
LSU AgCenter Hammond Research Station:
Dr. Yan Chen (firstname.lastname@example.org)
Dr. Allen Owings (email@example.com)
LSU AgCenter Dept. of Entomology:
Dr. Dennis Ring (firstname.lastname@example.org)
University of Florida IFAS Mid-Florida Research and Education Center:
Dr. Steven Arthurs (email@example.com)
Dr. Hayk Khachatryan (firstname.lastname@example.org)