Scouting, Insecticides Should Be Primary Focus From Late Spring Through Fall

Chilli thrips have become the most significant insect pest in Florida blueberry production and have now been recorded in Georgia. Careful scouting and appropriate application of suggested insecticides are important to help manage this invasive pest.

Chilli thrips are very small (smaller than flower thrips), with adults measuring < 1/16 inch in length. They have pale yellow bodies with incomplete dark stripes on their abdomen and dark fringed wings (Figure 1). 

Figure 1. Adult chilli thrips.

Credits: L. Buss, UF/IFAS

The typical life cycle is about 18-20 days under optimal conditions with four stages: egg, larva, pupa, and adult. Adults tend to disperse over short distances, initially forming “hot spots” in the fields and moving to adjacent plants when the amount and quality of foliage diminishes. Heavy infestations of chilli thrips can occur during prolonged hot and dry periods (June - September).

Chilli thrips typically feed on young, tender foliage and are most frequently observed on the new flush emerging after post-harvest hedging and subsequent flushes. Chilli thrips use piercing mouthparts to remove leaf cell contents, resulting in a bronzing necrotic pattern along leaf veins and petioles, as well as distortion of the leaves typically seen as curling and bubbling (Figures 2 and 3). 

Figures 2 and 3. Chilli thrips feeding damage.

Credits: D. Phillips, UF/IFAS

Scouting for the presence of chilli thrips should begin when new foliage emerges, before damage is observed. This is typically done by sharply tapping foliage onto a phone screen or sheet of paper, using yellow or white sticky cards, or observing leaves with a 20X hand lens. Since the thrips may be distributed throughout the field, sufficient samples or observations should be collected to accurately estimate the population.

A good cultural practice to help minimize chilli thrips populations is the removal of alternate hosts from areas in or adjacent to the production field, including Muscadine grape, Laurel cherry, sugarberry, Spanish needles, Peruvian water primrose, ragweed, sweetgum, and water oak. 

Insecticides are the primary means to manage chilli thrips in blueberry. These include tolfenpyrad (Apta®), novaluron (Rimon®), acetamiprid (Assail®), cyantraniliprole (Exirel®) sulfoxaflor (Transform®), and flupyradifurone (Sivanto®). Florida growers report that spinetoram (Delegate®) has not been effective on chilli thrips in recent years. Spinosad (Entrust®) can be used in organic production. In a recent field trial, tolfenpyrad, cyantraniliprole, and sulfoxaflor were the most effective  insecticides in reducing chilli thrips population. Some growers have also reported success using TriTek® oil or Tres® oil mixed with insecticides, and Surround® (kaolin clay). 

A list of products registered for managing chilli thrips in Florida blueberries along with their active ingredients and insecticide classes are provided in Table 1. Be sure to follow all insecticide label instructions. 

For more information see UF/IFAS EDIS Publication ENY-2053, Chilli Thrips on Blueberries in Florida (https://edis.ifas.ufl.edu/publication/IN1298).