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512
JounNu, oF THEAunRrclu Moseuno CoNrnol Assocrlrror.r
VoL.3,No.3
SEASONAL SIZE VARIABILITY IN CULICOIDES VARIIPENNIS
(DIPTERA: CERATOPOGONIDAE)IN SOUTHERN CALIFORNIA
BRADLEYA. MULLENS
Departmentof Entornolngy,Uniuersityof California,Riuersi.de,
CA92521
Adult body size is an important consideration
in assessingvector potential in blood-feeding
Diptera. Nasci (1986), for example, demonstrated a significant positive relationship be- E
tween body size and parity in Aedes uexans
(Meigen) and Cul.exsalinarius Coquillett, and
the trend was evident also for Ae. antlnnticus '
(Dyar and Knab) and Psorophora columbiae
(Dyar and Knab). Within the Ceratopogonidae,
adult female body size has been positively cortrend (Octoberl982-September
Fig. 1. Seasonal
related with fecundity in field-collected Culicoidesfurens (Poey) (Linley et al. 1970), C. 1983)in averagewing lengthsof femaleCulicoides
pondin
mell.eus(Coquillett) (Linley and Hinds 1976) uariipenniscollectedneara dairy wastewater
(air) are mean
and C. insignis Lutz (Kramer et al. 1985). Gen- RiversideCounty,CA. Temperatures
precedingeach
for a 10dayperiodimmediately
erally, the size of adult Culicoidesis inversely values
collection.
related to habitat temperatures (Linley et al.
1970,Linley and Hinds 1976,Akey et al. 1978,
suction traps. The study area was near a large
Mullens and Rutz 1983,Kramer et al. 1985).
in
Chino Basin near
Laboratory studies have shown that larger dairy wastewaterlagoon the
are provided in Mullens
adult females of C. uariipennrs (Coquillett) are Riverside,CA; details
(1985).Femaleswere sorted from each collecmore fecund and survive better than smaller
a single wing of each was measured
individuals(Akey et al. 1978).Wirth and Jones tion, and
arculus to the tip using a dissectbasal
the
from
(1957) noted that C. uariipennisfrom cool rewith an ocular micromgions of the U.S. were larger than those from ing microscopeequipped
in
which wings of 25 fecollections
Only
eter.
warm regions and also observedthat specimens
here, with the
reported
are
measured
were
males
from the same area were larger during cooler
(12 females)and De27
of
October
exception
periods of the year. I am aware of only 2 field
2 (17 females).
studies that examined seasonalsize variability cember
trend in wing length was very
The
seasonal
in detail in C. uariipennis. Zimmermanr and
(Fig.
1). The Iargest females (wing
distinctive
Linhares2both indicated that larger females of
were collectedon February 9,
mm)
2.02
Iength
this specieswere found in cooler periods of the
(wing length 1.48 mm) were
the
smallest
while
adult flight seasonin southwesternVirginia and
7. Pooling all collections,
on
September
collected
northern California, respectively. Linhares adyearly C. uariipennis wing length was
average
uariipen'
C.
that
larger
demonstrated
ditionally
mm. The seasonaltrend in adult size (as
nls were more fecund.The purposeof the pres- 1.73
by wing length) clearly was inversely
indicated
ent study was to document seasonalchangesin
air temperature. Figure 1 indicates
to
related
adult size of C. uariipennis in southern Califorair temperatures for the 10 day period
average
nia.
immediately preceding each collection' as reAdults of C. uariipennis were collected at 1-3
corded at the University of California at Riverweek intervals throughout the year (October
side. Temperatures of the larval habitat (mud)
1982to September1983)using small COz-baited
do not necessarilycorrespondexactly to air temperatures. Adult C. uariipennis size (y) was inl Zimmerman, R. H. 1981.Seasonalabundanceand fluenced (P < 0.001) bv air temperatures(x.)'
host preferenceof Culicoidesin Virginia: with empha- however, as described by the regression equafor this
sis oi the ecology of Culicoi.desuariipennis (Diptera: tion, y = 2.24 - 0.026 x (r2 : 88.7Vo\,
Ceratopogonidae).pl.n. dissertation, Virginia Poly- data set. This pronouncednegative regression
technic Institute and State University, Blacksburg' of adult size on temperature is similar to rela188pp.
of C. furens
'Linhare", A. X. 1984. The biology of Culicoides tionships observed in field studies
(Linlev
and Hinds
(Linley
C.
melletts
1970),
et
al.
uariipennis(Coquillett) (Diptera: Ceratopogonidae)in
insignis (Kramer et al. 1985).The
C.
and
1976)
of
University
dissertation,
Ph.D.
Califoinia.
nortirern
actual sizesof the field-collected C. variipennis
BerkeleY.153
California,
PP.
SEPTEMBER1987
OppnltroNer, eNo Scrputrrlc NorEs
513
Kramer, W. L., E. C. Greinerand E. P. J. Gibbs.1985.
Seasonal variations in population size, fecundity,
and parity mtes of Culiroides insignis(Diptera: Ceratopogonidae)in Florida, USA. J. Med. Entomol.
22:163-169.
Linley, J. R., H. T. Evans and F. D. S. Evans.1970.A
quantitative study of autogenyin a naturally occuring population of Culicoidesfurens (Poey) (Diptera:
Ceratopogonidae).J. Anim. Ecol. 39:169-183.
Linley, J. R. and M. J. Hinds. 1976.Seasonalchanges
in size, female fecundity and male potency in CuIicoidesmelleus (Diptera: Ceratopogonidae).J. Med.
Entomol. 13:151-156.
Mullens, B. A. 1985. Age-related adult activity and
sugar feeding by Culicoides uariipennis (Diptera:
Ceratopogonidae)in southern California, USA. J.
Med. Entomol. 22:32-37.
Mullens, B. A. and D, A. Rutz. 1983.Development of
immature Culicoi.desuariipennis (Diptera: Ceratopogonidae) at constant laboratory temperatures.
Ann. Entomol. Soc.Am. 76:747-751.
REFERENCES CITED
Nasci, R. S. 1986. Relationship between adult mosAkey,D. H., H. W. Potterand R. H. Jones.19?8. quito (Diptera: Culicidae) body size and parity in
Effectsof rearingtemperature
andlarvaldensityon
fi eld populations. Environ. Entomol. 15:874-876.
longevity,size, and fecundityin the biting gnat Wirth, W. W. and R. H. Jones. 195?. The North
Culicoidesuariipennis.Ann. Entomol. Soc. Am.
American subspecies of Culicoides uariipennis.
7l:4Il-418.
USDA Tech. Bull. 1170.35 pp.
in this study, relative to approximate mean temperatures,are fairly similar to those observedby
Mullens and Rutz (1983) for laboratory-reared
individuals of this species in New York. For
example, female C. uariipennis reared at 20'C
had an averagewing length of 1.79mm (Mullens
and Rutz 1983),while field-collectedC.uariipennis from mid-June and late October (ca. 20"C
air temperature) in the present study had average wing lengths of 1.71 and 1.69 mm, respectively. As discussedby Linley and Hinds (1976),
larger adult size during cooler months likely
reflects a prolonged period of larval development. This may serve to defer adult emergence
during cool periods and improve the survival
and reproductive capabilities of those adults
that do emergeat this time.
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