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Xestothrips glabratus (Priesner, 1927)
Panchaetothripinae, Thripidae, Terebrantia, Thysanoptera
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Xestothrips glabratus is an African thrips causes damage to coffee leaves. Both sexes fully winged. Body blackish brown; head and legs brown; tarsi and apices of tibiae yellow; antennal segments I & II light brown, III-V yellow in basal half; fore wings uniformly brown. Antennae 8-segmented; segments III & IV constricted into neck at base and apex, and with sense cone long and forked, sensorium on VI extending beyond antennal apex, III-V with long dorsal setae (Fig. 1). Head and pronotum without reticulation and smooth; cheeks sharply constricted to basal neck; ocellar setae III on anterior margins of triangle; with a distinct occipital ridge (Fig. 2). Pronotum with no long setae (Fig. 3). Mesonotum without median division. Metanotum with median triangle enclosing transverse lines of sculpture; with 1 pair of setae medially and 1 pair of campaniform sensilla (Fig. 4); metathoracic furca elongate and Y-shaped. Mid and hind tarsi 1-segmented. Fore wing first vein close or fused to costal vein, fore wing median third of first vein lacking setae, 8 setae basally and 4-6 setae distally; second vein with complete row of widely spaced setae; posteromarginal cilia undulated (Fig. 5). Tergites with lateral thirds reticulate; tergites III-VIII with median setae longer than distance between their bases (Fig. 6); VIII with many discal microtrichia and a complete posteromarginal comb of long microtrichia (Fig. 7 and 8); tergite X without longitudinal division. Sternites with 3 pairs of long median setae.
Male similar to female; sternites III-VII with small oval glandular area on antecostal ridge; tergite IX with 3 pairs of long and slender setae.
Species
Xestothrips glabratus (Priesner, 1927)
Taxonomic history
Brachyurothrips glabratus da Costa Lima, 1956
Brachyurothrips congoensis da Costa Lima, 1956
Selenothrips (Xestothrips) congoensis Priesner, 1938
Selenothrips glabratus Priesner, 1927
Common name
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The genus Xestothrips Priesner, 1938
There is only one African species recognized in this genus. It is unique within the Panchaetothripinae in having head and pronotum smooth and without any reticulate sculpture (Mound & Marullo 1996). Antennal segments with long setae, segments III and IV constricted apically and basally, and each segment with a long and forked sense cone. Head constricted to basal neck and has dorsally a distinct occipital ridge.
Typical key character states of Xestothrips glabratus
Coloration and body sculpture
Body color: mainly brown to dark brown
Surface of head, pronotum and fore legs: without obvious or with weakly reticulate sculpture
Antennae
Form of sense cones on antennal segments III and IV: emergent and forked on segments III and IV
Number of antennal segments: 8
Forked sense cone on antennal segment IV: extending to a point at least a third to base of segment V
Terminal antennal segments: VI-VIII forming a single unit
Head
Cheeks shape: constricted to basal neck
Head - occipital ridge dorsally: present
Head: not prolonged in front of compound eyes (misinterpreted: distinctly prolonged)
Ocelli: present
Occipital collar: no difference between surface sculpture of collar and rest of head
Prothorax
Pronotal blotch or internal apodeme: absent
Pronotum shape: broadly rectangular
Mesothorax
Mesonotum: with an incomplete median division
Metathorax
Metanotum with dominant sculptured triangle medially: with weakly defined reticulate or dominant sculptured triangular area medially
Shape of metathoracic furca: elongate and Y-shaped
Wings
Fore and hind wings: present, more than half as long as abdomen (macropterous)
Fringe cilia arising: from sockets
Fore wing veins: present
Fore- and hind wing surface: covered with microtrichia
Apex of fore wing: with prominent terminal setae
Fore wing anterior margin (costal vein): with setae and cilia but cilia longer than setae
Fore wing costal fringe cilia: arising at anterior margin of wing
Fore wing first vein: close to or fused to costal vein
Fore wing first vein setal row: incomplete, with setae not closely and uniformly spaced
Fore wing second vein setal row: complete, setae uniformly spaced
Fore wing shape: mainly parallel sided or margins run continuously towards each other
Fore wing surface: not reticulate
Fringe cilia on posterior margin near apex: distinctly wavy (undulated)
Length of fore wing costal setae at middle of wing: longer than half of median wing width
Shape of fore wing apex: with mainly posterior margin curved to join anterior margin
Fore wing extreme apex color: dark
Fore wings: uniformly dark or light brown
Legs
Mid and hind tarsi: with one segment
Color of fore tarsi: pale or yellow, sometimes apical shaded or brown
Abdomen
Tergite II: without specialised cuticle laterally
Tergites IV and V median setal pair: longer than distance between their bases
Tergite VIII to X: without unusually long and stout setae
Tergites: without distinctive tergal sculpture forming a series of arches on the antecostal ridges
Tergite X: not tubular, longitudinally incomplete
Setae on abdominal tergite X: all setae slender
Similar or related species
In contrast to other Panchaetothripinae, head and pronotum of Xestothrips glabratus are not covered with heavy reticulate sculpture. The very dark fore wings distinguish this species from most other panchaetothripine. The genus Xestothrips is similar to the genus Selenothrips, with dark fore wings too. However, Selenothrips rubrocinctus has the head and pronotum covered by strong transverse reticulations or striations, the head without a distinct occipital ridge, the first vein of fore wings with a complete row of evenly placed setae, and fore wing costal setae at middle of wing are up to twice as long as wing width. In contrast surface of head and pronotum in Xestothrips glabratus without obvious or with weakly reticulate sculpture, head with a distinct occipital ridge, the setal row on the fore wing first vein is widely interrupted on middle third, and fore wing costal setae at middle of wing are at most as long as wing width. Compared to other Panchaetothripinae with a distinct occipital ridge dorsally on head, only in Xestothrips glabratus there is no difference between surface sculpture of occipital collar and the rest of the head (in Helionothrips errans and Panchaetothrips noxius the occipital collar is in contrast to the rest of head weakly sculptured; in Monilothrips kempi the occipital collar is in contrast to the rest of head with heavy reticulate sculptures).
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. Adults may live for more than one month producing several generations in one year depending on seasons.
Host plants
Coffee (Coffea arabica).
Vector capacity
None identified, but possible mechanical distribution of phytopathogenic fungi and bacteria.
Damage and symptoms
Species feeds on the underside of arabica coffee leaves (McNutt 1975).
Detection and control strategies
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Central Africa. Congo, Nigeria (Lagos), Uganda.
African countries where Xestothrips glabratus has been reported
The species Xestothrips glabratus was not observed in surveys undertaken in East Africa on vegetables and associated weeds and crops.
Please click here for survey sites of all observed thrips species of Kenya, Tanzania and Uganda.
da Costa Lima AM (1956). Sobre um trips da pimenteira (Thysanoptera: Thripidae). Memorias do Instituto Oswaldo Cruz. 54 (3): 359-363
Lewis T (1973). Thrips: their biology, ecology and economic importance. Academic Press Inc., London Ltd., 349 pp
McNutt DN (1975). Pests of coffee in Uganda, their status and control. International Journal of Pest Management. 21 (1): 9-18
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
Pitkin BR & Mound LA (1973). A catalogue of West African Thysanoptera. Bulletin de ľInstitut Fondamental ďAfrique Noire, Série A. 35 (2): 407-449
Priesner H (1927). Neue und weniger bekannte Thysanopteren, gesammelt in Westafrika von Prof. Dr. F. Silvestri. Bulletino del Laboratorie di Zoologia Generale e Agraria della Facoltè Agraria in Portici. 21 (6): 61-83
Priesner H (1938). Thysanopteren aus dem Belgischen Congo (4. Beitrag). Revue de Zoologie et Botanique Africaines. 30 (3): 343-355
Wilson TH (1975). A monograph of the subfamily Panchaetothripinae (Thysanoptera: Thripidae). Memoirs of the American Entomological Institute. 23: 1-354
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Web links
Mound´s Thysanoptera pages