Ceratothripoides brunneus Bagnall, 1918

Thripinae, Thripidae, Terebrantia, Thysanoptera

Figures

Fig. 1: 8-segmented antenna, scape, pedicel and segment III, segments III and IV with forked sense cone, segments III-VIII
Fig. 2: Head dorsal with ocellar triangle
Fig. 3: Pronotum
Fig. 4: Meso- and metanotum
Fig. 5: Meso- and metasternum
Fig. 6: Fore- hind wing, fore wing distal region
Fig. 7: Fore wing clavus
Fig. 8: Tergites V-VII
Fig. 9: Tergites VIII with posteromarginal comb and tergite IX
Fig. 10: Sternites VI and VII
Fig. 11: Sternites V-VII with sternal pore plates, male
Fig. 12: Posteromarginal comb of tergite VIII and tergites IX-XI, male
Fig. 13: Adult female on a leaf

Ceratothripoides brunneus is a wide spread pest of solanaceous crops like tomato, eggplant, capsicum, chillies, African nightshade, African eggplant and potato. Both sexes fully winged. Body brown; all tarsi, apices of tibiae and antennal segment III yellow, IV-V variably yellow and brown; fore wings brown or deeply shaded. Antennae 8-segmented; segments III & IV with forked sense cone and many microtrichia, segment I with pair of dorso-apical setae (Fig. 1). Head with 3 pairs of ocellar setae, pair III very long and arising within ocellar triangle; compound eyes with no pigmented facets (Fig. 2). Pronotum with 2 pairs of elongate posteroangular setae (Fig. 3). Mesonotum without campaniform sensilla; mesosternal furca with spinula (Fig. 5). Metanotum sculptured lines transverse at anterior and irregular equiangularly at posterior; median setae longer than lateral setae and arising at anterior margin; campaniform sensilla absent (Fig. 4). Mid and hind tarsi 2-segmented. Fore wing first vein with about 7 setae basally and 2 setae distally; second vein with complete setal row; fore wing clavus with 6 or 7 marginal setae but no discal seta (Fig. 6 and 7). Tergites without ctenidia; tergite VIII posterior margin with complete comb of long and slender microtrichia (Fig. 8 and 9); X with dorsal split. Sternites III-VI with 3 pairs of marginal setae; marginal setae as long as sternites; VII with S1 and S2 arising well in front of posterior margin (Fig. 10).
Male sternites III-VII with 2 or more irregular transverse rows of small glandular areas (Fig. 11); tergite IX with median setae slender (Fig. 12).

The genus Ceratothripoides Bagnall, 1918
This genus comprises 5 Old World species from the Africa and the Oriental region. One of these species, Ceratothripoides claratris, is recorded as a tospovirus vector on tomatoes with different levels of virulence (Premachandra et al. 2005; Halaweh & Poehling 2009). Species of Ceratothripoides have following characters: 8-segmented antennae, antennal segments III & IV with forked sense cone, antennal segment I with a pair of small dorso-apical setae, tergite VIII posterior margin with complete comb of long microtrichia, sternites III-VI with 3 pairs of marginal setae, and sternite VII with S1 and S2 arising well in front of posterior margin (Mound & Nickle 2009). All of them have a wide gap in the setal row on the first vein of fore wing, and a complete setal row on the second vein. In some cases, like Ceratothripoides claratris and Ceratothripoides cameroni discrimination is difficult and not always clear.

Ceratothripoides brunneus is very similar to Ceratothripoides revelatus. Compared to other species of that genus from Africa, both species have brown or deeply shaded fore wings and compound eyes without pigmented facets (Ceratothripoides cameroni and Ceratothripoides claratris have uniformly pale fore wings and compound eyes with 4 to 5 weakly pigmented facets). Furthermore, in Ceratothripoides cameroni and Ceratothripoides claratris ocellar setae III arising always on anterior margin of ocellar triangle, and the distance between bases of ocellar setae III is always greater than width of first ocellus (in Ceratothripoides revelatus always less than width of first ocellus; in Ceratothripoides brunneus less, same or greater than width of first ocellus; both with ocellar setae III arising within ocellar triangle). Ceratothripoides brunneus differs from Ceratothripoides revelatus in having the metanotal sculptured lines transverse at anterior and irregular equiangular reticulations on posterior half, meso- and metanotum without campaniform sensilla, and the fore wing clavus with 6 or 7 marginal setae but no discal seta. Ceratothripoides revelatus has a metanotal median area mainly with equiangular reticulation, meso- and metanotum with campaniform sensilla, and the fore wing clavus with 5 or 6 marginal setae and 1 discal seta. The other two species (Ceratothripoides cameroni and Ceratothripoides claratris) exhibit the following characteristics: meso- and metanotum without campaniform sensilla, fore wing clavus with 5 or 6 marginal setae and no discal seta.
Species of Ceratothripoides are similar to species of Craspedothrips, Diarthrothrips coffeae, Lefroyothrips pictus, Megalurothrips sjostedti and Tenothrips frici in having 8-segmented antennae with forked sense cone on segments III and IV and 2 pairs of elongate pronotal setae posteroangularly, in lacking ctenidia laterally on tergites V-VIII and regular rows of fine microtrichia on lateral thirds of tergites. Species of Ceratothripoides as well as Lefroyothrips pictus differ from other species by the complete posteromarginal comb of slender microtrichia on tergite VIII, whereas other species have a continuous craspedum (Craspedothrips hargreavesi), no comb of microtrichia (Craspedothrips xanthocerus, Diarthrothrips coffeae) or a comb of short microtrichia only laterally on posterior margin of tergite VIII (Megalurothrips sjostedti and Tenothrips frici). Compared to Lefroyothrips pictus with distinctly bicolored body color, antennal segment I without any setae on dorso-apical margin, metanotal median area scarcely sculptured on posterior half, and median pair of marginal setae on sternite VII arising at margin, species of Ceratothripoides with usually uniformly brown body color, antennal segment I with a pair of small setae on dorso-apical margin, metanotal median area always sculptured with equiangular reticulations on posterior half, and median posteromarginal setae on sternite VII arise always in front of margin. Furthermore, species of Ceratothripoides have the fore wings usually uniformly brown or uniformly pale or yellow, compared to Lefroyothrips pictus with banded fore wings.

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 a 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
Particularly on solanaceous crops, also other cultivated crops.
Crops: African eggplant, African nightshade, amaranthus, banana, beans (cowpea, deer-eye beans (Mucuna sp.), French bean), capsicum, carrot, chillies, cocoa, coffee, cotton, citrus, eggplant, hibiscus, karela, kola nut, melon, orchid, papaya, passion fruit, potato, pumpkin, sweet pea, sweat, tea, tomato, watermelon.
Weeds: Ageratum conyzoides, Bidens pilosa, Galinsoga parviflora, Solanum incanum, Sonchus oleracea, Tithonia diversifolia.

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

Damage and symptoms
Damage symptoms include silvering of the abaxial leaf surface and the leaves crinkle. Malformed fruits with brown rusty lesions are also observed on the fruits.

Detection and control strategies
Ceratothripoides brunneus occurs as the major thrips species infesting tomato and other solanaceae crops grown in the low and mid-altitude regions. However this species is not observed in very high altitude regions beyond 2000 msl. In the high altitude region, Ceratothripoides brunneus is replaced by Western Flower Thrips in Kenya. They are naturally parasitized by Ceranisus menes. Ceratothripoides brunneus is also highly attracted to blue coloured sticky traps as compared to yellow and they are influenced by the kairomonal thrips attractants based on floral volatile signals.

Additional notes
Breeds mostly on the leaves

Biogeography

Africa, Puerto Rico, Malaysia, Netherlands (greenhouse), Australia. Angola, Burundi, Cameroon, Congo (Rutshuru, Bumba, Mahagi), Ethiopia, Gabon, Ghana (Aburi), Ivory Coast, Kenya, Mozambique, Nigeria (Ibadan), Sierra Leone, South Africa (KwaZulu-Natal), Togo, Kenya, Tanzania, Uganda.

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