Issues affecting the use of pheromones and other semiochemicals in orchards

Abstract

Pheromones represent one of the major components of ecologically based orchard pest management. This paper reviews recent progress and highlights outstanding issues. The greatest use of pheromones has been as lures for moth to traps, although identification of attractants for other insect groups is permitting diversification. Sex pheromone traps have been widely used for decision support, usually with thresholds for intervention using either broad-spectrum, or more recently, selective insecticides. Many of the issues associated with this type of application have been resolved, but new trapping systems need to ensure that lure longevity, trap efficiency, and other factors (e.g. interpretation, thresholds) are addressed. The use of kairomones (inter-specific cues) as lures in traps raises analogous issues. Attractants for beneficials (such as sex pheromones of wasp parasitoids) can offer additional benefits, including demonstrating the level of abundance or synchrony of the biological control agent with the target pest. Pheromones have also enjoyed considerable success for direct control of orchard pests, mainly through mating disruption. The technical and biological issues have been more challenging in direct control applications. There remain major knowledge gaps in the amount of pheromone required to achieve disruption, as well as the plume structure and behavioural mechanisms that operate with different types of formulations, blends and delivery systems. There has been a recent upsurge of interest in lure and kill tactic internationally. The challenges associated with direct control by mass trapping, lure and kill or lure and infect tactics need further research.