Vector Control Using Semiochemicals - Biological and Environmental Control of Disease Vectors - page 107

these odours are not as marked as those found
by morsitans group tsetse fl ies and further
research is underway, using couple gas
chromatography and electroantennography, to
identify other putative attractants from these
hosts so that new baits for palpalis group tsetse
fl ies could be produced in the future (Rayaisse et
al. , 2010).

concept of transferring this technology to
mosquitoes and other arthropods (e.g. Culicoides )
is a relatively new idea. For this to become
successful, a thorough understanding of the
ecology, biology and behaviour of the target
insects and their hosts is required (Kline, 2006).
Scientists have made much progress in this
respect in recent years, particularly for An.
gambiae mosquitoes, but mosquitoes still present
a challenge far greater than tsetse fl ies when it
comes to mass trapping. Mosquitoes breed
quicker and produce more of spring than tsetse.
They also have a greater diversity and travel
greater distances. Much of the successful mass
trapping with mosquitoes has been done on
islands, however, it remains to be seen whether
mass trapping could be used ef ectively on the
mainland.

6.3.2 Mosquitoes

Mass trapping of mosquitoes has been trialled
several times, with some success particularly in
Florida (USA) using Mosquito Magnet traps (see
Kline, 2006, 2007 for review). Mass trapping
has been done on several small islands in Florida
using MM-X traps where vast populations of
Ochlerotatus taeniorhynchus are a major nuisance
problem. In addition to the CO 2 and water
vapour generated by the combustion of propane,
each trap was also baited with 1-octen-3-ol.
MM-Pro traps were placed within an area of 23
acres (approximately one per square acre) and
the traps were modifi ed to collect mosquitoes in
an 11.5 l container instead of the standard net
due to such high numbers. Within 16 months,
the population pressure on the island was
reduced signifi cantly by approximately 80 to
90% - a level at which unmodifi ed traps with
smaller nets could be used (Kline, 2006). In
another study, the Salt Lake City Mosquito
Abatement District used the MM-Pro to target
Oc. sierrensis , a tree-hole mosquito species
(Hougaard and Dickson, 1999). When surveyed
by telephone, homeowners responded that the
MM-Pro traps had helped and that the
mosquitoes were under control. However, there
are also examples of where mass trapping has
failed to reduce populations of mosquitoes. For
example, assessed Mosquito Magnet® traps
were tested in Manitoba (Canada), Florida and
Louisiana (USA) and showed no signifi cant ef ect
on mosquito populations (Cilek and Hallmon,
2005; Collier et al. , 2006; Henderson et al. , 2006;
Smith et al. , 2010). Similarly, a study designed to
trap Culicoides midges using Mosquito Magnet
Pro traps at homes in Panama City, Florida, were
inef ective (Cilek and Hallmon, 2005).
Thus, the concept of using semiochemical-
baited traps and targets for trapping has been
clearly demonstrated for tsetse fl ies and the

6.4 Future Prospects

Direct control of pathogen vectors will grow in
importance. Even if vaccines for certain diseases,
currently proving intractable, become available,
and if the problems of cost associated with
medicines for pathogen control are solved,
vector control will remain as a major component
of integrated human and animal disease
management. Currently, the main tools, which
involve principally insecticides, are beginning to
fail through continued delivery problems,
growing target site and metabolic resistance,
and more recently behavioural resistance.
Specifi cally for malaria control, but with future
likely needs relating to other diseases with this
type of infection mode, personal protection will
be important. Although insecticides can be
highly selective and have high levels of safety
to most human and other animal individuals,
the potential for misuse and unexpected
susceptibility as a consequence of genomic
variation places even more pressure on further
development of intrinsically non-toxic solutions
such as is of ered potentially by semiochemicals.
The development of host and oviposition
site attractants for lure and kill systems is well
under way. However, a push-pull or stimulo-
deterrent diversionary strategy would maximize
the impact of the attractive semiochemicals by
integration with a repellent or anti-biting action.
We have a wide range of repellents, including