The mosquito A. aegypti is the main urban
vector of dengue and yellow fever, arboviral
diseases that can spread rapidly in explosive
epidemics in South America. Oviposition traps (ovitrap)
provide a very sensitive and economical method
for detecting Aedes mosquitoes”) when the
population density is low, whereas general
larval surveys and adult collections produce
unsatisfactory results. The addition of grass
infusion in the ovitrap enhances significantly
the number of eggs collected, thus increasing
the trap efficacy. We evaluated grass infusions
aiming to identify the volatiles that attract
gravid Ae. aegypti female mosquitoes to
ovitraps. We screened infusions of four grasses
(Pennisetum purpureum; Panicum maximum; Cynadon
plectosa chyus and Cynadon dactylon) and the
results showed that P. maximum associated traps
collected a significantly higher number of eggs
than the control. Infusions of fresh and dried
leaves of P. maximum were also evaluated and
showed that the egg detection of ovitraps baited
with fresh leaves infusions was significantly
higher than other treatments. The volatiles from
grass infusions are likely to be produced by
microorganisms, as ovitraps baited with aerobic
fermentation collected significantly more eggs
than those with anaerobic and sterilized
infusions. The fermentation period and
concentration of infusions are also important to
produce a blend of active compounds. The
identification of the volatiles released from
grass infusions that attract gravid Ae.
aegypti female mosquitoes to ovitraps has
being carried out in order to use specific
synthetic chemicals to eliminate the need to
create infusions. We also evaluated in
laboratory and field, larval holding water as
oviposition attractant and in combination with
grass infusions. The highest? concentration of
larval holding water increased significantly the
number of eggs collected and a synergistic
effect was observed when both stimuli were
presented in combination. Video recordings of
the oviposition behavior of gravid A. aegypti
females showed that there is a pattern of
behavioral sequences during the pre-oviposition
and oviposition period. Discrimination between
oviposition attractants and stimulants, and how
gravid female mosquitoes exploit baited ovitraps
will be discussed. Supported by CNPq, FAPEMIG,
FUNASA, IFS (Sweden)
Index terms: Aedes aegypti,
infusions, oviposition stimulants.
Copyright:
The copyrights of this original work belong
to the authors (see right-most box in title
table). This abstract appeared in Session 4
– CHEMICAL AND PHYSIOLOGICAL ECOLOGY
Symposium and Poster Session, ABSTRACT BOOK
I – XXI-International Congress of
Entomology, Brazil, August 20-26, 2000.