COMPARATIVE INGESTION RATES OF CULEX-QUINQUEFASCIATUS (DIPTERA, CULICIDAE) SUSCEPTIBLE AND RESISTANT TO BACILLUS-SPHAERICUS

Larvae of laboratory and field-collected strains of Culex quinquefasciatus susceptible and resistant (37- and 31-fold, upon selection) to Bacillus sphaericus strain 2362 were studied for their ingestion rates of this pathogen and other particulate materials. Larvae of the resistant strains (laboratory and field-collected) ingested B. sphaericus preparation at significantly lower rates than did larvae of the susceptible strains. Larvae of the resistant strains also ingested B. sphaericus preparation at significantly lower rates than yeast (nutritious), while larvae of the susceptible strains ingested B. sphaericus preparation at the same or higher rates than yeast. The reduced ingestion rates on B. sphaericus in resistant strains could possibly serve as a behavioristic mechanism of resistance against this microbial larvicide. (C) 1995 Academic Press, Inc.