Fig. 1: Antenna (inset: III. and IV. antennal segment)
Fig. 2: Head dorsal with ocellar triangle
Fig. 3: Pronotum
Fig. 4: Prosternal sclerite plates
Fig. 5: Meso- and metanotum
Fig. 6: Forewing
Fig. 7: Tergites IV - VI
Fig. 8: Tergite X
Liothrips varicornis Hood, 1912
Present taxonomic position:
Family: Phlaeothripidae Uzel, 1895
Subfamily: Phlaeothripinae (Uzel) Priesner, 1928
Genus: Liothrips Uzel, 1895
Species RecognitionGeneral information about the genus Liothrips:
There are 250 species of Liothrips described which make this genus the second largest in the Thysanoptera. This genus is closely related to the genus Rhynchothrips and the two genera are difficult to separate morphologically. Cott (1956) acknowledged that the character shape of the head was most often used to separate the two genera and became increasing muddied as new species came to light. Mound and Marullo (1996) support this theory describing the difficulties separating the species within Liothrips and reporting that some authors separate the species by host-specificity with little supporting evidence. Some of the characters that are used to define this genus include a uniformly dark body, abdominal segment X is tubular, the forewings are smooth without veins or setae, the abdominal tergites contain two pairs of wing-retaining setae, they lack praepectal plates, antennal segment III has one sense cone whereas segment IV has three, there are five pairs of pronotal setae, the body has dark long setae and the basantra is absent.
Typical character states of Liothrips varicornis:
Number of antennal segments: 8
Segment III - number of sense cones: 1
Segment IV - number of sense cones: 3
Segments III & IV sensoria: emergent and simple
Basal thirds of cheeks: without a pair of stout setae
Maxillary stylet position: about one fifth of head width apart
Postocular setae: about half to nine tenths as long as eye
Postocular setal apex: capitate to broadly expanded
Maxillary bridge: absent
Cheeks: without one pair of stout setae in basal third
Number of pairs of elongate pronotal setae: 4-5
Pronotum: with faint sculpture
Prosternal basantra: absent
Metanotum structure: weakly reticulate or with narrow longitudinalreticulations medially
Wings: present and more than half as long as abdomen
Forewing shape: parallel sided
Forewings: surface smooth, without veins, setae and microtrichia
Fore femur: without a strong, cylindrical tooth near the base
Abdominal segment X: complete tube in both sexes
Abdominal tergites: with curved wing-retaining setae
The biology of this species is not well known. 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. With greenhouse temperatures the developmental time from egg to adult can decrease to about one week.
Hibiscus, hollyhocks, Althea, Sida
Current known distribution:
Central and South America, North America
This species causes leaf rolls on hollyhock.
Bailey, SF (1957): The
thrips of California Part I: Suborder Terebrantia. Bulletin of the
California Insect Survey 4, no. 5: 143-220.
Cott, HE (1956): Sytematics of the suborder Tubulifera (Thysanoptera) in California. University of California Publications in Entomology Vol. 13, ppg. 216.
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.
Mound, LA & Kibby, G (1998): Thysanoptera: An identification guide, (2nd edition). CAB International, Wallingford and New York, 70pp.
Mound, LA & Marullo, R (1996): The thrips of Central and South America: An Introduction (Insecta: Thysanoptera). Associated Publishers, Gainesville.
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.
Stannard, LJ (1968): The thrips, or Thysanoptera, of Illinois. Illinois Natural History Survey Bulletin 29: 215-552.
Mound, LA (2005): Thysanoptera (Thrips) of the World - A Checklist. http://www.ento.csiro.au/thysanoptera/worldthrips.html