Larothrips dentipes Pitkin, 1973

Thripinae, Thripidae, Terebrantia, Thysanoptera

Figures

Fig. 1: 7-segmented antenna, segments III and IV with forked sense cone, terminal segments VI and VII
Fig. 2: Head dorsal with ocellar triangle
Fig. 3: Head and fore legs, tibiae with curved tooth
Fig. 4: Head ventral with mouth cone and fore legs (male)
Fig. 5: Pronotum
Fig. 6: Meso- and metanotum
Fig. 7: Meso- and metanotum (male)
Fig. 8: Fore wing and fore wing basal region
Fig. 9: Sternites IV-VI
Fig. 10: Tergites IV-VI
Fig. 11: Tergites VIII-XI

Larothrips dentipes can be found in yam flowers and is possibly a pollinating agent. Both sexes fully winged. Body color brown; apical two-thirds of antennal segment II, all of segment III, fore tibiae and all tarsi paler or yellow; fore wings uniformly brown except for paler area near the base. Antennae 7-segmented; segments III & IV slightly constricted at apex and with forked sense cone (Fig. 1). Head about as long as wide; with 2 pairs of ocellar setae, pair I absent, pair III small, about as long as pair II and arising just within ocellar triangle; postocular setae I-III about equal to ocellar setae III in length (Fig. 2-4). Pronotum without long setae; posterior margin with about 5-6 pairs of minor setae (Fig. 5). Mesofurca with spinula. Metanotum median area with sculptured lines transverse at anterior, but forming irregular longitudinal reticulations on posterior half; median setae arising behind anterior margin; campaniform sensilla present (Fig. 6 and 7). Mid and hind tarsi 2-segmented; fore femora and fore tibiae enlarged; fore tibiae bearing stout curved claw and small tubercle ventrally at apex (Fig. 4). Fore wing first vein usually with 2 setae on distal half; second vein with a complete row of about 11-15 setae; clavus with 6 marginal setae (Fig. 8). Tergite II with 3 lateral marginal setae; tergites V-VIII with ctenidia present laterally , on VIII posteromedial to spiracles; tergites II-VII with craspedum of unbroken border or flange on posterior margin (Fig. 10); posterior margin of VIII with continuous craspedum medially, but toothlike microtrichia laterally (Fig. 11). Sternites without craspeda; with a single row of 3-7 discal setae; median pair of marginal setae on sternite VII arise at posterior margin (Fig. 9).
Male similar to female, but smaller and pale or yellow (Fig. 4 and 7); tergite VIII without marginal comb of microtrichia, but with craspedum of unbroken border or flange on posterior margin; sternites III-VII usually each with narrow transverse glandular area.

The genus Larothrips Pitkin, 1973
Only 1 species are listed in this genus, Larothrips dentipes, from West Africa. It is closely related to the genus Thrips. Together with the genus Thrips ocellar setae I absent and a well developed tergal ctenidia posteromedial to the spiracles on tergite VIII present. But Larothrips dentipes has a distinctive craspedum of unbroken border or flange on the posterior margin of tergites II-VII, and no elongate pronotal setae (Pitkin 1973). Furthermore, Larothrips has 7-segmented antennae with forked sense cone on segments III & IV, a continuous craspedum medially and toothlike microtrichia laterally on tergite VIII, distinctly enlarged fore femora, and fore tibiae with a fore tibial apex bearing a stout curved claw ventrolaterally.

Larothrips dentipes is similar to species of the genera Stenchaetothrips and Thrips, and Fulmekiola serrata and Microcephalothrips abdominalis, because of absence of ocellar setae I, and tergites V-VIII bear a pair of ctenidia laterally, which on tergite VIII arranged posteromedial to the spiracle. Compared to Larothrips dentipes, the species of Stenchaetothrips and Thrips have no posteromarginal craspedum on tergites, and the pronotum usually has 2 pairs of long posteroangular setae. Fulmekiola serrata as well as Microcephalothrips abdominalis and Larothrips dentipes, all of them exhibit a posteromarginal craspedum on tergites, but in Fulmekiola serrata and Microcephalothrips abdominalis the craspedum on tergites II-VII consist of independent triangular lobes or teeth (Microcephalothrips abdominalis) or of medially rounded lobes fused at base and laterally large independent teeth (Fulmekiola serrata). Furthermore, in both the fore tibial apex is not extending around fore tarsus, both have the fore wing clavus with 4 (Fulmekiola serrata) or 5 marginal setae (Microcephalothrips abdominalis), and fore wing first vein with 3 discal setae. Compared to those, in Larothrips dentipes the craspedum on tergites II-VII consist of unbroken border or flange, fore femora and fore tibiae enlarged and fore tibiae bearing a stout curved claw ventrolaterally, the fore wing clavus has 6 marginal setae, and the fore wing first vein 2 discal setae. In contrast to Microcephalothrips abdominalis and Larothrips dentipes, Fulmekiola serrata has ocellar setae II much longer than III and longer than side of ocellar triangle, 2 pairs of elongate posteroangular setae and sternites without discal setae, but with craspeda on posterior margins. Whereas Microcephalothrips abdominalis and Larothrips dentipes have a pair of ocellar setae II which are about as long as ocellar setae III or shorter, no elongate (Larothrips dentipes) or 2 (Microcephalothrips abdominalis) pairs of moderately long posteroangular setae, and discal setae but no posteromarginal craspeda on sternites. Furthermore, Microcephalothrips abdominalis differs from Larothrips dentipes in having the posterior margin of tergite VIII with complete comb of long microtrichia on broadly triangular bases, sternites with a double row of usually 14-25 discal setae, and sternite VII median marginal setae arise in front of margin. Whereas Larothrips dentipes has the posterior margin of tergite VIII bearing a continuous craspedum medially, but toothlike microtrichia laterally, sternites with a single row of 3-7 discal setae, and the median marginal setae on sternite VII arise at margin.

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
In flowers of yam (Dioscorea cayenensis - yellow yam; Dioscorea rotundata - white yam; Dioscorea dumetorum - bitter yam).

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

Damage and symptoms
-

Detection and control strategies
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Additional notes
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Biogeography

West Africa. Ivory Coast, Nigeria.

Bournier J-P (1994). Larothrips dentipes Pitkin (Thysanoptera, Thripidae): description du mâle et de son polymorphisme. Journal of African Zoology. 108: 493-501

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

Lewis T (1997). Thrips as crop pests. CAB International, Wallingford, 740 pp

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

Pitkin BR (1973). Larothrips dentipes (Thysanoptera, Thripidae), a new genus and species of thrips from yam flowers in Nigeria. Bulletin of Entomological Research. 62 (3): 415-418