|Crop Knowledge Master|
Elixothrips brevisetis (Bangnall)
|Banana Rind Thrips|
Ronald F.L. Mau, Extension Entomologist
Jayma L. Martin Kessing, Educational Specialist
Department of Entomology
Updated by: J.M. Diez April 2007
In Hawaii, this thrips is found on banana, papaya, Wedelia trilobata. Outside of Hawaii it reportedly develops on Canna spp., Ficus spp., Cestrum pallidum, Dioscorea spp., Ipomoea alba, and Morinda citrifolia.
The banana rind thrips occurs in Anatathan, Eniwetok, Gilbert, Guam, Philippines, Saipan, and Taiwan in the Pacific and the Seychelles and Rodrigues Islands in the Indian Ocean (Sakimura, 1985). This thrips was first reported in Hawaii in 1981 on Oahu and later found on the Big Island in 1983. It has not been reported on any other islands.
Thrips feed on leaves, flowers, or stems with their mouth parts. Injured tissue takes on a silvery appearance and eventually turns dark brown. On leaves, their feeding on leaf tips results in wilting and curling. The undersides of leaves are spotted with small black fecal specks. Flowers become flecked, spotted, and deformed and many buds fail to open. Thrips can be found in greatest numbers between leaf sheaths and the stem (Metcalf, 1962).
The banana rind thrips is a polyphagous foliage feeder. There is no record of it causing significant injury to Canna spp., Ficus spp., Cestrum pallidum, Dioscorea spp., Ipomoea alba and Morinda citrifolia (Sakimura, 1985). We suspect that these are not developmental hosts. On many plant hosts, this thrips causes scaring, cracking and corky growth on fruit skins (Muruvanda, 1986).
The developmental statistics for this thrips has not been determined. This pest belongs to the thrips family that has four distinct stages between the egg and the adult stages. Although there is some disagreement in the names of the stages, we follow terminology used by Lewis (1973). After hatching, thrips pass through two feeding larval stages and two non-feeding stages (Prepupae and pupae). Durations of each stage may vary depending on species, host, temperature and humidity.
Although bisexual reproduction occurs in thrips, many species reproduce by facultative parthenogenesis. In these species, bisexual reproduction produces females and if no mating occurs only males are produced. In other species, males are rare and reproduction occurs by a form of parthenogenesis where unmated females lay eggs that develop into females. Most thrips lay eggs, but some species can birth live young. Generations are continuous in Hawaii and thrips of all stages may be found on the same locality of the plant.
There is some evidence that the banana rind thrips reproduces by female to female parthenogenesis. Males of this thrips have not been observed in Hawaii (Muruvanda, 1986).
Eggs of thrips belonging to the Thripidae group are kidney-shaped with rounded ends . The egg shell is smooth, delicate, and pale white or yellow in color. Eggs are very small, measuring less than 22/1000 inch (550 µ) long by 10/1000 inch (250 µ) wide. They are usually laid singly in a scattered pattern, but sometimes may occur in rows alongside or beneath veins. They are partially or completely inserted into an incision made in plant tissue made by the saw-like ovipositor of the female. Eggs are inserted into the underside of leaves, or indiscriminately into leaves, cotyledons, glumes, petals or sepals (Lewis, 1973). Eggs of many thrips species hatch in 3 to 6 days (Ananthakrishnan, 1984).
The first instar larvae are white or nearly transparent at first and turn yellow, orange, crimson, or even purple later. Their small bodies consist of the head, 3 thoracic segments and 11 abdominal segments, 3 pairs of similarly structured legs and no wing buds. In many thrips species, the duration of the first instar is about 1 to 5 days. When the first instars have doubled in size they find a protected spot and molt. The second instar larvae are slightly darker in color and the shape of their antennae has changed. At first they are slightly smaller than the first instars, but quickly grow to the size they will become as adults (Lewis, 1973).
The first instars of the pupal stage are called prepupae and represent an intermediate stage between the larvae and pupae. These individuals have wing buds (an early stage of wing development), rudimentary antennae, and do not feed or excrete. A single pupal stage follows after a molt. Pupae have developed antennae that curve back over the head, the wing pads have developed into long sheaths and the legs and body have assumed adult proportions (Lewis, 1973). Pupation occurs in protective crevices on the host plant. The entire pupal stage usually lasts from 3 to 10 days (Ananthakrishnan, 1984).
Egg laying begins within two weeks of adult emergence. Females lay from 30 to 300 eggs during their lifetime depending on the species, individual, and abundance and quality of food. (Lewis, 1973)
During the larval stages, the larvae must consume enough food for development into an adult. They are quite nimble and start to feed soon after hatching.
No records of natural enemies specific to the banana rind thrips was found in the literature. However, it is likely that this thrips is attacked by predators that are general thrips feeders such as pirate bugs (Anthocoridae).
Banana growers in South America used diazinon to control this thrips, but were experiencing resistance problems with its use in 1986 (Chia, et. al., 1986). Plastic bunch covers containing chlorpyrifos is effective, but manufacturers did not support its us in the U. S.
Diazinon is not labelled as of April 2007.
Ananthakrishnan, T. N. 1984. Bioecology of Thrips. Indira Publishing House: Oak Park, Michigan. 233 pages.
Chia, C. L., N. P. Kefford and W. T. Harada (Eds.). 1986. Agricultural Industry Analysis The Status, Potential, and Problems of Hawaiian Crops: Banana Industry Analysis Number 3. University of Hawaii, College of Tropical Agriculture and Human Resources.
Lewis, T. 1973. Thrips Their Biology, Ecology and Economic Importance. Academic Press: London, New York. 349 pages.
Metcalf, C. L. and W. P. Flint. 1962. Destructive and Useful Insects Their Habits and Control 4 Th. Edition (Revised by: R. L. Metcalf). McGraw-Hill Book Company; New York, San Francisco, Toronto, London. 1087 pages.
Muruvanda, D. A. 1986. Notes and Exhibitions. Proc. Hawaiian Entomol. Soc. 27:8.
Sakimura, K. 1985. Notes and Exhibitions. Proc. Hawaiian Entomol. Soc. 25: 2.
Sakimura, K. 1986. Notes and Exhibitions. Proc. Hawaiian Entomol. Soc. 26: 13-14.