Table Of ContentVolume 61, Number4 213
JournaloftheLepidopterists'Society
61(4),2007,213-221
PARASITISM OF BARRENS BUCK MOTH HEMILEUCA MAIA DRURYIN EARLYAND LATE
SUCCESSIONAL PINE BARRENS HABITATS
JenniferA. Selfridge
MD
MarylandDepartmentofNaturalResources,WildlifeandHeritageProgram,5S0TaylorAvenue,Annapolis, 21401,and
StateUniversityofNewYork-CollegeofEnvironmentalScienceandForestry,Syracuse,NY13210;email:[email protected]
Dylan Parry
StateUniversityofNewYork-CollegeofEnvironmentalScienceandForestry,Syracuse,NYT13210,
George H. Boettner
UniversityofMassachusetts-Amherst,Plant,SoilandInsectSciences,Amherst,MA01003
ABSTRACT.Barrensbuckmoth,Hemileucamaia,ispredominantlyassociatedwithearlysuccessionalpinebarrensdominatedbyscruboak,
Quercusilicifolia. TodetermineifH. maidsassociationwiththeseopenhabitatswithinpinebarrensonCapeCodisduetoreducedratesof
parasitism,wecomparedmortalityoff/, maialarvaeonscruboakinearlysuccessionalright-of-wayhabitatandclimaxpitchpinecommunities.
WeestablishedexperimentalpopulationsofH maiainbothhabitatsandassessedparasitismintwoconsecutiveyears. Contrarytoourhypoth-
esis,parasitismbydieintroducedgeneralisttachinidCompsiluraconcinnatadidnotvaryamonghabitatsineitheryear,nordiditcausesignifi-
cantmortalitytoH. maialarvaeineitheryear. In2002,mortalityfromthenativehymenopteranHijposoterfugitivuswassignificandvreduced
inforestplotsandin2003parasitismbvthenativetachinidLeschenaultiafulvipeswassignificantlyhigherinpowerlineright-of-wayplots. Par-
asitismratesinbodiyearsdidnotappearhighenoughtounderliethedocumenteddifferencesinhabitatselectionbybuckmoth.
Additionalkeywords: Habitatheterogeneity,Compsiluraconcinnata,enemy-freespace,naturalenemies,CapeCod,Quercusilicifolia.
The distribution ofmanyinsect herbivores is at least northeastern United States, a habitat threatened by
partially a function of the threat imposed by natural multiple anthropogenic factors (Tuskes et al. 1996,
enemies, either through direct attacks or by causing Wagneretal. 2003, Barbouretal. 1998). Furthermore,
herbivorestoseekoutnichesthatactas refuges (Schultz the distribution of H. maia within pine barrens is
1983, Jeffries & Lawton 1984, Price 1987, Bernays & concentrated in only a few habitats (Schweitzer 1983,
Graham 1988, Stamp 2001, Williams etal. 2001). Life Tuskesetal. 1996, Nelson2002) despitetheoccurrence
history strategies that avoid peak periods of natural ofitsprimaryhostplant, scruboak, across amuchlarger
enemy abundance are likely to be favored by natural geographicrange. NortheasternpopulationsofH. maia
selection (Schultz 1983, Jeffries and Lawton 1984, appeartobeparticularlyabundantinanthropogenicallv-
Tauberetal. 1986, Lill2001). Theseincludechangesto created, early-successional habitats including road
life history attributes such as development and margins andpowerline rights-of-way(Schweitzer 1991.
phenology,which minimizeexposuretonaturalenemies Nelson 2002, S. Haggerty, pers. com.). The occurrence
(Bernays & Graham 1988, Mira & Bernays 2002), ofH. maiainearlysuccessionalhabitats anditsapparent
chemical defenses (Dennoet al. 1990, Stamp 2001), or absence in later successional forests has not pre\iouslv
utilization of specific positions within a habitat where been explained. One possible factor is die effect of
pressure from natural enemies is reduced (Stamp & natural enemies, which is thought to increase with
Bowers 1988, Stamp & Bowers 1991). Habitat habitat complexity (Langellotto &: Denno 2004). The
structure may also play an important role in providing sparse vegetation and lack of stratification in earlv
enemy-free space for many insects (Ohsaki & Sato successional areas may offer enemv-free or at least
1990). enemy-reducedspace forH. maia.
Barrens buck moth (Hemileuca maia Drury, Numerous parasitoids attack the larvae of H. maia
Satumiidae),isaunivoltine, diurnalspecieswithspecial (Schaffner& Griswold 1934,Amaud 1978, Krombeinet
concern status in the state of Massachusetts (Nelson al. 1979, Piegler 1994, Boettneret al. 2000). Common
2002, NHESP 2007) and is considered to be rare species include Hijposoter fugitirus (Sav)
throughoutmostofnorthern NewEngland (Boettneret (Ichneumonidae) and Meteoms autographae
al. 2000). It appears to be restricted to isolated, (Muesebeck) (Braconidae) and the tachinid
remnant pitch pine (Pinus rigida Mill.) - scrub oak Leschenaultia fulvipes (Bigot) (Schaffner & Griswold
(Quercus ilicifolia Wangenh.) barrens in the 1934, Boettner et al. 2000). The non-native tachinid
214 Journalofthe Lepidopterists' Societi
Compsilura concinnata (Meigen), an important threat parasitism were collected in 2002 in a 1.5 km portion of
to saturniids (Boettneret al. 2000, Kellogget al. 2003) the main 2003 study area. First instar H. maia larvae
also parasitizes H. maia and the congener H. lucina were deployed in the field for 12 days on scrub oaks
(Stamp 1990, Boettneretal. 2000). within three distinct habitats. Each plot consisted of
Although the diversity of parasitoids attacking II. one scrub oak. Three plots were located within closed
maia has been documented, little effort has been made canopy forest (FOBEST), three were located alongthe
to quantify stage-specific mortality, which is forest / power line border (EDGE), and three were
instrumental in understanding population dynamics. within the power line / bike trail buffer (BUFFEB).
When stage-specific mortality has been determined, it The central portion ofthe power line corridorwas not
has focused onlyon early-instars (Boettneret al. 2000). useable, as it had been mowed the previous winter.
Thus, the impact of parasitoids on later instars and Sixty-five first instar larvae were released at each plot.
pupae is unknown. Larvae were monitored and counted on a daily basis,
Our study quantified mortality sources for H. maia and were retrieved after 12 days to prevent dispersal
larvae and pupae in two distinct habitats within pitch losses which increase in late instars. Larvae were
pine - scrub oak barrens on Cape Cod, MA. Besearch retrieved as late second and early third instars, then
focused on three separate but related hypotheses: (1) rearedindoors untilpupation oruntilparasitoids issued.
die spatial distribution of H. maia is influenced by Acontrolpopulationwas rearedentirelyinthelab. The
parasitoids, (2) habitat structure alters die species control group was collected as late first instars andthus
composition of the parasitoid fauna, and (3) habitat asmall proportionwere parasitized. To account forthe
structure influences the level of mortality caused by base level of parasitism within the control group,
parasitoids. Based on these hypotheses, we tested two Henderson-Tilton's formula for unequal populations
predictions: (i) the community ofparasitoids attacking was employedpriorto analysis (Henderson 1955).
H. maia will be richer in late successional (closed- In addition, five naturally occurring larval clusters
canopy forest) habitat as opposed to early successional were collected from the buffer area. Most of these
(open-area) habitat, and (ii) H. maia mortality from aggregations consisted ofthird and fourth instars. All
parasitoidswillbe reducedin early-successionalhabitat. larvae were collected and reared under the same
conditions as experimental larvae.
Materials and Methods
For indoor rearing, groups of 25-30 larvae were
Site description. Our study site was located on the placed in 31 cm x 23 cm x 10 1/2 cm ventilated plastic
peninsula oi Cape Cod in Massachusetts, USA. The boxes and maintained indoors at room temperature.
study area was located within Cape Cod National Larvaewereprovidedwithfresh scruboakfoliageevery
Seashore in Barnstable Count)', and consistedofa9km 2-3days. Florists' aqua-pickswereusedtokeep foliage
area running north-south throughout a portion ofthe fresh. Fifth and sixth instar larvae were transferred to
outerCape. The area included a40 m wide powerline disposable 0.47 L plastic cups (4-6 larvae /cup) with 5
right-of-waybounded bv a mature closed-canopy pitch cm ofpotting soil forpupation, and were fed as above.
pine foresttotheeast, andapavedbiketrailtothewest. Pupae were transferred to a 0.75 m2 wooden frame
Thepowerline right-of-waywas mechanicallycutevery rearing box covered with 2.5 mm wire mesh. The box
3-^4years, perpetuallymaintaininganearlysuccessional was filled with 5 cm of soil and kept at room
habitat. Abuffercorridorofpitchpine, scruboak,black temperature until adult emergence in September and
oak (Quercus velutina Lam.), black cherry (Primus October. Adults matedwithin the box, and redoak (O.
serotina Ehrh.), and beach plum (Prunus maritima rubra L.) branches were placed inside to provide
Marsh) was left intact parallel to the bike trail. The females with oviposition surfaces. Eggs were kept
vegetationwithinthepowerline right-of-waywascutto outdoors in aerated plastic containers throughout the
a height of <10 cm in 2002. By the summer of2003, winter.
scruboak, blackoak, pitchpine, cherryandbeachplum 2003 - In early May, overwintered egg masses were
had re-sprouted from the stumps or roots. Pitch pine moved indoors and kept refrigerated at a temperature
was the dominant tree in the closed canopy forest. of ~3°C until ready for use in field experiments.
Black, scarlet (O. coccinea Muenchh.) and scrub oak Hatching commenced on 31 May, with the majorityof
were also present as canopy and subcanopy trees. the egg masses hatchingby6June, coincidingwith bud
Temperature and light intensity were significantly break and egg hatch in natural populations. All larvae
higher in the power line corridor than in the closed- were hatchedby 14June.
canopyforest (JAS unpublished). Twelveplotswereselectedthroughoutthe9kmstudy
Larval mortality. 2002 - Baseline data on area in locations where naturally-occurring clusters of
Volume 61, Number4 215
H. maia were observed in 2002. The areawas divided developed more quickly during periods of warm, drv
into six 1.5 km sections with two plots in each section. weather. This sequential deploy, collect, and replace
All sections contained one plot along the power line technique (Boettneretal. 2000)was continueduntilthe
corridor and one plot within the closed canopy forest. fifth instar, and was used to quantify mortality of H.
This was done to ensure equal dispersion oftreatments maia throughout each ofits larval stages. To limit the
(Hurlbert 1984). The location of each plot was alreadylarge numberoflarvae requiredforthis method,
randomly selected within the habitat, with two fifth and sixth instars were considered together, and
restrictions: (i) plots were at least 50 m from one were deployed for aperiod of11 days. Retrieved larvae
another, and (ii) forestplotswere atleast40 m from the were reared in the laboratory until adults emerged or
eastern edge of the power line corridor. Each plot parasitoids issued.
consistedofonescruboaktree. Small (< 3 m tall) scrub Late stage H. maia lose their gregariousness and
oaks similar to those chosen by females in natural completetheirdevelopmentassolitarylarvae (Tuskeset
populations were selected (Sferra & Dunwiddie 1990, al. 1996, Nelson 2002). To account for this behavioral
Schweitzer 1991). In instances where an appropriate change, fewerfifth instarlarvaewere deployedon each
tree could not be located at the randomly selected treebutthenumberoftreesdieywere deployedonwas
distance, the nearest tree located due south of that increased. Three trees in each habitat, including the
locationwas chosen. originalplottree,were selectedinevery 1.5km section.
Approximately 50 first instar H. maia larvae were These additionaltreeswere selecteddue northanddue
deployed on eachtree; this numberis at the lowend of south ofeach original plot tree at a minimum distance
aggregations in natural populations but is within the of20 m from the original. Ten larvae were placed on
range ofnaturallyoccurring egg masses (Nelson 2002). each tree. As these trees were in relatively close
To prevent dispersal losses, wandering larvae were proximity to one another, and because die additional
confined to the immediate vicinity of scrub oak trees trees were chosen based on the location ofthe original
with 25 cm high aluminum flashinggroundbarriers (H. plot tree, theywere considered together as one plot in
maia can not ascend aluminum flashing) placed around all analyses.
eachtree outside the drip-line, approximately 1.75 min Pupal mortality. In 2003, we deployed a total of
diameter. Flashingwas countersunk approximately 10 120 H. maia pupae in marked locations in bodi forest
cm into the ground so that larvae could not go and power line habitats. At each ofthe 12 plots, ten
underneath it. Tall vegetation, sticks, leaves, and other pupaewereburiedapproximately5 cmbeneadithesoil,
debriswereclearedfromtheinnerperimetertoprevent approximating natural depths (Nelson 2002). Pupae
larvaefromclimbingonothermaterialstoreachthetop were buried in two rows of five in a north-soudi
of die flashing. When necessary, oak branches were direction, each a distance of 0.5 m from one another.
trimmedortiedtogetherso thatthe drip-line remained The sex of each pupa was recorded. The location of
widiin the flashing perimeter. Small-scale experiments eachpupawas markedwithadiscrete40cmsteel rodso
conducted in 2002 indicated that the ground barrier it could be relocated in the future. The sex ofpupae
method causes minimal short-term disturbance to the was determined prior to being buried on August 4 and
habitat yet was completely successful in preventing 5. Halfofthe pupae buried at each plotwere enclosed
larvae fromwandering. in small cylindrical cages made from 6 cm2 sections of
Mesh bird exclosures were placed around each tree 0.64 cm galvanized hardware cloth. One pupa was
onwhich larvae were deployed, enclosingboth the tree enclosed in each cage. This design eliminated small
and the aluminum flashing barrier. Exclosures were mammal predation but allowed access to invertebrate
constructedusingsections of1.9cm PVCpipescovered predators. All plots contained diree caged and diree
with 2.5cm netting (after Campbell et al. 1984). The uncaged males, and two caged and two uncaged
exclosures eliminated bird predation but still allowed females. Pupaewereretrievedon Sept. 21. Apupawas
unfettered access by parasitoids. Comparison of plots considered to have been depredated if it was not
with and without this type of exclosure indicated that retrieved from the marked release location, orifitwas
neitherdiversitynorabundance ofparasitoids attacking damaged.
H. maia in NewYorkwas affected (DP unpublished). Statistical Analysis. 2002 Larval mortalitv: Each
Larvaewerecountedatleasteveryotherday. Aftera differentmortalitysourcewasanalyzedseparatelyusing
period of 7-10 days (approximately the length of an the Kruskal-Wallis nonparametrictest. Onlylarvae diat
instar) the larvae were retrieved and replaced with 50 were retrieved from the field were included in die
laboratory-reared larvae ofthe next instar. This time analysis, since we could not determine causes of
period varied based on weather conditions, as larvae mortality for missing larvae. Two plots, one edge plot
!
216 Journalofthe Lepidopterists' Society
Table 1. MortalityofH. maia larvaecollected from naturally-occurringpopulationson CapeCod, MAin2002. Valuesindicate
diepercentageofparasitizedlarvaefromdiedifferentparasitoidspecies. CoCo=Compsiluraconcinnata, HyFu = Hyposoterjuej-
tivus, MeAu = Meteorusautographae,andLeFu = Leschenaultiafulvipes.
Site Date N Instar CoCo HyFu MeAu LeFu Survival"
NP1 20June 13 3 7.7 92.3
NP2 20June 24 3/4 4.2 79.2
NP3 21 June 15 4 6.7 13.3 80.0
NP4 21June 15 3/4 13.3 86.7
NP5 21 June 20 4 35.0 5.0 10.0 55.0
"Valuereflectstotal val andincludes mortalityfron -parasitoidsources.
and one buffer plot, were excluded from the analysis the experimental populations, the native tachinid
because no larvae were recovered. Only descriptive Leschenaultia fulvipes (Table 1). There was little
statistics are presented for the parasitism occurring in parasitism by M. autographae and H. fugitivus in
naturalpopulations. natural populations, although it is likely that these
2003 Larvalmortality:Analysiswas conductedusinga speciesparasitizedandkilledearlyinstarH. maialarvae
series oft-tests. All instars and mortality sources were beforetheywere collected.
analyzed separately. Cumulative mortality was Parasitism was markedly lower in 2003 than in the
calculated using the equation described in Elkinton et previousyear(Table2). Thethree speciesofparasitoids
al. (2006): recoveredfromthe2002experimentalpopulationswere
wChumeurleamt.ivisetMhoerftraalcittiyon=o1f-la(rlv-ame1d)y(iln-gmjd(urli-nmg3)i.n..s(tla-rmii.) pIrneasdednittiaogna,inL.infu2l0v0i3p,esthwoausghreicnovmeurcehd flrowoemrlnatuem-biensrtsa.r
2003 Pupal mortality: Pupal mortality data were
experimental H. maia larvae in 2003. As many as eight
analyzed as asplit-split plot to examine die interactions
individual L. fulvipes puparia were obtained from a
amonghabitat, sex, andtreatment (cagevs. nocage) for
single H. maia host. Additional sources of larval
parasitism andpredation.
mortality included a Beauvaria sp. fungus, a virus and
Results unknown factors.
With the exception ofL.fulvipes parasitism of fifth
Larval Mortality. In 2002, three species of
and sixth instar H. maia larvae, where parasitism was
parasitoids were recorded from experimental
significantly higher in power line plots (t =2.60,
populations ofH. maia larvae: Meteorus autographae, 5
p=0.048), all other comparisons for all instars were not
Hyposoter fugitivus, and the exotic Compsilura
significant. If a correction for multiple tests is
concinnata. In addition to parasitism, several larvae
conducted (adjusted akpha=0.0024), then even the
succumbed to a Beauvaria sp. fungus, and others died
difference in L. fulvipes parasitism of fifth and sixdi
of unknown causes. Parasitism by H. fugitivus was
instars becomes insignificant. While some advocate the
significantly higher in buffer plots (df = 2, p=0.009).
use ofcorrections for multiple tests (Peres-Neto 1999),
Therewere no otherdifferences in the parasitoid fauna
others maintain strong arguments against adjustingthe
amongthe three differenthabitattypes (Figure 1). alpha level (Gotelli & Ellison 2004), and we leave the
The 'control' population experiencedparasitism from
final determination to the reader's discretion. None of
three of the parasitoids, albeit in very low numbers.
the parasitoids, either acting alone or taken as awhole,
Control larvae succumbed to 1.7% mortality from C.
caused high levels ofmortalityto H. maia larvae, which
concinnata, 5.0% mortality from M. autographae, and
haduniformlyhigh survival.
5.0% mortality from H.fugitivus, all ofwhich emerged
Comparisons of cumulative mortality rates also
duringorpriortothethirdinstar. This indicatesthat all indicated that parasitism by L. fulvipes in power line
three parasitoids are capable ofattacking first instar H.
plots was significantly higher than in forest plots
maia larvae.
Naturally occurring H. maia larvae were collected (t6=2.49, p=0.047). Mortality inflicted by die other
parasitoid species did not differ between the different
primarily as late third and fourth instars, and were
habitats (Figure 2).
consequentlyexposedto parasitism foragreaterperiod
Pupal mortality. The test for interactions between
oftimethantheexperimentalpopulations. Theselarvae
had moderate levels of C. concinnata parasitism and habitat, sex, and treatment (cage vs. no cage) and all
combinations ofthese was not significant. The test for
were also parasitized by a fourth species not found in
Volume 61, Number4 217
Table2. Two-tailedtestresults for2003H. maia larval mortalitystudyon Cape Cod, MA, comparingpowerlinepopulations to
forest populations. Values indicate the percentage ofparasitized larvae from power line (POW) and forest (FOR) populations.
Where mortality sources are marked (°), there was insufficient information to conduct statistical analyses, as only 1 of12 sites
showedevidenceofmortalityfrom thatsource. CoCo = Compsiluracondnnata, HyFu = Hyposoterfugitivus MeAu = Meteorus
,
autographae, LeFu =Leschenaultiafuhipes.
Mortality Instar POW FOR DF T P
CoCo 1 - - -
HyFu 1 - - -
MeAu 1 1.55 ± 0.98 5 -1.58 0.175
LeFu 1 - - -
Fungus" 1 0.68 ± 0.68 - - -
Virus 1 6.02 ± 2.2 8.47± 2.6 9 -0.71 0.495
Unknown 1 S.25 ± 3.5 8.75 ± 2.2 8 -0.12 0.906
Survival 1 85.79 ± 4.8 80.6 ± 2.8 8 0.94 0.376
CoCo" 2 0.3.5 ± 0.35 _ _ _
HyFu" 2 0.33 ± 0.33 - - -
MeAu" 2 0.38 ± 0.38 - - -
LeFu 2 - - -
Fungus 2 0.68 ± 0.43 0.33 ± 0.33 9 0.64 0.537
Virus 2 5.72 ± 3.1 5.48 ± 2.8 9 0.06 0.957
Unknown 2 6.75 ± 1.2 7.18 ± 1.1 9 -0.27 0.796
Survival 2 86.52 ± 3.2 86.3 ± 3.4 9 0.05 0.958
CoCo" 3 4.25 ± 4.25 _ _ _
HyFu 3 - - -
MeAu 3 - - -
LeFu 3 - - -
Fungus" 3 1.07 ± 1.07 - - -
Virus 3 0.8 ± 0.51 1.4 ± 0.68 9 -0.70 0.500
Unknown 3 3.6 ± 0.59 5.67 ± 0.73 9 -2.20 0.055
Survival 3 95.61 ± 1.0 87.62 ± 4.8 5 1.62 0.166
CoCo" 4 4.87 ± 4.87 _ _ _
HyFu 4 - - -
MeAu 4 - - -
LeFu 4 1.15 ±0.51 0.67 ± 0.67 9 0.57 0.580
Fungus 4 3.67 ± 1.7 1.03 ± 0.71 6 1.40 0.210
Virus 4 1.9 ± 1.1 2.33 ± 1.5 9 -0.23 0.821
Unknown 4 4.37 ± 2.0 6.78 ± 2.3 9 -0.S0 0.443
Survival 4 88.92 ± 3.8 84.33 ± 7.0 7 0.58 0.5S1
CoCo 5/6 3.58 ± 2.4 5 -1.49 0.196
HyFu 5/6 - - -
MeAu 5/6 - - -
LeFu 5/6 19.2 ± 6.0 2.98 ± 1.6 5 2.60 0.04S
Fungus 5/6 3.33 ±2.27 5 1.47 0.203
Virus" 5/6 0.55 ± 0.55 - - -
Unknown 5/6 2.87 ± 1.6 3.65 ±1.3 9 -0.39 0.709
Survival 5/6 74.65 ± 7.5 89.27±4.1 7 -1.72 0.129
*
218 Journalofthe Lepidopterists" Society
CO
'cc
O
i—
"ccO
o
C.concinnata M.autographae H. fugitivus Fungus Unknown Total
Mortality Source
AnFoigt.at1i.onMoorft'anlsi'tiyndoifcHa.temsadiiaatldariveaceoomnpaCraipseonCoisd,noMtAstaitnis2t0ic0a2l.lysMiogrntiafliciatnytwaatsalcpalhcau0l.a0t5e.duAsninagstKerruisskka(l°-)Wianldliicsatneosnpaasrtaatmiesttirciaclltyessitsg.-
nificantcomparisonatalpha0.05.
DPower Line Plots
mForest Plots
ns
CO
S 15
ns
ns
T I :-:
C. concinnata L fulvipes H. fugitivus M. autographae
Source of Mortality
Fig.2. Meancumulativemortality(±SE)ofH. maialarvaebyparasitoidsin2003onCapeCod, MA.Anotationof'ns'indicates
diatthecomparisonis notstatisticallysignificant atalpha0.05. An asterisk(")indicates astatisticallysignificantcomparisonatal-
pha0.05.
Volume 61, Number4 219
differences between habitat and sex was also not produced from each parasitized early instar larva in
significant. There was a significant difference between 2002, while in 2003 multiple emergence occurred in
die predation of caged and uncaged pupae (t,=24.21, 38.5% of larvae, with as many as five C. concinnata
p=<.0001), with 5.8 ± 8.8% (mean ± SE) of caged producedfrom asingle host.
pupae and 38.4 ± 21.5 (mean ± SE) ofuncaged pupae The 2003 study was designed to specifically assess
depredated. With one exception, all predated pupae parasitism oflate-instar larvae. While our observations
were simply missing. In onlyone instancewas a caged accurately reflect the mortality inflicted on H. maia
pupa eaten, presumably by an insect predator. We larvae in 2003, this may not be representative of all
found noparasitism ofeithercagedoruncagedpupae. years. In odier years, our study (2002) and those of
others (Boettneretal. 2000) haveshownhigherrates of
Discussion parasitism. However, a similar study in New York's
Fourspecies ofparasitoidswere rearedfromH. maia Albany Pine Bush in 2005 found no parasitism by C.
on Cape Cod during the two-year study. Meteorus concinnata and very low parasitism by hymenopterans
autographae and H.fugitivus were primarily associated (DP and B. Hoven, unpublished data). In that study,
with earlyinstarH. maia larvae. Leschenaultiafulvipes onlyL.fulvipeswas common.
wasnotrecovered fromthe experimentalpopulationsin The apparent greater abundance ofH. maia in open,
2002, which spanned only the first three instars. early successional habitats like powerline right-of-ways
Leschenaultiafulvipes did occur in wildpopulations of does notappeartobeafunction ofchangesinparasitoid
late instar H. maia larvae in 2002, and again in late- pressure. There was some evidence diat parasitoid
instar experimental H. maia larvae in 2003, suggesting species varied spatially among habitats based on die
that L.fulvipes is predominantly associated with later highpercentageofH.fugitivus recoveredfromlarvaein
instar H. maia. However, extensive parasitism by L. bufferplots in2002andthe decreasedrateofparasitism
fulvipes in early instar larvae has been frequently byL.fulvipes in power line plots in 2003, but all odier
observed in odier Hemileuca populations Tuttle, comparisons were not significant. However, parasitism
(J.
pers. com.). While it is possible that L. fulvipes is butone ofseveralbiotic factors that mavinfluenceH.
parasitizedandkilledtheirearlyinstarhostsbefore they maia distribution. The abundance of predators, die
werecollectedas3rdand4thinstars, it shouldbe noted distribution andqualityofhostplants, fire management,
that L. fulvipes was not represented in the control and microclimate conditions are all factors diat mayact
population. aloneorincombinationtoaffecttheovipositionchoices
The recoveryofMeteorus autographae from H. maia made byH. maia adult females. Microclimate maybe
is a new host record. Several previously collected of major importance and should not be overlooked.
specimens identified as M. hyphantriae from Plymouth Increases in temperature and light intensity mav
and Brewster Counties in Massachusetts also were enhance behavioral thermoregulation dirough the
identified as M. autographae. We suggest that M. absorptionofsolarenergy(Seymour 1974, Cornelletal.
hyphantriae records from H. maia in old collections be 1987, Klok and Chown 1999, Hunter 2000). This may
reexamined for possible misidentifications, because be particularly important for H. maia larvae on Cape
many historic records appear to be from the same Cod, as these populations are at the extreme northern
region (S. Shaw, pers. com.). limit oftheirgeographic range.
The tachinid Compsilura concinnata was also more We recorded modest levels ofmortalityin die pupal
prevalent in late-instar H. maia, consistent with prior stage, although it is unclearwhat effect, ifany diis has
observations with other Lepidoptera (Webber & on its overall distribution. While pupal mortality is
Schaffner 1926, Burgess & Crossman 1929, Boettneret common in many other insect species (e.g., Weseloh
al. 2000, Kellogg et al. 2003). However, in 2002, C. 1985, Gould et al. 1990, Fuester & Taylor 1996,
concinnata was reared from second and third instars, Tanhuanpaa et al. 1999, Hastings et al. 2002). we are
and on one occasion even attacked a first instar larva. unaware of additional studies that examine pupal
Although most C. concinnata larvae successfully mortality of H. maia. Thus, we cannot competently
emerged from smaller H. maia hosts and formed assess whether the mortality levels diat we observed
puparia, 14% ofthese puparia died, and adults that did constitute significant losses fordiis species. Therewas
emerge were half the size or less of adults emerging noevidenceofpupalparasitism ineitherhabitat. There
frompupariarearedfromlateinstars. Significant fitness was also no evidence diat predators prefer die larger
costs may be incurred by flies attacking smaller femalepupaetothe smallermalepupae. Asignificandv
individuals (e.g., Baupp & Denno 1983, Reavey 1993). greater number ofuncaged pupae were depredated as
Further, only one C. concinnata puparium was compared to those in cages. This suggests that
220 Journalofthe Leridopterists' Society
predation was caused by birds, mammals, and/or large Denno, R.F, S. Larsson & K.L. OLMSTEAD. 1990. Role ofenemy-
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smaller invertebrates. In only one instance was there Elkinton,J.S.,D.Parry&G.H.Boettner.2006. Implicatinganin-
clear evidence that a small invertebrate predator troducedgeneralistparasitoidintheenigmaticdemiseofthein-
consumedacagedH. maia pupa. Fuesvtaesri,veRb.rWo.wn&taiPlBm.otTha.yloErc.ol1o9g9y6.87D:i2f6f6e4r-e2nt6i7a2l.mortalityin male
The lack ofsignificant mortality from the introduced andfemalegypsymoth(Lepidoptera:Lymantriidae)pupaebyin-
C. concinnata offers some hope forfuture management vertebratenaturalenemiesandotherfactors. Environ. Entomol.
ofH. maia because it suggests that populations can be Gote2l5l:i5,36N-.J5.47&.A.M. Ellison. 2004. APrimerofEcological Statis-
enhanced through habitatprotection and management. tics. SinauerAssociates,Inc. Sunderland,MA.510pp.
In contrast, management of several other species of Gould,J.R.,J.S. Elkinton &WE.Wallner. 1990. Density-depen-
threatened satumiids in the northeast maybe thwarted dentsuppressionofexperimentallycreatedgypsymoth,Lyman-
triadispar(Lepidoptera: Lymantriidae),populationsbynatural
by the dominance ofthis tachinid as a mortality factor. enemies. AnimalEcol.59:213-233.
Our data do suggest that the well-documented decline Hastings,F.L.J., F.P. Hain, H.R. Smith,S.P.Cook&J.F. Monahan.
in populations ofmany satumiids in the northeast may 2002. Predationofgypsymoth (Lepidoptera: Lymantriidae)pu-
pae in threeecosystems alongthe soudiem edgeofinfestation.
be due to more than one factor, and the role of C. Environ. Entomol.31:668-675.
concinnata, which has been proposed as a major Henderson, G.F. 1955.Testwidiacaricideagainstthebrownwheat
contributortothedecline,willdependonthespeciesin mite.J. Econ. Entomol.48:157-160.
Hunter,A.F.2000.Gregariousnessandrepellentdefensesindiesur-
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WewouldliketothankScott ShawandNinaZitaniforiden- Jeffries,M.J.&J.H.Layvton. 1984.Enemy-freespaceandthestruc-
tfiufnygiin.gpWareasitthoaindks aDinldloAnnnFiHnaajn,ekCfoolrleiedenntOi'fCyoinngneplalthaongdenJseannndy Kelltougrge,ofS.eKc.o,loLg.iSc.alFicnomkm&uniLt.iPesB.roBiwoelr..J.2L0i0n3n..PSaorca.si2t3i:s2m69o-f2n8a6t.ive
Smith for their enormous efforts both in field and in the lab. Lunamoths, Actias luna (L.) (Lepidoptera: Satumiidae) by the
Forguidanceonvarious aspects oftheproject,we thank Mike introduced Compsilura concinnata (Meigen) (Diptera: Ta-
Nelson, Dale Schweitzer, Paul Goldstein and Eric Quinter. chinidae)inCentralVirginia,andtheirhyperparasitismbytrigo-
Many thanks to Nancy Finley and the Cape Cod National nalid wasps (Hymenoptera: Trigonalidae). Environ. Entomol.
tSheaanskhoJriemfTourttplreoavniddianngabnootnhyhmoouussinrgevainedwerfifeoldrpsritoevsi.diWngeheallps-o Klok3,2:C1.J0.19&-1S0.2L7..Chown. 1999. Assessingthe benefits ofaggrega-
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