DEVELOPMENT AND USE OF PHEROMONES FOR MONITORING LEPIDOPTERAN FOREST DEFOLIATORS IN NORTH-AMERICA

Pheromone-baited traps are increasingly used in forestry to detect and monitor infestations of lepidopteran defoliators. Pheromone-based detection surveys, as exemplified by gypsy-moth trapping in Canada, are designed to indicate the presence and geographical distribution of pests and trigger other surveillance techniques, such as ground searches for egg masses. Pheromone monitoring systems are designed to quantitatively assess insect populations and provide early warning of outbreaks or damage. Key elements in developing monitoring systems are selection of trap design and lure potency that are effective over a wide range of population densities without trap saturation, and establishment of criteria for interpreting trap catches. Examples of recently developed pheromone monitoring systems for three serious forest pests, the Douglas-fir tussock moth, Orgyia pseudotsugata, the western spruce budworm, Choristoneura occidentalis, and the spruce budworm, C. fumiferana, are examined in detail.