Efficacy of ivermectin jetting fluid against strike by some primary and secondary blowflies of sheep.

Merino sheep, which were hand jetted with ivermectin jetting fluid, and untreated sheep were challenged with larval implants of Lucilia cuprina, Lucilia sericata, Calliphora nociva and Chrysomya rufifacies at intervals of about 2 weeks from 6 to 16 weeks after treatment. Both Lucilia species produced strike rates of about 90% in untreated sheep; the respective rates were lower for Chr rufifacies (55%) and C nociva (60%). Strike rates for the treated group were about 17, 11, and 9% for L cuprina, L sericata, and Chr rufifacies, respectively. Only 1 implant site in the treated group was struck by C nociva. Treated sheep had significantly (P < 0.01) longer time to first strike than did untreated ones for each species of fly. L sericata, Chr rufifacies, and C nociva larvae implanted on treated animals had significantly (P < 0.05) longer time to first strike than did L cuprina larvae.