Assessing pest control using changes in instantaneous rate of population increase: Treated targets and stable fly populations case study

The instantaneous rate of population increase was used to assess the ability of attractive targets coated with permethrin to control stable fly populations on 3 dairy farms in south central Ontario, Canada. Two attractive targets were deployed over 10 wk in 2001 at each of 6 dairy farms. Three farms were outfitted with 2 untreated targets and 3 were outfitted with 2 targets treated with permethrin [Ectiban-impregnated Coroplast (Ectiban: Schering-Plough Canada Inc., Pointe-Claire, Québec, Canada; Coroplast: Great Pacific Enterprises Inc., Granby, Québec, Canada)]. Population growth rate was measured in terms of degree-days above a 10°C developmental threshold (rDD10). The rDD10 at the 3 treated dairy farms were significantly lower than rDD10 at the 3 neighboring untreated dairy farms (mean rDD10: treated = 0.0088, untreated = 0.013), but not in the previous year when targets were not installed (mean rDD10: treated = 0.012, untreated = 0.015). This supports a long-term approach to management that lowers population growth rates in those regions where stable fly numbers increase exponentially from spring until winter, by shortening the period of economic impact of this pest.