Insect Pests June 2002 IP-10 Banana Rust Thrips Damage to Banana and Ornamentals in Hawaii Arnold H. Hara 1 , Ronald F. L. Mau 1 , Ronald Heu 2 , Christopher Jacobsen 1 , and Ruth Niino-DuPonte 1 1 CTAHR Department of Plant and Environmental Protection Sciences, 2 Hawaii Department of Agriculture B anana rust thrips, Chaetanaphothrips signipennis (Bagnall) (Thysanoptera: Thripidae), was collected once in 1954 from an outdoor planting of anthurium in Manoa, Oahu, and was not seen again until 1996, when it was collected from several commercial nurseries and farms on the island of Hawaii, after causing severe dam- age to anthurmium, ti, dracaena, and banana. Banana rust thrips are present in parts of Australia (Queensland and New South Wales) and Central America (Honduras, Panama), Brazil, Fiji, Sri Lanka, and India. They are also established in Florida. The banana rust thrips is similar in appearance to two other introduced Chaetanaphothrips species, the an- thurium thrips, C. orchidii (Moulton) (see Hara et al. 2002), and C. leeuweni (Karny), which also share the same hosts, including banana, ti, and anthurium. Banana rust thrips can be differentiated from the other two spe- cies by clear differences in body features (specifically, the presence in females of body hairs and glands that are visible only with a microscope [Sakimura 1975]). Hosts The primary hosts of banana rust thrips are anthurium, ti, dracaena, and banana. They also infest immature fruits of orange, tangerine (mandarin), and tomatoes, as well as green beans. Damage The appearance of feeding damage caused by banana rust thrips varies with the host plant species. In most cases, thrips prefer to feed on very young, succulent, immature fruits, flowers, and foliage. On dracaena and ti (Fig. 1a), thrips can be observed feeding in the whorls of immature leaves, causing dis- coloration and silvering (characterized by long white streaks) as well as random squiggles or curlicues near the petiole end of developed, unfurled leaves. Also, par- ticularly on red ti varieties, the immature leaves may fail to unfurl and thus appear as deformed leaf whorls (Fig. 1b). On anthurium, banana rust thrips damage appears as white streaks or scarring on the front and back of the spathe, deformed spathes, and, with age, bronzing of injured tissues (Fig. 1c). In severe cases, mature anthu- rium spathes fail to open, plant growth may be reduced, and the foliage may be affected by deformity, bronzing, and streaking. Damage by banana rust thrips to certain anthurium cultivars, such as ‘Kalapana’ and ‘Ozaki’, may appear as curlicues rather than streaks. On banana, feeding damage is observed on the pseudostem, but it is the injury to the fruit that signifi- cantly affects marketability (Fig, 2). Thrips feeding in leaf sheaths results in characteristic dark, V-shaped marks on the outer surface of leaf petioles. Damaged tissue becomes bronzed or rust-colored with age. Feeding dam- age to the fruit occurs on fingers soon after the flower petals dry, initially typified by a water-soaked appear- ance. Young fruits may have dark, smokey-colored ran- dom squiggle or curlicue feeding tracks on the surface. On mature fruit, oval-shaped, reddish “stains” may be seen where the fingers touch. Extensive damage may cover more of the fruit surface with reddish-brown or black discoloration and superficial cracks. Though un- marketable, such fruits are still edible. Published by the College of Tropical Agriculture and Human Resources (CTAHR) and issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Andrew G. Hashimoto, Director/Dean, Cooperative Extension Service/CTAHR, University of Hawaii at Manoa, Honolulu, Hawaii 96822. An Equal Opportunity / Affirmative Action Institution providing programs and services to the people of Hawaii without regard to race, sex, age, religion, color, national origin, ancestry, disability, marital status, arrest and court record, sexual orientation, or veteran status. CTAHR publications can be found on the Web site <http://www2.ctahr.hawaii.edu> or ordered by calling 808-956-7046 or sending e-mail to ctahrpub@hawaii.edu.