Astrothrips roboris (Bagnall, 1919)

Panchaetothripinae, Thripidae, Terebrantia, Thysanoptera

Figures

Fig. 1: 8-segmented antenna, terminal segments V-VIII more or less fused
Fig. 2: Head dorsal with ocellar triangle
Fig. 3: Head ventral with mouth cone
Fig. 4: Pronotum
Fig. 5: Meso- and metanotum
Fig. 6: Fore wing, basal region of fore wing
Fig. 7: Tergite II anterolaterally with numerous recurved claw-like microtrichia
Fig. 8: Tergites IV and V
Fig. 9: Sternites IV and V
Fig. 10: Tergites VIII-XI and ovipositor
Fig. 11: Tergites VIII-XI

Astrothrips roboris is a polyphagous pest on various flowers and leaves. Female macropterous; body brown; abdominal segments 9 & 10 often paler, apex of 10 shaded; antennae, tarsi and apices of tibiae yellow; fore wings yellowish brown, two dark brown cross bands bearing dark veinal setae, wing apex pale (Fig. 6). Antennae apparently 5-segmented; segments V-VIII more or less fused into one long segment, III & IV with simple sensorium (Fig. 1). Head constricted to base; cheeks bearing reticulate sculpture with strongly raised walls (Fig. 2 and 3); ocellar area slightly elevated over antennal bases. Pronotum with anterolateral margins raised, posterior submargin with strong transverse ridge (Fig. 4). Mesonotum weakly cleft medially. Metanotum without heavily defined triangle medially; median setae arising near posterior (Fig. 5). Mesofurca without spinula; metafurca elongate and Y-shaped. Mid and hind tarsi 1-segmented.Fore wing first vein close or fused to costal vein (Fig. 6), first vein with irregular row of stout setae; second vein with about 9 setae; costal fringe cilia longer than setae. Tergite II anterior margin strongly constricted, anterolaterally with many claw-like microtrichia (Fig. 7); tergite VIII with marginal craspedum entire medially but toothed laterally; median split on X complete (Fig. 11).
Male similar to female; tergite IX without stout setae; sternites IV-VII with U-shaped glandular area.

The genus Astrothrips Karny, 1921
The genus Astrothrips currently includes 12 species, of which 10 are recorded from countries between India and New Guinea, but with 2 species from Africa. All of them are small dark species with banded wings, seem to be polyphagous, and they can be recognised by the elaborate raised sculpture on the head and pronotum, and the area of specialised cuticular processes laterally on tergit II (Mound & Kibby 1998).

Compared to other Panchaetothripini like Heliothrips, Hercinothrips and Caliothrips, Astrothrips roboris has an elaborate raised and reticulate sculpture on the head and pronotum, tergite II with an area of specialised cuticular structures (anterolaterally many claw-like microtrichia), and antennal segments V-VIII are more or less fused and apparently 5- or 6-segmented. Whereas other species possess head and pronotum with mostly reticulate sculpture not raised, no claw-like microtrichia on tergite II, and antennae with 7 or 8 distinct segments.

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
Apparently polyphagous on various flowers and leaves.
Crops: banana, cabbage, capsicum, cucurbit, Lima bean, palm, taro (old cocoyam), tobacco.

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

Detection and control strategies
-

Biogeography

Bagnall RS (1919). Brief descriptions of new Thysanoptera - X. Annals and Magazine of Natural History, Zoology, Botany and Geology. (Serie 9) 4: 253-277

Bhatti JS (1968). The Tryphactothrips-complex in India, with a key to the world genera (Thysanoptera: Thripidae). Oriental Insects. 1 (3-4): 139-191

Hood JD (1925). Four new Thysanoptera from Africa. Proceedings of the Entomological Society of Washington. 27: 8-12

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

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

Mound LA (1970). Studies on heliothripine Thysanoptera. Proceedings of the Royal Entomological Society of London. 39 (3-4): 41-56

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

Palmer JM (1990). Identification of the common thrips of Tropical Africa (Thysanoptera, Insecta). Tropical Pest Management. 36 (1): 27-49

Palmer JM, Mound LA & Du Heaume GJ (1989). 2. Thysanoptera, 73 pp. In Betts CR [ed.], CIE Guides to insects of importance to man. CAB International, Wallingford, Oxon, UK

Pitkin BR & Mound LA (1973). A catalogue of West African Thysanoptera. Bulletin de l’Institut Fondamental d’Afrique Noire, Série A. 35 (2): 407-449

Priesner H (1964). A monograph of the Thysanoptera of the Egyptian deserts. Publications de l’Institut du Desert d’Egypte (1960). 13: 1-549

Wilson TH (1975). A monograph of the subfamily Panchaetothripinae (Thysanoptera: Thripidae). Memoirs of the American Entomological Institute. 23: 1-354