Figures
Fig. 1: Antenna (inset: VI. - VIII. [IX.] antennal segment)
Fig. 2: Head dorsal with ocellar triangle
Fig. 3: Head ventral with clypeogenal suture
Fig. 4: Pronotum
Fig. 5: Meso- and metanotum
Fig. 6: Fore- and hindwing, base of fore wing with alula
Fig. 7: Tergites V and VI
Fig. 8: Tergites VIII - X
ITS-RFLP gel patterns (1&8 ladder, 2 PCR-product, 3 RSAI, 4 HaeIII, 5 MspI, 6 HinfI, 7 AluI)
Fig. 9: Primer pair CS249/CS250
Fig. 10: Primer pair O1/18J
Fig. 11: Primer pair P1/28Z
Fig. 12: Primer pair TODA1/TODA2
Taxonomic Information
Species:
Anaphothrips obscurus (Müller, 1776)
Synonyms:
Anaphothrips discrepans Bagnall, 1933
Anaphothrips cecili Girault, 1928
Anaphothrips sexguttus Girault, 1928
Anaphothrips collaris Priesner, 1926
Anaphothrips grisea Priesner, 1926
Anaphothrips angustipennis Reuter, 1925
Anaphothrips virgo Uzel, 1895
Physopus obscurus Provancher, 1890
Thrips striata Osborn, 1883
Limothrips poaphagus Comstock, 1875
Thrips obscurus Müller, 1776
Common name:
American grass thrips
Present taxonomic position:
Family: Thripidae Stephens, 1829
Subfamily: Thripinae (Stephens) Karny, 1921
Genus: Anaphothrips Uzel, 1895
Species Recognition
General information about the genus Anaphothrips:Cosmopolitan, the species in this genus are found on various herbs, grasses, shrubs and trees. Relationships within this genus are unclear (probably restricted to less than 40 species, (Nakahara 1995)). Antennal segments VII and VIII less than 0.5 times as long as segment VI (this segment is often divided by a suture near the apex), sometimes wingless or with short wings (pads). Several species are quite common on many different hosts. Head and pronotum are without well-developed setae (bristles or hollow hairs).
Typical character states of Anaphothrips obscurus:
Body color
Mainly brown - mainly pale or yellow, with some darker markings
Antennae
Number of antennal segments: 8 (-9)
Segment IV - forked sensorium: scarcely extending beyond base of segment V
Segments II and III shape: more or less symmetric
Segments III & IV sensoria: emergent and forked
Base of sensorium on antennal segment VI: no more than 2 times as wide as base
of nearest seta
Terminal antennal segments: rarely elongate.
Head:
Distance between bases of ocellar setae III: greater than width of first ocellus
Head shape between compound eyes: not prolonged (- distinctly prolonged rare)
Ocellar setae III on head: arising on anterior margin of, or in front of, ocellar triangle
Postocular setae I: present
Surface of head, pronotum and fore legs: without strong reticulate sculpture
Ocellar setae I in front of anterior ocellus: present
Prothorax
Number of pairs of elongate pronotal setae: 0-3
Number of pairs of elongate posteroangular pronotal setae: 0
Pronotum shape: rectangular
Mesothorax
Mesothoracic endofurca: without median spinula
Metathorax
Metanotum: without campaniform sensilla
Metanotum major sclerites: with two major sclerites, metascutum and metascutellum
Metanotum median area: with at least some equiangular reticulation
Metanotum sculpture: without dominant sculptured triangle medially
Metathoracic endofurca: transverse, sometimes with simple median spinula
Wings
Wings: absent, or not longer than thorax width or present and more than half as long as abdomen
First vein of forewing: distinct from costal vein
Forewing anterior margin: with setae and cilia but cilia longer than setae
Forewing color: uniformly pale or weakly shaded
Forewing costal fringe of cilia: arising at anterior margin of wing
Forewing costal setae at middle of wing: shorter than median width of wing
Forewing first vein setal row: incomplete, with setae not closely and uniformly spaced
Forewing posterior margin cilia: undulated near apex
Forewing second vein setal row: incomplete, with setae not closely and uniformly spaced
Forewing surface: not reticulate
Forewings surface: with veins, setae and microtrichia
Legs
Fore tibial apex: not extending around fore tarsus
Mid and hind tarsi: with two segments
Abdomen:
Abdominal pleurotergites: not covered in microtrichia
Abdominal segment X: never tubular, longitudinally incomplete ventrally in both sexes
Abdominal sternite II: with marginal setae but no discal setae
Abdominal sternite III of female: without glandular areas
Abdominal sternite VII median marginal setae: arising in front of margin
Abdominal sternites IV , V and VI: with marginal setae but no discal setae
Abdominal tergites: without curved wing-retaining setae
Abdominal tergites IV & V median setal pair: longer than distance between their bases
Abdominal tergites V-VII: without paired ctenidia,
sometimes with irregular microtrichia
Setae on abdominal tergite X: slender
Surface of lateral thirds of abdominal tergites: without
regular rows of fine microtrichia
Ctenidia on tergite VIII: not present,
but groups of microtrichia
Tergite VIII posteromarginal comb of microtrichia:
present, complete medially
Tergite VIII posteromarginal microtrichia:
long, slender and irregular
Biology
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, cereal crops: maize, oats, rye, wheat, (Poaceae).
Vector capacity:
None identified
Current known distribution:
In temperate and subtropical regions throughout the world.
Additional notes:
Causing 'silver top' on blue grass,
death of the tops of grasses and sterile seeds from feeding, stunts other
grasses by feeding on the developing shoots. Only females are found and
are either fully winged or short winged (pads). The fully winged individuals
are yellow with dark markings on the head and abdominal tergites whereas
the short winged individuals are generally clear yellow.
Bibliography
Ananthakrishnan, TN (1984): Bioecology
of thrips. Indira Publishing House, Oak Park, Mich. 233 pp.
Bailey, SF (1957): The thrips of California. Bulletin
of the California Insect Survey. Vol. 4:5, 1-220.
Braman, SK & Beshear, RJ (1994): Seasonality of
predaceous plant bugs (Heteroptera, Miridae) and phytophagous thrips
(Thysanoptera, Thripidae) as influenced by host-plant phenology of native
Azaleas (Ericales, Ericaceae). - Environmental Entomology 23 (3): 712-718.
Kamm, JA (1971): Silvertop of bluegrass and bentgrass produced by Anaphothrips obscurus Thysanoptera-Thripidae. - Journal of Economic Entomology 64 (6): 1385-1387.
Lewis, T (1973): Thrips their biology, ecology and economic
importance. Academic Press Inc., London Ltd. 349 pp.
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 microscopial methods. CBIT, University of Queensland,CDROM ISBN 1-86499-781-8.
Nakahara, S (1995): Review of the nearctic species of Anaphothrips (Thysanoptera:
Thripidae). Insecta Mundi 9: 221-248.
Nakao, S (1996): Wing length variation and seasonal changes in wing form composition
of two Anaphothrips species (Thysanoptera: Thripidae). - Japanese Journal of
Applied Entomology and Zoology 40 (1): 15-24.
Stannard, LJ (1968): The Thrips, or Thysanoptera, of Illinois.
Illinois Natural History Survey. Vol. 29:4, 215-552.
Zwahlen, C, Nentwig, W, Bigler, F & Hilbeck, A (2000): Tritrophic interactions
of transgenic Bacillus thuringiensis corn, Anaphothrips obscurus (Thysanoptera
: Thripidae), and the predator Orius majusculus (Heteroptera : Anthocoridae).
- Environmental Entomology 29 (4): 846-850.
Links:
Mound, LA (2005): Thysanoptera (Thrips) of the World
- A Checklist. http://www.ento.csiro.au/thysanoptera/worldthrips.html