Glaucothrips glaucus (Bagnall, 1914)

Thripinae, Thripidae, Terebrantia, Thysanoptera

Figures

Fig. 1: 8-segmented antenna, segments III and IV with forked sense cone, terminal segments VI-VIII
Fig. 2: Head dorsal with ocellar triangle
Fig. 3: Pronotum
Fig. 4: Meso- and metanotum
Fig. 5: Fore- and hind wing, fore wing distal region
Fig. 6: Tergites III-V
Fig. 7: Sternites VI and VII
Fig. 8: Tergite VIII with posteromarginal comb and tergite IX

Glaucothrips glaucus breeds in flowers of Proteaceae like Queen Protea (Protea barbigera) and plum tree (Prunus sp.). Both sexes fully winged; body color brown; legs and antennal segments I & III pale; fore wings brown shaded. Antennae 8-segmented; segments III & IV with short forked sense cone (Fig. 1). Head wider than long; postocular region with about 8 transverse lines; 3 pairs of ocellar setae present, pair III on anterolateral margins of ocellar triangle and a little shorter than one side of triangle; 5 pairs of postocular setae, pair II from midline close to posterior ocelli (Fig. 2). Pronotum transversely striate; with 1 pair of elongate posteroangular setae and 4 pairs of posteromarginal setae (Fig. 3). Meso- and metafurca without spinula. Metanotum irregularly reticulate; median setae shorter than lateral sete and arise well behind anterior margin; campaniform sensilla present (Fig. 4). Mid and hind tarsi 2-segmented. Fore wing with 2 complete rows of veinal setae - first vein with 15-22 setae, second vein with 13-15 setae (Fig. 5). Tergites with transverse reticulations medially (Fig. 6); median setae on VI-VIII at least one third as long as the tergite; posterior margin of tergite VIII with a complete comb of long (Fig. 8), slender irregular or regular microtrichia with stout bases; tergite X with a complete longitudinal split. Sternites without discal setae but with 3 or 4 pairs of posteromarginal setae; sternite VII with median and submedian setae arising in front of posterior margin (Fig. 7).
Male similar to female but smaller; glandular area medially only on sternites III indicated.

The genus Glaucothrips Karny, 1921
There are only 1 species in this genus, which is widespread in South Africa with following characters: 8-segmented antennae with short forked sense cone on segments III & IV, pronotum with 1 pair of elongate posteroangular setae and 4 pairs of posteromarginal setae, fore wing first and second vein with complete row of setae, and posterior margin of tergite VIII with a complete comb of long and regular microtrichia with stout bases.

Glaucothrips glaucus is similar to species of the genus Frankliniella and Megalurothrips sjostedti in having the fore wing first and second vein complete rows of setae (in Megalurothrips sjostedti the fore wing first vein is almost complete but usually with a short subapical gap followed by 2 setae), and in having 8-segmented antennae with forked sense cone on segments III and IV. Compared to Glaucothrips glaucus, species of Frankliniella and Megalurothrips sjostedti have 2 pairs of elongate posteroangular setae, and metanotal median setae are longer than lateral setae and arising at anterior margin (Glaucothrips glaucus with only 1 pair of elongate posteroangular setae, and metanotal median setae shorter than lateral setae and arising behind anterior margin). Furthermore, species of Frankliniella with paired ctenidia laterally on tergites V-VIII (absent in Glaucothrips glaucus and Megalurothrips sjostedti), and in Megalurothrips sjostedti the posteromarginal comb of short microtrichia is broadly absent medially (complete in Glaucothrips glaucus). Other species of the subfamily Thripinae with complete setal rows on fore wing first and second vein (Bolacothrips striatopennatus, species of Synaptothrips, Thrips australis, Thrips orientalis, and Thrips parvispinus) have either 7 or 9 antennal segments.

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

Host plants
Proteaceae like Queen Protea (Protea barbigera), plum tree (Prunus sp.).

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

Detection and control strategies
-

Biogeography

South Africa (Western Cape: Cape Town, Mossel Bay, Rawsonville, Stellenbosch, Betty's Bay).

Bagnall RS (1914). Brief descriptions of new Thysanoptera - II. Annals and Magazine of Natural History, Zoology, Botany and Geology. (Serie 8) 13: 22-31

Karny H (1921). Zur Systematik der Orthopteroiden Insekten, Thysanoptera. Treubia. 1: 211-269

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

Moulton D (1936). Thysanoptera from Africa. Annals and Magazine of Natural History, Zoology, Botany and Geology. (Serie 10) 17: 493-509

Mound LA (1968). A review of R. S. Bagnalľs Thysanoptera collections. Bulletin of the British Museum (Natural History), Entomology. Supplement 11: 1-181

Nickle DA (2003). A checklist of commonly intercepted thrips (Thysanoptera) from Europe, the Mediterranean, and Africa at U.S. ports-of-entry (1983-1999). Part I. Key to genera. Proceedings of the Entomological Society of Washington. 105 (1): 80-99

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 (1968). New records of South African Thysanoptera with description of a new Phlaeothripid genus. Journal of the Entomological Society of Southern Africa. 31 (2): 365-372