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During a survey in Trinidad and Grenada for putative vectors of palm lethal decline phytoplasmas, three species of planthopper in the genus Melanoliarus (Hemiptera, Cixiidae) were collected. Melanoliarus maidis was collected from coconut palms in Grenada, M. kindli was collected from grasses in a coconut plot in Trinidad and a new species of Melanoliarus was collected from coconut palms in Trinidad. Herein the novel taxon is described with supplementary molecular data for the cytochrome c oxidase subunit I (COI) gene, 18S rRNA gene, and histone 3 (H3) gene to support placement in the genus Melanoliarus in the strict sense.

Haplaxius is a large genus of cixiid planthopper found in the New World. The genus is of particular interest due to the ability of H. crudus to transmit the phytoplasmas for lethal decline in various palm species, primarily in the Caribbean and Florida, U.S.A. During recent vector survey work in Jamaica, a specimen was collected at Castleton Botanic Garden and determined to be a new species of Haplaxius. The novel taxon is herein described, Haplaxius fornicus sp. n., and corresponding DNA sequence data is provided for the barcoding region of the cytochrome c oxidase subunit I (COI) gene, 18S rRNA gene, and histone 3 (H3) gene. An updated phylogeny of the genus is provided with currently available taxa demonstrating additional support for the placement of H. fornicus sp. n. in Haplaxius.

“Huanglongbing” (HLB) is one of the most devastating diseases of citrus orchards worldwide. Samples from 183 citrus plants of different cultivars and rootstock/cultivar combinations, showing HLB symptoms in three Caribbean countries (Cuba, Jamaica, and Guadeloupe-France), were collected to verify the possible co-infection of ‘Candidatus Phytoplasma’ and ‘Candidatus Liberibacter’ species. The 64% of the samples resulted positive to the ‘Ca. L. asiaticus’ and the 27% to diverse ‘Ca. Phytoplasma’-related species, moreover about the 14% of the samples infected with ‘Ca. Liberibacter’ were also found positive to phytoplasmas, indicating the presence of mixed infection especially in the orchards located in Cuba. Moreover, in one of the samples from Jamaica mixed phytoplasma infection was detected. Moreover the detection of only phytoplasmas in 11 symptomatic citrus samples collected from Cuba and Guadeloupe without ‘Ca. Liberibacter’ detection, confirmed that the symptomatology cannot be the sole criterium to discriminate between the presence of the two pathogens, and molecular detection is necessary to identify single or mixed infections. Diaphorina citri insects collected from Cuba and Guadeloupe resulted infected with ‘Ca. L. asiaticus’ confirming its active role in the dissemination of the pathogen. Only one insect of the Cicadidae family, collected in Guadeloupe, was found positive for phytoplasma presence. Considering that the phytoplasmas belonging to some ‘Candidatus species’ were detected in the three countries in different citrus varieties, a relevant role as phytoplasma reservoir can be attribute to citrus orchards.

“Huanglongbing” (HLB) is one of the most devastating diseases of citrus orchards worldwide. Samples from about 200 citrus plants of different cultivars and rootstock/cultivar combinations, showing HLB symptoms in Cuba, Jamaica and Guadeloupe-France, were tested to verify the possible presence of 'Candidatus Phytoplasma' in 'Candidatus Liberibacter asiaticus' infected species. About the 14% of the samples infected with 'Ca. Liberibacter' were also found positive to phytoplasmas, indicating the presence of mixed infection especially in the orchards located in Cuba. Moreover, in one of the samples from Jamaica mixed phytoplasma infection was detected. Further, the detection of only phytoplasmas in several symptomatic citrus samples collected from Cuba and Guadeloupe, confirmed that the symptomatology cannot be the sole criterium to discriminate between the presence of the two pathogens, and molecular identification of the bacteria is necessary to verify the sanitary status of symptomatic plants. Diaphorina citri insects collected in Cuba and Guadeloupe resulted positive to the 'Ca. L. asiaticus' presence confirming its active role in the dissemination of the pathogen in the Caribbean areas. Only one insect of the Cicadidae family, collected in Guadeloupe, was found positive for phytoplasma presence. Phytoplasmas enclosed in groups 16SrI and 16SrXII were identified in all the three islands; the 16SrII, 16SrIV, 16SrVII, 16SrX and 16SrXI groups were present in both Guadeloupe and Cuba. This could indicate that the surrounding cultivated species are influencing the phytoplasma population composition in citrus orchards as indicated by the relevant presence of the lethal yellowing phytoplasmas that was severely affecting the Cuban palm plantations in the past. Moreover the identification of phytoplasmas enclosed in groups 16SrIII, 16SrVI and 16SrIX only in Guadeloupe and of 16SrXV group only in Cuba is corroborating this hypothesis (Bertaccini et al., 2019; Luis-Pantoja et al., 2021). Considering that diverse 'Candidatus Phytoplasma'-related species were detected in the three countries in different citrus varieties, a relevant role as phytoplasma reservoir can be attributed to citrus orchards for the natural and agricultural ecosystems.

Descriptions of lethal yellowing (LY) in coconut plants were documented in the late 19th century in the Caribbean region, but the first widespread devastation of coconuts due to LY took place in Jamaica during the 1960s. Subsequently, reports of LY began to emerge in other countries such as the USA (Florida), Mexico, Belize, Honduras, Guatemala, and various other Caribbean islands including Bahamas, Cayman Islands, Cuba, Haiti, Dominican Republic and St. Kitts and Nevis in the Leeward Island, Antigua and Barbuda and St. Maarten. Similar diseases known collectively as lethal yellowing-type syndromes have also been described elsewhere in the tropics. In West Africa: Awka wilt in Nigeria, Cape St. Paul wilt in Ghana and Ivory Coast, Kaïncopé in Togo, and Kribi in Cameroon. In East Africa, a lethal disease also occurs in Kenya, Tanzania and Mozambique. Bogia syndrome in Papua New Guinea and Solomon Islands and a lethal wilt in Australia have been described. In spite of the different names the disease symptoms are very similar, while the associated phytoplasmas are diverse in the various geographic areas. Five 'Candidatus Phytoplasma' species are reported as associated with lethal yellowing syndromes in palms in the diverse continents: 'Ca. P. palmicola' and 'Ca. P. cocostanzaniae' in Africa, 'Ca. P. palmae' in America, 'Ca. noviguineense' and 'Ca. P. dypsidis' in Papua New Guinea and Australia. Other non-lethal yellowing phytoplasma-associated diseases are described in coconut in south and south-east Asia, such as Weligama wilt in Sri Lanka and Kerala wilt in India, and in different palm species such as oil palm, date palm and arecanut palm in Colombia, Indian subcontinent, Saudi Arabia and Kuwait where 'Ca. P. asteris', 'Ca. P. oryzae', 'Ca. P. wodyetiae' and 'Ca. P. cynodontis' were respectively reported (Yankey et al., 2018 ). Although the transmission of phytoplasmas to and among palms has been intensively studied, to date the only insect vector identified is Haplaxius crudus proved to transmit 'Ca. P. palmae' in America. For this phytoplasma the possibility of embryo transmission was also recently proved. For all the other reported lethal yellowing syndromes there is scattered information about possible insect vectors and some of these in both Africa and America have only recently been reported. The management of these diseases is mainly through integrated management approaches including monitoring to detect palms with early LY symptoms, elimination of these palms as soon as they are detected, replanting and weeding. Search for resistant varieties appears however the long lasting approach to be pursued together with the continuous monitoring of phytoplasma strains present in the diverse areas.

“Huanglongbing” (HLB) is one of the most devastating diseases of citrus orchards worldwide. Samples from 183 citrus plants of different cultivars and rootstock/cultivar combinations, showing HLB symptoms in three Caribbean countries (Cuba, Jamaica, and Guadeloupe-France), were collected to verify the possible co-infection of ‘Candidatus Phytoplasma’ and ‘Candidatus Liberibacter’ species. The 64% of the samples resulted positive to the ‘Ca. L. asiaticus’ and the 27% to diverse ‘Ca. Phytoplasma’-related species, moreover about the 14% of the samples infected with ‘Ca. Liberibacter’ were also found positive to phytoplasmas, indicating the presence of mixed infection especially in the orchards located in Cuba. Moreover, in one of the samples from Jamaica mixed phytoplasma infection was detected. Moreover the detection of only phytoplasmas in 11 symptomatic citrus samples collected from Cuba and Guadeloupe without ‘Ca. Liberibacter’ detection, confirmed that the symptomatology cannot be the sole criterium to discriminate between the presence of the two pathogens, and molecular detection is necessary to identify single or mixed infections. Diaphorina citri insects collected from Cuba and Guadeloupe resulted infected with ‘Ca. L. asiaticus’ confirming its active role in the dissemination of the pathogen. Only one insect of the Cicadidae family, collected in Guadeloupe, was found positive for phytoplasma presence. Considering that the phytoplasmas belonging to some ‘Candidatus species’ were detected in the three countries in different citrus varieties, a relevant role as phytoplasma reservoir can be attribute to citrus orchards.

A new species of the genus Agoo Bahder & Bartlett, Agoo beani sp. n. was found associated with coconut (Cocos nucifera L., Arecaceae) in Jamaica. This species was discovered as part of a survey of the Caribbean basin to document planthopper diversity on palms. Cytochrome c oxidase subunit I (COI) and 18S sequence data strongly support placement of the new species in Agoo. The morphological features of Omolicna cocoana Rodriguez-Leon & Hidalgo-Gato from Cuba are reviewed and this species transferred into the genus Agoo.

The coconut is a palm of economic and social importance; it is cultivated in 90 countries around the world and the markets of some of its products have been growing exponentially, representing a very promising future for the coconut cultivation and industry. Unfortunately, this is threatened by decreased fruit production due to ageing palms and lethal yellowing (LY) and related phytoplasma diseases (LYDs) that have been devastating coconut palms, particularly in countries of Latin America and the Caribbean (LAC), and Africa, although such diseases are also present in countries in Asia and Oceania. Much research has been carried out to understand LY and LYDs, and associated phytoplasmas have been identified. There are about 16 different strains within nine 16Sr phytoplasma groups. The more diverse group so far is the 16SrIV group, present in countries in the Americas, but also reported in Asia and Oceania. A search of vectors has resulted in one confirmed case in the Americas, a leafhopper (Haplaxius crudus Van Duzee, 1907), and other candidates have been identified but yet to be confirmed. Fifty palm species (including coconut) and 14 non-palm species have been reported as phytoplasma hosts. Screening for resistance has identified resistant germplasm in the Americas which has been used for replanting programs, and similar efforts are being conducted in other parts of the world. Methods for detection and diagnosis have been developed using PCR techniques. Micropropagation has been developed for massive propagation of the selected coconut germplasm. Management practices based on the above are currently being applied. However, even with all the progress achieved, there is still a lot to be done in order to move forward in how to deal more effectively with LY and LYDs. For this purpose, it is very important that research is carried out based on a global strategy, working worldwide in an organized and coordinated fashion, in collaboration with organizations such as ICC and COGENT.

Sustainable approaches to control phytoplasma-associated diseases are of utmost importance. The use of phytoplasma-resistant host plants and of phytoplasma-free material for new plantings could represent a starting point for phytoplasma disease management. The early identification of infected host plants and insect vectors represent necessary tools in preventing epidemics of diseases through the appropriate management of agro-ecosystems subjected to epidemic outbreaks. This approach can be integrated with the use of resistance inducers and of biocontrol microorganisms able to act as against phytoplasmas and/or their insect vectors. Furthermore comparative genomic approach facilitates the identification of candidate genes involved in the interactions with hosts, and together with the cultivation of phytoplasmas is a key point for improving the knowledge of these bacterial pathogens aimed to implement effective integrated management control strategies.

Coconut lethal yellowing (LY) is the single most important disease presently affecting the coconut production worldwide. Symptomatic and asymptomatic coconut plants were sampled in some selected areas to verify the identity of phytoplasmas associated with LY in Cuba. Diverse phytoplasma ribosomal groups were detected in the samples from symptomatic palms such as 16SrXII, 16SrVII, and 16SrI. In several other palms 16SrIV-A subgroup phytoplasmas were identified, in the groEL gene the only positive plant from Pilón resulted diverse from the others and identical to the 16SrIV-A strains detected in Jamaica LY infected coconut palms. This is the first record of occurrence of 16SrI, -VII and -XII groups in coconut palms in Cuba.

A new species of cixiid planthopper (Hemiptera: Fulgoroidea) in the genus Oecleus Stål, Oecleus mackaspringi sp. n., is described from Spring Garden, Jamaica. This new taxon is associated with coconut palm (Cocos nucifera L.) and was found while surveying palm plots with active cases of lethal yellowing (LY). This is the first report of the genus Oecleus from Jamaica. Sequence data for the COI gene and 18S gene are also provided.

“Huanglongbing” (HLB) is one of the most devastating citrus diseases in the world. Citrus samples with symptoms referable to HLB were collected in different Caribbean Countries to verify the possible association of ‘Candidatus Phytoplasma’ and HLB. In Cuba, 140 samples out of 142, resulted positive for HLB and 32 were positive also for phytoplasmas. In Jamaica, out of 6 samples, 5 were positive to HLB and 1 was positive to phytoplasmas. In Guadeloupe, 17 samples were positive for HLB and 7 for phytoplasmas. These results indicate that the symptomatology is not discriminating between the two pathogens and the mixed infection is not an uncommon event.

The relentless spread of the fatal disease lethal yellowing (LY) throughout the coconut growing areas is having a serious impact on many vulnerable communities. Phytoplasmas from the 16SrIV group are the associated agents. These obligated phytopathogenic mollicutes systemically colonize phloem tissues inducing numerous biochemical and physiological changes leading to symptom development and ultimate death of coconut palms. Large numbers of coconut trees succumbed to the disease over the past three decades. There are different subgroups of the 16SrIV phytoplasmas affecting palms in the Americas. It is important for these to be properly identified along with the epidemiology of the disease. The effective molecular tools used to identify these subgroups show variations in some conserved genomic regions. In the Americas the subgroups have been identified, the current distribution of LY in Jamaica and Mexico and the 16SrIV subgroups occurring in these countries and in other Caribbean countries are described.

We applied Bayesian population assignment methods to assess the trueness to type of four populations of the coconut cultivar Panama Tall (PNT) located in Jamaica and found that two of them presented a high percentage of off-types, while genetic contamination was low in the two others. The PNT is the pollen parent of the MAYPAN hybrid, which used to be planted in Jamaica to control an epidemic disease: Lethal Yellowing. The main source of contamination was the susceptible Jamaica Tall, thus increasing the susceptibility in the resulting MAYPAN progeny. The incidence of genetic contamination seems however to be insufficient to be the only cause of the latest outbreak of the disease. Neither the MAYPAN nor its parents can be said resistant in the present context of Jamaica.

In Jamaica, the Maypan, a hybrid of Malayan Yellow Dwarf (MYD) and Panama Tall coconut, previously considered highly resistant, is currently being devastated by an epidemic outbreak of lethal yellowing disease. There are several possible causes for this change. In this study, we checked that affected planting material in Jamaica is genetically the same as the material shown to be resistant. We compared the deoxyribonucleic acid (DNA) of MYD sampled in four locations in Jamaica with a reference DNA of the same cultivar collected in five different countries. The results of our analyses showed more variation at 34 simple sequence repeat loci in Jamaica than in the rest of the world providing clear evidence for the presence of about 16% of alleles that do not match the usual typical MYD genotype. These alleles appear to have already been present in the introduced germplasm. This rules out a possible cause of the new outbreak: The observed heterogeneity may have caused some loss of resistance but is insufficient to explain a massive outbreak of the disease.