Infusion-baited ovitraps to survey ovipositional height preferences of container-inhabiting mosquitoes in two Florida habitats.

Abstract

To ascertain mosquito species-specific oviposition height preferences, a study was conducted evaluating the response of field populations of container-inhabiting mosquitoes to water, oak (Quercus spp.),or oak-pine (Pinus spp.) infusion-baited ovitraps in four suburban and four sylvatic habitats in north central Florida. In total, 48 ovitraps, 24 suspended at each height of 1 or 6 m (near the ground or tree canopy, respectively), were monitored weekly for 5 mo. Throughout our study, we collected 13,276 mosquito eggs, representing five species from four genera, the most common being Aedes triseriatus (Say), Aedes albopictus Skuse, and Orthopodomyia signifera (Coquillett). Significantly more Ae. triseriatus and Ae. albopictus eggs were oviposited in containers with oak and oak-pine infusions compared with water alone. Significantly more Ae. albopictus eggs were recovered from traps at 1 m in suburban habitats, whereas more Ae. triseriatus eggs were recovered at 6 m in sylvatic habitats.

Full text

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VECTOR-BORNE DISEASES, SURVEILLANCE, PREVENTION
Infusion-Baited Ovitraps to Survey Ovipositional Height Preferences of
Container-Inhabiting Mosquitoes in Two Florida Habitats
P. J. OBENAUER,1,2P. E. KAUFMAN,1S. A. ALLAN,3AND D. L. KLINE3
J. Med. Entomol. 46(6): 1507Ð1513 (2009)
To ascertain mosquito species-speciÞc oviposition height preferences, a study was
conducted evaluating the response of Þeld populations of container-inhabiting mosquitoes to water,
oak(Quercusspp.),oroakÐpine(Pinusspp.)infusion-baitedovitrapsinfoursuburbanandfoursylvatic
habitats in north central Florida. In total, 48 ovitraps, 24 suspended at each height of 1 or 6 m (near
the ground or tree canopy, respectively), were monitored weekly for 5 mo. Throughout our study,
wecollected13,276mosquitoeggs,representingÞvespeciesfromfourgenera,themostcommonbeing
Aedestriseriatus(Say),AedesalbopictusSkuse,andOrthopodomyiasignifera(Coquillett).SigniÞcantly
more Ae. triseriatus and Ae. albopictus eggs were oviposited in containers with oak and oakÐpine
infusionscomparedwithwateralone.SigniÞcantlymoreAe.albopictuseggswererecoveredfromtraps
at1minsuburbanhabitats,whereasmoreAe.triseriatuseggswererecoveredat6minsylvatichabitats.
ABSTRACT
KEY WORDS
Aedes albopictus, Aedes triseriatus, Orthopodomyia signifera, traps, surveillance
The recorded introduction of invasive container mos-
quitoes such as Aedes albopictus (Skuse) (Hawley et
al. 1987), Aedes bahamensis (Berlin) (Pafume et al.
1988), Aedes togoi (Theobald) (Belton 1980), and
Aedes japonicus japonicus (Theobald) (Peyton et al.
1999)intotheUnitedStatesrepresentsaseriousthreat
to human and animal health because most are vectors
of pathogens. Surveillance for these container-inhab-
iting mosquitoes often requires careful sampling of
natural and artiÞcial containers, because these are
primary habitats for oviposition and larval develop-
ment. However, searching for containers can be a
time-consuming process, and many are overlooked or
remain inaccessible, such as tree holes located in tree
canopies.Ovitrapsofferanalternativetosearchingfor
natural and artiÞcial containers, because they can be
setatspeciÞclocationsandhaveproventobeauseful
tool to detect the presence of mosquito species in
particular habitats as well as to estimate adult popu-
lation size (Service 1993). The rapid introduction of
invasive container-inhabiting mosquitoes within the
past 20 yr underscores the necessity for enhancement
of ovitrap sensitivity to enable rapid detection and
possibly prevent their establishment in new environ-
ments.Toadequatelydeterminetheriskthesespecies
pose,tomitigatetheirimpactonnativemosquitopop-
ulations,andtoallowforanunderstandingofchanges
in existing disease transmission cycles, their oviposi-
tion habitat preferences must be better understood
(Juliano and Lounibos 2005).
Typically, ovitraps are constructed from materials
such as black plastic cups containing an oviposition
substrateandpositionedontheground.Thisapproach
preferentially selects for mosquitoes that naturally
oviposit near the ground but fails to collect those
mosquitoes ovipositing at greater heights. The most
common approach to deter many container mosqui-
toes from breeding within suburban areas is the re-
moval of artiÞcial containers from the surrounding
environment. However, if some of these species ovi-
posit in the tree canopy as well as at ground level,
changes in vector surveillance and control strategies
may be warranted. In addition, many suburban back-
yards in north central Florida contain natural and
artiÞcial containers that collect fallen leaves and pine
needlesfromwateroak,QuercusnigraL.,andlongleaf
pine, Pinus palustris Mill, potentially creating more
attractive larval habitats for a number of container-
inhabiting species. Although many studies document
enhanced oviposition responses to hay and leaf infu-
sions (Holck et al. 1988, Allan and Kline 1995, Trexler
etal.1998),thereislimitedinformationonoviposition
responses to detritus from coniferous trees.
Theadditionofinfusionstoovitrapshasbeenshown
to increase trap effectiveness compared with water
alone (Holck et al. 1988). Organic infusions, often
composed of fermented plant material, attract gravid
mosquitoes by volatiles released through microfauna
fermentation (Trexler et al. 2003). Often, the types of
materials used in an infusion increases the level of
attractiveness for speciÞc mosquito species. Hay (Al-
The views expressed in this article are those of the authors and do
notnecessarilyreßecttheofÞcialpolicyorpositionoftheDepartment
of the Navy, Department of Defense, nor the U.S. government.
1Department of Entomology and Nematology, P.O. Box 110620,
Bldg. 970, Natural Area Dr., University of Florida, Gainesville, FL
32611.
2Corresponding author, e-mail: pjoben@uß.edu.
3USDAÐARS, Center for Medical, Agricultural, and Veterinary
Entomology, 1600 SW 23rd Dr., Gainesville, FL 32608.

Page 2

lan and Kline 1995) and bamboo (Ponnusamy et al.
2008) are attractive to Aedes aegypti (L.), whereas
white oak, Quercus alba L. (Trexler et al. 1998); red
oak,QuercusrubraL.(Burkettetal.2004);andmaple,
AcerbuergerianumMiq.(Diengetal.2003),leavesare
attractive to Ae. albopictus. Furthermore, oviposition
response to these volatile attractants is often depen-
dentonthemicrobialspeciescontainedintheinfusion
(Trexler et al. 2003).
There is also variability in the vertical stratiÞcation
of oviposition among container-inhabiting mosqui-
toes. Studies within urban areas in the Republic of
TrinidaddeterminedthatAe.aegyptipreferredtoovi-
posit in traps placed 1.2 m above ground compared
with ovitraps set at ground level, or traps that are
elevatedto3.0and4.6maboveground(Chadee1991).
In Sri Lanka, Amerasinghe and Alagoda (1984) dem-
onstrated that although Ae. albopictus oviposited at
7 m, it preferred to oviposit at ground level. Studies in
Wisconsin demonstrated
(Cockerell) predominantly oviposits at 3Ð9 m above
ground (Loor and DeFoliart 1969, Scholl and DeFo-
liart 1977). Our objectives were two-fold: 1) deter-
mine the effectiveness of ovitraps at detecting con-
tainer-inhabiting mosquitoes at 1- and 6-m heights in
two habitats and 2) determine if container-inhabiting
mosquitoesdemonstratepreferencesforovitrapscon-
taining oak or oakÐpine infusions compared with wa-
ter alone.
that Aedes hendersoni
Materials and Methods
Site Selection. Ovitraps were set from May to Oc-
tober 2008 in four suburban and four sylvatic sites
previously described in Obenauer et al. (2009). Sub-
urban habitat sites (29? 37.837? N, 82? 27.800? W; 29?
34.248? N, 82? 24.644? W; 29? 39.019? N, 82? 23.234? W;
29? 42.481? N, 82? 24.745? W) were residential neigh-
borhoods in and around the city limits of Gainesville,
FL, whereas sylvatic habitat sites (29? 43.574? N, 82?
27.252? W; 29? 44.048? N, 82? 26.458? W; 29? 43.574? N,
82? 27.233? W; 29? 44.238? N, 82? 28.138? W) were
located throughout San Felasco Hammock Preserve
StatePark,alsonearGainesville.Allsylvaticsiteswere
at least 0.8 km from any artiÞcial residential structure.
Both habitats contained deciduous and coniferous
trees, primarily live oak, Quercus virginiana P. Mill;
water oak; laurel oak, Quercus laurifolia Michx.; lon-
gleaf pine; and slash pine, Pinus elliottii Engelm.
Ovitraps. A modiÞed ovitrap, originally described
by Weinbren and OÕGower (1966) to capture Ae.
aegypti was used. Lidless steel cans (11 cm in height
and 7.5 cm in diameter) were attached at three loca-
tions to an inverted circular aluminum dish (7.5-cm
base and 12.5-cm outside diameter) by bending wires
into a closed loop. The dish served as a cover to
prevent leaves and other debris from falling into the
trap, possibly altering the infusion. A 1-cm drain hole
was made 7.5 cm above the bottom of the can, to
preventßooding.Theentireovitrapwasspray-painted
with ßat black paint. To remove any paint odors or
contaminants,ovitrapswerepreconditionedandaged
byÞllingthemwithwellwaterandlettingthemsitfor
2 wk in a semishaded environment (Burkett et al.
2004). Seed germination paper (76#, Anchor Paper,
St. Paul, MN) (22 by 8 cm) was pressed against the
inside surface of each can to serve as an oviposition
substrate.Tosuspendtheovitrap,aneyeboltwasÞtted
throughthetopofthedish.A168-gÞshingweightwas
attached to the bottom of the eyebolt providing ad-
ditional weight and stability. Each ovitrap was Þlled
with 270 ml of either an infusion or well water. Infu-
sions were generated by Þrst diluting the concentrate
to 35% (70 ml) with 200 ml of deionized water before
Þlling the traps. This concentration was based on pre-
vious laboratory and Þeld-cage studies demonstrating
a high degree of attractiveness by using the same
infusions (Obenauer 2009).
Infusions. Infusions were developed by collecting
fallen dry water oak (oak) leaves and longleaf pine
needles (pine) from the grounds at the University of
Florida, Gainesville, FL. Leaves and needles were vi-
sually inspected to ensure that they were free of for-
eign organic matter. Infusions were prepared by fer-
menting 120 g of leaves, 7 g of brewerÕs yeast (MP
Biomedicals, LLC, Solon, OH), and 7 g of lactalbumin
(Sigma-Aldrich, St. Louis, MO) in 12 liters of well
water(AllanandKline1995).A50:50mixture(60gof
pine needles and 60 g of oak leaves) was used to
develop the oakÐpine infusion. Mixtures were held at
ambient temperature between 25 and 27?C for 10 d in
asealedplasticbucket.Infusionswerepassedthrough
sterile gauze dressing to remove large organic matter
andtransferredintoplasticcups,sealed,andfrozenat
?20?C. When used, frozen aliquots were placed in a
warm bath for 30 min or until melted and used within
4 h on the day of ovitrap collection. Four individual
batches of oak and pine infusion were developed to
ensure infusion replication throughout the experi-
ment.
Trapping, Collecting, and Egg Identification. Each
oftheeightsites(foursuburbanandfoursylvatic)was
partitioned into three stations. Stations were placed
20mfromeachotherandatleast10mfromresidential
structures at suburban sites. In total, 48 ovitraps were
used during a given trapping period, with two traps
placedateachofthethreestationsateachoftheeight
sites. At each station, one ovitrap was suspended at
1 m, with the second suspended at 6 m. Ovitraps at
each station were baited with one of the three treat-
ments:eitheranoak,oakÐpineinfusion,orawellwater
control. The three treatments were randomized at
every collection period within each site to eliminate
positionorplacementbias.Therefore,thethreetreat-
ments were represented at each height at a given site
and placement period.
Ovitraps were suspended using 6.35-mm-diameter
interwoven nylon rope containing 1-m markings.
Trapsweresetat1or6mbyusingapulleysystemthat
wascomprisedoftworopesasdescribedinObenauer
et al. (2009). Ovitraps placed at 6 m were suspended
fromaselectedtreebranch,whereasthoseat1mwere
suspended from a shepherds hook. Traps were set
between0800and1400hoursandleftinplacefor1wk
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Page 3

(one trapping period). At this time, the contents of
each ovitrap were checked, and the infusion, water,
and seed germination paper were replaced. A visual
inspection for mosquito eggs and larvae was con-
ducted for each ovitrap, and all seed germination pa-
pers were placed in sealed plastic bags for later iden-
tiÞcation and enumeration. Occasionally, some
larvae had eclosed; these were counted, transferred
to mosquito breeding containers (Bioquip, Rancho
Dominguez, CA), and returned to the laboratory for
further identiÞcation. To ensure that old infusion was
not present, all ovitraps were thoroughly rinsed with
deionized water to remove any organic matter before
replacing with fresh infusion and paper.
Asecondinspectionoftheeggpaperwasconducted
in the laboratory. Seed germination papers were
placedonpapertowelsandallowedtodryfor2h.Eggs
were counted and identiÞed to species under a dis-
secting microscope based on their color, size, luster,
and shape. To ensure accuracy, a subsample (10%) of
eggs from each collection period was reared to adults
under laboratory conditions and positive identiÞca-
tion was made using Darsie and Morris (2003). In
addition, those mosquito larvae that were collected in
theÞeldwererearedtoadultsandidentiÞedusingthe
same methods. In total, 20 consecutive weekly trap-
ping periods in each locale were conducted from 15
May to 3 October 2008.
Statistical Analysis. A nested analysis of variance
(ANOVA)wasusedtodeterminewhetherdifferences
in mean mosquito egg capture were statistically dif-
ferent due to infusion batch, infusion type, and habi-
tat:height (suburban or sylvatic) (Proc GLM, SAS
Institute2006).Dataweretransformedwithlog10(n?
1) before analysis. After it was determined that infu-
sionbatchwasnotstatisticallysigniÞcant(P?0.4837),
it was removed from the model before Þnal analysis.
Infusiontype,habitat:height,andtheinteractionterm
infusion type by habitat:height were included as Þxed
effects, whereas trial was included as a quantitative
effect in the model because this variable was a mea-
sure of seasonal progression. In this analysis, the site
variablewasnestedwithinthehabitat:heightvariable.
Multiple mean comparisons were made with the
RyanÐEinotÐGabriel-Welsh multiple range test (? ?
0.05). Untransformed means are presented in all ta-
bles. Storms caused damage to several ovitraps, re-
sulting in lost data during a portion of the study. For
statistical purposes, lost data were treated as missing
values.
Results
In total, 13,276 mosquito eggs were collected, rep-
resenting Þve species: Ae. albopictus, Aedes triseriatus
(Say), Culex quinquefasciatus (L.), Orthopodomyia
signifera (Coquillett), and Toxorhynchites rutilus ruti-
lus (Coquillett) (Table 1). The majority of eggs col-
lected during this study from ovitraps at all habitats
and heights were Ae. triseriatus (6,275) (Table 1).
However,eggsofthisspecieswerenotrecoveredfrom
any ovitrap until the seventh week of the study (4
July), with the greatest number (1,457) recovered on
18 July. The majority of Ae. triseriatus eggs (45.0%)
were recovered in ovitraps containing oakÐpine infu-
sions, with only 36.7 and 17.7% of eggs from ovitraps
containing oak infusion or water, respectively. Al-
though no signiÞcant difference was detected be-
tween infusion-containing treatments, signiÞcantly
fewereggswererecoveredinovitrapscontainingonly
water (3.60 ? 1.00) compared with traps containing
oakÐpine (9.20 ? 1.80) or oak (7.40 ? 1.61) (F ? 5.88;
df ? 2, 910; P ? 0.0020) infusions (Table 2). SigniÞ-
cantly more Ae. triseriatus eggs were recovered from
ovitraps placed in sylvatic habitats at 6 m (17.90 ?
2.97) than those sylvatic habitats at 1 m (5.44 ? 1.27),
orsuburbanhabitatsat6or1m(1.29?0.70and2.63?
0.96,respectively)(F?30.17;df?3,910;P?0.0001)
Table 1.
tured using ovitraps baited with infusionsaor well water and sus-
pended at 1- and 6-m heights in suburban and sylvatic locales from
May to October 2008 in Gainesville, FL
Total number and percentage of Culicidae eggs cap-
Mosquito species
Habitat type
Totals (%) SuburbanSylvatic
1 m6 m 1 m6 m
Ae. albopictus
Ae. triseriatus
Or. signifera
Cx. quinquefasciatus
Tx. r. rutilus
Total
4,896
630
392
302
396
1,262
256
4,081
633
5,940 (45)
6,275 (47)
667 (5)
348 (2)
46 (1)
13,276
0034
0
13
328 20
15
729
0
5 13
5,8591,7054,983
aTraps were baited with oak and oak-pine infusions (35% concen-
tration) that were changed weekly.
Table 2.
heights in suburban and sylvatic locales from May to October 2008 in Gainesville, FL
Numbers (mean ? SE) of mosquito eggs collected per trapping period from infusion-baited ovitrapsaplaced at 1- and 6-m
Species
Infusion-baited ovitrapsb
FP
OakÐpine Oak Well water
Ae. albopictus
Ae. triseriatus
Or. signifera
Cx. quinquefasciatus
Tx. r. rutilus
9.30 ? 2.03a
9.20 ? 1.80a
1.64 ? 0.84a
0.87 ? 0.62a
0.05 ? 0.13a
8.00 ? 1.45a
7.40 ? 1.61a
0.06 ? 0.06a
0.18 ? 0.18a
0.08 ? 0.03a
1.80 ? 0.43b
3.60 ? 1.00b
0.43 ? 0.40a
0.07 ? 0.05a
0.02 ? 0.00a
7.95
5.88
2.26
1.22
2.74
0.0004
0.0029
0.1049
0.2953
0.0650
aTraps were baited with infusions (35% concentration) that were changed weekly.
bMeans within each row followed by the same letter are not signiÞcantly different (RyanÐEinotÐGabrielÐWelsh multiple range test), ? ?
0.05, trap periods ? 20, 1 trap period ? 1 wk; df ? 2, 910 (n ? 312).
November 2009OBENAUER ET AL.: MOSQUITO OVIPOSITIONAL HEIGHT PREFERENCE
1509

Page 4

(Table 3). Although no discernible differences in egg
collectionwasdetectedbetweensuburbanhabitatsat
1- and 6-m heights, more eggs were recovered in
ovitraps placed in sylvatic habitats at 1 m than those
placed at the same height in suburban habitats (Table
1). SigniÞcant differences were detected among sites
within sylvatic habitat:height treatment effect (F ?
5.90;df?12,910;P?0.0001),withmoreAe.triseriatus
eggs collected in traps located at sites furthest from
urbanized development, including highways.
In total, 5,940 Ae. albopictus eggs were collected
during this study (Table 1). Almost half (48.8%) were
ovipositedintrapscontaininganoakÐpineinfusion.In
suburban sites, 5,288 Ae. albopictus eggs were recov-
ered: 50% were taken from oakÐpine-baited ovitraps,
39% from oak-baited ovitraps, and 9% from the water
control.Ofthe652Ae.albopictuseggsrecoveredfrom
sylvatic sites, 58% were deposited in oak-baited ovit-
raps, whereas 33 and 7% were recovered from oakÐ
pine and water-baited ovitraps, respectively.
Although no signiÞcant difference were detected
between oakÐpine and oak infusions, signiÞcantly
moreAe.albopictuseggswereovipositedintrapscon-
taininginfusionsthanthosewithonlywater(F?7.95;
df ? 2, 910; P ? 0.0004) (Table 2). A signiÞcant
interaction effect was detected between the infusion
type and habitat:height treatment effects (F ? 4.67;
df ? 6, 910; P ? 0.0001). SigniÞcantly more Ae. albop-
ictus eggs were recovered from ovitraps placed in
suburban sites at 1 m than any other location (F ?
79.31; df ? 3, 910; P ? 0.001) (Table 3). Only 13% of
recovered Ae. albopictus eggs were from sylvatic hab-
itats.
Theremainingmosquitoesspecies,Or.signifera,Cx.
quinquefasciatus, and Tx. r. rutilus, made up less than
9% of the total egg capture. Or. signifera eggs repre-
sented the third most common mosquito collected in
ovitraps,anditwasonlyrecoveredinsylvatichabitats
(Table 1). A greater number of Or. signifera eggs was
recovered from ovitraps placed at 6 m (2.78 ? 1.27)
than at 1 m (0.15 ? 0.09) (Table 3). Cx. quinquefas-
ciatus eggs were only recovered in suburban habitats,
and the majority of eggs were in ovitraps containing
infusions.Intotal,39Tx.r.rutiluseggswererecovered
with the majority collected at sylvatic sites (57%) and
at 6-m heights (61%) (Table 1).
Discussion
Our study demonstrated ovipositional height pref-
erences of Ae. triseriatus and Ae. albopictus in sylvatic
and suburban habitats, although we failed to demon-
strate a mosquito oviposition preference for a partic-
ular infusion type.
Four of the Þve mosquito species collected, Ae.
albopictus, Ae. triseriatus, Tx. r. rutilus and Or. signif-
era, are species commonly collected as larvae in Flor-
ida tree holes, and their respective abundance seen
here reßects that of past studies (Bradshaw and Hol-
zapfel 1983, Lounibos 1983). Ae. hendersoni, another
mosquito that inhabits tree holes, possesses similar
adult physical characteristics as Ae. triseriatus and is
known to exist in some northern Florida counties
(Darsie and Morris 2003). We reared ?1,300 eggs to
adults and did not recover any Ae. hendersoni in our
collections. Past studies have shown that Ae. hender-
soni is infrequent at best in Florida (Bradshaw and
Holzapfel1983).Inaddition,wedidnotdetectanyAe.
aegypti, and although small populations may exist in
Gainesville (J. Butler, personal communication), oc-
currence of this species is currently rare in north
Florida, with populations mainly conÞned to south
Florida (Lounibos et al. 2001). Furthermore, we did
not collect these two mosquito species using host-
seekingtrapsinthesameareaduringthepreviousyear
(Obenauer et al. 2009). Therefore, although we did
notrearoutallcollectedeggs,theredoesremainalow
possibility that some samples may have contained
these species, although it is unlikely that this would
signiÞcantly impact our conclusions.
Ae. triseriatus oviposited more often at 6 m in syl-
vatic habitats (Table 3). In south Florida, Lounibos et
al. (2001) reported similar Þndings where Ae. trise-
riatus was more frequently collected in undisturbed
hammock habitats compared with Ae. albopictus. Ae.
triseriatus have shown a strong preference for inhab-
iting tree canopies up to 27 m (Novak et al. 1981).
Therefore, it is possible that Ae. triseriatus preference
for ovitraps placed at 6 m in sylvatic habitats was due
to the high concentration of tree holes found at
heights of ?6 m and its propensity to feed on forest-
associated mammals such as chipmunks and gray
squirrels (Nasci 1982). Past studies report that Ae.
Table 3.
suspended at 1- and 6-m heights in suburban and sylvatic locales from May to October 2008 in Gainesville, FLb
Numbers (mean ? SE) of mosquito eggs collected per trapping period using ovitraps baited with infusionsaor well water and
Mosquito species
Habitat type
FP SuburbanSylvatic
1 m6 m1 m6 m
Ae. albopictus
Ae. triseriatus
Or. signifera
Cx. quinquefasciatus
Tx. rutilus
20.40 ? 2.95a
2.63 ? 0.96cb
0.00 ? 0.00b
1.37 ? 0.84a
0.02 ? 0.00a
1.67 ? 0.59b
1.29 ? 0.70c
0.00 ? 0.00b
0.09 ? 0.06ab
0.06 ? 0.03a
1.71 ? 0.73b
5.44 ? 1.27b
0.15 ? 0.09ab
0.00 ? 0.00b
0.06 ? 0.02a
1.12 ? 0.58b
17.90 ? 2.97a
2.78 ? 1.27a
0.00 ? 0.00b
0.06 ? 0.02a
79.31
30.17
4.10
3.76
1.02
?0.0001
?0.0001
0.0066
0.0107
0.3883
aTraps were baited with oak and oakÐpine infusions (35% concentration) that were changed weekly.
bMeans within each row followed by the same letter are not signiÞcantly different (RyanÐEinotÐGabrielÐWelsh multiple range test), ? ?
0.05, trap periods ? 20, 1 trap period ? 1 wk; df ? 3, 910 (n ? 240).
1510JOURNAL OF MEDICAL ENTOMOLOGY
Vol. 46, no. 6

Page 5

triseriatus oviposition had predominantly occurred at
ground level (Loor and DeFoliart 1969, Scholl and
DeFoliart 1977). However, these studies were con-
ducted in Wisconsin, where Ae. hendersoni coexists
withAe.triseriatusbyovipositingintheforestcanopy.
Therefore, it is possible that in Florida Ae. triseriatus
exhibits increased arboreal oviposition in the absence
of Ae. hendersoni.
In contrast, Ae. albopictus demonstrated an ovipo-
sition preference for suburban habitats at 1 m com-
pared with other locations or heights, because 86% of
eggswerecollectedatthisheight(OÕMearaetal.1993,
Obenauer et al. 2009). This is probably due to the
numerous artiÞcial containers available in suburban
habitats and the abundance of hosts, including dogs,
cats and humans at this level (Richards et al. 2006).
Amerasinghe and Alagoda (1984) also demonstrated
that Ae. albopictus oviposited more often at ground
level (?1 m) than at 3.5 and 7.0 m. Due to its pro-
pensitytousebothnaturalandartiÞcialcontainers,Ae.
albopictus is difÞcult to control using those source
reductionmethodsthatareeffectiveatcontrollingAe.
aegypti(Estrada-FrancoandCraig1995).Researchon
controlling this species using an ultralow volume for-
mulation of Bacillus thuringiensis variety israelensis
(Bti) is ongoing by several research groups and may
prove effective if most larvae are found in natural
containers ?1 m in height where the Bti will more
readilyreach(C.A.Stoops,personalcommunication).
Our oviposition infusion results with Ae. albopictus
are similar to those found in binary-choice bioassays
byAllanandKline(1995)whodemonstratedagreater
percentageofeggswereovipositedincontainerswith
hay infusion compared with well water. Numerous
other studies also have shown mosquito oviposition
preferencesfororganicinfusionsoverwater(Holcket
al. 1988, Trexler et al. 1998).
A variety of factors are known to inßuence infusion
attractiveness. Ingredients used in infusion prepara-
tion and the duration of fermentation are factors that
can rapidly change the microbial fauna, thereby al-
tering the chemical content of most organic infusions
(Beehler et al. 1994). Also, although the ovitrap cover
prevented the entrance of foreign debris, it did not
eliminate all fauna. Occasionally, tree frogs, paper
wasps, and beetles were found inside the ovitrap, per-
haps altering the attractiveness of some traps. It is
known that increased bacteria levels can change the
attractiveness of mosquito oviposition sites (Pon-
nusamy et al. 2008). The addition of lactalbumin may
haveincreasedtheconcentrationofbacteria,resulting
in a “masking” effect that altered the mosquitoÕs re-
sponse to these infusions. Repeated experimentation
with natural tree hole water or fermented oak leaf
water without lactalbumin would be necessary to de-
termine whether this was a natural response or was
due to infusion ingredients.
Evaluating plant detritus used for infusions may
elucidatesomeofthefactorsresponsibleforinßuenc-
ing intra- and interspeciÞc competition between con-
tainer-inhabiting mosquito species. A recent study by
Murrell and Juliano (2008) determined that Ae. al-
bopictus larvae outcompeted Ae. aegypti in water con-
taining oak and pine detritus and surmised that detri-
tus type was responsible for altering interspeciÞc
competition between these species. In addition, Reis-
kind et al. (2009) demonstrated that larval develop-
ment and survival of Ae. albopictus and Ae. triseriatus
was enhanced when reared in water infused with
mixed leaf detritus, compared with that containing a
single leaf species. Therefore, knowledge of FloridaÕs
local ßoral abundance and variation, coupled with its
resultant detritus, may help determine where species
are competitive and where they coexist, especially in
areas where oak and pine dominate the landscape.
The increased oviposition by Ae. albopictus to oakÐ
pineinfusioninsuburbancomparedwithOakinfusion
in sylvatic habitats may have resulted from other ovi-
position factors, such as light intensity and/or tem-
perature and humidity, rather than infusion type. In
addition, it is possible that the density of oak trees or
lack of pine trees in the sylvatic habitats used in the
current study may have interacted with the infusion,
causing more Ae. albopictus to oviposit in traps con-
tainingoakinfusion,perhapsthroughpreconditioning
in their larval habitat. Furthermore, the low numbers
of Ae. albopictus eggs collected in sylvatic habitats
suggest their populations are considerably smaller
than those found in suburban habitats.
The use of host-seeking and oviposition traps can
effectively elucidate height preferences, feeding hab-
its and habitat preferences for a number of mosquito
species. For example, previous host-seeking studies
(Obenauer et al. 2009) determined that 87% of adult
Ae. albopictus were recovered at 1 m, whereas the
current study recovered 81% of the eggs at 1 m, sug-
gesting a similar, but not exclusive, pairing of host-
seeking and oviposition activity areas. This height
preference was not detected in sylvatic habitats, in-
dicating that other environmental variables may have
inßuenced gravid females to select higher oviposition
sites. Amerasinghe and Alagoda (1984) have noted
thattemperature,humidity,andlightmayplayalarge
role in the attractiveness of Ae. albopictus to their
breeding areas.
In addition, mosquito oviposition site selection is
considered species dependent, whereby the interac-
tionofchemicalandphysicalfactorsinßuencespeciÞc
species to oviposit in a particular environment (Bent-
leyandDay1989).Therefore,sylvaticsiteswithfewer
larval supporting containers may have resulted in
gravid Ae. albopictus being more opportunistic, seek-
ing available, but less desirable, higher oviposition
sites compared with traditionally preferred lower
sites. This scenario is evident in suburban habitats
wheremanycontainersarepurposelyorinadvertently
maintained with water, whereas sylvatic sites rely en-
tirely on rain events for maintenance of container-
inhabiting mosquito populations.
Ae.triseriatusalsowereprobablyinßuencedbysev-
eral physical oviposition cues. Field studies deter-
mined that oviposition attraction for dark colors was
astrongerfactorthanorganicmatterforAe.triseriatus
in selection of oviposition sites (Loor and DeFoliart
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