Repellency of forty-one aromatic plant species to the Asian citrus
psyllid, vector of the bacterium causing huanglongbing
Huanglongbing (HLB) is the most devastating citrus disease worldwide.
The causal organism of the disease is spread by an insect vector,
Diaphorina citri, commonly known as Asian citrus psyllid (ACP). Current
management of HLB relies either on physical removal of the infected
plants or on chemical control of ACP. Both methods are not overly
effective and costly. In addition, public concerns regarding insecticide
residues in fruit have greatly increased in recent years. It has been
hypothesized that plant volatiles could act as repellents to ACP, thus
reduce the incidence of HLB. To test this hypothesis, the repellency of
fresh tissues of 41 aromatic plant species to ACP was investigated. The
repellency of individual species was determined using a Y-tube
olfactometer. Our results showed that volatiles of five plant species
were highly effective in repelling ACP with repellency as much as 76%.
Among these, the tree species, Camptotheca acuminate, and the two
shrubs, Lantana camara and Mimosa bimucronata, could potentially be
planted as a landscape barrier. The two herbs, Capsicum annuum and
Gynura bicolor, could potentially be used as interrow plantings in
orchards. This is the first time that the repellency of fresh tissues
from a diverse range of plant species to ACP has been determined.
Although further field evaluation of various interplanting regimes and
landscape barriers are needed to assess their effectiveness, our results
showed that these aromatic species, being highly repellent to ACT, offer
great potential as more cost-effective and environmentally sustainable
alternatives to the current methods of managing HLB.