Asian tiger mosquito, Aedes albopictus (Skuse) (Diptera Culicidae), larvae in pitchers of Nepenthes ventricosa blanco (Nepenthaceae) in Virginia

2007·2 MB·

by  Richard M Duffield

PROC. ENTOMOL. SOC. WASH.
109(2), 2007, pp. 489-492
Note
Asian Tiger Mosquito, Aedes albopictus (Skuse) (Diptera: Culicidae),
Larvae in Pitchers of Nepenthes ventricosa Blanco (Nepenthaceae)
in Virginia
Cultivating unusual exotic plants has protozoa, crustaceans, and larvae of
been popular with horticulturists since several families of Diptera including
Darwin's time. These include Old World mosquitoes (Kitching 2000).
tropical pitcher plants belonging to the Meadowview Biological Research Sta-
genus Nepenthes (Nepenthaceae). Since tion (MBRS) in Caroline County, Vir-
their discovery by Europeans in Mada- ginia, maintains living collections of
gascar in the 17th century, over 60 many species of pitcher plants. One of
species ofNepenthes have been described the species that is maintained in large
(Clark 1997). Many of the species are numbers in the collections is the purple
restricted to the tropical rain forests of pitcher plant, Sarracenia purpurea L.,
Malaysia and Borneo where their vines which occurs naturally in Virginia.
attach to trees and extend vertically Found living in S. purpurea leaves are
above the ground (Clark 1997, 2001). larvae of the species-specific mosquito,
Others are found in drier open areas Wyeomyia smithii (Coq) (Buffington
where they are non-climbers. Because 1970). During the summer at MBRS in
Nepenthes is dioecious, species some- the area of the S. purpurea plant beds,
times hybridize in nature. Nurserymen several Nepenthes plants are suspended
and collectors also create dozens of from a chainlink fence. Although Wy.
hybrids and cultivars. smithii larvae were not expected to be
The modified traps or pitchers of found in the Nepenthes leaves, we de-
Nepenthes form at the ends of tendrils cided to test this by sampling water from
emanating from the tips ofthe leaves and leaves ofA^. ventricosa Blanco. We found
they vary considerably in size and shape. that several leaves contained mosquito
Not all leaves form traps. The pitcher is larvae. To determine the species, we
a cuplike structure with a lip. It has reared the immature specimens to adults.
a ribbed upper rim, a waxy zone and To broaden the scope of the initial
a pool of fluid which assists in the observation, we contacted some local
breakdown of prey items (Adams and Nepenthes growers to see if other species
Smith 1977). Prey are attracted to the ofNepenthes contained mosquito larvae.
traps by a combination ofcues including The plants studied in this investigation
the release of extrafloral nectar, purple were maintained outdoors during the
markings on thebody and rim ofthe trap, warmer months and indoors during the
odors released by the decaying matter in winter months. Seventeen leaves were
the fluid-filled traps, and leaf morpholo- sampled from two A^. ventricosa plants at
gy. Some insects attracted to the traps the MBRS and leaves from one plant at
crawl along the lip of the cuplike leaves Fredericksburg, Spotsylvania County,
and fall into and drown in the liquid Virginia. At that location six additional
contents. In time they are degraded by species of Nepenthes were also sampled
a combination ofleaf-produced enzymes, including A^. ampullaria Jack., TV. alata
microorganisms, and associated inverte- Blanco, A^. rafflesiana Jack., A^. coccinea
brates. The invertebrates include rotifers. {{N. rafflesiana X A^. ampularia) X A^.
490 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
niirabilis (Lour.) Druce], N. albomargi- identified as Aedes albopictus (Skuse),
nata Lobb & Lindl, and A^. trimcata the Asian tiger mosquito (Darsie and
Macfarlane. Ward 2005).
All samples were collected in October, In addition to A^. ventricosa, six other
2004. Fluid in each leaf was stirred with species were sampled at the Fredericks-
a tapered spatula to re-suspend debris burg site, namely TV. ampullaria, N. alata,
and organisms. The suspended contents N. rafflesiana, N. coccinea, N. albomar-
were removed using a pipette (0.4 cm ginata, and TV. trimcata. None of the
internal diameter) with an attached water samples from these six species
rubber bulb. This material was placed contained mosquito larvae.
in a 50 ml conical plastic tube and Aedes albopictus was first documented
transported to the laboratory. in the United States in Harris County,
Samples were processed within 24 h of Texas, in 1985 (Sprenger and Wuithir-
collection. In the laboratory, each sam- anyagool 1986). The following year this
ple was assigned an accession number mosquito was detected throughout the
and was examined for mosquito larvae southeastern states. Authorities believe
using a dissecting stereo microscope. The the mosquito entered the United States
water was also checked for rotifers, several years before its first detection
copepods, and other invertebrates. based on its distribution and subsequent
Samples containing mosquito larvae spread. Aedes albopictus and other exotic
were transferred to 40 ml glass Syracuse mosquito species were intercepted in
dishes that contained 20 ml ofleafwater. shipments of used tires entering the
The larvae were fed brewers yeast. Each United States from Asia (Moore et al.
day the samples were checked and pupae 1988). Today this mosquito is well
were removed. Each pupa was reared established in the United States and has
individually in a 50 ml. screw cap, been documented in 26 states (Moore
conical centrifuge tube that contained 1999).
1 ml of leaf water. All specimens were In temperate climates, Ae. albopictus
labeled with individual accession num- overwinters in the egg stage (Lyon and
bers. The dates of pupation and emer- Berry 1991). The eggs are laid singly on
gence were recorded. Adult mosquitoes the sides of water holding containers.
were removed and frozen. The eggs usually hatch upon submersion.
Voucher specimens were preserved The larvae feed on fine organic matter in
and labeled N. ventricosa study [2004- the water. At room temperature and with
IX-27-(76 & 77; 2004-X-10-27]. They are adequate food supply, the larval stage
deposited at the Georgia Museum of lasts five to ten days and another two
Natural History, University of Georgia, days in the pupal stage.
Athens, Georgia. TheAsian tigermosquito is amajorpest
From the two A^. ventricosa plants at species. Adults feed opportunistically and
MBRS
the Station, out of 17 leaves aggressively during the daytime on hu-
sampled, five leaves contained 34 mos- mans, as well as a wide variety of
quito larvae and pupae. A total of 19 mammalian species, including natural
adults were reared out of this material, hosts for several arboviruses of humans
and the remaining larvae and pupae were and animals. For example, Ae. albopictus
preserved 70% ethyl alcohol. From the has been shown to be a competent vector
twelve leaves sampled from Fredericks- of La Crosse virus and dengue. Although
burg, one contained 16 mosquito larvae. not theprimaryepidemicvectorofdengue,
Twelve adults were reared from this it may be involved in the maintenance
material. All reared mosquitoes were cycle ofdengue (Moore et al. 1988).
VOLUME NUMBER
109, 2 491
Nepenthes ventricosa is native to the Nepenthes can be started from cuttings
Philippine Islands (Cheers 1992). The or from seed. Collectors frequently
natural distribution of Ae. albopictus amass large living collections ofmultiple
includes the Philippine Islands (Knight species and they are placed around
and Hull 1952). If the two species occur patios and backyards during the summer
naturally in the same area, they might be months. Unfortunately cultivated Ne-
associated together when introduced into penthes may provide breeding sites for
a new region of the world. the Ae. albopictus as well as other
Aedes albopictus is primarily found container-breeding species. In the fall,
along the edges of forests. In North local plants have to be brought indoors
America, it has quickly adapted to to protect them from freezing. Trimming
breeding in both natural and artificial the pitchers off is one easy method to
containers. In some situations, Ae. albo- prevent bringing mosquitoes indoors
pictus displaces existing species. For during the winter months.
We
example, interspecific experimental stud- express our thanks to Al Gustin
ies by Livdahl and Willey (1991) between and Mike Hammond for allowing us to
the eastern tree-hole mosquito, Ae. collect water samples from their living
triseriatus (Say) and Ae. albopictus, collections of Nepenthes species. We
showed the latter always prevailed. extend our appreciation to F. Christian
The presence of Ae. albopictus larvae Thompson, Systematic Entomology
in the leaves of A^. ventricosa documents Laboratory, ARS, USDA for identifying
the adaptability of this species to exploit the mosquitoes.
a variety of phytotelmata (structures
Literature Cited
formed by non-aquatic plants that im-
pound rainwater). Lounibos et al. (2003) Adams, R. M. and G. W. Smith. 1977. An SEM
reported that Ae. albopictus occurs in the survey of the five carnivorous pitcher plant
genera. American Journal of Botany 64:
water-holding tanks and axils of orna-
265-272.
mental bromeliads found in gardens in Buffington, J. 1970. Ecological considerations of
Florida. The numbers of Ae. albopictus the cohabitation of pitcher-plants by Wyeo-
in ornamental bromeliads were signifi- myia smithii and Metriocnemus knabi. Mos-
cantly higher in northern Florida sites quito News 30: 89-90.
Cheers, G. 1992. Letts Guide to Carnivorous
than southern sites. Plants of the World. Charles Letts & Co.
It is interesting that leaves from A^. Ltd, London, England. 172 pp.
ventricosa plants from two different loca- Clarke, C. M. 1997. Nepenthes ofBorneo. Natural
tions contained Ae. albopictus larvae. We History Publications (Borneo), Kota Kina-
havenoexplanationwhynoneofthewater- balu. 207 pp.
2001. Nepenthes ofSumatra and Peninsu-
filled leaves of the other species of Ne- lar. Malaysia. Natural History Publications
penthes contain mosquito larvae. One (Borneo), Kota Kinabalu. 326 pp.
hypothesiswouldbethattherearechemical Darsie, R. F. Jr. and R. A. Ward. 2005. Identifi-
cues that attract A. albopictus to A^. cation and Geographical Distribution of the
Mosquitoes of North America, North of
ventricosa or that the other species exhibit
some surface compound, possibly a wax, KitchMienxgi,coR..ULn.iv2e0r0s0i.tyFPoroedssWoefbFsloraindda,C3o8n3tapipn.er
that is a deterrent to the Asian tiger Habitats: The Natural History and Ecology of
mosquito. While collecting samples we did Phytotelmata. Cambridge University Press,
observe that many samples smelled putrid. 431 pp.
Closerinspection oftheleaves revealedthat Knight, K. L. and W. B. Hull. 1952. The Aedes
they contained large numbers of dead mosquitoes of the Philippine Islands. II.
Subgenera Skusea, Christophersiomyia, Geo-
insects primarily earwigs (Dermaptera). It skiisea, Rhinoskusea, and Stegomyia (Diptera:
appeared the leaves were eutrophic. Culicidae). Pacific Science 6: 157-189.
492 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
Livdahl, T. P. and M. S. Willey. 199L Prospects of disease vector. Journal of the American
an invasion: competition between Aedes albo- Mosquito Control Association 4: 356-361.
pictusandnativeAedes triseriatiis. Science253: Sprenger, D. and T. Wuithiranyagool. 1986. The
189 9L discovery and distribution ofAedes albopictus
Lounibos, L. P., G. F. O'Meara, N. Nishimura, in Harris County, Texas. Journal of the
and R. L. Escher. 2003. Interactions with American Mosquito Control Association 2:
nativemosquito larvaeregulate the production 217-219.
of Aedes albopictus from bromeliads in Flor-
ida. Ecoogical Entomology 28: 551-558. Richard M. Duffield and Phil Sheri-
Lyon, W. F. and R. L. Berry. 1991. Asian tiger dan. (RMD) Department of Biology,
mosquito. Ohio State University Extension Howard University, Washington, DC
Fact Sheet HYG-2148-98.
Moore, C. G. 1999. Aedesalbopictus in the United 20059, U.S.A. (e-mail: rduffield@
States: current status and prospects for future howard.edu); (PS) Meadowview Biologi-
spread. Journal of the American Mosquito cal Research Station, 8390 Fredericks-
Control Association 15: 221-227. burg Turnpike, Woodford, VA 22580,
Moore, C. G.. D. B. Francy, D. A. Eliason, andT.
P. Monath. 1988. Aedes albopictus in the U.S.A. (e-mail:meadowview(^pitcherplant.
United States: rapid spread of a potential org)