Monitoring populations of Phthorimaea operculella in potato fields and in storage in Senegal

This study provided information on periods of peak trapping for the potato tubermoth (Phthorimaea operculella) in potato fields and in storage facilities in the Niayes area of Senegal. Delta sticky traps baited with P. operculella synthetic pheromone, IT053 ISCA lure, were used to monitor adult male moth populations in 2011 and 2012. In each trapping year, four peaks were observed with the maximum number of moths recorded in February, 2012. A Weibull regression model was developed to predict the incidence of P. operculella in potato fields using the number of male adults caught in pheromone-baited traps. The Weibull model provided a good fit to percentage cumulative mean trap catches for both 2011 and 2012 (R-2 = 0.99; P < 0.0001). Based on the Weibull models for the sampling periods in 2011 and 2012, 50% of cumulative mean number of moths were trapped by day 85 (26 March) in both years, 63.2% (= alpha) were trapped by day 103 and 104 (13 April and 14 April), and 95% were trapped by day 179 and 190 (28 June and 9 July), respectively. Male moths continued to be trapped after potatoes were harvested, but the numbers decreased compared to captures before harvest. This information will be useful for predicting the most appropriate times to institute intervention measures to mitigate damage to potatoes by the moth. Laboratory investigation revealed that abandoned tubers in the field were the source of sustained incidence of the moth on farms following the harvesting of potatoes. The number of male moths trapped in stores tapered with the number of weeks the bagged tubers stayed in storage.