Thrips palmi Karny
Taxonomic placing: Insecta, Hemimetabola, Thysanoptera, Terebrantia, Thripidae.
Common name: melon thrips.
Geographical distribution: The pest occurs throughout the tropics, as well as in the subtropical region of Florida, and has recently been found in Western Europe.
Morphology: The female is about 1.0-1.3 mm long, yellowish to dark-yellow in color, bearing two pairs of large setae on the posterior edge of the prothorax and little or no banding on the abdomen. The dorsum of the metathorax has convergent striations on its posterior margin. The antennae are seven-segmented, the terminal segments mostly dark-brown.
Host plants: About 120 plants are attacked by this pest, including vegetables such as cucurbits, legumes and solanaceous crops, field crops like cotton and sunflower, and even fruit trees, including avocado, citrus and mango. In addition, the melon thrips infests many weed species.
Life history: At 25ºC the pest raises a generation in about 18 days and each female may deposit ca 200 eggs, whose stalks are placed into the host-plant tissue. The emerging thrips often begin to feed inside the tightly rolled leaves, at the growing points of the plant. They undergo two nymphal and two “pupal” stages, and then live on the underside of expanding leaves and in the blossoms.
Economic Importance: The melon thrips is a major quarantine pest that has not yet been reported from the Middle East. It has a rapid rate of development, which means that much damage may occur quickly. Its feeding causes silvery spots on the leaves, which brings about their stunting, wilting and drop. When present in the blossoms, pest feeding causes irregular fruit growth and scarring. Heavy infestations may kill entire plants. In addition, the pest can transmit plant viruses of the tospovirus group.
Monitoring: The small size of the melon thrips hinders its recognition, and various methods for its identification are in use, including whole plant examinations under strong light and color traps. Recognition of the pest’s presence is of much importance due to its rapid development, especially in regions with a long growing season.
Chemical control: Pesticides like imidacloprid and abamectin can provide good control, but pyrethroids should be avoided, as they may cause pest population outbreaks.
Biological control: Ceranisus menes is an important parasitoid of T. tabaci in Japan. Other enemies include generalist predators like Phytoseiidae, bugs of the genus Orius spp. and entomopathogenic fungi.
Castineiras, A., Baranowski, R.M. and Glenn, H. 1997. Distribution of Neoseiulus cucumeris (Acarina: Phytoseiidae) and its prey, Thrips palmi (Thysanoptera: Thripidae) within eggplants in south Florida. Florida Entomologist 80: 211-217.
Castineiras, A., Peña, J.E., Duncan, R. and Osborne, L. 1996b. Potential ofBeauveria bassiana and Paecilomyces fumosoroseus (Deuteromycotina: Hyphomycetes) as biological control agents of Thrips palmi (Thysanoptera: Thripidae). Florida Entomologist 79: 458-461.
Etienne, J., Guyot, J. and, van Waetermeulen, X. 1990. Effect of insecticides, predation, and precipitation on populations of Thrips palmi on aubergine (eggplant) in Guadeloupe. Florida Entomologis 73: 339-342.
Girling DJ. (ed.) 1992. Thrips palmi. A Literature Survey with an Annotated Bibliography. International Institute of Biological Control, Silwood Park, Ascot, U.K. 37 pp.
Tsai, J.H., Yue, B., Webb, S.E., Funderburk, J.E. and Hsu, H.T. 1995. Effects of host plant and temperature on growth and reproduction of Thrips palmi (Thysanoptera: Thripidae). Environmental Entomology 24: 1598-1603.