Abstract:
Fast and effective monitoring and surveillance techniques are crucial for the swift implementation of control methods to
prevent the spread of Huanglongbing, a devastating citrus disease, and its invasive psyllid vector, Asian citrus psyllid,
Diaphorina citri, into South Africa, as well as to control the native vector, African citrus triozid, Trioza erytreae. Monitoring
for citrus psyllid pests can be improved by using semiochemical odorants to augment already visually attractive
yellow sticky traps. However, environmental variables such as temperature and humidity could influence odorant release
rates. Five field cages were used to test the ability of a selection of odorants to improve yellow sticky trap efficacy in
capturing citrus psyllids. Environmental effects on odorant loss from the dispensers were also investigated. The odorants
that most improved yellow sticky trap captures in field cages were then tested under open field conditions alongside lower
concentrations of those same lures. Gas chromatography-mass spectrometry was used to calculate odorant release rates as
well as to determine if any contamination occurred under field conditions. None of the odorants under field cage or field
conditions significantly improved psyllid capture on yellow sticky traps. Temperature influenced odorant loss, and release
rate from polyethylene bulbs decreased over time. Based on these results, the use of unbaited yellow sticky traps seems
to be the most effective method for monitoring of Huanglongbing vectors.
