1a. Objectives (from AD-416)
Identify repellents or attractants that could be used to manage the Asian citrus psyllid.
1b. Approach (from AD-416)
Cooperator will provide ARS with various guava essence fractions, which ARS will screen for repellency or attractancy to the psyllid using olfactometer and EAD/EAG studies. Cooperator will further fractionate active fractions, and ARS will screen these as well. The chemical nature of any repellents or attractants found will be determined, if possible.
3. Progress Report
This project is related to Objective 3c: Investigate basic biology and ecology of the Asian citrus psyllid and its natural enemies in Florida citrus. Research commenced on evaluating psyllid responses to a mix of guava volatiles. The objective of the project is to find a volatile that is either attractive or repellent to the psyllid. A guava essence from Givaudan was provided for testing. Those interested in the essence thought that, perhaps, one of the volatiles associated with this mix of guava volatiles might have repellency to the psyllid. If so, it might be relatively easy for a commercial product to be formulated for use by citrus growers. Olfactometer studies, a cage bioassay, and electro-antenna-gram detection assays that indicated a guava essence was not repellent to the psyllid. In fact, these results suggested that the essence is attractive to the psyllid. If an attractant for the psyllid could be identified and synthesized, it might be useful for monitoring psyllid populations. Currently, there is no known chemical attractant for the psyllid. Adult Asian citrus psyllids are strongly attracted to the color yellow, thus yellow sticky traps are commonly used to detect and monitor adult psyllid populations. A sticky trap baited with a chemical attractant would likely be far superior. Regulatory agencies would use baited traps to track psyllid invasions. Citrus growers would use baited traps to make psyllid management decisions and gauge the efficacy of psyllid management tactics. A good attractant might be used to disrupt psyllid mating or in an attract and kill station. Research on the essence indicated that males may be more attracted to the essence than females. Males may be more attracted to lower concentrations of the essence while females may be more attracted to higher concentrations. A cage bioassay was conducted in which adult psyllids were given free choice to infest a young citrus shoot treated with the essence or two other citrus shoots not treated with the essence. Results of this assay indicated significant attraction to the essence. Electroantennagram detection indicated essence volatiles that eluded during the first 10 minutes elicited the most psyllid antennal responses, with little or no response after the first 10 minutes. The Givaudan guava essence is actually a mix of several smaller fractions. Research has commenced on some of these individual fractions. Progress was monitored through email and telephone discussions of project plans.