Avocado cultivar and tree-to-tree leaf compositional differences affect infestation severity of Pseudocysta perseae (Hemiptera: Tingidae)

Authors: BOSCH, MICHAEL - Orise Fellow; Liang, Peishih; Sun, Xiuxiu; HALL, SIERRA - University Of Hawaii; LOVE, KEN - Hawaii Tropical Fruit Growers; COX, DAVID - Kane Plantation Avocados; Matsumoto Brower, Tracie; Follett, Peter; STOCKTON, DARA - Animal And Plant Health Inspection Service (APHIS)

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/17/2024
Publication Date: 7/11/2024
Citation: Bosch, M.J., Liang, P., Sun, X.N., Hall, S., Love, K., Cox, D., Matsumoto Brower, T.K., Follett, P.A., Stockton, D.G. 2024. Avocado cultivar and tree-to-tree leaf compositional differences affect infestation severity of Pseudocysta perseae (Hemiptera: Tingidae). Environmental Entomology. https://doi.org/10.1093/ee/nvae066.
DOI: https://doi.org/10.1093/ee/nvae066

Interpretive Summary: Since the arrival of Avocado lace bug in Hawaii in 2019, efforts to management the pest have been limited by an incomplete understanding of host preferences and reproductive biology. This study aimed to gather data on which avocado cultivars were at highest risk of ALB infestation in Hawaii and used a combination of on-farm field surveys and experimental collections and leaf sample evaluations to address these concerns. Our data showed that some cultivars were more at risk than others, in particular 'Sharwil', 'Beshore', and 'Kahaluu.' Traits from West Indian lineage trees appeared to be preferred by ALB. The Hawaiian variety 'Malama' was lower in risk, likely due to lower overall soluble sugar content in the leaves.

Technical Abstract: Avocado lace bug, Pseudocysta perseae (Hemiptera: Tingidae), is a sap-feeding insect that feeds on the underside of avocado leaves. In 2019, populations of P. perseae were observed on the island of O’ahu. Since then, P. perseae has spread to most of the Hawaiian islands, causing premature leaf drop and suggested decrease in avocado yield. Due to Hawai’i's approximately 200 cultivar varieties comprised of all three avocado races, we were able to investigate whether certain cultivars were more prone to experiencing higher P. perseae abundances and infestations compared to others. We conducted longitudinal abundance surveys on Hawai’i Island across several common avocado varieties monitoring changes in P. perseae abundance. These surveys were supplemented with longitudinal infestation severity surveys across four avocado lineages (M, G, WI, and GxWI hybrid). Additionally, we collected leaves of Sharwil, Hass, Kahalu’u, and Nishikawa cultivars looking at associations between P. perseae abundance and cultivar, herbivory-related biomechanical traits, and soluble sugar content. We found that some cultivars, such as Malama, typically experience lower P. perseae abundances compared to cultivars such as Kahalu’u, Beshore, and Sharwil. Guatemalan x West Indian hybrid trees were also shown to have a higher probability of experiencing more severe P. perseae infestations compared to other lineages. Lastly, soluble sugar content, specifically fructose content, had a positive effect on juvenile P. perseae abundance. These findings suggest that cultivar differences in P. perseae infestations may exist, but tree-to-tree leaf compositional differences, such as soluble sugar content, may be a large driver of variation in P. perseae abundance.