Genetic variablity of Hapalaxius crudus, based on the 5' region of the cytochrome c oxidase subunit 1 gene shed light on epidemology of palm lethal decline phytoplasmas

Authors: HUMPRHINES, ALESSANDRA - University Of Florida; Ascunce, Marina; GOSS, ERICA - University Of Florida; HELMICK, ERICKA - University Of Florida; BARTLETT, CHARLES - University Of Delaware; MYRIE, WAYNE - Coconut Industry Board; BARRANTES, EDWIN - Universidad De Costa Rica; ZUMBADO, MARCO - Universidad De Costa Rica; BUSTILLO, ALEX - Cenipalma Oil Palm Research Center Corporation; BAHDER, BRIAN - University Of Florida

Submitted to: PhytoFrontiers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/16/2021
Publication Date: 8/3/2021
Citation: Humprhines, A.R., Ascunce, M.S., Goss, E.M., Helmick, E.E., Bartlett, C.R., Myrie, W., Barrantes, E.A., Zumbado, M.A., Bustillo, A.E., Bahder, B.W. 2021. Genetic variablity of Hapalaxius crudus, based on the 5' region of the cytochrome c oxidase subunit 1 gene shed light on epidemology of palm lethal decline phytoplasmas. Phytofrontiers. 1:127-134. https://doi.org/10.1094/PHYTOFR-12-20-0048-R.
DOI: https://doi.org/10.1094/PHYTOFR-12-20-0048-R

Interpretive Summary: Phytoplasmas are an economically important group of plant pathogen microorganisms that impact a wide variety of agricultural (e.g. coconuts, dates, sugar cane). ornamental and native palms. These microorganisms are transmitted primarily by phloem-feeding hemipteran insects, including leafhoppers, plant hoppers and psyllids. Phytoplasma diseases result in yellowing, wilting and death of palms causeing major outbreaks that led to the losses of million of coconut and other palm speciess. The most common vector of this disease if the planthopper Haplaxius crudus that is widespread and abundant throughout the Caribbean basin in Florida. Genetc tools allowed the indentification of 12 different mitochondrial DNA sequences amoung 236 insects collected. In Florida there is a single most common sequence that is also present in insects collected in Georgia, South Carolina and Jamaica, while the sequences from Texas and Mississippi represented distinct haplotypes. Sequences found in insects from Costa Rica and Colombia were highly different from the USA and Jamaica sequences. These findings highlight measurable levels of genetic variability of this insect in the USA and highlight the need for more robust sampling throughout the Caribbean to better understand movement and invasion potential of this species. This needed information would lead the improvement of control and preventative measurements to stop new introductions.

Technical Abstract: Hapalaxius crudus is an economically important group of cixiid planthopper that is widespread and abundant throughout the Caribbean basin. It is the vector of lethal yellowing (LY) and putative vector of lethal bronzing (LB), both phytoplasma diseases of palms that cause death, in Florida and the Caribbean. The primary objective of this study was to evaluate the genetic diversity of H. crudus in Florida to determine if divergent populations existed. The five prime region of the cytochrome c oxidase subunit 1 (CO1) gene was used as the molecular marker. DNA sequences were obtained from 236 specimens collected throughout Florida, U.S.A. as well as populations from southeasten United States. Populations from Costa Rica, Colombia, and Jamaica were included to complare differences between isolated populations. In Florida, four haplotypes were discovered with 97% of individuals belonging to a single haplotype, two smaller haplotypes compromised of six and four individuals, and a single haplotype compromised of one individual. Populations from Texas and Mississippi represented distinct haplotypes whereas populations from Georgia and South Carolina were identical to the predominant haplotype in Florida. Populations from Costa Rica and Colombia were highly divergent while the populations in Jamaica was 100% identical to the predominant population in Florida. These findings highlight measurable levels of genetic variability of H. crudus in Florida and the similarity to populaitions from Jamica highlight the need for more robust sampling thoughout the Caribbean to better understand movement and invasion potential of this species.