Repellency of selected Psidium guajava cultivars to the Asian citrus psyllid, Diaphorina citri. (June 2016)

• Record Type: Journal Article
• Authors: Silva, José A.A.; Hall, David G.; Gottwald, Timothy R.; Andrade, Moacir S.; Maldonado, Walter; Alessandro, Rocco T.; Lapointe, Stephen L.; Andrade, Eduardo C.; Machado, Marcos A.
• Is Part Of: Crop protection. Volume 84(2016)
• Page Start: 14
• Page End: 20
• Publication Date: 2016-06
• Subjects: Huanglongbing -- Citrus greening -- Candidatus Liberibacter -- Guava; Plants, Protection of -- Periodicals; 632.05
• DOI: 10.1016/j.cropro.2016.02.006
• Languages: English
• ISSNs: 0261-2194

Abstract

Abstract: Huanglongbing (HLB) is the most devastating disease of citrus worldwide. It is caused by bacteria of the genus ' Candidatus Liberibacter' and transmitted by two psyllid species, the Asian citrus psyllid (ACP) Diaphorina citri, and the African citrus psyllid Trioza erytreae . Considerable research has been conducted toward developing and implementing HLB and ACP management strategies. With respect to ACP control, of interest is that reports indicate guava, Psidium guajava, can be repellent to ACP. We conducted research to further evaluate repellency of guava to ACP. In one set of experiments, guava oil from five Brazilian guava cultivars ('J3', 'Pedro Sato', 'Século XXI', 'Thailand' and 'Paluma') was extracted from leaves (immature and mature) by hydro-distillation in a Clevenger-type apparatus and evaluated for psyllid repellency. In a second set of experiments, repellency of guava leaves to ACP was investigated using leaves (immature and mature) from two guava cultivars in Florida, 'Pink' and 'Thai White'. In each set of experiments, repellency was evaluated by releasing ACP adults into a cage with two large vials, one containing a young flush shoot (= immature leaves) of Murraya exotica (a favored host plant of the psyllid, the flush of which is highly attractive to ACP) and one with M. exotica flush and the test material of interest (guava oil, immature guava leaf or mature guava leaf). The adults were free to move throughout the cage and into the vials, and the number of psyllids in each vial was counted after 24 h. The results showed that all guava materials tested had at least some repellency to ACP. Mature leaves tended to have a greater repellent effect than immature leaves. Each of the five oils exhibited repellency. A report in the literature suggested that sulfur compounds associated with guava may be responsible for ACP repellency. Interestingly, the five guava oil extracts we studied were repellent to ACP but none contained any sulfur compounds. Identification of the constituents responsible for repellency could lead to new ACP management tactics. Highlights: The Asian citrus psyllid transmits bacteria responsible for huanglongbing, a serious citrus disease. Guava has been identified as having repellency to the psyllid. We found that extracts from the leaves of five different guava cultivars repelled the psyllid. We also found that guava leaves repelled psyllids, with mature leaves more repellent than young leaves. Identification of the constituents responsible for repellency could lead to new ACP management tactics.