Repellency effect of volatile compounds against the potato psyllid, Bactericera cockerelli (Sulc)

The potato psyllid, Bactericera cockerelli (Sulc), is a polyphagous pest that can reproduce on a wide variety of host plant species, including potato, in different regions around the world. In potatoes, direct feeding of this pest causes retarded growth, chlorosis, distorted leaves and small tuber production. It also transmits the bacterial pathogen “Candidatus Liberibacter psyllaurous” that causes a disease in potatoes known as Zebra Chip. Zebra Chip has caused millions of dollars in losses to the potato industry in the USA. The most common method to control B. cockerelli is the application of foliar chemical insecticides, but repeated applications may lead to pesticide resistance. We therefore explored repellents as alternative method of control. The behavioral response of psyllid adults to 12 essential oils and 3 natural insecticides was studied in a glass Y-tube olfactometer. Six different doses (2000, 1000, 500, 100, 10 and 1 μl) were used for each material. Only four of the essential oils (cedar wood, thyme, lime and savory) had a repellent effect on the psyllids at all doses and this effect was residual for more than 15 days except with cedar wood oil. Future work will include field experiments with the most effective essential oils that demonstrated a strong repellency to B. cockerelli adults in the laboratory.