Selenothrips rubrocinctus (Giard) (Thysanoptera: Thripidae)
Red-banded thrips, Selenothrips rubrocinctus (Giard), have been a serious pest of cacao in the French West Indies from as early as 1901 (Russel, According to Hill (1975), red-banded thrips have an almost completely pantropical distribution, but has not been recorded in Australia while records are rather scattered in some other areas. In Taiwan symptoms similar to those caused by H. haemorrhoidalis result from the feeding of S. rubrocinctus (Giard). This species can be a problem in California, Florida, South-Africa-Australia, Reunion and Taiwan.
Part of plant damaged: Leaves and Fruit
In Florida, and Australia, infested leaves are spotted on the upper surface with dark reddish brown fecal pellets. According to Hill (1975), the red-banded thrips feed on the ventral leaf surfaces. Damaged areas turn rusty with numerous small, shiny black spots of excreta and edges of affected leaves curl up. Heavy feeding on fruit causes a russetted appearance, cracking and decay. Greenhouse thrips damage fruit and tend to feed on the larger and more mature fruit. They are found most frequently where two fruits are in contact or where a leaf contacts the fruit. Fruits are damaged by slight russetting, show a leathery scarring and cracks on the skin.
Eggs are inserted into the leaf tissue. They are white, kidney-shaped and about 0.25 mm long (Hill, 1975). The first and second nymphal stages are yellow with a bright red b around the base of the abdomen. When fully grown, the second instar is about 1 mm long. The tip of the nymph’s abdomen is turned up and carries a drop of excreta on anal setae (Hill, 1975). The pre-pseudo pupa is yellowish with red eyes, with a red band across the first three abdominal segments. The pseudo-pupa has an almost similar appearance as the pre-pseudo pupa with larger wing knobs (Hill, 1975). The adult female is dark brown and just over 1 mm long. Males are smaller and rare (Hill, 1975). Reproduction by the red-banded thrips is parthenogenetically (Avidov and Harpaz, 1969). Females live about 7 weeks and lay an average of 25 eggs. Eggs hatch in 12 - 18 days (Hill, 1975). The nymphal stage lasts 6 - 10 days and the pre-pseudo pupa; the pseudo pupal stage together 3 - 6 days.
Monitoring and Action Levels
Make observations on leaves and fruit for red-bed thrips during summer and fall for any developing infestation. Frequent inspections of fruit are recommended for greenhouse thrips beginning in early August and continuing until fruit harvest.
The following materials are labelled for use against thrips: malathion (various labels), permethrin (Pounce, Ambush), pyrethrins + rotenone (Pyrellin). (Peña and Johnson, 1999). In Australia, the pest is generally suppressed by the frequent sprays of endosulfan applied to control fruitspotting bugs (Waite and Pinese, 1991).
Peña, J., and Johnson, F. (1999). Insect management of avocados. Insect Management Guide, Department of Entomology and Nematology, Florida Cooperative Extension Service, University of Florida; http://edis.ifas.ufl.edu/Body_IG068
Hill, D. (1975) Agricultural Insect Pests of the Tropics and their Control. Cambridge Press, London. 516pp.