Fig. 1: Antenna (inset: II. and III. antennal segment)
Fig. 2: Head dorsal with ocellar triangle
Fig. 3: Pronotum
Fig. 4: Meso- and metanotum
Fig. 5: Forewing
Fig. 6: Sternites I and II
Fig. 7: Sternite II and III
Fig. 8: Tergites VIII and IX
Frankliniella williamsi Hood, 1915
Frankliniella spinosa Moulton, 1936
Frankliniella flavens Moulton, 1928
Frankliniella williamsi Hood, 1915
Present taxonomic position:
Family: Thripidae Stephens, 1829
Subfamily: Thripinae (Stephens) Karny, 1921
Genus: Frankliniella Karny, 1910
Species RecognitionGeneral information about the genus Frankliniella:
The members in this genus are sometimes quite difficult to separate from one another and the classification has been in flux with many species later synonymized in association with color variations. There are about 180 species in this genus most having three pairs of ocellar setae well developed, 8 segmented antennae with III and IV having forked sense cones, well developed setae on the anterior and posterior margins of the pronotum, when present wings with complete rows of setae on the wing veins, two segmented tarsi, without accessory setae on abdominal sternites, with a ctenidia laterally on abdominal segments with ctenidia anterior to spiracle on segment VIII and with males generally smaller and paler than the females (Stannard, 1968).
Typical character states of Frankliniella williamsi:
Mainly pale or yellow, with some darker markings - bicolored
Number of antennal segments: 8
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
Shape of pedicel of antennal segment III: simple
Distance between bases of ocellar setae III: greater than width of first ocellus
Head shape between compound eyes: not prolonged
Major postocular setae: more than half as long as ocellar setae III
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
Number of pairs of elongate pronotal setae: 4-5
Number of pairs of elongate posteroangular pronotal setae: 2
Pronotum shape: rectangular
Number of pairs of pronotum posteromarginal minor setae: 4-5
Number of pairs of pronotum anteromarginal minor setae: 3
Mesothoracic endofurca: with median spinula
Metanotal median area sculptured lines: transverse at anterior, but forming irregular longitudinal reticulations on posterior half
Metanotal median setae length: longer than lateral metanotal setae
Metanotal median setae position: arising at anterior margin
Metanotum: with campaniform sensilla or without campaniform sensilla
Metanotum major sclerite: with two major sclerites, metascutum and metascutellum
Metanotum median area: with no equiangular reticulation
Metanotum sculpture: without dominant sculptured triangle medially
Metathoracic endofurca: transverse, sometimes with simple median spinula
Wings: 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 first vein setal row: complete, with setae closely and uniformly spaced
Forewing posterior margin cilia: undulated near apex
Forewing second vein setal row: complete, with setae closely and uniformly spaced
Forewing surface: not reticulate
Forewings: with veins, setae and microtrichia
Fore tibial apex: not extending around fore tarsus
Mid and hind tarsi: with two segments
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: with marginal setae but no discal setae
Abdominal sternite VII median marginal setae: arising at margin - 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: much shorter than distance between their bases
Abdominal tergites V-VII: with pair of ctenidia laterally
Setae on abdominal tergite X: slender
Surface of lateral thirds of abdominal tergites: without regular rows of fine microtrichia
Ctenidia on tergite VIII: anterolaterad to spiracle
Tergite VIII posteromarginal comb of microtrichia: present, complete medially
Tergite VIII posteromarginal microtrichia: long, slender and regular on broadly triangular bases
As with other thrips species the life cycle from egg to adult is dependent on temperature. The full cycle for Frankliniella occidentalis 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).
Maize, grasses (Poaceae)
Current known distribution:
Asia, Australia, New Zealand, Central and South America, North America
Feeds between the blades/husks of the grass leaves. Males: with transverse glandular areas on sternites III, IV, V, VI, and VII, body small and pale compared with females, and tergite VII with a craspedum and VIII with a comb similar to the females.
Bailey, SF (1957): The
thrips of California Part I: Suborder Terebrantia. Bulletin of the
California Insect Survey 4, no. 5: 143-220.
Bhatti, JS (2006): The Classification of Terebrantia (Insecta) into Families. Oriental Insects 40: 339-375.
Buntin, GD & Beshear, RJ (1995): Seasonal abundance of thrips (Thysanoptera) on winter small grains in Georgia. - Environmental Entomology 24 (5): 1216-1223.
Cach, NT, Lenis, JI, Perez, JC, Morante, N, Calle, F & Ceballos, H (2005): Inheritance of useful traits in cassava grown in subhumid conditions. - Plant Breeding 125 (2): 177-182.
Campbell, L, Robb, K & Ullman, D (2006): The complete Tospovirus resource page. http://www.oznet.ksu.edu/tospovirus/welcome.htm.
Jiang, XQ, Meinke, LJ, Wright, RJ, Wilkinson, DR & Campbell, JE (1992): Maize Chlorotic Mottle Virus in Hawaiian-grown maize - Vector Relations, Host Range and Associated Viruses. - Crop Protection 11 (3): 248-254.
Lewis, T (1973): Thrips their biology, ecology and economic importance. Academic Press Inc., London Ltd. 349 pp.
Lewis, T (1997): Pest thrips in perspective, pp. 1-13. In Lewis, T [ed.] Thrips as Crop Pests. Wallingford, UK: CABI. 740 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.
Mound, LA (2002): The Thrips and Frankliniella genus groups: the phylogenetic significance of ctenidia, pp. 379-386. In Marullo, R & Mound, LA [eds.], Thrips and Tospoviruses: Proceedings of the 7th International Symposium on Thysanoptera. Australian National Insect Collection, Canberra., Reggio de Calabria, Italy.
Mound, LA & Marullo, R (1996): The thrips of Central and South America: An Introduction (Insecta: Thysanoptera). Associated Publishers, Gainesville.
Mound, LA & Kibby, G (1998): Thysanoptera: An identification guide, (2nd edition). CAB International, Wallingford and New York, 70pp.
Nickle, DA (2003): A checklist of commonly intercepted thrips (Thysanoptera) from Europe, the Mediterranean, and Africa at U.S. ports-of-entry (1983-1999). Part 1. Key to genera. Proceedings of the Entomological Society of Washington 105: 80-99.
Nickle, DA (2004): Commonly intercepted thrips (Thysanoptera) from Europe, the Mediterranean, and Africa at U.S. ports-of-entry. Part II. Frankliniella Karny and Iridothrips Priesner (Thripidae). Proceedings of the Entomological Society of Washington 106: 438-452.
O'Donnell, CA, Mound, LA & Parrella, MP (2001): A multilevel identification system for thrips asscoiated with flower crops in North America. UC Davis (Thesis_I_III.pdf).
Palmer, JM, Mound, LA & Du Heaume, GJ (1989): 2. Thysanoptera, pp. 73. In Betts, CR [ed.], CIE Guides to Insects of Important to Man. CAB International, Wallingford.
Sites, RW, Chambers, WS & Nichols, BJ (1992): Diel periodicity of thrips (Thysanoptera, Thripidae) dispersion and the occurrence of Frankliniella williamsi on onions. - Journal of Economic Entomology 85 (1): 100-105.
Mound, LA (2005): Thysanoptera (Thrips) of the World - A Checklist. http://www.ento.csiro.au/thysanoptera/worldthrips.html