ISSN:
1365-2109
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
This research assessed the effects of two chemicals, cypermethrin (Excis) and azamethiphos (Salmosan), used in the treatment of sea lice Lepeophtheirus salmonis (Kroyer) on American lobster Homarus americanus H. Milne Edwards larvae under laboratory conditions. Larvae were exposed to concentrations of 5, 0.5, 0.05, 0.005 and 0 p.p.b. cypermethrin and 100, 10, 1, 0.1 and 0 p.p.b. azamethiphos for durations of 5, 30 and 60 min, 6 and 12 h in artificial seawater. Both treatment chemicals caused significant mortality (P 〈 0.05) of the lobster larvae below the recommended treatment doses of 5 p.p.b. cypermethrin for 1 h and 100 p.p.b. azamethiphos for 1 h. Temperature affected mortality significantly (P 〈 0.05). and interactions between treatment duration and treatment concentration were also significant (P 〈 0.05). LC50 values calculated for the treatment durations ranged from 0.66 to 0.058 p.p.b. at 10 °C and 1.69–0.365 p.p.b. at 12 °C for cypermethrin, and 33.9–1.3 p.p.b. at 10 °C and 50.4–0.9 p.p.b. at 12 °C for azamethiphos treatment, at the above treatment durations. The lowest LC50 values correspond to ≈ 1/90th of the recommended treatment dose for cypermethrin (Excis) at 12 °C and 1/14th at 10 °C; and 1/110th of the recommended treatment dose for azamethiphos (Salmosan) at 12 °C and 1/75th at 10 °C. The research determined variations in observed behavioural treatment effects on lobster larvae exposed to both cypermethrin and azamethiphos (temperature × treatment duration × treatment concentration; cypermethrin P 〈 0.001, azamethiphos P = 0.008). The pattern of effects that occurred at each temperature were, however, similar (cypermethrin P = 0.764; azamethiphos P = 0.218), and ‘intensity of effect’ of the treatment chemicals was positively correlated with an increasing treatment concentration high (r2 = 0.915, r2 = 0.905).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1046/j.1365-2109.1999.00372.x
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