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Sea lice population and sex differences in P‐glycoprotein expression and emamectin benzoate resistance on salmon farms in the Bay of Fundy, New Brunswick, Canada
Author(s) -
Igboeli Okechukwu O,
Burka John F,
Fast Mark D
Publication year - 2014
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/ps.3620
Subject(s) - emamectin benzoate , bay , biology , population , fishery , zoology , ecology , geography , pesticide , demography , archaeology , sociology
BACKGROUND Parasitic sea lice are a major challenge for salmon aquaculture. This is especially due to the recent development of resistance to emamectin benzoate ( EMB ) in the parasite. We investigated: (1) whether EMB treatment success in Grand Manan, Bay of Fundy, NB , Canada can be explained through EMB bioassay and P‐glycoprotein (P‐gp) mRNA expression studies; (2) if other populations of sea lice not under EMB selective pressure possess similar EMB sensitivity as Grand Manan sea lice populations; and (3) the heritability of EMB resistance in Lepeophtheirus salmonis . RESULTS EMB bioassay results indicated population, species, sex and temporal differences in EMB EC 50 values. RT‐qPCR analyses revealed population and sex differences in P‐gp mRNA levels, correlating with the bioassay results. Laboratory‐reared sea lice maintained their EMB sensitivity status up to the F3 generation. Caligus elongatus , collected from Grand Manan showed more than twofold lower EMB EC 50 values compared with L. salmonis collected from the same site. Concurrent exposure to EMB and verapamil yielded no increase in C. elongatus sensitivity to the parasiticide . CONCLUSION Sea lice bioassay and P‐gp mRNA studies can be used to track EMB resistance and sex differences in EMB sensitivity and P‐gp mRNA levels exist in the parasite. © 2013 Society of Chemical Industry