Neohydatothrips samayunkur Kudo, 1995

Sericothripinae, Thripidae, Terebrantia, Thysanoptera

Figures

Fig. 1: 8-segmented antenna, segments III and IV with forked sense cone, terminal segments V-VIII
Fig. 2: Head dorsal with ocellar triangle
Fig. 3: Pronotum
Fig. 4: Meso- and metanotum
Fig. 5: Furca of meso- and metasternum
Fig. 6: Meso- and metasternum
Fig. 7: Fore- and hind wing, fore wing distal region
Fig. 8: Tergites II and III
Fig. 9: Tergites VII and VIII
Fig. 10: Sternites VIII and IX (male)

Neohydatothrips samayunkurbreeds in the flowers and the leaves of Tagetes species. Both sexes fully winged; body strikingly bicolored, mainly dark brown with abdominal segments 3-6 yellowish with brown antecostal ridge; anterior margin of pronotum yellow, also all tarsi, base and apex of tibiae, and much of antennal segments II-V; fore wings pale with small brown area at base and two transverse brown bands, apex pale. Antennae 8-segmented; segments III and IV with sense cone forked and relatively short, VI with base of sense cone elongate and about half as long as this segment (Fig. 1). Head wider than long, with occipital ridge not close to eyes; postocular region short; ocellar triangle with irregular lines of sculpture; 3 pairs of curved ocellar setae, pair III on anterior margins of triangle; 3 pairs of postocular setae (Fig. 2). Pronotum with transversely elongate reticles on anterior half, the darker pronotal blotch with more closely spaced transverse striae and deeply emarginate posteriorly on posterior half; 1 pair of long posteroangular setae (Fig. 3). Metanotum median area with sculptured lines, transverse at anterior but longitudinal and parallel on posterior half; median setae at anterior margin, campaniform sensilla absent; metasternum with anterior margin almost transverse (Fig. 4). Meso- and metafurca with stout median spinula (Fig. 5 and 6). Mid- and hind tarsi 2-segmented, Fore wing first vein distinct from costal vein and with continuous row of setae; second vein without setae (Fig. 7). Lateral thirds of tergites I-VIII with many rows of fine and regular microtrichia (Fig. 8); I-VI with posteromarginal comb of microtrichia present laterally, incomplete medially; tergites VII and VIII with complete comb of long and regular microtrichia; tergites I-VIII with median pair of setae not similarly placed, nor of similar size on all tergite; median setal pairs longer than distance between their bases (Fig. 9), sternites without discal setae but fully covered with rows of microtrichia; posterior margins with comb of long microtrichia between the marginal setae. Sternite VII median posteromarginal setae S1 arising in front of margin.
Male similar to female but smaller and more slender; tergite IX discal setae long; sternite VII with weak glandular area.
Second instar larva white with grey shading on tibiae, antennae and laterally on thorax, also distal half of tergite X; with much red internal pigment; tergal major setae with fimbriate, broadly expanded and asymmetric, apices, the median pair on IX close together; spiracles on VIII surrounded by extensive sculptured area (Fig. 10).

The genus Neohydatothrips
The genus Neohydatothrips is widespread around the world in tropical and subtropical countries and is currently used for a group of 100 species, several have bodies that are prominently bicolored as well as banded wings while others are uniformly pale or yellow. Neohydatothrips is a member of the subfamily Sericothripinae, closely related to Hydatothrips and Sericothrips. These thrips all have numerous closely spaced rows of microtrichia on the lateral thirds of the tergites, fore wings with a complete row of setae on the first vein whereas second vein without or only with 2 setae. Most of them have a remarkably elongate base to the sense cone on the sixth antennal segment, and a distinctive colored and/or sculptured area on the pronotum, the pronotal blotch. Bhatti (1973) has given identification keys to distinguish the various genera involved. All species of Neohydatothrips have the metasternum with a transverse line behind anterior margin, this line medially with a T-shaped or Y-shaped apodeme.

Neohydatothrips samayunkur is closely related to Hydatothrips adolfifriderici and Sericothrips sativus. Compared to these both species, Neohydatothrips samayunkur has a dark pronotal blotch which is deeply emarginate posteriorly, and metanotal median area sculptured lines are transverse at anterior, but longitudinal and parallel on posterior half. Neohydatothrips samayunkur as well as Sericothrips sativus have the metasternum anterior margin almost transverse. In Hydatothrips adolfifriderici the metasternum has an anterior margin deeply U-shaped and median V-shaped apodeme, the dark pronotal blotch is not emarginate posteriorly, and metanotal median area sculptured lines are also transverse at anterior, but forming irregular longitudinal reticulations on posterior half. In Sericothrips sativus the pronotal blotch is pale, and the metanotal median area sculptured lines are transverse striate. Neohydatothrips samayunkur as well as Hydatothrips adolfifriderici have no microtrichia on metascutellum, dense microtrichia only on lateral thirds on tergites I-VIII and median area smooth or with sparse microtrichia, tergites I-VI posteromarginal comb of microtrichia is present laterally but incomplete medially, median setae are short on tergites I-IV and longer on V-VIII, and the median setal pair is longer than distance between their bases. Whereas Sericothrips sativus has a metascutellum covered with bands of microtrichia medially, also tergites I-VIII completely covered with microtrichia, complete posteromarginal comb of microtrichia on tergites I-VI, the tergal median setae are similarly placed and of equal size, and the median setal pair is shorter than distance between their bases.

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. With greenhouse temperatures the developmental time from egg to adult can decrease to about one week.

Host plants
Mainly on Tagetes spp. (Asteraceae).
Crops: amaranth, garlic, kale, potato, pyrethrum, spinach, sweet potato, tomato.
Weeds: Acacia sp., Asystesia mysoorensis, Bidens pilosa, Galinsoga parviflora, Nycandra physalodes, Occimum gratissimum ssp. gratissimum, Rotheca myricoides (butterfly bush), Sida acuata,Solanum incanum, Sonchus oleracea, Tagetes spp., Veronica sp.

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

Damage and symptoms
Attacked plants showed leaves with scarring, silvering and distortion. Flowers showed no symptoms. In the field, the presence of the pest is indicated by the distortion and purple patches on leaves. Neohydatothrips samayunkur limit the growth of marigold seedlings and also adult plant development (Monteiro et al. 1999).

Detection and control strategies
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Biogeography

Africa, Asia, Australia, New Zealand, Central and South America, North America. Kenya, Uganda.

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