Identification Of Osmia kenoyeri And O-Virga (Hymenoptera, Megachilidae), 2 Blueberry Pollinators

5 Pages·1993·1.8 MB·English

by  R W Rust

Vol. 104,No. 3. May&June, 1993 113
IDENTIFICATION OF OSMIA KENOYERI AND
O. VIRGA (HYMENOPTERA: MEGACHILIDAE),
TWO BLUEBERRY POLLINATORS1' 2
RichardW. Rust3 EbenA. Osgood4
,
ABSTRACT:ThesexesofOsmiakenoyeriandO. virgaareassociated and the femalesof
both aredescribed. Both species visitlowbush blueberry, Vaccinium spp. forpollen and
nectar.The nestingbiologyofO. kenoyeriis described.
The genus Osmia contains over 130 species in North America
(Sandhouse 1939, Hurd 1979). Many ofthe species are only known by
one sex, often the male, because ofdistinctive abdominal sternal and
genitaliccharacters.Hereweassociatethesexesanddescribeforthefirst
timethefemalesofOsmiakenoyeriCockerellandO. virgaCockerell.Both
species havebeencollectedon Vaccinium angustifolium Art. and V. myr-
tilloides Michx. in thelowbush blueberrycomplex inMaine(Boulanger
etal. 1967, Stubbs etal. 1992).
Osmia (Acanthosmioides) kenoyeri Cockerell
Female: Length 10mm; forewing6.5 mm; headwidth 3.5 mm. Colordarkgreenish-
blue;antennae,mandibles,legsdarkredbrowntoblack;tegulaeblackwithgreenish-blue
apicaledge.Pubescenceofvertex,pronotum.scutum,scutellumwhite;metasomaltergum
1 whitewithsomeblackhairs;tarsiwithwhitetoreddishbrownhairs;restofbodyinclud-
ingscopablack. Headwiderthanlong,denselycoveredwithpunctures,all puncturesof
approximaelysimilardiameter;compound eyesslightlyconvergentbelow;dorsal 1/3of
gena visible beyond compound eye, gena wider than compound eye; clypeal margin
broadlyconcave,apical margin narrowlyimpunctate,clypeus in profileslightlyconvex,
denselypunctate;hypostomalcarinamoderatelyraised,abruptlyreducedbeforeangleto
halfits height; ocelli equally spaced betweencompound eyes and each other; length of
flagellomere1onlyslightlylessthan2and3together;mandiblewith4teeth(Fig. 1),apical
distance(betweenteeth)twicewidthofmedianconstriction,carinaeparallel,lowertwice
aswideasupper,uppertoothoblique,nexttoothsmallestofthe4withventralmargintrun-
cate,thirdtoothtriangular,fourthtooth(lowest)longest;maxillarypalpalsegments2and3
subequal,equallinglengthof4and 5together;labial palpalsegments 1 shorterthan2,3
equalto4;ventralmarginofgaleawithdense,shorthairs.Thoraxdenselycoveredwithfine
punctures, equalling those on head; propodeal triangle minutely rugose; propodeal pit
oval shining; hindtibial spursstraight,onlyapical 1/5bent;strigiliswith velum shallow
concave,amluslong,acutelypointed; forewingwith apical papillaesmall,cellscovered
1 ReceivedJuly21, 1992.Accepted December 18, 1992.
2Contribution No. 1656from the MaineAgricultural Experiment Station.
3 DepartmentofBiologyand Program in Ecology.EvolutionandConservation Biology,
UniversityofNevada,Reno,NV89557.
4DepartmentofEntomology,UniversityofMaine,Orono. ME04469-0118.
ENT. NEWS 104(3): 113-117. May&June. 1993
ENTOMOLOGICALNEWS
14
with few, short, light hairs, vein A 3 times B. Metasomal terga 1-4 with wide apical
impunctatebands,bands 1/4to 1/3 punctateportion.
Male:ThemaleofO.kenoyeriisextremelydistinctiveandcanbedistinguishedfromall
otherOsmia bythestructureofmidtarsus1,theshapeofthegenitaliaandmetasomalster-
num2(Sandhouse 1939).
Type:TheholotypeoWsmiakenoyeri,amale,isfromNebraskaHill,Coloradoandwas
collected on Trifolium. It is located at the University of Colorado Museum, Boulder,
Colorado. Males from Mainewere identical with the holotype.
Distribution: Osmia kenoyeri is known from Deblois, Washington County, Maine;
GrandSableDunes,AlgerCounty,Michigan(M.Arduser,pers.comm.);andSandhouse
(1939)reported it fromColorado,California,Alberta,and theYukon.
Remarks: InWhite(1952),the femaleofO. kenoyeri keysoutwith O.
IntegraCresson(couplet 18)butdiffersfromO. Integrainthesmallsizeof
the fore wing papillae and the white pubescence on the dorsum ofthe
thorax.InMitchell(1962),thefemaleofO. kenoyerialsokeystoO. Integra
(couplet 12)andthemalekeyswithOsmiafeltiCockerell(couplet9)butis
easily separated by the globose first segment ofthe mid tarsus.
Sandhouse (1939) placed O. kenoyeri in the subgenus Acanthos-
mioides. White (1952) excluded O. kenoyeri from Acanthosmioides and
placed it in the subgenusMelanosmia (equals Centrosmia). His decision
was based primarily on character similarities with Osmia bucephala
Cresson. Hurd (1979) placed O. kenoyeri in the subgenus Acanthos-
mioides. He provided no explanation for the placement. However, with
the correct association of the female, O. kenoyeri appears to be more
closelyassociatedwithAcanthosmioides. In the female,the broad apical
width ofthe mandible, general body and pubescence coloration, and
apical marginsofterga and in the male, thebodycoloration, mandible,
metasomal sterna 2 to 7, genitalia, and leg characters strongly suggest
Acanthosmioides.
Sandhouse(1939)suggestedthatOsmiahendersoniCockerell maybe
thefemaleofO.kenoyeri.ThetypeofO.hendersoni(U.S.NationalHistory
Museum #27891) was examined and found not to be the female ofO.
kenoyeri. The shape ofthe mandible and hypostomal carina, and im-
punctatebandsonabdominal terga2and3weredifferent.ThetypeofO.
hendersoni is extremely worn with badly torn wings and missing
flagellomeres.
Biology: A nesting site ofO. kenoyeri was found on the "blueberry
barrens" in Deblois, Washington County, Maine (EAO). Females were
observed to excavate burrows in the sandy loam soil in late May and
mm
adultactivitycontinuedtomidJune.Burrowsvariedfrom40to75 in
diameter and were not symmetrical in construction. They entered the
ground at about a 30 angle and terminated in a series oflinear cells
within 2 to 3 cm ofthe soil surface. One nest contained 3 urn-shaped
cells, 2 with developing larvae while the third was open and not pro-
Vol. 104,No.3,May&June, 1993 115
mm
visioned.Cellswereapproximately80x 110 andcomposedofamix-
tureoffineplantfibers,notleaforleafpieces,andsoil.Cellwallsvaried
mm
from0.75to 1.5 thick.Cellswereeasilyseparatedfromthesurround-
ing soil and remained intact when excavated. Larvae were mature by
earlyJulyand incocoons.Thecocoonwascomposedoftwolayers.The
outerlayerwasadensematofsilkfibersthatadheredtothesoil-fibercell
wallandtheinnerlayerwasthinner.Ahighlypolishedredbrownmatrix
with individual silk threads was visible and easily separated from the
outer layer. The outer anterior surface ofthe cocoon was formed by a
large, flat white nipple which separated the cocoon from the top ofthe
soil-fibercell.Nineteenmalesand9femaleswerecollectedthefollowing
May from a 30x 30cm screened areaofthe nestingsite. Noparasitesor
predators were recovered from the cages.
Examination of the pollen grains remaining in the fecal pellets
showed both the tetrad grain structure ofEricaceae (Vaccinium) and a
smaller, tricolporate grain, perhaps a Fabaceae.
Osmia (Chenosmia) virga Sandhouse
Female: Length 10mm; forewing7.0mm; headwidth3.0mm.Colorolive-greenish
blue;flagellomeres,legsreddishbrown,scapeblack,mandibleredbrownwithblackedges.
Pubescence white; mandibles, tarsi with golden to red brown hairs, scopa black. Head
slightlywiderthanlong,puncturescontinuousandofsimilarsize;genawithupper1/3visi-
blebeyondcompoundeye,twiceaswideascompoundeye;innermarginofcompoundeye
convergent below; lateral ocelli 2'/2 diameters distant from compound eye, less than 1
diameter from median ocellus; clypeal apical margin truncate, slightly wavy, narrowly
impunctate;hypostomalcarinalow,uniform,nottoothed;mandiblewith4teeth(Figure
1),apicalwidthonlyslightlygreaterthanmidwidth,carinaedivergent,lowertwiceaswide
asupper;flagellomere1longerthan2or3;maxillarypalpalsegment3longerthan2.twice3
Figure 1. Female mandiblesofOsmiakenoyeriCockerel! (left)andOsmia virgaCockerell
(right),scaleline is 1.0 mm.
ENTOMOLOGICALNEWS
16
and4together,galeaventralsurfacewithnumerousshortstraighthairs,dorsalsurfacewith
fewscattered, straight hairs; labial palpal segment2 longerthan 1.Thoraxdensely and
evenlypunctate,puncturesizesimilartovertex;propodealtrianglerugoseabove,granular
below; propodeal pitnarrow,parallelsided; tegulaealmostimpunctate; wings minutely
andevenlyhaired,veinAtwiceB;strigiliswithmalusmargintruncate,velumveryshort.
Abdomenwithimpunctatebandsofmetasomalterga1to3Viaswideaspunctateportion,4
to6narrower.
Male. The male ofO. virga is easily identified by the wide impunctate bands on
metasomalterga 1 to4,thetruncatemarginofmetasomalsternum4,andthestructureof
thegenitalia,especiallythebroad penisvalves(Sandhouse 1939,Mitchell 1962).
Type.ThetypespecimenisfromWaterTank,PennsylvaniaandislocatedintheUnited
StatesNaturalHistoryMuseum.Washington,D.C.(Holorype#52883).Mainemaleswere
identicaltotheholotype.
Distribution:WehaveseenspecimensfromDebloisandOrono,Maine. Sandhouse
(1939)reportedO. virga from Massachusetts,NewJersey,Connecticut,andVirginiaand
Mitchell(1962)addedWisconsinand Pennsylvania.
Remarks: In Mitchell (1962), the female of O. virga keys out as
O. atriventris Cresson (couplet 17) from which it differs in body color,
hypostomal carina, mandibular carinae, impunctate bands of meta-
somal terga 4 and 5, structure ofthe strigilis, and scopal color.
Stubbs et al. (1992) reported 99% Vaccinium pollen from the pollen
load ofO. virga from Maine.
DISCUSSION
ThedistributionalpatternseeninO. kenoyeri.RockyMountainsand
northeastern U.S. and Canada, is not uncommon within the genus.
Osmia Integra, O. bucephala, O. subaustralis Cresson, O. inermis (Zet-
terstedt),andO. nigriventris(Zetterstedt)showsimilardistributionswith
thenortheasternandRockyMountaindistributionsconnectedthrough
northern Canada and Alaska (Sandhouse 1939, Mitchell 1962, Rust
1974). The latter two species are Holarctic. Biologically, O. kenoyeri
groups with two otherAcanthosmioides, O. nigrobarbata Cockerell and
O. unca Michener, in excavatingburrows in the ground where the cells
are lined with plant materials and soil (Rust etal. 1974). Also, the two
layered construction ofthe cocoon and the large, flatwhite nipple area
are characteristics observed in otherAcanthosmioides species.
ACKNOWLEDGMENTS
We would like to thank D. Bowers (University of Colorado, Boulder) and R. J.
McGinley(U.S.NationalMuseum)fortheloanoftypespecimens,M.Arduser(St.Louis,
MO)forfirstsuggestingthattheMainematDerAialmightbeO.kenoyeriandfortheMichigan
distributional records,T. Griswold (U.S. Bee Biology and Systematics Laboratory,
Logan, UT) and F. A. Drummond (University of Maine, Orono) for reviewing the
manuscript.
Vol. 104. No. 3. May &June, 1993 117
LITERATURE CITED
Boulanger, L.W., G.W. Wood, E.A. Osgood, and C.O. Dirks. 1967. Native bees
associatedwiththelow-hushblueberryinMaineandeasternCanada.MaineAgr.Exp.
Stat. Bull.T26: 22pp.
Hurd, P.D.Jr. 1979.Apoidea.In:CatalogofHymenoptera inAmerica north ofMexico.
eds: K.V. Krombein, P. D. HurdJr.. D.R. Smith,and B.D. Banks. Smithsonian Press.
Washington, D.C.
Mitchell,T.B. 1962. Beesoftheeastern United States. Vol.2. North Carolina Agr. Exp.
Stat.Tech. Bull 152: 557pp.
Rust, R.W. 1974. The systematics and biology of the genus Osmia. subgenera Osmia.
Chalcosmia, and Cephalosmia. Wasmann J. biol. 32: 1-93.
Rust,R.W.,R.W.Thorp,andP.F.Torchio. 1974.TheecologyofOsmianigrifronswitha
comparison tootherAcanthosmioides.J. Nat. Hist. 8: 29-47.
Sandhouse,G.A.1939.TheNorthAmericanbeesofthegenusOsmia. Mem.Entomol.Soc.
Washington 1: 1-167.
Stubbs, C.S., H.A. Jacobson, E.A. Osgood, and F.A. Drummond. 1992. Alternative
forage plants for native (wild) bees associated with lowbush blueberry. Vaccinum
Acanthosmioidesspp.. in Maine. MaineAgr. Exp. Stat. Bull.T148:54pp.
White,J.R. 1952.ArevisionofthegenusOsmia.submenusAcanthosmioides(Hymenoptera:
Megachilidae). Univ. Kansas Sci. Bull. 35: 219-307.
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