Table Of ContentHYM. RES.
J.
Vol. 9(2), 2000, pp. 370-376
Load-lifting Constraints on Provisioning and Nest Building in the
Carpenter Wasp, Monobia quadridens L.
(Hymenoptera: Eumenidae)
Paula K. Edgar and Joseph R. Coelho
(PKE) Department of Instructional Services, John Wood Community College, 150 South 48th
Street, Quincy, Illinois 62301, USA; (JRC) Department of Biology, Culver-Stockton College, One
College Hill, Canton, Missouri 63435, USA
—
Abstract. The foraging and mud-carrying capacity ofthe trap-nesting carpenterwasp,Monobia
quadridens L., was examined in relation to load-lifting ability. The body mass of caterpillar prey
collected increased over the course of the season. Consequently, the ability of the wasps to carry
prey became compromised late in the season. Caterpillar mass was not correlated with wasp size,
but the mass of mudballs used in nest construction was related to wasp size. Wasp foragingmay
be constrained by the size of pyralid caterpillars available at any particular time, which changes
becauseofcaterpillargrowth. Mudballsareconstructedbythewaspsthemselves;therefore,wasps
maybe able to optimize mudball size in accordance with their ownsize, but mudballsweremuch
lighter than caterpillars and never approached the upper limit ofthe wasps' ability to carry them.
Optimal foraging theory suggeststhatan Drury (Coelho 1997), and Sphex ichneu-
animal will experience increased fitness as moneus L. (Coelho and LaDage 1999). In
it becomes more efficient at obtaining food the present study we investigate load car-
or energy. One obstacle encountered by riage during provisioning and mud-car-
flying insects that carry food loads is the rying in Monobia quadridens L. (Hymenop-
need to generate sufficient lift force to re- tera: Eumenidae), an aerial nester.
main airborne. Prey selection may be lim- Aerial nesting may apply additional
ited by the size of the prey the insect can constraints to load carriage. Two ground
successfully carry while in flight. Marden nesting species, the cicada killer (Sphecius
(1987) demonstrated thatmaximum still-air speciosus) and the great golden digger
lift force in flying animals depends primar- wasp (Sphex ichneumoneus) are able to car-
ily on flight muscle mass (MhJ. A fixed ry heavier loads than are theoretically pos-
minimum ratio of flight muscle mass to to- sible, primarily by climbing vegetation,
tal mass lifted, the marginal flight muscle then flying toward their burrows (Coelho
ratio, is required for successful takeoff. An- 1997, Coelho and LaDage 1999). Although
imals with higher flight muscle ratios presumably using maximum power, such
(FMR) have greater maneuverability, and overloaded wasps can only descend. Ae-
should bebetter able to lift and carryloads, rial nesters lack this option, as the final
seize prey, avoid predators and vie for ter- flight to the nest requires a vertical take-
ritories and mates (Marden 1987). off and ascent to the nest entrance. M.
Recent studies examining the relation- quadridens may not attempt to carry near-
ship between maximum lift force and ac- maximal loads if the load compromises
tual load carriage in foraging and provi- flight maneuverability and nest entry.
sioning wasps have used ground-nesting The carpenter wasp, M. quadridens, read-
species, including Vespula spp. (Coelho ily nests in old borings of carpenter bees,
and Hoagland 1995), Sphecius speciosus Xylocopa spp. (Tandy 1908, Rau 1935), and
Volume 9, Number 2, 2000 371
is the largest vespoid wasp to use wood and mudballs that are near the maximum
trap-nests (Krombein 1967). A mature fe- load-lifting capacity without exceeding it
male removes debris inside the nest cavity in order to save time and energy by re-
and collects mudballs by moistening soil ducing the number of trips. In other
with water stored in the wasp's crop words, a female carrying prey or mudballs
(Spradbery 1973) or with saliva (Evans and should have a FMR slightly above the
Eberhard 1970). Mudballs are used to con- marginal FMR for Hymenoptera, 0.179
struct the nest's interior plug, cellular par- (Marden 1987).
titions and exterior plug. Prior to mass pro- MATERIALS AND METHODS
visioning with paralyzed caterpillar prey, a
female deposits an egg near the inner end Field research was conducted fromJune
of the cell (Krombein 1967, Spradbery through September 1996, 1997 and 1998 at
1973). A partition is constructed between Alice L. Kibbe Life Science Station, Han-
A
cells. vacant space, the vestibular cell, is cock County, Illinois. Observations and
made near the nest's opening and sealed data collection were limited to sunny days
with a thick exterior plug. Monobia quadri- because M. quadridens was not very active
dens takes four to seven days to provision on overcast or rainy days.
a nest (Krombein 1967). M. quadridens females were nesting in
The larva emerges 5 to 8 days after the abandoned carpenter bee holes in the
egg is laid, feeds on the paralyzed cater- wooden support beams beneath the upper
pillars, applies a varnish to the cell's in- level porch on the east side of the Frank
terior and pupates. The elapsed time be- House, a wooden frame building housing
tween pupation and adult emergence av- the field station's education center. To
erages 17 days for males and 18 days for provide additional nesting sites for M.
females (Krombein 1967). Teneral adults quadridens, artificial trap-nests were con-
remain inside their cells for 2 to 3 days structed according to Krombein (1967). A
while their integument and wings sclero- 12.7-mm diameter hole was drilled along
tize, then chew through the cell partition the central longitudinal axis of straight-
mm mm
to escape from the nest (Krombein 1967, grain pine boards (38.1 X 38.1 x
Cowan 1991). 200 mm) to a depth of approximately 152
Monobia quadridens often provisions its mm. 12.7 mm dia holes adequately accom-
nest with a single species of Lepidoptera; modate M. quadridens females' large size
with pyralid caterpillars the most fre- (Krombein 1967). Metal brackets held the
quent. Stenomid and tortricid caterpillars traps in place on the faces of the support
were also used to provision nests (Krom- beams at two meters.
bein 1967). FemaleM. quadridens collecting Initially, female wasps without prey
long caterpillars, 10-18 mm, used fewer were captured with an insect net and co-
caterpillars per cell than those using prey axed individually into a 1.5 ml microcen-
mm
that were only 6-13 in length (Krom- trifuge tube (ventilated by puncturing a
bein 1967). Theoretically, wasps carrying hole in the lid) and placed in the refrig-
larger loads make fewer trips, thus con- erator for 30 minutes. Wasps were marked
serving time and energy (Reavey 1993). on the dorsal side of the thorax with one
The demands of temporal and energetic or two small dots of enamel hobby paint.
efficiency therefore interact with the con- Special care was taken to avoid getting
straints of load-lifting. paint on antennae, wings or spiracles.
This study examines how load-lifting Body mass (Mb) for each wasp was deter-
limitations influence the provisioning and mined to the nearest 0.001 g on an OhausK
mud-carrying strategies of M. quadridens. electronic balance. The wasp was then
A
female wasp should carry caterpillars placed outdoors near the nesting site and
372 Journal of Hymenoptera Research
allowed to recover fully and fly away. In- 0.35
dividuals recaptured over the course of ~ 0.3
M
several days had h measured for each of <u/)) 0.25
ns
those days. E 0.2
Subsequent captures of marked females !CLo.15
were made whenever they returned with £ 0.1+
°nj
a caterpillar or mudball. Wasp and cater- 0.05
pillar were collected and placed into a
ventilated tube and unventilated tube, re- 180 200 220 240 260
spectively. The caterpillar's body mass Julianday
(Mprey) was determined to thenearest0.001 Fig. 1. The effect of time of year on body mass of
g. Wasps returning with mudballs were caterpillars carried by Monobia quadridens.
also captured. Wasp and mudball were
collected and placed into a ventilated tube used to determine all descriptive statistics
and unventilated tube, respectively. Gen- for each of these categories to avoid pseu-
tle handling of the mudballs was em- doreplication (Zar 1996). Statistical analy-
ployed to prevent them from crumbling. ses were performed using Systat' 6.0 for
The mudball's mass (Mmud) was deter- Windows (SPSS Inc., Chicago, IL), Corel
mined to the nearest 0.001 g. In both sit- Quattro Pro' 6.02 for Windows (Corel
uations, marked wasps were chilled, re- Corp. Ltd.), and StatMost" (Datamost
weighed, and released as previously de- Corp.)
scribed. Multiple caterpillars and/ormud- RESULTS
balls were often collected from a single
individual. After a wasp arrived with its Data were collected on a total of 54 fe-
third (at most) caterpillar it was placed in male M. quadridens: 10 from 1996, 24 from
an airtight tube and frozen. The number 1997 and 20 from 1998. Thirteen wasps re-
of mudballs collected before the wasp was turned more than once with loads prior to
taken was highly variable. For two indi- being sacrificed, thus sample sizes differ
viduals, both caterpillar and mudball data for prey, mudballs and total wasps. All
were obtained. Female wasps were frozen prey carried by M. quadridens were in the
and transported to the laboratory for ad- family Pyralidae. M M
ditional measurements. An Ohaus analyt- Regression analysis of prey on b for
iuwcsaaselpdb.atTlohanedceheteaeadrc,mcuiarnbaetdeoMmtebon,f±orle0g.es0a0ac0hn1dfgweimwnaaglsse aMwlalpsrewv0a.os2np1s8M4wt±ha(s0P.0n>0o59t0,.0sn5i)g.=nifT5i4hc.eanTtah,veenrsoamrgalelweMasstb
were cut away and thorax mass (Mlh) was wasp (0.09 g) was observed hauling two
measured. Because flight muscle compos- caterpillars simultaneously with a total
es 95% of thorax mass in Hymenoptera prey mass of0.104 g. This load was almost
(Marden 1987), flight muscle ratio was cal- identical to the average load carried by a
culated as 0.95Mth/Mb. Operational (load- female nearly three times the size of the
ed) flight muscle ratio (FMR,,) was deter- smallest wasp.
mined as 0.95Mth/(Mb + mass of load car- Caterpillar body mass increased over
ried). Voucher specimens were deposited the course of the season and was linearly
in the Entomology Museum of Western Il- related to Julian day (M = -0.299 +
linois University. 0.0019day, n = 74, R2 = 0p.r3e1y6, F = 33.3, p
Average Mb and unloaded FMR were < 0.0001) (Figure 1). Late-seasMon caterpil-
calculated for individual wasps that car- lars were nearly double the b of those
ried multiple caterpillars and/or mud- taken during June and July.
balls. The individual averages were then Increasing caterpillar size affected the
Volume 9, Number 2, 2000 373
U.4
20
cc 0.35 18
-o 0.3
-C>2O.0.25 £ -3. 5 12 MaFrgMiRnal
*
0.2+ E 8
-marginal I 6
0.15
4
180 200 220 240 260
Julianday 2 HH.
Ll-Dil
Fig. 2. The effect of time of year on operational 0.14 0.18 0.22 0.26 0.3 0.34 38 42
(prey-loaded) flight muscle ratio in wasps carrying Prey-loaded FMR
cmautemrpifllliagrhst.mTuhseclmearragtiinoarleqlueivreeldifnodricsautcecsesstfhuelmtiankie-- Friagt.io3s.amTohnegdiwsatrsipbsuticoanrroyfinogpecraatteiropnialllarfsl.ighTthemumsacrl-e
off. ginal level indicates the minimum flight muscle ratio
required for successful take-off.
prey loaded FMR„ (0.2633 ± 0.0054, n =
c71o)u,rwsehicohf dtehcereasseeadsosnign(iFfMiRca,n,tly=ov0e.r54t4h-e l=oa2d7e)dwwaisthwemluldbaablolvse,t(h0e.3m0a9r9gi±na0l.00F3M3R,.n
0.0131day, n = 71, R2 = 0.267, F = 25.1, p DISCUSSION
<
0.0001) (Figure 2). Late in the season,
the increase in prey mass caused the load- Wasp body mass and thorax mass did
ed FMRs to fall below the marginal FMR not affect the size of prey provisioned. If
for Hymenoptera. females were actively selecting prey by
In four of 71 (5.6%) foraging events, the size, they should take the largest caterpil-
wasp had an average loaded FMR below lars they can lift. Thus, larger wasps
the marginal FMR (Figure 3). Each ofthese would be choosing larger prey, as occurs
individuals carried large caterpillars in S. ichneumoneus (Coelho and LaDage
wMweaisgh2i3n3g%angraeavteNeroragtehaofn0t.h2e52ovg.erTahlilsmmeaasns w(19oG9uw9ly)dnnasenpdenaPdnadlliensoDsdoetdsismoleanevfiov1re9an8gt3ir)in.sg FCaernmedaslseeonsn-
enprewva(s0p.10a8pgp)r.oacheeadrltyh-eseamsaorng,inparley-FlMadR- ergy would be conserved. However, ob-
for Hymenoptera. servations of M. quadridens did not sup-
As wasp size increased, the size ofmud- port this hypothesis.
balls (mean = 0.0513 ± 0.0032 used As the season progressed, caterpillar
g)
during nest construction increased. Signif-
icant relationships demonstrated the effect 0.1
M
ofwasp mass on mudball mass: versus
MR2mu=Ad 0(.M27m0u,d F= =0.01035.13, +p 0=.109.40300M8b), bn(F=igMu3r8e, _la>o0.0068
4). M weaker, but significant effect of lh E
on mud was also present (Mmiu) = -0.0054 I 04
+ 0.6072M,,,, n = 27, R2 = 0.205, F = 6.44, 5T3
= 0.02
p 0.018).
The average mudball mass was 50% less
than and significantly different from (t = 14 0.16 18 2 0.22 0.24 0.26 0.28 0.3 32
7.36, df = 99, p < 0.0001, t-test) the aver- Waspbodymass(g)
aCognesperqeuyenmtalsys, (t0h.e10m8e1agn±F0M.R006f9o,rnfe=ma7l4e)s. Fmiugd.ba4.llsThcaerreifefdecbtvofMownaobsipabqouaddvridmeanss.s on mass of
374 Journal of Hymenoptera Research
size increased, consequently decreasing time and energy resulting from failed for-
the FMRo of foraging wasps. Early in the aging attempts on large caterpillars sug-
season, females exhibited no difficulty in gests that either small caterpillars were in
carrying prey. Prey mass was never large short supply, or that success was frequent
enough to substantially decrease the enough to outweigh failure. Indeed, onoc-
FMR,,; therefore, loaded females remained casion females successfully brought in
well above the marginal FMR for Hyme- prey larger than themselves. In one case,
noptera. In August, however, provision- a female was loaded with a caterpillar 1.5
ing females encountered load-lifting con- times greater than her own body mass,
straints because of the increasingly large Similar effects of changing prey size be-
caterpillars. As a result, the FMR ofloaded cause ofprey growth are known from oth-
individuals dropped near or slightly be- er species. Seasonal variation in caterpillar
low the marginal FMR. size also dramatically affects the provi-
Considering the prey cues available to sioning style of the solitary digger wasp
predatory wasps and their acute visual Ammophila sabulosa L. (Field 1992). Large
abilities, it is doubtful thatearly in the sea- prey are taken more frequently during the
son M. quadridens females would be inca- second part of the nesting period (entire
pable of finding larger caterpillars if such nesting period runs from late June
prey were present (Stamp and Wilkens through early September) and are carried
1993). It is more likely that females pro- on foot. Early in the season, when smaller
visioned smaller prey at this time because prey are more common, provisioning
they were the most readily available, ifnot wasps require a greater number of small
the only suitable prey available. prey, which they carry in flight. Further-
In early summer, females, regardless of more, smaller wasps multiply-provision
individual size, primarily foraged on their nests (using smaller prey) more fre-
small-bodied caterpillars. Caterpillars pre- quently than larger wasps (Field 1992).
sumably grew as the summer progressed, Brockman and Grafen (1992) describe
and late in the season M. quadridens fe- the effect of the growth of spiders on their
males were not always successful in their predator, the mud-dauber, Trypoxylon pol-
attempts to carry the larger caterpillars. Hum Say. At the start of the season, wasps
On one occasion a female made no at- forage on a genus of spiders (Eustala) that
tempt to recover a large caterpillar after overwinter as adults. The majority of the
dropping it. Another low-flying wasp fell season, wasps provision with the genus
to the ground without dropping the prey Neoscona, which overwinter as spiderlings.
item, crawled 30 cm up a beam then flew As spider size gradually increases, wasps
183 cm (horizontal flight) and landed on a late in the season experience difficulty
chair. Again, she tumbled to the ground hauling the larger spiders, frequently
and dragged the caterpillar 147 cm dropping them. Additionally, wasps ex-
through the grass prior to abandoning it. pend more energy and risk being attacked
These two late season caterpillars had an by large adult spiders. Landes et al. (1987)
average mass of 0.256 g, which was twice found that "wasps collected spiders in
the size of the largest early season cater- numbers relative to their seasonal and rel-
pillar. As a result, individual FMR,, fell to ative abundance, accessibility as prey, or
between 0.239 and 0.165, and caterpillars size suitability."
were dropped. In addition to carrying caterpillar prey,
Typically, predators choose prey that female M. quadridens also carried mud-
are large enough to make it worth their balls used in nest construction. Wasp
time and energy, yet small enough to be body mass significantly influenced the
easily carried (Reavey 1993). The loss of mass of mudballs carried. This effect sug-
Volume 9, Number 2, 2000 375
gests that females constructed mudballs of when prey are carried. Only 5.6% of pro-
a size proportional to their individual visioning events caused M. quadridens to
body size. These findings are consistent have an FMR,,below marginal. In contrast,
with Archer's (1977) study of Paravespula Sphecius speciosus and Sphex ichneumoneus
vulgaris (L.), in which forager body size provision at levels below marginal FMR„
was significantly correlated to the earthen 90% (Coelho 1997) and 25% (Coelho and
load carried by wasps leaving the nest. LaDage 1999) of the time, respectively.
In contrast to several of the prey-loaded Therefore, M. quadridens is on average
FMRs that dropped below the marginal more maneuverable when provisioning
FMR, females never carried mudballs than the ground nesters. Aerial nesting
large enough to substantially decrease may, in fact, carry maneuverability restric-
their FM^. The FMRmud values were far tions as predicted.
greater than the marginal FMR. M. quad- ACKNOWLEDGMENTS
ridens may not optimize energy costs of
mudball production and carriage because Appreciation is given to Richard V. Anderson and
of the style used to carry mudballs. Wasps Gregg Dieringer fortheirsupportand insightful sug-
may be restricted to making small, round gestions. Gratitude is extended to RobertW. Longair
rmiueddbailnltsheciormmpaancdtibelneosu.gThhteobdeifefaesrielnycecairn- faodrviicdee.ntSihfayriongnMBorniongbeira,qQuuadorcidGeinsanagndanfdorBhriisanheKlrpafusl-
kiewicz provided additional assistance in the field.
carriage style between prey and mud per- Matthew McClure helped identify the caterpillars.
haps best explains why female M. quadri- Andy Edgar constructed the trap nests.
dens could haul heavier prey loads than
LITERATURE CITED
mudballs. Caterpillars were grasped with
all legs and held lengthwise against the fe- Archer, M. E. 1977. The weights of forager loads of
male's underside without altering the cen- Paravespula vulgaris (Linn.) (Hymenoptera: Ves-
ter of gravity (Evans 1962). In contrast, pidae)and the relationshipofload weight tofor-
mudballs carried with the mandibles and ager size. Insectes Sociaux 24: 95-102.
forelegs placed additional weight toward Broclkimfeanh,istHo.ry].paanttderAn.sGorfafaesno.li1t9a9r2y.wSaesxp,raTtrioyspoaxny-d
the head, altering balance. To compensate, lon (Trypargilum) politum (Hvmenoptera: Spheci-
individuals may have been restricted to dae). Behavioral Ecologyand Sociobiology 30: 7-27.
hauling mudballs that were much lighter Coelho, J. R. 1991. The effect of thorax temperature
thaOnnthe prey. M. unloaded hononefyorbceee p(rAopdisuctmeilolnifedrau)ridnrgonetse,thewroerdkefrlsi,ghtanidn
FMR average, quadridens' queens. Physiological Zoology 64: 823-835.
(0.385), although higher than the Coelho, J. R. 1997. Sexual dimorphism and flight be-
mean for Hymenoptera (0.34 ± 0.013, n = havior in cicada killers, Sphecius speciosus. Oikos
15; data from Marden 1987, Coelho 1991, 79: 371-375.
1997, Coelho & Hoagland 1995, Coelho Coelho, J. R. and J. Hoagland. 1995. Load-lifting ca-
and LaDage 1999), is similar to that ofoth- ppualcai)tiefsoroafgitnhgreoenspheocnieevs-boefeyeclolropws-ejs.ackFeutnscti(\oneasl
er vespoids such as Vespula (Coelho and Ecology9: 171-174.
Hoagland 1995). M. quadridens' FMR was Coelho,J.R.and L.D. LaDage. 1999. Foragingcapacity
considerably lower than that of the of the great golden digger wasp, Sphex ichneu-
moneus L. Ecological Entomology 24: 4S0-4S3.
g(0r.o4u1n6,d-Cnoeeslthinog1s9p9h7e)ciadnsdSpShpehceixusiscphenceiuomsou-s Cowadna,e.D.pp.P.3139-9713..TIhne: sKo.liGt.aryRoasnsdapnrdesRo.daV]V.veMsapti--
neus (0.462, Coelho and LaDage 1999). M. thews (eds), The Social Biology <' Wasps. Corn-
quadridens is therefore less maneuverable stock Publishing Associates, Ithaca, 673 pp.
than the ground nesters when unladen. Evans, H. E. 1962. The evolution ol prey-carrying
Hriodweensvesrh,oulthdebmeamsastcalhleodcattoiotnheofmaM.xiqmuaudm- EvansmU,neicHvh.earEns.iitasynmdsofMin.MwJi.acEshbpiegsrahna/rvdPor.leus1tsi9,o7n0.A1nT6:hne46AW8rasbp4os8r.3T2h6e5
demands of load carriage, which occur PP
376 Journal of Hymenoptera Research
Field, J. 1992. Patterns of provisioning and parental ey (eds), Caterpillars: Ecological and Evolutionary
investment in the solitary digger wasp Ammo- Constraints on Foraging. Chapman and Hill, New
phila sabulosa. Ecological Entomology 17: 43-51. York, 587 pp.
Gwynne, D. T. and G. N. Dodson. 1983. Nonrandom Rau, P. 1935. The courtship and mating of the wasp,
provisioning by the digger wasp, Palmodes laevi- Monobia quadridens (Hymen.:Vespidae). Entomo-
ventris (Hymenoptera: Sphecidae). Annals ofthe logical News 16: 57-58.
Entomological Society ofAmerica 76: 434^436. Spradbery, J. P. 1973. Wasps: an Account ofthe Biology
Krombein, K. V. 1967. Trap-Nesting Wasps and Bees: and Natural History of Solitary and Social Wasps.
Life Histories, Nests, and Associates. Smithsonian University ofWashington Press, Seattle, 408 pp.
Press, Washington, D.C., 570 pp. Stamp, N. E. and R. T. Wilkens. 1993. On the cryptic
Landes, D.A., M.S.Obin, A.B.Cady,andJ. H.Hunt. sideoflife:being unapparenttoenemiesand the
1987. Seasonal and latitudinalvariationinspider consequences for foraging and growth of cater-
prey of the mud dauber Chalybion californiatm pillars, pp. 283-330. In: N. E. Stamp and T. M.
(Hymenoptera:Spechidae).JournalofArachnology Casey (eds), Caterpillars: Ecological and Evolution-
15: 249-256. ary Constraints on Foraging. Chapman and Hill,
Marden, ]. H. 1987. Maximum lift productionduring New York, 587 pp.
takeoff in flying animals. Journal ofExperimental Tandy, M. 1908. The carpenter mud wasp (Mo)iobia
Biology 130: 235-358. quadridens). Entomological News 19: 231-232.
Reavey, D. 1993. Why body size matters to caterpil- Zar, J. 1996. Biostatistical A>ialysis. Prentice-Hall, New
lars, pp. 248-279. In: N. E. Stamp andT. M. Cas- Jersey, 620 p.
