Bacterial insecticides have been used for the control of
nuisance and vector mosquitoes for more than two
decades. Nevertheless, due primarily to their high cost and
often only moderate efficacy, these insecticides remain of
limited use in tropical countries where mosquito-borne
diseases are prevalent. Recently, however, recombinant
DNA techniques have been used to improve bacterial
insecticide efficacy by markedly increasing the synthesis of
mosquitocidal proteins and by enabling new endotoxin
combinations from different bacteria to be produced
within single strains. These new strains combine
mosquitocidal Cry and Cyt proteins of Bacillus
thuringiensis with the binary toxin of Bacillus sphaericus,
improving efficacy against Culex species by 10-fold and
greatly reducing the potential for resistance through the
presence of Cyt1A. Moreover, although intensive use of B.
sphaericus against Culex populations in the field can result
in high levels of resistance, most of this can be suppressed
by combining this bacterial species with Cyt1A; the latter
enables the binary toxin of this species to enter midgut
epithelial cells via the microvillar membrane in the
absence of a midgut receptor. The availability of these
novel strains and newly discovered mosquitocidal
proteins, such as the Mtx toxins of B. sphaericus, offers the
potential for constructing a range of recombinant
bacterial insecticides for more effective control of the
mosquito vectors of filariasis, Dengue fever and malaria.