Control with Arthropods - Biological and Environmental Control of Disease Vectors - page 13

eat the older, larger mosquito larvae (Howard et
al ., 2007). Cyclopoid copepods (hereafter
copepods) can be very ef ective at reducing
mosquito populations; one copepod adult can
kill between 20 and 40 Stegomyia larvae per day
(Dieng et al ., 2002; Micieli et al ., 2002).
Mesocyclops preferentially eat Stegomyia larvae
instead of Anopheles and Culex (Marten and
Reid, 2007). A laboratory trial that placed 50
Stegomyia aegypti and 50 Culex pipiens larvae
together with one Mesocyclops adult female
found that after 72 h, 76% of Stegomyia and just
24% of Culex larvae had been killed (Micieli et
al ., 2002). In this way, Stegomyia populations
can be reduced by as much as 99-100% by
Mesocyclops copepods (Marten and Reid, 2007).
In addition to this intrinsic preference,
Mesocyclops are often used to control Stegomyia
dengue vectors, because they can readily live
and form stable populations in typical Stegomyia
breeding sites.
Copepods have many inherent char-
acteristics that make them ideal for biological
control of vector mosquitoes:
 They are found throughout the globe, so
their use does not require exotic introduc-
tions.
 They are hardy and can self-replicate readily
in most water containers.
 Although they are voracious mosquito
predators, they eat a variety of aquatic prey
and so the population can be sustained even
when mosquitoes are not present.
 No seriously adverse environmental ef ects
have been reported from the use of copepods.

with 400 blocks being protected during
transport by a lunch box. They were then
transported to various fi eld locations throughout
Vietnam using the postal system. On arrival at
the target destination, each foam block was
immersed directly into the water container, thus
releasing the copepods for colonization. Other
similar mass-production methods have been
outlined in a recent review (Marten and Reid,
2007). Even though copepod mass production is
relatively simple, it is not always necessary.
Copepods are found throughout the world and
many species are predatory. The fi rst step is
usually to collect native copepod species from
the area that requires Stegomyia control and
examine their predatory behaviour in the
laboratory. Once it has been determined that the
native species is predatory to Stegomyia larvae,
then these copepods can be collected from the
environment with a bucket and ladle and seeded
into Stegomyia breeding habitats. In this way,
repeat inoculations can be carried out even if
copepod populations are lost from habitats
during Stegomyia control programmes.
For the past 30 years, the potential of
copepods to control mosquitoes has been
examined throughout the world with a long
history of successful copepod use in Louisiana,
USA (Marten and Reid, 2007). However, most of
the large-scale fi eld trials specifi cally targeting
dengue vectors have been carried out in
Vietnam. This work was started just east of
Hanoi in northern Vietnam in 1993 (Nam et al .,
1998). The aim was to test whether Mesocyclops
copepods would be ef ective as the primary
control measure to control the abundant
St . aegypti population. The authors used two
villages (control and treatment), both with
approximately 400 houses and both with large
St . aegypti populations and a history of dengue/
dengue haemorrhagic fever epidemics. Within
the treatment village, all cement water tanks,
ceramic jars, backyard wells and other water
storage containers were treated with fi eld-
caught Mesocyclops . One year after Mesocyclops
introduction, the number of St . aegypti per
house had been reduced by 30-97% when
compared to the control village. Thereafter,
community involvement was solicited and the
environment cleared of recyclable breeding
habitats such as bottles, tyres and other peri-
domestic items. During 5 months of community-

 They can be mass produced and transported

cheaply and easily in the fi eld using unso-
phisticated equipment.

The last point is of particular importance
because many vector-borne diseases mainly
occur in rural areas in developing (and usually
resource-poor) countries that do not have ready
access to expensive and sophisticated equipment.
For Mesocyclops production in Vietnam, Nam et
al . (2000) used plastic garbage bins fi lled with
water, Paramecium and boiled wheat seed. After
standing for 1 week, the bins were inoculated
with 50 adult copepods. Three weeks later,
almost 5000 copepods were found in each bin.
Around 50 copepods were packed into
individually hollowed out polystyrene blocks,