Scolothrips rhagebianus Priesner, 1950

Thripinae, Thripidae, Terebrantia, Thysanoptera

Figures

Fig. 1: 8-segmented antenna, segments III-V, terminal segments VI-VIII
Fig. 2: Head dorsal with ocellar triangle
Fig. 3: Pronotum
Fig. 4: Meso- and metanotum
Fig. 5: Fore wing, basal and distal region of fore wing
Fig. 6: Tergites III-V

Scolothrips rhagebianus is a predator of Tetranychid mites and thrips. They are associated with many different plants, particularly cotton, Cucurbita sp., Solanum sp. Body color yellow with grey brown markings laterally on pronotum, also metascutellum and at least tergites III-VI medially grey brown; all femora with an irregular grey spot, fore and middle tibia with a grey ring beyond base; antennal segments I & II pale, III & IV shaded with grey, V-VIII greyish; fore wings pale with 2 small dark transverse bands, basal half of clavus also dark. Antennae 8-segmented; segments III & IV with long forked sense cone (Fig. 1). Head wider than long; without sculpture between ocelli; 3 pairs of ocellar setae present, pair III very long and arising on anterior margins of ocellar triangle; postocular setae small (Fig. 2). Pronotum with 6 pairs of very long setae (1 pair anteroangularly, 1 pair anteromarginally, 1 pair laterally, 2 pairs posteroangularly, and 1 pair posteromarginally) (Fig. 3). Meso- and metafurca with spinula. Metanotum with transverse reticulate sculpture, weakly at anterior; median setae longer than lateral setae and arising at anterior margin; campaniform sensilla absent (Fig. 4). Mid and hind tarsi 2-segmented. Fore wing costal setae about twice as long as median wing width; first and second veins each with an incomplete row of about 6-9 long setae; clavus with 3 veinal setae (Fig. 5). Tergites with no sculpture medially (Fig. 6); VIII without posteromarginal comb; X with no median longitudinal split. Sternites without discal setae; median setae on sternite VII arising in front of posterior margin.
Male unknown.

The genus Scolothrips Hinds, 1903
There are about 15 species listed in this genus, originally from the Old World. All species are known to be predators of spider mites (Mound & Kibby 1998). Members of the genus are easily distinguished from other Thripidae by the presence of 6 pairs of very long setae on the pronotum (Mound & Marullo 1996). Furthermore setae on head and fore wing also long and conspicuous. Priesner (1950) studied taxonomic relationships of this genus and provided a key to the known Scolothrips species in the middle of the last century, and zur Strassen (2003) a key to 6 species of Europe including Canarian Islands.

Scolothrips rhagebianus can be distinguished from other species by the 6 pairs of long setae on the pronotum, and the costal setae which are longer than costal cilia and about twice as long as median wing width. These chaetotaxy of Scolothrips species appears to be unique amongst all adult Thripidae.

Life history
As with other thrips species the life cycle from egg to adult is dependent on temperature. The full cycle can take about 15 days (Lewis 1973) to over a month and adults may live for more than one month producing several generations in one year depending on seasonal weather.

Host plants
Collected from many different plants, particularly cotton, Cucurbita sp., Hibiscus esculentus, Solanum sp.

Vector capacity
None identified, but possible mechanical distribution of phytopathogenic fungi and bacteria.

Damage and symptoms
-

Detection and control strategies
-

Additional notes
Predatory on leaf-feeding mites like Tetranychids and Tenupalpids, and commonly taken on legume crops (Xu et al., 2007; Pakyari et al. 2009; Pakyari, 2011; Mound, 2011; Pakyari et al 2012). The pronotal chaetotaxy of Scolothrips species appears to be unique amongst adult Thripidae, but it is interesting to note that a similar arrangement of long setae is found on the pupae of Thrips tabaci.

Biogeography

India, Africa. Egypt (Beni Suef; Malaka; Wadi Halfa), South Africa, Sudan.

Ananthakrishnan TN (1969). Indian Thysanoptera. Council for Scientific and Industrial Research, Zoological Monograph, No. 1. Publications and Informative Directorate CSIR, New Delhi, 171 pp

Bournier J-P (2002). Les thysanoptères du cotonnier. Les déprédateurs du cotonnier en Afrique tropicale et dans le reste du monde, No. 12. CIRAD-CA, Montpellier, 104 pp

Lewis T (1973). Thrips: Their biology, ecology and economic importance. Academic Press Inc., London Ltd., 349 pp

Lewis T (1997). Thrips as crop pests. CAB International, Wallingford, 740 pp

Moritz G (2006). Thripse. Pflanzensaftsaugende Insekten, Bd. 1, (1. Auflage). Westarp, Hohenwarsleben, 384 pp. ISBN-13: 978 3 89432 891 7

Moritz G, Morris DC & Mound LA (2001). ThripsID - Pest thrips of the world. ACIAR and CSIRO Publishing Collingwood, Victoria, Australia, CDROM ISBN 1 86320 296 X

Moritz G, Mound LA, Morris DC & Goldarazena A (2004). Pest thrips of the world - an identification and information system using molecular and microscopical methods. Centre for Biological Information Technology, University of Queensland, Australia, CDROM ISBN 1 86499 781 8

Mound LA (2011). Species recognition in the genus Scolothrips (Thysanoptera, Thripidae), predators of leaf-feeding mites. Zootaxa 2797: 45-53

Mound LA & Kibby G (1998). Thysanoptera: An identification guide, (2nd edition). CAB International, Wallingford and New York, 70 pp

Mound LA & Marullo R (1996). The thrips of Central and South America: An introduction (Insecta: Thysanoptera). Memoirs on Entomology, International, Vol. 6. Associated Publishers, Gainsville, 487 pp

Pakyari H, Fathipour Y, Rezapanah M, Kamali K (2009). Temperature-dependent functional response of Scolothrips longicornis (Thysanoptera: Thripidae) preying on Tetranychus urticae. Journal of Asia-Pacific Entomology 12: 23-26

Pakyari H (2011). Development rate of Scolothrips longicornis (Thysanoptera: Thripidae) at various temperature. Academic Journal of Entomology 4 (1): 1-6

Pakyari H, Maafi MA, Kim DS, Enkegaard A (2012). Oviposition model of Scolothrips longicornis fed on Two-spotted Spider mite. Academic Journal of Entomology 5 (2): 65 - 72

Priesner H (1950). Studies on the genus Scolothrips (Thysanoptera). Bulletin de la Société Fouad 1er ďEntomologie. 34: 39-68

Xu LD, Juan T, Rui SZ (2007). Functional response of the predator Scolothrips takahashii to hawthorn spider mite, Tetranychus viennensis effect of age and temperature Biocontrol 52 (1): 41-61

zur Strassen R (1960). Catalogue of the known species of South African Thysanoptera. Journal of the Entomological Society of Southern Africa. 23 (2): 321-367

zur Strassen R (2003). Die terebranten Thysanopteren Europas und des Mittelmeer-Gebietes. Die Tierwelt Deutschlands und der angrenzenden Meeresteile nach ihren Merkmalen und nach ihrer Lebensweise, 74. Teil. Goecke & Evers, Keltern, Germany, 277 pp