Stenchaetothrips biformis (Bagnall, 1913)

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 and VI
Fig. 8: Tergites V and VI
Fig. 9: Tergite VIII
Fig. 10: Sternites III-V with glandular pore plates (male)
Fig. 11: Tergites IX and X (male)

Stenchaetothrips biformis is a pest of rice and other cereal crops (Poaceae), and damages the developing leaves. Both sexes fully winged. Body color brown to dark brown; tarsi and fore tibiae paler; antennal segment III and apex of II yellow, IV light brown, V-VII brown; fore wings light brown, clavus darker. Antennae 7-segmented; segments III & IV with short forked sense cone (Fig. 1). Head about as long as wide or slightly longer; without sculpture between ocelli; 2 pairs of ocellar setae present, pair I absent, setae III shorter than setae II and arising on anterior margin of ocellar triangle; postocular setae variable, pair 1 present or absent, pair III longer than other postoculars and as long as distance between hind ocelli (Fig. 2). Pronotum with 2 pairs of long posteroangular setae; posterior margin with 2 or 3 pairs of setae; anterior margin with 4 or more setae, all of them of equal length and arising at margin (Fig. 3). Metanotal median area sculptured lines transverse at anterior, longitudinally striate on posterior half; median setae arising behind anterior margin; campaniform sensilla absent (Fig. 4). Meso- and metafurca without spinula (Fig. 6). Mid and hind tarsi 2-segmented. Fore wing first vein with 2-4 setae on distal half; second vein with complete row of about 12 setae (Fig. 5). Tergites II-VIII with no sculpture medially; median setae small and wide apart; posterior margin of tergites II-VII with small (Fig. 8), laterally directed teeth; V-VIII with paired ctenidia laterally, on VIII posteromedial to spiracles; on VIII posteromarginal comb complete with irregular slender microtrichia (Fig. 9). Sternites without discal setae, but frequently bearing irregular and dentate discal microtrichia; posterior margins with irregular, small dentate microtrichia; sternites IV-VI sometimes with small and poorly developed glandular area medially; median setae on sternite VII arising just in front of posterior margin.
Male similar to female but smaller; posterior margin of tergites II-VII with small, laterally pointing teeth, VIII with similar teeth arranged irregularly; sternites frequently bearing many discal microtrichia, posterior margins with irregular dentate microtrichia, III-VII with transverse glandular area (Fig. 10 and 11).
Second instar larva yellow, antennae grey, head with grey marking anteromedially and laterally; tergites with transverse rows of linear plaques, IX & X without grey band; IX with campaniform sensilla arising anterior to median setae, posterior margin with row of very small teeth.

The genus Stenchaetothrips Bagnall, 1926
The genus Stenchaetothrips includes 34 species, all associated with grasses and all originally from the Old World tropics (Mound 2011). The genus is closely related to the genus Thrips and has the common character of paired ctenidia laterally on the tergites V-VIII with the pair on tergite VIII arising posterior to the spiracle. In addition, the antennae are 7-segmented, antennal segments III and IV with forked sense cone, absence of ocellar setae I on the head, pronotum with 2 pairs of elongate posteroangular setae, and the metanotal median area is generally longitudinally striate on posterior half. Compared to Thrips, all members of the genus have ocellar setae II much longer than III, mesosternum as well as metasternum without median spinula, and sternites always without discal setae (Mound & Kibby 1998).

It differs from the related species Stenchaetothrips melanurus in having a dark body color, brown antennal segments except for segment III and apex of II, all anteromarginal pronotal setae have the equal length and arising at the margin, tergite VIII with a complete comb of long and slender microtrichia, and posterior margin of tergites II-VII with small and laterally directed teeth. In contrast, Stenchaetothrips melanurus has a pale yellow body color (only antennal segments VI & VII and abdominal segments 9 & 10 are dark brown), 1 pair of pronotal anteromarginal setae which is elongate and arising behind the anterior margin, tergite VIII without a comb of microtrichia, and posterior margin of tergites II-VII without teeth or 2 or 3 triangular teeth laterally.
As in members of the genus Thrips, Microcephalothrips abdominalis, Larothrips dentipes and Fulmekiola serrata, tergites V-VIII of Stenchaetothrips bear a pair of ctenidia laterally, which on tergite VIII lie posteromedial to the spiracle, and all species have no ocellar setae I. In contrast to the species with craspedum on tergites II-VII (Microcephalothrips abdominalis, Larothrips dentipes, Fulmekiola serrata), species of Thrips and Stenchaetothrips have no posteromarginal craspedum on tergites and sternites. Fulmekiola serrata as well as species of Thrips and Stenchaetothrips possess 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, Fulmekiola serrata and species of Stenchaetothrips have sternites always without discal setae, a mesosternal furca without median spinula, and ocellar setae II much longer than III.

Life history
The period from egg to adult varies between 14 and 21 days (Nugaliyadde & Heinrichs 1984). The duration of newly hatched larvae to adults was 9 days at 23.3ºC and 4 d at 36ºC. The average fecundity of a female thrips was 93 and a maximum of 147 eggs at 25°C. Egg period lasted for 3 days (Pathak & Khan 1994).

Host plants
Cereal crops: maize, rice, sugarcane.

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

Damage and symptoms
This species is a pest of rice and other grasses and damages the sheath by feeding and laying eggs. The larvae develop and feed on developing leaves. The damaged leaves show a silvery appearence or yellowish streaks where the sap is sucked from the mesophyll cells, which become occupied by air (Nugaliyadde & Heinrichs 1984). Thrips are frequently reported as key pests in the dry season and mostly during the seedling and flowering stages of the crop (Pathak & Khan 1994).

Detection and control strategies
Flooding the rice fields for 2days to completely submerge the seedlings provides effective control of thrips. Rice varieties IR62, IET1444, Ptb 21, Ptb 33 and wild rices such as Oryza eichingeri, Oryza glaberrima, Oryza minuta, Oryza nivara, Oryza officinalis, Oryza perennis, Oryza rufipogon, and Oryza sativa f. spontanea exhibit resistance to thrips infestation (Pathak & Khan 1994). Traditional rice cultivars "Ratnachudi" is found to be resistant to thrips infestation (Prashanta Kumar et al. 2012). Application of neem oil at 2% was effective against rice thrips (Pillai & Ponnaiah 1988).

Additional notes
-

Biogeography

Asia, Africa, Central and South America, Europe. South Africa.

Ananthakrishnan TN & Jagadish A (1967). Studies on the genus Chloethrips Priesner from India. Zoologischer Anzeiger. 178: 374-388

Ananthakrishnan TN & Kandasamy C (1977). On the trends of infestation of two species of Baliothrips Uzel on paddy, maize and their weed hosts. Current Science. 46 (10): 344-345

Bagnall RS (1913). Further notes on new and rare British Thysanoptera (Terebrantia) with descriptions of new species. Journal of Economic Biology. 8: 231-240

Bailey SF (1948). Grain and grass-infesting thrips. Journal of Economic Entomology. 41 (5): 701-706

Bhatti JS (1982). Revision of the Indian species of Stenchaetothrips Bagnall (Thysanoptera: Thripidae). Oriental Insects. 16 (4): 385-417

Bhatti JS & Mound LA (1980). The genera of grass- and cereal-feeding Thysanoptera related to the genus Thrips (Thysanoptera: Thripidae). Bulletin of Entomology. 21: 1-22

Girault AA (1929). New pests from Australia VI. Published privately, Brisbane, 4 pp

Karny H (1925). Die an Tabak auf Java und Sumatra angetroffenen Blasenfüsser. Bulletin van het deli Proefstation te Medan. 23: 1-55

Knechtel (1964). O noua specie dobrogeana din genul Thrips (Thysanoptera). Studii Åi CercetÄri de Biologie, Seria Zoologie. 16: 479-480

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

Madhusudhan VV & Gopalan M (1989). Studies on the biology of rice thrips, Stenchaetothrips biformis (Bagnall) in India. Tropical Pest Management. 35 (4): 394-396

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

Mound LA (1968). A review of R. S. Bagnalľs Thysanoptera collections. Bulletin of the British Museum (Natural History), Entomology. Supplement 11: 1-181

Mound LA (2011). Grass-dependent Thysanoptera of the family Thripidae from Australia. Zootaxa 3064: 1-40

Mound LA & Kibby G (1998). Thysanoptera: An identification guide,(2nd edition). CAB International,Wallingford and New York, 70 pp

Mound LA & Marullo R (1996). The thrips of Central and South America: An introduction (Insecta: Thysanoptera). Memoirs on Entomology, International, Vol. 6. Associated Publishers, Gainsville, 487 pp.

Nugaliyadde L & Heinrichs EA (1984). Biology of rice thrips, Stenchaetothrips biformis (Bagnall) (Thysanoptera, Thripidae) and a greenhouse rearing technique. Journal of Economic Entomology. 77 (5): 1171-1175

Nugaliyadde L & Heinrichs EA (1984). Resistance of Oryza spp. to thrips, Stenchaetothrips biformis (Bagnall) (Thysanoptera, Thripidae). Crop Protection. 3 (3): 305-313

Palmer JM, Mound LA & du Heaume GJ (1989). 2. Thysanoptera, 73 pp. In Betts CR [ed.], CIE Guides to insects of importance to man. CAB International, Wallingford, Oxon, UK

Pathak MD & Khan ZR (1994). Insect pests of rice. International Rice Research Institute, Philipines. p 89

Pillai MAK & Ponniah S (1988). Neem for control of rice thrips. International Rice Research Newsletter 13(5):33 - 34

Prashanta Kumar GK, Pradeep S, Sridhara S & Manjunatha M (2012). Incidence of sucking pests on promising traditional paddy cultivars in organic situation. Plant Archives 12 (1): 23-26

Velusamy R (1990). Relative susceptibility of high-yielding rice varieties to the thrips, Stenchaetothrips biformis (Bagnall) (Thysanoptera, Thripidae). Crop Protection. 9 (3): 193-196

Velusamy R & Saxena RC (1991). Genetic evaluation for resistance to rice thrips (Thysanoptera, Thripidae) in leafhopper-resistant and planthopper-resistant rice varieties. Journal of Economic Entomology. 84 (2): 664-668

Williams CB (1916). Thrips oryzae, sp. nov., injurious to rice in India. Bulletin of Entomological Research. 6: 353-355

zur Strassen R (1975). Thysanopterologische Notizen (3) (Insecta: Thysanoptera). Senckenbergiana Biologica. 56 (1-3): 75-88

zur Strassen R (2003). Die terebranten Thysanopteren Europas und des Mittelmeer-Gebietes. Die Tierwelt Deutschlands und der angrenzenden Meeresteile nach ihren Merkmalen und nach ihrer Lebensweise, 74. Teil. Goecke & Evers, Keltern, Germany, 277 pp