Exothrips papyri (Faure, 1956)

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 pigmented ocelli
Fig. 3: Head dorsal with ocellar triangle
Fig. 4: Pronotum
Fig. 5: Meso- and metanotum
Fig. 6: Meso- and metasternum
Fig. 7: Fore- and hind wing, mid region of fore wing
Fig. 8: Tergite VIII

Exothrips papyri breeds only on papyrus, Cyperus papyrus. Both sexes macropterous; body yellow; antennal segment I almost colorless, VI-VIII brown, VI paler basally; fore wings pale grey to brown in basal third, towards apex more and more paler and almost colorless in distal third. Antennae 8-segmented; segments III & IV with forked sense cone, microtrichia on III-VI (Fig. 1). Head wider than long; 3 pairs of ocellar setae, pair III arising just within ocellar triangle, anterior to tangent of anterior margin of hind ocelli, pair II subequal to pair III in length (Fig. 2 and 3). Pronotum with distinct transverse lines of sculpture; without elongate setae or 1 pair of moderately elongate posteroangular setae (Fig. 4). Metanotal median area transverse lines at anterior but with longitudinal and parallel lines of sculpture on posterior half; median setae longer than lateral setae and arising well behind anterior margin, campaniform sensilla present (Fig. 5). Meso- and metafurca without median spinula (Fig. 6). Tarsi 2-segmented. Fore wings first vein with 3 setae in distal half; second vein with usually 4 setae; costal setae short (Fig. 7). Tergites II-VIII and sternites II-VII on posterior margin with craspedum of unbroken border or flange (Fig. 8); tergit X with longitudinal split above. Sternites without discal setae; median setae on sternite VII arising in front of margin.
Male similar to female; posteromarginal craspedum of tergites IV-VII laterally with minute teeth; tergit IX with 1 dorso-median pair of sharp peg-like setae; sternite VIII with posteromarginal craspedum; all sternites without glandular areas.

The genus Exothrips Priesner, 1939
A total of 19 species are listed in this genus. Most are from India, but 5 are from Africa and one from Europe. Bhatti (1975) provided a key to 10 species, and indicated that these are associated with Poaceae. Species in this genus have the following common characters: antennae 8-segmented with forked sense cone on segments III & IV, pronotum with 6-7 pairs of posteromarginal setae (the outermost usually longer and stouter than the rest), and tergites II-VIII and sternites II-VII (males II-VIII) with prominent posteromarginal craspedum of unbroken border or flange (Bhatti 1975).

Exothrips papyri is similar to Arorathrips mexicanus, Chirothrips frontalis and Craspedothrips hargreavesi in having more or less a complete craspedum of unbroken border or flange on tergites II-VII, and without posteromarginal comb of microtrichia on tergite VIII. Euphysothrips minozzi and Larothrips dentipes possess a complete craspedum of unbroken border or flange on tergites II-VII, but a complete comb of long, slender and irregular microtrichia (Euphysothrips minozzi) or a continuous craspedum medially and toothlike microtrichia laterally (Larothrips dentipes) on tergite VIII. In contrast to these species, Exothrips papyri has no or a small pair of elongate pronotal setae except for Larothrips dentipes without any elongate pronotal setae. Fore wing costal setae at middle of wing are shorter than median width of wing (other species with 2 pairs of elongate posteroangular setae, and fore wing costal setae at middle of wing are longer than median width of wing). Furthermore Exothrips papyri, Euphysothrips minozzi, Larothrips dentipes as well as Craspedothrips hargreavesi have a forked sense cone on antennal segments III & IV, whereas the other 2 species have a simple sense cone on segments III & IV.

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
Papyrus, Cyperus papyrus

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

Damage and symptoms
-

Detection and control strategies
-

Additional notes
-

Biogeography

East Afica. Kenya, Sudan (Sudd region - Bor; Jongli; Schuba - Rejaf), Uganda (Napoleon Gulf, Lake Victoria).

Bhatti JS (1975). A revision of Exothrips Priesner and two related genera (Thysanoptera: Thripidae). Oriental Insects. 9 (1): 45-92

Bhatti JS (1978). Studies in the systematics of Rhamphothrips. Oriental Insects. 12 (3): 281-303

Faure JC (1956). Thysanoptera from papyrus in the Sudan. Journal of the Entomological Society of Southern Africa. 19 (1): 100-117

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

Mound LA & Ng YF (2009). An illustrated key to the genera of Thripinae (Thysanoptera) from South East Asia. Zootaxa. 2265: 27-47

Priesner H (1939). Thysanopteren aus dem Belgischen Congo (6. Beitrag). Revue de Zoologie et Botanique Africaines. 32 (2): 154-175