Figures
Fig. 1: Antenna (inset: III. and IV. antennal segment)
Fig. 2: Head dorsal with ocellar triangle
Fig. 3: Pronotum
Fig. 4: Meso- and metanotum
Fig. 5: Fore- and hindwing
Fig. 6: Sternite VII
Fig. 7: Tergites III and VI
Fig. 8: Tergites VIII and IX
Taxonomic Information
Species:
Megalurothrips usitatus (Bagnall, 1913)
Synonyms:
Taeniothrips distalis Karny, 1937
Taeniothrips longistylus Karny, 1922
Physothrips mjobergi Karny, 1920
Physothrips cinctipennis Bagnall, 1916
Frankliniella nigricornis Schmutz, 1913
Frankliniella obscuricornis Schmutz, 1913
Frankliniella vitata Schmutz, 1913
Physothrips usitatus Bagnall, 1913
Common name:
Bean blossom thrips
Present taxonomic position:
Family: Thripidae Stephens, 1829
Subfamily: Thripinae (Stephens) Karny, 1921
Genus:
Megalurothrips Bagnall, 1915
Species Recognition
General information about the genus Megalurothrips:There are eight species known in this genus all of which live and breed in legume flowers. Two species are discussed within this key both have brown bodies with eight antennal segments, antennal segment III yellow, segments III and IV have constricted necks apically and forked sense cones, the pronotum contains four long setae, there are a pair of pores on the metanotum, and both have a complete comb of slender microtrichia on tergite VIII.
Typical character states of Megalurothrips usitatus:
Body color
Mainly brown
Antennae
Number of antennal segments: 8
Segment IV - forked sensorium: extending to a point at least 30% distal to 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
Major postocular setae: less 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
Prothorax
Number of pairs of elongate pronotal setae: 0-3
Number of pairs of elongate posteroangular pronotal setae: 2
Pronotum shape: rectangular
Mesothorax
Mesothoracic endofurca: with median spinula
Metathorax
Metanotal median area sculptured lines: transverse at anterior but scarcely sculptured postero-medially
Metanotal median setae length: longer than lateral metanotal setae
Metanotal median setae position: arising at anterior margin
Metanotum: 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
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: alternating bands of dark and light
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: complete, with setae closely and uniformly spaced
Forewing surface: not reticulate
Forewings: 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 III of female: without glandular areas
Abdominal sternite VII: with marginal setae but no discal setae
Abdominal sternite VII median marginal setae: arising in front of margin
Abdominal sternites IV , V and VI: with marginal setae but no discal setae
Number of lateral marginal setae on abdominal tergite II: 3
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: 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 laterally, incomplete medially
Tergite VIII posteromarginal microtrichia: short and irregular in length
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. With greenhouse temperatures the developmental time from egg to adult can decrease to about one week.
Host plants:
Beans, flower feeding
Vector capacity:
None identified
Current known distribution:
Asia, Australia, New Zealand
Additional notes:
Megalurothrips usitatus is a pest of groundnut, mung bean and soybean. This species breeds in the flowers of these bean plant species reducing crop yields.
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Links:
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- A Checklist. http://www.ento.csiro.au/thysanoptera/worldthrips.html