To study the potential for the emergence of resistance in
Aedes aegypti
populations, a wild colony was subjected to selective pressure with Cry11Aa, one of four endotoxins that compose the
Bacillus thuringiensis
serovar
israelensis toxin. This bacterium is the base component of the most important biopesticide used in the control of mosquitoes worldwide. After 54 generations of selection, significant resistance levels were observed. At the beginning of the selection experiment, the half lethal concentration was 26.3 ng/mL and had risen to 345.6 ng/mL by generation 54. The highest rate of resistance, 13.1, was detected in the 54
th generation. Because digestive proteases play a key role
in the processing and activation of
B. thuringiensis toxin, we analysed the involvement of insect gut proteases in resistance to the Cry11Aa
B. thuringiensis serovar
israelensis toxin. The protease activity from larval gut extracts from the Cry11Aa resistant population was lower than that of the
B. thuringiensis serovar israelensis susceptible colony. We suggest that differences in protoxin proteolysis could contribute to the resistance of this
Ae. aegypti colony.
