Hostname: page-component-78c5997874-lj6df Total loading time: 0 Render date: 2024-11-14T22:28:37.360Z Has data issue: false hasContentIssue false
  • English
  • Français

NUMBER OF INSTARS OF LARVAE OF THE ALFALFA LEAFCUTTER BEE, MEGACHILE ROTUNDATA (F.) (HYMENOPTERA: MEGACHILIDAE)

Published online by Cambridge University Press:  31 May 2012

G.H. Whitfield ,
K.W. Richards  and
T.M. Kveder
G.H. Whitfield
Affiliation:
Agriculture Canada Research Station, Lethbridge, Alberta, Canada T1J 4B1
K.W. Richards
Affiliation:
Agriculture Canada Research Station, Lethbridge, Alberta, Canada T1J 4B1
T.M. Kveder
Affiliation:
Agriculture Canada Research Station, Lethbridge, Alberta, Canada T1J 4B1
Get access Rights & Permissions [Opens in a new window]

Abstract

The number of instars of larvae of the alfalfa leafcutter bee, Megachile rotundata (F.), was determined by direct observation, frequency distribution plots, and linear regression of head-capsule measurements. For all three methods, developmental polymorphism was observed; larvae were grouped according to the number of instars. The majority of larvae (77%) had four larval instars and the remainder had five. Mortality of bee larvae, apparently a result of physical injury during measurement of head-capsule width, was high but results were based on data for 259 individuals that completed development to the prepupal (= pharate pupa) stage. Direct observation of larval moults was found to be the only accurate method for determining instar designation but analysis of head-capsule width did describe the number of instars present in a population and provided estimates of head-capsule width for each instar. A morphological key for separation among four instars is presented as a practical alternative for instar determination in field studies.

Résumé

Le nombre de stades larvaires de la mégachile de la luzerne, Megachile rotundata (F.), a été établi par observation directe, par courbes de distribution de fréquence et par régression linéaire des mesures de la capsule céphalique. Les trois méthodes ont mis en évidence un polymorphisme embryologique. Les larves ont été groupées selon le nombre d’instars. La majorité (77%) en avaient quatre, le restent cinq. La mortalité des larves, apparemment à cause de blessures infligées lors des mensurations de la capsule céphalique, était élevée, mais les résultats ont été basés sur les données provenant de 259 insectes qui ont atteint le stade prépupal (= pharate). L’observation directe des mues larvaires s’est révélée la seule méthode exacte d’identification de l’instar mais l’analyse de la largeur de la capsule céphalique décrivait bien le nombre d’instars présents dans une population en plus de fournir des estimées de ce caractère pour chaque stade larvaire. Une clé morphologique distinguant quatre instars est proposée comme solution pratique d’identification de l’instar dans les études sur le terrain.

Type
Articles
Information
The Canadian Entomologist , Volume 119 , Issue 10 , October 1987 , pp. 859 - 865
Copyright
Copyright © Entomological Society of Canada 1987

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Batra, S.W.T. 1966. The life cycle and behaviour of the primitively social bee Lasioglossum zephyrum (Halictidae). Univ. Kans. Sci. Bull. 66(10): 359–423.Google Scholar
Cymborowski, B., Bogus, M., Beckage, N.E., Williams, C.M., and Riddiford, L.M.. 1982. Juvenile hormone titres and metabolism during starvation-induced supernumerary larval moulting of the tobacco hornworm, Manduca sexta L. J. Insect Physiol. 28: 129–135.CrossRefGoogle Scholar
Daly, H.V. 1985. Insect morphometrics. Annu. Rev. Ent. 30: 415–438.CrossRefGoogle Scholar
Dyar, H.G. 1890. The number of molts of lepidopterous larvae. Psyche 5: 420–422.CrossRefGoogle Scholar
Eves, J.D., and Johansen, C.A.. 1974. Population dynamics of larvae of alfalfa leafcutting bee, Megachile rotundata, in eastern Washington. Wash. Agric. Exp. Sta. Tech. Bull. 78. 13 pp.Google Scholar
Eves, J.D., Mayer, D.F., and Johansen, C.A.. 1980. Parasites, predators, and nest destroyers of the alfalfa leaf-cutting bee, Megachile rotundata. Coop. Ext. Serv., Wash. State Univ. WREP 32. 15 pp.Google Scholar
Fox, R.C., Anderson, N.H., Garner, S.C., and Walker, A.I.. 1972. Larvae head-capsules of the Nantucket pine tip moth. Ann. ent. Soc. Am. 65: 513–514.CrossRefGoogle Scholar
Gaines, J.C., and Campbell, F.L.. 1935. Dyar's rule as related to the number of instars of the corn ear worm, Heliothis obsoleta (Fab.), collected in the field. Ann. ent. Soc. Am. 28: 445–461.CrossRefGoogle Scholar
Gerber, H.S., and Klostermeyer, E.C.. 1972. Factors affecting the sex ratio and nesting behaviour of the alfalfa leafcutter bee. Wash. Agric. Exp. Sta. Tech. Bull. 73. 11 pp.Google Scholar
Hackwell, G. A., and Stephen, W.P.. 1966. Eclosion and duration of larval development in the alkali bee, Nomia melanderi Cockerell (Hymenoptera: Apoidea). Pan-Pacif. Ent. 42: 196–200.Google Scholar
Hansen, J.D., Owens, R.C., and Huddleston, E.W.. 1981. Relation of head-capsule width to instar development in larvae of the range caterpillar, Hemileuca oliviae Cockerell (Lepidoptera: Saturniidae). J. Kans. ent. Soc. 54: 1–7.Google Scholar
Hoxie, R.P., and Wellso, S.G.. 1974. Cereal leaf beetle instars and sex, defined by larval head-capsule widths. Ann. ent. Soc. Am. 67: 183–186.CrossRefGoogle Scholar
Hill, B.D., Richards, K.W., and Schaalje, G.B.. 1984. Use of dichlorvos resin strips to reduce parasitism of alfalfa leafcutter bee (Hymenoptera: Megachilidae) cocoons during incubation. J. econ. Ent. 77: 1307–1312.CrossRefGoogle Scholar
Klostermeyer, E.C. 1982. Biology of the alfalfa leafcutting bee. Proc. 1st Intern. Symp. Alfalfa Leafcutting Bee Management. Univ. Sask., Saskatoon, Sask. pp. 10–19.Google Scholar
Michener, C.D. 1974. The social behaviour of the bees. Harvard Univ. Press, Cambridge. 404 pp.Google Scholar
Richards, K.W. 1983. Impact of damage by the driedfruit moth, Vitula edmandsae serratilineela (Lepidoptera: Pyralidae), a pest of the alfalfa leafcutter bee, Megachile rotundata (Hymenoptera: Megachilidae). Can. Ent. 115: 1549–1553.CrossRefGoogle Scholar
Richards, K.W. 1984. Alfalfa leafcutter bee management in western Canada. Agric. Can. Publ. 1495 (revised). 56 pp.Google Scholar
Richards, K.W. 1985. Detection of chalkbrood fungus, Ascosphaera aggregata, in larvae of the alfalfa leafcutter bee (Hymenoptera: Megachilidae) from western Canada. Can. Ent. 117: 1143–1145.CrossRefGoogle Scholar
Richards, K. W., Whitfield, G.H., and Schaalje, G.B.. 1987. Effects of temperature and duration of winter storage on survival and period of emergence for the alfalfa leafcutter bee (Hymenoptera: Megachilidae). J. Kans. ent. Soc. 60: 70–76.Google Scholar
Schmidt, F.H., Campbell, R.K., and Trotter, S.J.. 1977. Errors in determining instar numbers through head-capsule measurements of a Lepidopteran — a laboratory study and critique. Ann. ent. Soc. Am. 70: 750–756.CrossRefGoogle Scholar
Sokal, R.R., and Rohlf, F.J.. 1969. Biometry. W.G. Freeman and Co., San Francisco. 776 pp.Google Scholar
Stephen, W.P., Vandenberg, J.D., and Fichter, B.L.. 1981. Etiology and epizootiology of chalkbrood in the alfalfa leafcutting bee, Megachile rotundata, with notes on Ascosphaera species. Oregon State Univ. Agric. Exp. Sta. Bull. 653. 10 pp.Google Scholar
Tirgari, S. 1963. The biology and management of the alfalfa leafcutter bee Megachile rotundata. Unpub. M.S. thesis, Utah State Univ., Logan, Utah.Google Scholar
Undurraga, J.M. 1978. Effect of temperature and other abiotic and biotic factors on development and survival of the immature stages of the alfalfa leafcutting bee, Megachile pacifica (Panzer) (= rotundata (F.)) (Hymenoptera: Megachilidae). Unpubl. Ph.D. thesis, Oregon State Univ., Corvallis, Oregon.Google Scholar
Vandenberg, J.D., and Stephen, W.P.. 1982. Etiology and symptomatology of chalkbrood in the alfalfa leafcutting bee, Megachile rotundata. J. Insect Pathol. 39: 133–137.CrossRefGoogle Scholar
Vanderwerker, G.K., and Kulman, H.M.. 1974. Stadium and sex determination of yellowheaded spruce sawfly larvae, Pikonema alaskensis. Ann. ent. Soc. Am. 67: 29–31.CrossRefGoogle Scholar
Whitfield, G.H., and Richards, K.W.. 1985. Influence of temperature on survival and rate of development of Pteromalus venustus (Hymenoptera: Pteromalidae), a parasite of the alfalfa leafcutter bee (Hymenoptera: Megachilidae). Can. Ent. 117: 811–818.CrossRefGoogle Scholar
Whitfield, G.H., and Richards, K.W.. 1987. Postdiapause development and adult emergence of Pteromalus venustus Walker (Hymenoptera: Pteromalidae) during alfalfa leafcutter bee incubation. Can. Ent. 119: 491–493.CrossRefGoogle Scholar