Essential oils as repellents of the Asian citrus psyllid

The Asian Citrus Psyllid, Diaphorina citri Kuwayama (Hemiptera:Psyllidae), is one of the most devastating pests of citrus. D. citri vectors the bacterium ‘Candidatus Liberibacter asiaticus’ (‘CLas.’), which is associated with the ‘Huanglongbing’ disease (HLB; Citrus Greening). Native to Asia, this pest and its associated bacteria have spread to other countries, including the United States. Adults and nymphs can transmit CLas when they feed on newly developed citrus leaves. Foliage dieback, asymmetrical chlorosis, seed malformation, stunted growth, bitter fruits, premature fruit drop, and decline of root abundance are symptoms observed on HLB affected trees. The disease can progress with time and may eventually cause tree death. HLB management consists primarily of foliar insecticide applications for the psyllid vector. However, this strategy is not a sustainable long-term solution. Environmental contamination, mortality of beneficial organisms, and the development of chemical resistance by populations of psyllids are some of the challenges facing current management practices. To this end, volatiles from botanical oils have been found to discourage D. citri feeding on citrus. A cost-effective odorant delivery device for botanical oil volatiles, such as lavender, citronella, thyme, and fir oil, shown to deter psyllids is currently in development. The goal of this project is to evaluate the efficacy of this product for a subset of predetermined volatiles in a controlled laboratory setting.