Field study area
The field study was conducted on the Loyola College campus,
Nungambakkam (an urban area), located in the Chennai District of
Tamil Nadu, southern India, during January 2013. This field site
contains many breeding areas for different species of mosquitoes in
the genera Anopheles, Culex, Aedes, Armigeres, and Mansonia. The
usual sunset time in this area is 18:30 h.
Field repellent assay
The best repellent cream formulation recognized in the laboratory
study (CF2) and DEET (12%, w/w) were tested against a field population
of mosquitoes according to an established method with slight modifications
(Kamsuk et al., 2006). For each test, 5 mg/cm2 of cream formulation
(CF2) and 5 mg/cm2 of DEET cream (12%, w/w) were taken as
test concentrations and smeared evenly on an exposed region of each
volunteer's legs (knee to foot) and arms (elbow to wrist). The experiments
were tested in triplicate both during the day (14:00–17:00 h)
and at night (19:00–22.00 h). One volunteer served as the control (no
repellent) and another volunteer served as the standard reference
control (DEET-12%, w/w). Untreated areas on the volunteers were
protected from mosquito bites by clothing, including headnets and
gloves. Both test and control volunteers exposed both legs and hands
for 180 min (3 h). All mosquitoes landing on the legs and hands of
each volunteer were continuously captured using a manual aspirator
before the proboscis could be inserted. We ensured that no mosquitoes
were able to bite the volunteers. The collected mosquitoes were