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“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.