Da. Dame et al., MOSQUITO (AEDES-TAENIORHYNCHUS) RESISTANCE TO METHOPRENE IN AN ISOLATED HABITAT, Journal of the American Mosquito Control Association, 14(2), 1998, pp. 200-203
Salt-marsh mosquitoes (Aedes taeniorhynchus), collected on 2 barrier i
slands in Lee County, Florida, that had been treated from 1989 to 1994
with 150-day methoprene briquets, were bioassayed with technical s-me
thoprene in the laboratory. Susceptibility of the indigenous Captiva s
train (median lethal concentration [LC50] estimate, 6.71 ppb) collecte
d from Captiva Island was 14.9-fold lower than the naive Flamingo stra
in (LC50 estimate, 0.45 ppb) from Everglades National Park. The Lover'
s Key strain (LC50 estimate, 6.66 ppb) was 14.8-fold less susceptible
than the naive strain. Determinations of the susceptibility of nearby
foci of the mainland mosquitoes exposed in the past several years to m
ethoprene have not been completed, but probit analysis of laboratory e
xposures revealed that the only mainland strain tested (Burnt Store) w
as no less susceptible (1.06-fold) than the naive Flamingo strain. The
se findings support the theory that the observed resistance might be r
estricted to the barrier islands. The known resistance foci (generated
with briquet formulations) are located west of the mainland where the
re is minimal likelihood of inflow of genome from the mainland. On the
other hand, the mainland mosquitoes, which were exposed to liquid for
mulations of methoprene from 1987 to 1994, are believed to have substa
ntial gene flow between exposed and nonexposed populations and thus a
reduced likelihood of selection for resistance.