Biological fitness of a Culex quinquefasciatus population and its resistance to Bacillus sphaericus.

Biological fitness components of a field-collected colony of Culex quinquefasciatus Say that was highly resistant to Bacillus sphaericus strain 2362 (resistance ratio greater than 163,000) after 46 generations of selection were compared to those of a susceptible colony (CqSF) that had originated from the same parental cohort but that had not been exposed to B. sphaericus. The effect of B. sphaericus on the fitness of Cx. quinquefasciatus was determined in terms of fecundity, fertility, and development time. The resistant colony (CqRL) showed significantly lower fecundity and fertility, and slower development than the susceptible colony. Development time from egg to egg showed a 20% increase in CqRL compared to CqSF. The generation time increased from 21.6 days to 26 days for highly resistant generations of CqRL.