Table Of ContentVolume59, Number 3 143
JournaloftheLepidopterists'Society
59(3),2005,143-160
EXTRINSIC EFFECTS ON FECUNDITY-MATERNALWEIGHT RELATIONS IN
CAPITAL-BREEDING LEPIDOPTERA
William E. Miller
DepartmentofEntomology,UniversityofMinnesota, St. Paul, Minnesota55108USAemail: [email protected]
Abstract. Capital-breedingLepidopteradependforreproductiononmetabolicresourcesassembledeitherentirelyorprimarily
bydieirlarvae, dieformertermed 'perfect' the latter 'imperfect'. Empiricalevidencesuggeststhatmaternal size detWerminescapi-
tal-breederfecundity.Thefecundity-maternalsizerelationisusuallyformulatedasF =foW+a,whereFisfecundity, isfinalma-
ternalsizein unitssuchasweightofnewlytransformedpupae,bistheslope, anda theintercept. Exhaustivesearchyielded71 fe-
cundity-maternalpupalweightrelationsfor41capitalbreedersin 15families,58ofwhich,including2previouslyunpublished,were
basedonindividualspecimens, and 13ongroupedspecimens. In22individual-specimenrelations,cohorts dividedinto2ormore
subgroupswere rearedsimultaneouslyatdifferenttemperatures, on differentdiets, orexposedtootherextrinsicfactors. These22
'multiform' relations were compared with 36 'uniform' relations, and where possible cohort subgroups were compared. Pupal
weightsofcohortsubgroupswereaffectedmuch oftenerthan underlyingslopes and intercepts. Individual-specimenslopes based
ontransformeddataranged0.52-2.09withameanandstandarderrorof1.13±0.04, andslopes did notdiffersignificantlyamong
perfect,imperfect,multiform,anduniformcategories. Despitetheevidentsimilarity,onerelationdoesnotapplytoallcapitalbreed-
ers.Tradeoffssometimesoccurbetweenfecundity,F,andmeaneggweight, E. Reactionnormsoffecundityandpupalweightacross
extrinsic-factorrangeswereoverwhelminglycongruent,whichsupportsaxiomaticstatusforthedependenceoffecundityoncapital-
breedermaternalsize.Coolerrearingtemperaturesusuallyproducedheavierfemalepupaeandgreaterfecundities,aphenomenon
ofpopulationdynamicsinterest.Thetwosidesofpracticallyall fecundity-maternalweightregressionsarenotstatisticallyindepen-
dent, in effectstatingF = fo(W+ [FXE]) + a,which artificiallyinflatesteststatistics. Wheredesirable,thefullyindependent rela-
tion R =fe(W- [FxE]) +acanbeused,where Risreproductivebulk,the mathematicalproductofFx E.
Additionalkeywords: temperature,dietquality, populationdynamics
'Capital-breeding' describes Lepidopterathatdepend from long empirical observation. Direct fecunditv-size
for reproduction entirely or primarily on metabolic relations occur in the lepidopteran phylogenetic
resources assembled by their larvae, in contrast to sequence at least as early as Tineidae, the basal-most
'income-breeding', which describes those that depend lineage of Ditiysia (Titschack 1922, Kristensen and
for reproduction primarily or entirely on resources Skalski 1999) and are probablvpart ofthe ground plan
assembled by their adults (Boggs 1992, Miller 1996, of Ditiysia, if not all Lepidoptera. This dependence
Tammaru and Haukioja 1996). The gypsy moth, implies that whatever influences maternal size may
Lyinantria dispar (L.) (Lymantriidae), is a capital influence fecundityandits associated qualityattributes,
breeder; the monarch butterfly, Danaus plexippus (L.) and thus population fluctuations. Fecundity can be a
(Nymphalidae), an income breeder. In four butterfly proxyfor net reproductive rate (Carey 1993, Huev and
income breeders in two families, income contributed Berrigan 2001) and has been implicated in capital-
> 80% to fecundity, and capital <20% (Boggs 1997, breeder population fluctuations, as in Bupalus piniaria
Fischer and Fiedler 2001a). Based on sizes of L. (Geometridae) (Klomp 1966), Bucculatiix
superfamilies (Kristensen and Skalski 1999) and the pijiivorella Kuroko (Bucculatricidae) (Fujiie 1980),
extent to which income breeding is phylogenetically Leucopteraspartifoliella (Hiibner) (Lyonetiidae) (Agwu
limited, probably ~90% of extant Lepidoptera are 1974), and in capital-breeding Noctuidae (Spitzeret al.
capital breeders. Most outbreak Lepidoptera also are 1984).
capital breeders (Miller 1996, Tammaru and Haukioja Traditionally, the relation between fecundity, F, and
1996). Capital breeders have an ovigenyindex, OI, of1 maternal weight, W, usually has been defined bvlinear
W
or >> 0, referringtotheproportion oflifetimepotential regression as F = fcW + a, where refers to newly
fecundity that consists of mature eggs at eclosion, transformed pupae or newly eclosed adults, h is die
whereas incomebreeders have an OIof or <<1 (Jervis slope, anda is the interceptorscalingparameter. Honek
and Ferns 2004). Capital breeders with nonfeeding (1993) devised a fecundity-maternalweight relation for
adults and OIs of1 are here termed 'perfect', whereas insects generally, as well as one for Lepidoptera, but he
thosewith OIs of>>0whose adults mayfeed, but do so did not segregate capital breeders forspecial study nor
less than income breeders, are termed 'imperfect'. exhaustively seek examples. Honek noted that weight
Maternal size is widely believed to determine appears on both sides of fecundity-maternal weight
fecundity in capital breeders (Leather 1988, Honek regressions, but that statisticallyindependent measures
1993). This beliefderives notfrom experimentationbut of fecundity and maternal weight are practically
I
144 Journalofthe Lepidopterists' Society
nonexistent. In effect, such relations state that F = i>(W for Philosamia ricini Hutt. (Singh and Prasad 1987),
+ [F x E]) + a, where E is mean egg weight. The which seemed too anomalous. In the 13 grouped-
resulting nonindependence inflates test statistics and specimen relations, most weights and fecundities were
minimizes variation between response and explanatory available in numerical form (Table 2).
variables. The practical usefulness of the traditional Study relations consisted of perfect and imperfect
regressions is not necessarily impaired, but their groups and uniform and multiform subsets. 'Uniform'
statistics should notbe usedwhere strict independence denotes homogeneous conditions of development
between the variables is assumed. As discussed further expected to produce only intrinsic effects, and
on, a fully independent alternative relation emerged 'multiform' denotes heterogeneous conditions expected
from this study. to produce extrinsic as well as intrinsic effects. I
In any capital-breeder reared under homogeneous examined relations for extrinsic effects first by meta-
conditions, intrinsic effects alone will produce a direct analysis (Gates 2002) and second by comparing cohort
relation between fecundity and maternal size. If a subgroup relations provided in sources or obtained by
cohort ofeggs or hatchlings is divided into subgroups, deconstruction.
and each subgroup reared at a different level of an A standardized maternalweight was desirable, and I
extrinsic factor, such as adifferent temperature, oron a chose fresh pupalweight. Bythe pupal stage metabolic
different diet, then extrinsic effects are likely to be resources for ovigenesis are in place. Moreover, pupal
added to the intrinsic ones. Here I examine extrinsic weight has been most often used in describing
effects on fecundity-maternal pupal weight relations fecundity-sizerelations (42of58relationsinTable 1, 12
during rearing of capital breeders. I—focus on effects of 13 in Table 2), and explanatory variables based on
produced by different temperatures as might occur weight outnumber those based on lineal dimensions
during anomalous weather, or betw—een microhabitats, such as forewing length and pupal diameter. I
or between generations or seasons and by differing maximized the number of relations for study by
— W
diet quality as might occur on variably stressed or convertingfemale adultfreshweight, tofreshpupal
W W W ,
different kinds of foodplants, or on different kinds or weight, where x 1.85, a factor based on
to p', p a
amounts ofadultnourishment. four observations: (1 first-day female pupae of
Malacosoma disstria (Hbn.) (Lasiocampidae) in a
Materials and Methods
previously unpublished study averaged 1.98 times
I assembled as many statistical fecundity-maternal heavierthan first-dayadults (n = 30weighings, paired);
weight relations as possible from a personal reference (2) a corresponding value of 1.81 for Epiphyas
collection, electronic databases including Biosis, postvittana (Walker) (Tortricidae) (n >130 weighings,
Biological Abstracts, and the Zoological Record, and unpaired) (Danthanarayana 1975); (3) a corresponding
from citations in references. Most relations were based value of 1.74 for Streblote panda (Hbn.) (Calvo and
on observations of specimens individually, a few on Molina2005); and (4) acorrespondingvalue of1.67for
means of grouped specimens. Individual-specimen Cnephasiajactatana (Walker) (Tortricidae) (Ochieng1-
relationswere admitted ifbasedon samples numbering Odero 1990).
>20, grouped-specimen relations if based on groups Fecundity had been estimated in sources byvarious
numbering >5. No relationswere excluded because of methods, all internallyconsistent andall acceptedhere.
non-English text. Methodsincludedcountingunlaideggsin dissectionsof
In the 58 assembled individual-specimen relations, newlyeclosed females, countingonlyeggs actuallylaid,
weights and fecundities were available in numerical and combining eggs laid with residual eggs in ovaries
form for three published and two unpublished ones afterdeath.
(Table 1); weights and fecundities for the remainder For meta-analysis, I transformed fecundities and
were transcribed from enlarged photocopies of pupal weights ofeach relation to percentages oftheir
published scatterplots. Because transcription creates midranges (Honek 1993) ([individual value/midrange
— —
error when one point covers another, forinstance value] x 100, where midrange = 0.5 x [minimum value
tested slopes of transcribed relations against + maximum value]). This transformation enabled
correspondingslopesgiveninsources. Afewdepartures comparisonofrelations fordifferentspecies andgroups
were statisticallysignificant, butmostwere not (F-tests, on a single scale, as between large saturniids and small
P = 0.99-0.009; median P = 0.76; n = 35). IfP was < tortricids.
0.25, I retranscribed, but in no case did retranscription StatisticsweregeneratedbySYSTAT(1992) software.
changetheoutcome appreciably. I acceptedscatterplots Student's t used pooled variances except where noted
at face value despite minor inconsistencies, except that otherwise. Inanalyzingandcomparingcohortsubgroup
Volume 59, Number 3 145
relations, I usednontransformedtranscribeddatawhen Slopes offecundity-maternal pupal weight relations
tabulated datawere unavailable. In tests ofdifferences varied from 0.52-2.09 (Table 1, Fig. 3), with the mean
amongfecundity-maternal weight regressions ofcohort and standard error, SE, 1.13±0.04. This overall mean
subgroups, I includedacategoricalexplanatoryvariable, significantlyexceeds 1.00 (Student'st [one-tailedtest] =
as well as a maternal weight x group interaction term, 3.02; df= 57;P = 0.02). Slopesforperfectandimperfect
thelatterenablingtestsofdifferences amongslopes and groups average 1.14 and 1.12; those for uniform and
the former enabling tests ofdifferences among heights multiform subsets also 1.14 and 1.12. The four slopes
ofregression lines. Height testswere used here as tests for perfect-uniform and perfect-multiform, and
of intercept differences. Where subgroup relations imperfect-uniform and imperfect multiform categories
withinmultiform relationswerenotprovidedin sources average 1.13 and 1.15, and 1.14 and 1.09. Differences
and deconstructionwas notpossible, the factis noted. amongthem are not significant (F = 0.08; df = 3, 54; P
Whereverpossible, I reportwhether reaction norms = 0.97). Pooled slopes are likewise unrelated to
offecundity and maternal pupalweight are congruent. midrange pupalweight (Pearson's r = 0.06; df= 56; P =
A reaction norm is the trajectory of response values 0.68) orto range (Pearson's r = 0.04; df= 56; P = 0.77).
across the range ofan extrinsic factor (Schlichting and Although a positive correlation among relations
Pigliucci 1998). Congruencvsignifies that fecundityand between range and number ofobservations either as n
female pupal weight peak at the same value of an or logn could be expected statistically, it did not
extrinsicfactor. Reaction normstorearingtemperatures materialize (Pearson's r = 0.16; df= 56;P = 0.24). Slope
are illustrated in Fig. la, and those to different diets in variabilityas SE /£> amongperfect-uniform andperfect-
t
Fig. 2a. In sourceswhereitwas notpossibletoevaluate multiform categories averaged 9.5 and 8.9, and among
congruency, itis noted as indeterminate. imperfect-uniform and imperfect-multiform, 13.0 and
15.7. The mean for the entire imperfect group, 14.8, is
Results
seeminglyhigherthan that forthe entire perfect group,
The 71 assembled fecundity-maternal pupal weight 9.3, but the difference is not strictly significant
relations represent 41 capital breeders in 15 families (Student's f [separate variances] = 1.85; df= 27.4; P—=
(Tables 1 and 2). The 58 individual-specimen relations 0.07). So-called funnel diagrams—plots ofSE vs. b
fc
(Table 1) consist of35 in perfect and 23 in imperfect visually suggest greater scatter among imperfect than
groups, 36ofthe58uniform and22 multiform. Perfect- perfect groups (Fig. 3a, b).
uniform and perfect-multiform categories number 23 Spatial and temporal effects. Coefficients of
and 12, and imperfect-uniform and imperfect- fecundity-maternal pupalweight relations forthe same
multiform categories eachnumber 13. The 13grouped- species often differ geographically (Table 1), but onlv
insect relations (Table 2) consist of 10 of the perfect diose obtainedinthe samewaybythe sameworkerscan
kind and 3 of the imperfect, with 5 uniform and 8 be meaningfully compared, as in the following
multiform. Individual-specimen relations areunaffected examples. Lorimer (1979) found slopes and intercepts
by aggregation bias and thus receive more attention oftwo uniform relations for Malacosoma disstria from
here than grouped-specimen relations. In all Indiana and Michigan to differ significantly. Parrvet al.
discussions, attributes and their numerical values (2001) found four of the six M. disstria slope
appear in parallel sequences. 'Tradeoffs' refer to any comparisons for Michigan, Manitoba, and Louisiana
change in proportion between fecundity and egg size. between twoyears to differsicrnificantlv. aswell as all of
Eggsize refers tothe meanweight ofone eggin an egg thesixinterceptcomparisons. InM.disstria, however, a
load. tradeoff between fecundity and egg size occurs as a
Individual-specimen relations geographic NW-SE cline (Parr)' et al. 2001). At two
Meta-analysis. Midrange maternal pupal weight, Quebeclocations, slopes of0.26and0.18 forLymantria
which approximates the mean,varied from 12-9435 nig dispar differed significantly (F = 20.5; df= 1, 111: P <
(Table 1), averaging 1401 and 63 mg for perfect and 0.001) (transcribed data) (Madrid and Stewart 1981).
imperfect groups. The difference is highly significant Egg size is notably plastic in L. dispar (Rossiter 1991).
(Student's t [separate variances] = 3.74; df = 34.1; P < Lorimer and Bauer (1983) found that fecunditv-pupal
0.001). Rangeintransformedweightsofpupae (greatest weight slopes for Choristoneura fumiferana differed
% ofmidrange minus smallest % of midrange) varied between New Hampshire and Minnesota; atvpicallv.
from 34—179 (Table 1), averaging 97 and 99 forperfect significant correlation was absent in the latter
and imperfect groups. Corresponding uniform and (transcribed data). Harvey (1983) demonstrated a
multiform ranges are 34-179 and 48-143 (Table 1), geographic NW-SE cline in C. fumiferana egg size, as
averaging97 and 100. well as a clear geographic tradeoffbetween fecunditv
1i ' • »
146 Journalofthe Lepidopterists' Society
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Table2. Regressionsrelatingfecundity, F ,topupalweight, ,incapitalbreedersbasedontransformedvaluesforgroupedspecimens.
No. Species Family No.groups Groupsize Equation Sourceofdan
(Fp=/;Wp+«)
Perfect-uniform
AntheraeamylittaDrury Salurniidae 6 20 0.60 34.9 Badhera 1992
SamiacynthiariciniBoisd.' 6 30 1.98 -96.0 Kotikaletal. 1989
3. Lymantriadispar(L.) Lymantriidae 8 1-83 1.40 -47.8 Lewinsky 1961
4. Dendrolimusspectabilis Lasiocampidae 14 32-244 1.27 -24.0 Kokubo 1973
3
Butler
5- D.pini{L.f 5 2-19 1.35 -33.6 Rudclt 1935
Perfect-multiform
6. AntheraeaassamaWestw. Salurniidae 40 10 1.70 -70.5 Barah&Sengupla
1991
' Lymantriatlispar1' Lymanlriidae 18 1-58 1.12 -144 Lewitt 1934
8. DendrolimuspunctatusWlkr.,
jsioena Lasiocampidae 40 1-40 1.34 -36.9 Tsaietal. 1958
y- D.punctatus,winteringgen. " 1-22 1.24 -25.1
10. Hyphantriacunea(Drury) Arctidae 24 =30 1.35 -34.5 Morris&Fulton
Imperfect-multiform
'' Trichoplusiain(Hbn.)a Noctuidae 12 10 1.21 -16.2 Henneberry&
Kishaba 1966
12 Diatraeasaccharalis(F.)a Crambidae =29-=90 2.06 -104.1 VanDinther&
Goosens 1970
13. HofmannophUa Oecophondac 21 1-27 1.17 -14.0 Woodroffe 1951
pseudospretella(Staint.)
Basedon numericaldatainsource.
Pupal weightestimatedas 1.85Xadultweight.
Volume 59, Number 3 151
and egg size. Temporally, only one of three pairs of In the subsample, both fecundity and female pupal
available Malacosoma disstria slopes differed weight peaked at 25° C (Fig la), making their reaction
—
significantly 0.58and0.72forLouisianabetween 199S norms across the rearing temperatures congruent. A
and 1999 (F = 4.14; df = 1, 95; P = 0.045) (transcribed fecundity-maternal pupal weight relation for each
data) (Parryet al. 2001). temperature was computed (Fig. lb), but neithertheir
Temperature effects. Nine multiform relations slopes nor intercepts differed significantly (slope F =
involved different larval rearing temperatures among 0.80; df= 2, 25; P = 0.46, interceptF = 0.85; df= 2, 25:
cohortsubgroups (Nos. 24, 25,29-31, 34, 35, 53, and58 P = 0.44). Thethree cohortsubgroups are pooledinthe
inTable 1), andeach relation is discussedbelow. summaiyrelation (Fig. lc, Table 1).
Relation 30. This previously unpublished M. disstria Relation 24. Zwolfer (1933) reared Lijmantria
relationis discussedfirstbecause ittypifiestheeffectsof monacha at six arbitrary constant temperatures from
multiform rearing temperatures on fecundity-maternal 11-28° C. Both fecundity and female pupal weight
pupal weight relations. The data derive from peaked at =25°, making their reaction norms across the
overwintered egg rings collected in April from quaking rearing temperatures congruent. Points in the source
aspen, Populus tremuloides Michx. (Salicaceae), near scatterplot were noncoded, which precluded
International Falls, Minnesota. Larvae hatching from deconstruction forfurtheranalysis.
several egg rings were mixed and subdivided into three Relation 2.5. Maksimovic (1958) reared Lijmantria
subgroups. The subgroups were laboratory-reared on dispar at six arbitrary constant temperatures from
source foliage through pupation, one subgroup each at 15.5-31.9° C. Both fecundity and female pupal weight
arbitrary temperatures of 20, 25, 30° C in separate peaked at =15.5°, making their reaction norms
growth chambers fluorescent-illuminated on a 12:12 congruent. I divided these data into two temperature
D:N schedule. Rearing containers were transparent, classes for further analysis, 15.5-24.5° and 27.6-31.9°.
screen-topped 20-liter plastic garment boxes. Foliage Mean female pupalweights were 1533 mgatthe cooler
was renewed every third day and its turgidity temperatures and 1189 at the warmer, and the
maintained by sealing stem bases in water bottles. difference is highly significant (Student's f = 3.6; df =
Pupae were weighedwithin 24 hr after transformation 50; P < 0.001) (tabulateddata). Slopes and intercepts of
and placed singly in 25-ml cream cups for eclosion. A fecundity-maternal weight relations for the two classes
subsample ofnewlyeclosed female adults developingat were 0.41 and -43.4, and 0.46 and -157.8, neidier
each temperature was frozen for egg counting. differenceprovingsignificant (slopeF = 0.20; df= 1,48;
Essentiallv all M. disstria eggs are mature at eclosion P = 0.66, intercept F = 0.72; df = 1, 48; P = 0.40)
(OI = 1). (tabulateddata).
In the whole sample, mean weights offemale pupae Relation 29. Mehmet (1935) reared Malacosoma
reared at 20, 25, and 30° were 326, 461, and 331 mg, neustria at four arbitrary constant temperatures from
and the 461 mg weight at 25° is inferred to be 18.5-31.5"C. The mean femalepupalweight of551 mg
statisticallythehighest(F = 65.6; df= 2, 109; P < 0.001). at 22.7° is inferred to be significantly greater than the
Fig. 1.Fecundity-maternalweightrelationsincohortsofMalacosomadisstriarearedatdifferentconstanttemperatures,a. Reactionnormsof
femalepupalweightandfecunditytorearingtemperatures.Weightsbasedon21-56individuals;fecunditiesbasedon4-14individuals,b.
Scatterplotandregressionsoffecundityvs.femalepupalweightforeachrearingtemperature. Equations:at20°C,F=0.44W-19.5,r2=
0.86;at25°,F=0.54W-81.7,r=0.94;at30°,F=0.56W-57.3,r2=0.90.c. Scatterplotandsummaiyrelationoffecundityvs.femalepupal
weightaftertransformationtopercentagesofpooledmidrangevalues.EquationisF = 1.35W - 18.3,r2=0.81.
%
Pupalweight(mg)- -Fecundity Fecundity(F) Fecundityas of
pooledmidrange(Fp)
- 175
230 150
480 '
Fecundity -|165 200 30
440 •
110 -
155
400
360
70
320
280 125
20 25 30 35 300 400 500 600 50 70 90 110 130 150
Rearingtemperature(C) Pupalweight(mg)(W) Pupalweightas%ofpooledmidrange(Wp)
152 Journalofthe Lepidopterists' Society
Fic.2. Fecundity-materna]weight relationsincohortsofEnnomossubsignariusrearedondifferentfoodplantsin thelaboratory,a.WPupal
weightsandfecunditiesbvfoodplant.b.Scatterplotofprecedingdata,withregressionstatisticsasfollows:pignuthickory, F= 1.14 -67.1,
=0.81;northernredoak,F= 1.11 W-63.8,>-- 0.79;whiteoak, F =O.SSYV-24.9,r2=0.66.c. ScatteqjlotandWsummaryrelationof
fecundityvs.pupalweightaftertransformationtopercentagesofpooledmidrangevalues. EquationisF = 1.31 -34.7,r2=0.92.Data
transcribedfrom Drooz(1965).
Pupalweight(mg) -Fecundity Fecundity(F) Fecundityas%of
pooledmidrange(Fp)
290 - 265
(a)
265
Pupal
240 O weight
Fecundity
215
190
40 " • Pignuthickory
165 D Northernredoak
a Whiteoak
Nroerdthoearkn hPiicgknourty Wohaikte 100Pupa1l50weig2h0t0(nig)25(0W) 300 50 Pu3p0alwe5i0ght7a0s%9o0fpoo1l1e0dm1i3d0ran1g5e0(W1p70)
467,485, and406mgat 1S.5,25.4, and31.5°(F= 11.55; Relation 35. Mizutaet al. (1969) rearedJapanese and
df= 3, 90; P < 0.001) (transcribeddata). Both fecundity Chinese varieties ofBombyx inori, and resulting points
and female pupal weight peaked at 22.7°, making their on theirscatteiptlotoffecundityvs. female pupalweight
reaction norms congruent. Points on the pertinent were coded as spring or summer and assumed to
source scatterplot were not temperature-coded, which represent individual specimens. No rearing
precluded deconstruction. temperatures were given, but temperatures in spring
Relation 31. Calvo and Molina (2005) reared were likely cooler than those in summer. Mean spring
Streblotepanda at fourarbitraryconstant temperatures and summerfemale pupal weights were 1451 and 1133
from 19-28° C on two foodplants. Congruency of mg, and the difference, 318 mg, is highly significant
fecundityand maternalweight to the temperatures and (Student's t = 10.5; df = 144; P < 0.001) (transcribed
foodplants is indeterminate, and the noncoded data). Corresponding fecundity-maternal weight slopes
scatterplotprecludeddeconstruction. and intercepts are 0.30 and 70.8, and 0.45 and -128.3.
Relation 34. Kamata and Igarashi (1995) reared Theslopesdonot strictlydiffer(F = 3.0; df= 1, 142; P =
Quadricalcarifera punctatella at arbitrary constant 0.085), nor do the intercepts (F = 3.79; df= 1, 142; P =
temperatures from 10-25° C. At the lower 0.053). Occurrence of a fecundity-egg size tradeoff
temperatures, mostlarvaehadfourstadia, andathigher couldnotbe ascertained, butgiventhemanyvarietiesof
ones, most had five. The authors also field-collected B. mori involved here and known generally (Hiratsuka
pupae for comparison with the laboratory rearings. 1999),tradeoffswouldnotbesurprising. Congruencyof
Points on their scatterplot offecundityvs. adult female fecundityand maternalweight is indeterminate.
weight were coded as four-stadium, five-stadium, and Relation 5.3. This previously unpublished
field-collected, which permitted deconstruction for Choristoneurafumiferana relationis drawn from atwo-
analysis andcomparisonof cohortsubgroup regressions. part experiment. The first part used the whole sample,
After adult-to-pupal weight conversion, female pupae which focused on the response offemale pupal weight
averaged 390, 520, and 741 mg for the four-stadium to different rearingtemperatures. Thesecondpartused
(cooler), five-stadium (warmer), and field-collected, all a subsample ofthe whole in which fecundityas well as
of which are inferred to differ significantly from one female pupal weight was measured. Certain
another (F = 391.8; df = 2, 74; P < 0.001) (transcribed comparisons in both groups are abbreviated because
data). In the three subgroup fecundity-maternal weight some data were unfortunately lost as detailed further
relations, slopes and intercepts were 0.72 and -108.4, on. Foliage harboring overwintered second instars
0.64 and -74.8, and 0.64 and -48.3. The slopes did not within 3 m of the ground was collected in early May
differ significantly (F = 0.82; df = 2, 71; P = 0.44), nor from Abies balsamea (L.) Mill, and Picea glauca
did the intercepts (F = 0.88; df = 2, 71; P = 0.42) (Moench) Voss (both Pinaceae) near Cloquet, Minn.
(transcribed data). Congruency of fecundity and The second instars were light-extracted (Miller 1958)
maternalweight is indeterminate. and placed at densities of 1 and 3 per cup in 25 ml
