Thrips orientalis (Bagnall, 1915)

Thripinae, Thripidae, Terebrantia, Thysanoptera

Figures

Fig. 1: 7-segmented antenna, segments III and IV with forked sense cone, terminal segments V-VII
Fig. 2: Head dorsal with ocellar triangle
Fig. 3: Pronotum
Fig. 4: Meso- and metanotum
Fig. 5: Fore wing and fore wing distal region
Fig. 6: Meso- and metasternum
Fig. 7: Sternites V-VII
Fig. 8: Sternite VII
Fig. 9: Tergites VIII and IX

Thrips orientalis is a polyphagous flower-dwelling thrips, particularly associated with the perfumed white flowers of Jasminum, Gardenia and Plumeria. Both sexes fully winged. Body and legs brown, but tarsi and apices of tibiae yellow; antennal segments III-VII paler than I & II, III mainly yellow, also base of IV & V; fore wings uniformly brown, but with small white spot near veinal fork. Antennae 7-segmented; segments III & IV elongate with apex constricted and forked sense cone (Fig. 1). Head wider than long; with 2 pairs of ocellar setae, pair I absent, pair III small and arising on anterior margins of ocellar triangle; postocular setae I & III about as long as ocellar setae III, postocular setae II minute (Fig. 2). Pronotum with 2 pairs of long posteroangular setae; posterior margin with 3-4 pairs of setae; anterior margin with 3-5 pairs of setae (Fig. 3). Metanotum with mainly equiangular reticulation, reticles with conspicuous internal sculptured markings; median setae longer than lateral setae and arising well behind anterior margin; campaniform sensilla absent (Fig. 4). Mesofurca with spinula (Fig. 6). Mid and hind tarsi 2-segmented. Fore wing first vein highly variable on distal half, from almost complete to only 2 setae medially and 4 distally; second vein with a complete row of setae; clavus with 5 marginal setae, clavus terminal seta shorter than subterminal seta (Fig. 5). Tergite II with 3 lateral marginal setae; V-VIII with ctenidia present laterally, on VIII posteromedial to spiracles; posterior margin of VIII with comb broadly interrupted medially and with a few small microtrichia laterally (Fig. 9); pleurotergites without discal setae. Sternite II with 2 pairs of marginal setae, III-VII with 3 pairs, median marginal setae on VII arising in front of posterior margin; sternites with discal setae variable (0-2 setae on II, but III-VI with 2-6 discal setae placed laterally), discal setae always absent on sternite VII (Fig. 7 and 8).
Male similar to female in structure and color; tergite VIII with no posteromarginal comb; sternites III-VII each with broad transverse glandular area, discal setae often not developed.

The genus Thrips L., 1758
There are nearly 300 species currently recognized in the genus Thrips making this genus one of the largest taxa within the order Thysanoptera. The genus was redefined progressively during the 1970's (see Mound et al. 1976), to include many species previously placed in Taeniothrips. The genus Thrips now includes a range of species, some with the antennae 7-segmented, others 8-segmented, and a few with the number of segments varying between 7 and 8. Similarly, some species have few setae on the fore wing first vein, whereas others have a complete row of setae on this vein. The species with a complete setal row on the first vein were placed from some taxonomists in the genera Isothrips or Isoneurothrips. However, all of the species in Thrips have the following character states: antennal segments III & IV with forked sense cone, absence of ocellar setae I, pronotum with 2 pairs of elongate posteroangular setae, paired ctenidia laterally on the tergites V-VIII, tergite VIII ctenidium arising posterior to the spiracle (in contrast to species of the genus Frankliniella). Other character states, such as number of antennal segments, number of setae on the fore wing veins, and number of discal setae on the abdominal sternites are variable between species (Mound & Masumoto 2005; Nakahara 1994; Palmer 1992). Identification keys are available for the species of this genus from many parts of the world. Of particular importance is the published key by Mound (2010) for members of the genus Thrips from Afro-tropical region as well as previous Lucid keys from Moritz et al. (2001, 2004, 2009).

Thrips orientalis is very similar to some other Thrips species - like Thrips parvispinus. Thrips orientalis has discal setae on sternites III-VI but not on sternite VII, and no discal setae on pleurotergites (Thrips australis, Thrips microchaetus, Thrips subnudula and Thrips tenellus, all of them have sternites III-VII with at least 1 pair of discal setae and pleurotergites with discal setae; Thrips acaciae, Thrips brevisetosus, Thrips florum, Thrips gowdeyi, Thrips hawaiiensis and Thrips simplex, all of them have sternites III-VII with at least 1 pair of discal setae and pleurotergites without discal setae; Thrips nigropilosus, Thrips palmi, Thrips pusillus and Thrips tabaci, all of them have sternites and pleurotergites without discal setae).
Thrips orientalis differs from Thrips parvispinus in having sternites III-VI with no more than 6 discal setae placed laterally, metanotal equiangular reticulations with many conspicuous internal sculptured markings, brown fore wings only with small white spot near veinal fork, on fore wing clavus the terminal veinal seta is shorter than subterminal seta, and the fore wing first vein is highly variable on distal half, from almost complete to only 2 setae medially and 4 distally. Thrips parvispinus has sternites III-VI with 6-13 discal setae in an irregular row, metanotal equiangular reticulations rarely with faint internal sculptured markings, brown fore wings with base sharply paler, on fore wing clavus the terminal veinal seta is longer than subterminal seta, and the fore wing first vein setal row is complete.
Species of the genus Thrips are similar to species of Stenchaetothrips, Microcephalothrips abdominalis, Larothrips dentipes and Fulmekiola serrata because of tergites V-VIII bear a pair of ctenidia laterally, which is placed on tergite VIII posteromedially to the spiracle, and all species have no ocellar setae I. In contrast to species with craspedum on tergites II-VII (Microcephalothrips abdominalis, Larothrips dentipes and Fulmekiola serrata), species of Thrips and Stenchaetothrips have no posteromarginal craspedum on tergites and sternites. Species of the genus Thrips as well as Fulmekiola serrata and species of Stenchaetothrips have 2 pairs of elongate posteroangular setae (Microcephalothrips abdominalis with 2 pairs of moderately elongate pronotal setae and Larothrips dentipes without elongate setae). Compared to the species of Thrips, Microcephalothrips abdominalis, and Larothrips dentipes, which have ocellar setae II on head much shorter than or about as long as III, Fulmekiola serrata and species of Stenchaetothrips have ocellar setae II much longer than III, and sternites always without discal setae.

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
Particularly associated with the perfumed white flowers of Gardenia, Jasminum and Plumeria.

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

Damage and symptoms
-

Detection and control strategies
Soil amendments with vermicompost, and foliar application of vemiwash significantly reduced thrips numbers on Jasmine (Meenatchi et al. 2011). Application of 5% Neem Seed Kernal Extract can reduce the thrips numbers.

Biogeography

Asia, Australia, Caribbean, Africa. Tanzania (Dar-es-Salaam).

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