Download Symposium Susceptibility monitoring and resistance management

Symposium
Susceptibility monitoring and resistance management
Lysinibacillus sphaericus resistance in Culex pipiens in Salt Lake City, UT
T. Steven Su1, Greg White2, Ary Faraji2, Jennifer Thieme1, Taylor Lura1 and Min Lee Cheng1
1
West Valley MVCD, 1295 E. Locust St., Ontario, CA 91761.
2
Salt Lake City MAD, 2020 N Redwood Rd, Salt Lake City, UT 84116.
Bacillus sphaericus Neide, recently renamed as Lysinibacillus sphaericus Meyer and
Neide, is a spore-forming bacterium that possesses various levels of larvicidal activity against
some mosquito species. Products based on most active strains such as 2362, 2297, 1593, C3-41
that bear binary toxins have been developed to combat mosquito larvae worldwide. Resistance in
wild Culex mosquito populations has been reported since 1995 from France, Brazil, India, China,
Tunisia and USA. Laboratory studies to evaluate resistance development risk have been
conducted by many groups of scientists. Management tactics to prevent resistance development
and restoration of susceptibility to B. sphaericus have also been developed and implemented.
The use of product based on B. sphaericus strain 2362 has increased considerably since invasion
of West Nile virus. This report documents the second occurrence of high levels resistance to B.
sphaericus in a natural population of Cx. pipiens in north America, where resistance ratio was
12,988-25,975-fold at LC50 and 31,105-62,210-fold at LC90 as compared with susceptible
laboratory and field populations. Resistance management and susceptibility monitoring strategies
are discussed.