Mosquito-borne pathogens are the cause of important, often deadly diseases
worldwide; and, use of repellents is one of the components of mosquito control programs.
The most effective mosquito repellent is N,N-dimethyl-m-toluamide, known as DEET.
Speculation on the adverse effects of DEET have been on the rise since the 1980s, and
manufacturers are searching for a safe and long lasting insect repellent that may be used
on the skin as well as possess spatial applications.
Olfactometers used in the bioassays for evaluating repellents usually do not
measure repellency, but rather measure non-attraction. Therefore, I designed a novel
olfactometer that divides host-seeking behavior of mosquitoes into attraction and
repellency at close range. I compared my olfactometer with another similar olfactometer
and found no difference when attraction was measured. However, the new olfactometer
assesses true repellency. I also added a new term to the terminology of host-seeking
behavior, that is 'inhibition'. Inhibition occurs in combination with at least two
chemicals and causes failure of mosquitoes to respond to a previously attractant stimulus.
I evaluated 80 inert and active ingredients of commercially available products on
eleven volunteers and determined that four were true repellents.
I unexpectedly discovered that DEET did not attract nor repel the mosquitoes
when applied on skin. I conducted a series of experiments to elucidate the behavioral
mode of action of DEET. Lactic acid was used as a control attractant. I demonstrated
that DEET attracted mosquitoes in the absence of a host. When DEET was combined
with lactic acid, it neither repelled nor attracted mosquitoes. I concluded that DEET
works in combination with lactic acid on the skin by inhibiting lactic acid, rather than
being a true repellent.
In this study, I developed a novel device measuring attraction, repellency and
inhibition. I contributed to the mode of action of DEET by proving that DEET is not a
repellent but an inhibitor, and I identified five true repellents that are worth consideration. / Graduation date: 1998
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/33856 |
| Date | 18 February 1998 |
| Creators | Do��an, Elif Barc��in |
| Contributors | Rossignol, Philippe A. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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