Chirothrips guillarmodi (Hood, 1954)

Thripinae, Thripidae, Terebrantia, Thysanoptera

Figures

Fig. 1: 8-segmented antenna, together with tibia and tarsus of right fore leg
Fig. 2: Head dorsal with ocellar triangle
Fig. 3: Pronotum
Fig. 4: Meso- and metanotum
Fig. 5: Fore- and hind wing, fore wing basal region
Fig. 6: Meso- and metasternum with furca
Fig. 7: Metanotum craniale and tergite I
Fig. 8: Tergites VII and VIII
Fig. 9: Tergites IX-XI
Fig. 10: Pregenitialregion of the abdomen strongly infected with nematods
Fig. 11: Pregenitalregion of abdomen with embryonic stages of roundworm endoparasites (Nematoda)

Chirothrips guillarmodi damages forage grasses. Female macropterous; body blackish brown; all tarsi and tips of fore tibiae yellow; antennal segments dark blackish brown except for the yellowish brown segments III & IV; fore wings dark brownish gray. Antennae 8-segmented; antennal segment II external margin not prolonged, segments III & IV with forked sense cone (Fig. 1). Head small and scarcely prolonged in front of eyes; with 3 pairs of ocellar setae, pair III anterolateral to fore ocellus (Fig. 2). Pronotum trapezoidal; with 2 pairs of elongate posteroangular setae (Fig. 3). Meso- and metafurca with well-developed lateral flanges (Fig. 6), but without median spinula. Metanotum irregularly reticulate; median pair of setae shorter than lateral pair and arise at anterior margin; campaniform sensilla present (Fig. 4). Mid and hind tarsi 2-segmented (Fig. 1); fore tibia not prolonged around fore tarsus. Fore wing nearly straight and pointed at apex; first vein with 2 or 3 setae on distal half; second vein with 5 or 6 setae (Fig. 5). Tergites with weak lines of sculpture medially; tergites II-VIII and sternites II-VI on posterior margin with craspedum of closely approximated, but independent, elongate lobes (Fig. 8). Sternites with 3 pairs of marginal setae, median pair on VII arise scarcely in front of margin.
Male macropterous and similar to female, but the antennae are paler, segment II almost yellow; more or less circular glandular area near the anterior margin of each of the sternites III-VII.

The genus Chirothrips Haliday, 1836
Chirothrips currently includes about 45 to 50 species worldwide. Zur Strassen (1960) provided an identification key and catalogue of this genus for over 50 species, and Bhatti (1990) created six new genera for these species originally placed in the genus Chirothrips, and one of these, Arorathrips, is discussed in comparison to Chirothrips. Chirothrips appears to be a genus of Holarctic species, whereas Arorathrips is from the New World with a typical reduced mesothoracic endofurca. This genus has consistent characters that include small heads, short antennae with 8 segments, antennal segment II mostly expanded laterally (except in this key for Chirothrips guillarmodi), and a trapezoidal pronotum with 2 pairs of long posteroangular setae.

The species can be distinguished from other species of the genus Chirothrips by the antennal segment II which has the external margin not prolonged and symmetric, and the forked sense cone on antennal segments III & IV (antennal segments III & IV of other species with simple sense cone except for Chirothrips meridionalis with sense cone on segment III emergent and simple and on IV forked). Chirothrips manicatus as well as Chirothrips frontalis have a asymmetric antennal segment II with prolonged external margin bearing an exactly terminal small seta at tip. Whereas Chirothrips ah has a very slender and acute, slightly hook-shaped projection of the second antennal segment which bears a small sensorium at its apex, in Chirothrips meridionalis it is not strongly produced on outer margin, but drawn out into a sharply pointed angle, and in Chirothrips pretorianus it is asymmetric with prolonged external margin bearing a apical sense area. Most of Chirothrips species with ocellar setae III arranged anterolateral to fore ocellus, and metanotal median setae are shorter than the lateral pair and arising behind anterior margin (except for Chirothrips ah with ocellar setae III on anterior margins of ocellar triangle and median metanotal setae which are distinctly longer than lateral metanotal setae and arising at anterior margin; Chirothrips guillarmodi and Chirothrips meridionalis with metanotal median setae arising at anterior margin). In Chirothrips guillarmodi the tergites have a complete craspedum of closely approximated but independent elongate lobes at the posterior margin (compared to Chirothrips frontalis with a craspedum of unbroken border or flange; Chirothrips ah and Chirothrips meridionalis with broadly rounded independent lobes fused at bases into continuous craspedum; Chirothrips manicatus has a continuous craspedum with margin of weakly and rounded lobes; and Chirothrips pretorianus has a craspedum with independent small, triangular lobes). Posterior margin of sternites of Chirothrips guillarmodi has also a craspedum of closely approximated but independent elongate lobes. Whereas Chirothrips pretorianus as well as Chirothrips frontalis have the posterior margin of sternites without a craspedum, Chirothrips ah and Chirothrips meridionalis with a craspedum of independent small pointed lobes, and Chirothrips manicatus with entire margin and a series of distinctive tubercles. Moreover, the species has tergites II-VIII discal campaniform sensilla situated between the discal setae S1 and S2 or posteriorly (like in Chirothrips meridionalis and Chirothrips ah); other species of the genus Chirothrips have tergites II-VIII discal campaniform sensilla placed in front of the discal setae S1 but somewhat farther apart than the setae.
Species of the genus Chirothrips are similar to Arorathrips mexicanus, but Arorathrips mexicanus has a greatly reduced mesothoracic furca (furcal pits widely separated), fore tibia prolonged at apex around the external margin of the first fore tarsal segment, and tergites II-V with transverse row of small tubercles along antecostal ridge. Whereas all species of the genus Chirothrips have furcal pits on mesosternum fused in the middle line, fore tibia not prolonged around fore tarsal segment, and the sculpture of antecostal ridge on tergites II-V is more or less elongated. Compared to described species of Chirothrips, Arorathrips mexicanus has the sternite VII median posteromarginal setae arising at margin, whereas in species of Chirothrips these setae arise in front of posterior 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
Forage grasses (Eragrostis chloromelas - weeping love grass; Bromus catharticus - rescue grass), maize and the weed Lantana camara.

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

Damage and symptoms
All species in this genus Chirothrips breeding in grass flowers, sometimes their larvae and especially pupae are transported around the world within commercial grass seed.

Detection and control strategies
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Biogeography

Eastern and Southern Africa. Kenya, Lesotho (Mamathes), Mozambique (Umbeluzi - southwest of Maputo), South Africa (Gauteng: Pretoria; Limpopo; Mpumalanga; North West; Free State: Bethlehem, Heilbron; KwaZulu-Natal: along the Pongola River east of Ingwavuma), Uganda (Ngora), Zimbabwe.

Bhatti JS (1990). On some genera related to Chirothrips (Insecta: Terebrantia: Thripidae). Zoology (Journal of Pure and Applied Zoology). 2 (4): 193-200

Hood JD (1954). A new Chirothrips-like genus of Thysanoptera from South Africa. Revue de Zoologie et Botanique Africaines. 49 (1-2): 1-5

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

Minaei K & Mound LA (2010). Grass-flower thrips of the genus Chirothrips (Thysanoptera: Thripidae), with a key to species from Iran. Zootaxa. 2411: 33-43

Moritz G (2006). Thripse. Pflanzensaftsaugende Insekten, Bd. 1, (1. Auflage). Westarp, Hohenwarsleben, 384 pp. ISBN-13: 978 3 89432 891 7

Moritz G, Morris DC & Mound LA (2001). ThripsID - Pest thrips of the world. ACIAR and CSIRO Publishing Collingwood, Victoria, Australia, CDROM ISBN 1 86320 296 X

Moritz G, Mound LA, Morris DC & Goldarazena A (2004). Pest thrips of the world - an identification and information system using molecular and microscopical methods. Centre for Biological Information Technology, University of Queensland, Australia, CDROM ISBN 1 86499 781 8

Moritz G, O'Donnell C & Parrella M (2009). Pest thrips of North America. Centre for Biological Information Technology, University of Queensland, Australia, CDROM ISBN-13: 978 1 86499 940 2

Nakahara S & Footit RG (2012). Review of Chirothrips and related genera (Thysanoptera: Thripidae) of the Americas, with descriptions of one new genus and four new species. Zootaxa 3251: 1-29

zur Strassen R (1960). Key to and catalogue of the known species of Chirothrips Haliday, 1836 (Thysanoptera: Thripidae). Journal of the Entomological Society of Southern Africa. 23 (1): 144-176

zur Strassen R (1960). Catalogue of the known species of South African Thysanoptera. Journal of the Entomological Society of Southern Africa. 23 (2): 321-367

zur Strassen R (1971). Thysanopterologische Notizen (1) (Ins.: Thysanoptera). Senckenbergiana Biologica. 52 (3-5): 247-254