Hydatothrips adolfifriderici Karny, 1913

Sericothripinae, Thripidae, Terebrantia, Thysanoptera

Figures

Fig. 1: 8-segmented antenna, segments III and IV with forked sense cone, terminal segments VI-VIII
Fig. 2: Head dorsal with ocellar triangle
Fig. 3: Pronotum
Fig. 4: Meso- and metanotum
Fig. 5: Meso- and metasternum with meso- and metasternal furca
Fig. 6: Fore wing, fore wing distal region
Fig. 7: Tergites II-V
Fig. 8: Tergites VI-VIII
Fig. 9: Tergites VI and VIII with posteromarginal comb
Fig. 10: Tergites VIII-XI
Fig. 11: Adult female

Hydatothrips adolfifriderici causes damage on leaves of many legumes, particularly cowpea and soya bean crops. Female macropterous; body strikingly bicolored, mainly brown with abdominal segments 4 & 5 yellow, also anterior region of pronotum and posterior region of head; tibiae and tarsi yellow or pale, also antennal segments I-III and basal half of IV and V; fore wings light brown with sub-basal pale band. Antennae 8-segmented; segments III and IV with sense cone long and forked, VI with base of sense cone elongate (Fig. 1). Head wider than long; postocular region with transverse reticulation; ocellar triangle with transverse lines of sculpture; 3 pairs of ocellar setae, pair III on anterior margins of triangle; 3 pairs of small postocular setae; with a distinct occipital ridge (Fig. 2). Pronotum broadly reticulate on anterior half and laterally, but with pronotal blotch bearing closely spaced transverse lines on posterior half, pronotal blotch dark and not emarginate posteriorly, 1 pair of moderately long setae near posterior angles (Fig. 3). Meso- and metafurca with stout median spinula. Metanotum median area with sculptured lines transverse at anterior, but forming irregular longitudinal reticulations on posterior half; median setae varying in position; campaniform sensilla absent (Fig. 4); metasternum with distinctive V-shaped anterior margin (Fig. 5). Mid- and hind tarsi 2-segmented. Fore wing first vein distict from costal vein and with a continuous row of setae; second vein without setae (Fig. 6). Lateral thirds of tergites I-VIII with many rows of fine and regular microtrichia; tergites I-VI with posteromarginal comb of microtrichia present laterally, incomplete medially (Fig. 7); tergites VII and VIII with complete comb of long and regular microtrichia on broadly triangular bases (Fig. 8-10); tergites I-VIII with median pair of setae not similarly placed, nor of similar size on all tergites, median setal pair longer than distance between their bases. Sternites without discal setae but fully covered with rows of microtrichia; posterior margins with comb of long microtrichia between the marginal setae; sternite VII posteromarginal seta S1 arising in front of margin.
Male similar to female; with a specialised cuticular area spanning the anteriorly on each of sternites VI & VII; sternites without glandular areas.

The genus Hydatothrips Karny, 1913
About 40 species are included in this genus from various parts of the tropics. Hydatothrips is a genus of the subfamily Sericothripinae, closely related to members of the both genera of Neohydatothrips and Sericothrips. These thrips all have numerous closely spaced rows of microtrichia on the lateral thirds of the tergites. Most of them have a distinctive colored and/or sculptured area on the pronotum, the pronotal blotch. In almost all of the species the sense cone on the sixth antennal segment has a remarkably elongate and narrow base, and the fore wing first vein has a complete row of setae but the second vein has no or only 2 setae. Bhatti (1973) has given identification keys to distinguish the various genera involved. All of the species of Hydatothrips have the anterior margin of the metasternum deeply recessed to form a V-shaped sclerite and most of them are strikingly bicolored with banded wings.

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

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 one 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
Mostly on leaves of Fabaceae.
Crops: African nightshade, alfalfa, amaranth, arrowroot, beans (broad bean, common bean, cowpea, French bean, hyacinth bean, snow pea, soyabean, zombi pea), brocolli, cashew, chillies, eggplant, green gram, kale, leek, maize, mango, okra, onion, passion fruit, potato, pumpkin, red gram, sweet potatao, tomato, watermelon.
Weeds: Bidens pilosa, Clerodendron myricoides, Datura suaveolens, Galinsoga parviflora, Nycandra physalodes, Ocimum sp., Senna bicapsularis, Senna occidentalis, Sesbania sesban, Stachytarpheta jamaicensis, Tagetes minuta, Tephrosia villosa ssp. ehrenbergiana.

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

Damage and symptoms
Hydatothrips adolfifriderici was one among the key pest thrips of French beans in Kenya along with Frankliniella occidentalis, Frankliniella schultzei and Megalurothips sjostedti (Nyasani et al. 2012) and 68 - 70% yield losses was observed due the thrips complex infesting French beans.

Detection and control strategies Adults of Hydatothrips adolfifriderici were attracted to yellow coloured sticky traps, while they were not attracted to blue coloured sticky traps (Muvea 2011). Captures of Hydatothrips adolfifriderici on yellow sticky traps are significantly enhanced by addition of the kairomonal attractant LUREM-TR (Nielsen et al. 2010; Muvea 2011). In Kenya, populations of the African bean flower thrips (Megalurothips sjostedti) and Hydatothrips adolfifriderici on cowpea buds were almost halved by intercropping the cowpea with sorghum and maize (Dissemond & Hindorf 1990).
Sprays on cowpea with 2.5% to 10% aqueous Neem Seed Kernal Extract effectively repelled the adults of Hydatothrips adolfifriderici (=Sericothrips occipitalis) and Megalurothips sjostedti. This resulted in more than 60% increase in pod yield (Dreyer 1986). Application of entomopathogenic fungi, Metarhizium anisopliae isolate ICIPE69 effectively reduced the numbers of Hydatothrips adolfifriderici and was comparable to application of alpha-cypermethrin (Muvea 2011). The eulophid parasitoid, Cerenisus menes did not parasitize both first and second instars of Hydatothrips adolfifriderici (Kwamboka et al., unpublished data).

Biogeography

Afrotropical Region. Congo (Nioka, Kivu), Ethiopia (Akaki river - Addis Ababa), Gabon, Kenya (Mbita), Mozambique, (Chinanganine), Namibia (Kaokoland), Nigeria (Ibadan), Rwanda (Lake Bolero), South Africa (Limpopo: Pietersburg, Zebediela; Gauteng: Pretoria; KwaZulu-Natal: Hlabisa, St. Lucia, St. Lucia Lake, Port Shepstone; North West: Rustenburg), Sudan (Khartoum, Wad Medani, Rejaf), Tanzania (Ol Joro), Uganda, Zimbabwe (Harare).

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