Efficient mass trapping: catching the pest, Calliphora vicina, (Diptera, Calliphoridae), of Norwegian stockfish production.

Attracting high numbers of adult females, extensive trapping prior to damage, and a pest species with a predominantly univoltine lifecycle, are important factors contributing to the success of mass-trapping programs. We conducted a mass-trapping experiment over 4 years, using yellow sticky traps and odor-baited funnel traps for control of the blowfly Calliphora vicina in stockfish production areas in Loften, Norway. Blowfly-related damage to fish in five mass-trapping sites was compared with damage at five control sites. Population monitoring established a connection between blowfly activity and damage. Blowfly activity in the period from mid-April to mid-May was correlated with damage to fish in the same year. Interception (sticky) traps, based on visual cues, caught blowflies during the early drying period, whereas odor-baited funnel traps were more effective during the later drying period, and continued to catch flies throughout the year until late autumn. In the funnel traps, 80% of the captured flies were females. Compared to control sites, mass trapping reduced overall damage to stockfish by 8-31%. In the final year of the experiment, we compared mass-trapping and control treatments, controlling for drying time period and sun exposure (which both contribute to damage), and found a damage reduction of 63%. Thus, mass-trapping with a female-attracting kairomone, and using traps of different functionality to extend the critical trapping period, in accord with pest phenology, is an efficient method for control of C. vicina in stockfish production.