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been shown to be another ef ective method of
collecting Cx. quinquefasciatus (Muturi et al. ,
2007) and, as gravid traps collect mosquitoes
that have previously taken at least one blood
meal, they are more likely to collect infected
mosquitoes. A comparison of dif erent types of
commercially available gravid traps performed
in a LF-endemic country, Tanzania, demon-
strated that the CDC gravid traps collected
signifi cantly more gravid Cx. quinquefasciatus
mosquitoes than the Frommer Updraft, Reiter-
Cummings and Harris County gravid traps (Irish
et al ., 2013).
One limitation of gravid traps is that they
typically use a plant infusion beneath the trap to
attract gravid mosquitoes searching for a
suitable oviposition site (see Lorenz et al .,
Chapter 4, this volume). Organic infusions are
pungent (Santos et al. , 2010), can be dii cult to
transport to the trap sites and, as their
attractiveness changes over time (Isoe et al. ,
1995), make direct comparisons between
studies dii cult. The use of an optimum synthetic
lure could reduce the smell, as found in one
study (Leal et al. , 2008), facilitate the logistics of
trap placement, and improve the standardization
of odours. To the best of our knowledge, no
synthetic lures are in widespread use by
organizations responsible for monitoring LF
transmitted by Cx. quinquefasciatus . However, a
synthetic attractant, AtrAedes lure, is currently
used in a large-scale monitoring programme in
Brazil (Eiras and Resende, 2009), in
MosquiTRAPs, for the collection of Stegomyia
aegypti , a vector of dengue (Braga and Valle,
2007). As AtrAedes lure was derived from
chemicals isolated from grass infusion (Favaro et
al. , 2006), and as grass infusions are attractive
for Cx. quinquefasciatus , it might also be ef ective
for C x. quinquefasciatus . Initial trials of
MosquiTRAPs (using the AtrAedes lure) for
collection of Cx. quinquefasciatus in Tanzania
were not successful (Thornton, 2011), but it was
not clear whether this was due to the type of trap
or to the lure. A recent study evaluated the use
of the AtrAedes lure for collection of Cx.
quinquefasciatus in CDC gravid traps and found
that it did not signifi cantly improve catches
compared with tap water, so it was concluded
that grass infusion remains the most ef ective
and cost-ef ective attractant for xenomonitoring
programmes where large numbers of mosquitoes
are required (Irish et al ., forthcoming). One
important logistical fi nding is that smaller
volumes of grass infusion (2 l) can be used,
rather than standard operational volumes (4 l),
without signifi cantly af ecting the number of
gravid Cx. quinquefasciatus collected in CDC
gravid traps (Irish et al. , 2012).
Stegomyia mosquitoes
As Stegomyia mosquitoes are active during the
day, common trapping methods, such as CDC
light traps, used for other mosquito genera, will
be inef ective. Surveillance and monitoring tend
to rely on the exploitation of their oviposition
behaviour, and much research has been per-
formed to optimize oviposition cues (visual or
chemical) with dif erent ovitraps or gravid traps.
Stegomyia , like Culex mosquitoes, respond to the
presence of conspecifi c immatures. For example,
it was shown, using two-choice laboratory
bioassays, that gravid St. aegypti , unlike St.
albopicta , oviposited more eggs on strips of paper
containing conspecifi c and heterospecifi c eggs
than blank fi lter paper controls, but both species
oviposited more on larval rearing water from
St. albopicta compared with water controls
(Allan and Kline, 1998). In contrast, other
investigators found that gravid St. aegypti laid
around four times as many eggs on S t. aegypti
larval rearing water than on St. albopicta larval
rearing water, but laid similarly high numbers
of eggs on mixed species larval rearing water
(Nunes Serpa et al. , 2008). The chemical
heneicosane was identifi ed as an oviposition-
attractant pheromone of larval origin in St.
aegypti (Mendki et al. , 2000), and dodecanoic
and (Z)-9-hexadecenoic acids were identifi ed as
egg-derived oviposition attractants (Ganesan et
al. , 2006). Following dif erent bioassays and
electrophysiological studies, it was proposed that
application of n-heneicosane at 10 ppm (10 mg
l −1 ) to oviposition sites may be useful for
attracting gravid St. aegypti mosquitoes to
ovitraps for surveillance and monitoring
(Seenivasagan et al. , 2009). Acute toxicity tests
were performed on doses of n-heneicosane,
combined with the IGR difl ubenzuron, and it was
shown that, although toxic to Stegomyia , the
formulation exhibited extremely low mammalian
toxicity (no observed adverse ef ect level was
more than 500 mg kg −1 ) (Bhutia et al. , 2010).
 
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