Huanglongbing (HLB) is a serious disease of Citrus sp. worldwide. in Africa and the Mascarene islands, a similar disease is known as African citrus greening (AcG) and is associated with the bacterium Candidatus Liberibacter africanus (Laf). in recent years, Candidatus Liberibacter asiaticus (Las) associated with the severe HLB has been reported in ethiopia. thus, we aimed to identify the Liberibacter species affecting citrus, the associated vectors in Eastern Africa and their ecological distribution. We assessed the presence of generic Liberibacter in symptomatic leaf samples by quantitative PCR. Subsequently, we sequenced the 50 S ribosomal protein L10 (rplJ) gene region in samples positive for Liberibacters and identified the species by comparison with public sequence data using phylogenetic reconstruction and genetic distances. We detected generic Liberibacter in 26%, 21% and 66% of plants tested from Uganda, Ethiopia and Kenya, respectively. The rplJ sequences revealed the most prevalent Liberibacters in Uganda and Ethiopia were LafCl (22%) and Las (17%), respectively. We detected Las in Kenya for the first time from three sites in the coastal region. Finally, we modelled the potential habitat suitability of Las in eastern Africa using Maxent. the projection showed large areas of suitability for the pathogen in the three countries surveyed. Moreover, the potential distribution in Eastern Africa covered important citrus-producing parts of Ethiopia, Kenya, Uganda and Tanzania, and included regions where the disease has not been reported. These findings will guide in the development of an integrated pest management strategy to AcG/HLB management in Africa. Huanglongbing (HLB) is presently one of the most destructive plant diseases affecting citrus groves worldwide 1. The disease is associated with Candidatus Liberibacter asiaticus (Las) and Candidatus Liberibacter americanus (Lam), which are phloem-limited, fastidious, gram-negative bacteria belonging to the alpha subdivision of Proteobacteria 2,3. Las is heat-tolerant and associated with the severe HLB which is transmitted by the Asian citrus psyllid Diaphorina citri Kuwayama (Liviidae) 4. Diaphorina citri is distributed in Asia, the United States, Central America, Ethiopia and Brazil 5-10. In addition to Las and Lam, the citrus-infecting Liberibacter genus contains another species: Candidatus Liberibacter africanus (Laf) 1. Laf is heat-sensitive and is associated with African citrus greening disease (ACG) 11-13. This pathogen is principally transmitted by Trioza erytreae (Del Guercio) (Triozidae), also known as the African citrus triozid 14,15. Additionally, several subspecies of Laf have been reported, including Candidatus Liberibacter subsp. capensis (LafC), Candidatus Liberibacter africanus subsp.

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Aim To quantify current and predict future distribution of the citrus greening pathogens “Candidatus Liberibacter asiaticus” (Las) in Africa and “Candidatus Liberibacter africanus” (Laf) globally. Location Africa. Methods Three species distribution models (MaxEnt, BIOCLIM and Boosted Regression Trees) were used to predict the current and future potential distribution of Las in Africa, and the potential global distribution of Laf, using long‐term bioclimatic variables. Two climate change scenarios (moderate and extreme) were employed to determine how future climate alterations may affect the potential distribution of Las in Africa. Presence data from global reports of Las, as well as the new positional points obtained in this survey, were used to predict the habitat suitability of the pathogen in Africa, while the presence data points of Laf were used to predict the global habitat suitability. Testing data comprised 25% of the presence only points. Results Consensus of the three models predicted a potential distribution of Las in large areas of Western, Eastern and sub‐Saharan Africa. North Africa was mostly unsuitable for Las, except for the northern fringes. The potential distribution of Laf included South and Central America, Asia and Australia. In Europe, the United Kingdom and the Iberian Peninsula showed marginal suitability for Laf. The projections under the future climate change scenarios showed an increase in the Laf habitat suitability hotspots under the extreme scenario. Main conclusions This study highlights the potential establishment and distribution in Africa of Las‐associated Huanglongbing and globally for Laf‐associated with African citrus greening disease. The ensemble modelling approach for the distribution of plant pathogens is a valuable tool for the development of strategies for crop protection. These results constitute an early alert for citrus‐producing regions that should inform strategies for surveillance and preventive management against the invasion and spread of this destructive disease.

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Cannibalism and intraguild predation can play important roles in determining spread and survival or death of organisms which share the same resource. However, the relationship between cannibalism and intraguild predation, and the costs and benefits of such behaviours, is difficult to establish within insect communities, and little is known about how such behaviours are affected by invasive species. The present study was aimed at assessing the interactions between larvae of fall armyworm (Spodoptera frugiperda) and maize stemborers (native to Africa, Busseola fusca, and Sesamia calamistis and native to India, Chilo partellus) in relation to cannibalism and intraguild predation when they utilize the same resource. Experiments involving treatments with either single species of S. frugiperda or any of the stemborers or pairwise species combinations with S. frugiperda were conducted under laboratory conditions. The experimental insect larvae were reared on maize leaves and monitored until the last developmental stage where cannibalism and/or intraguild predation, larval survival, and relative growth rate were recorded. Results of the intraspecific interaction indicated that S. frugiperda exhibited cannibalism to a larger degree than the stemborers species, especially at the late instars. The higher cannibalism trait in S. frugiperda turned, however, to competitive advantage as it led to a higher degree of intraguild predation when they cohabit with stemborer species and allowed FAW to gain a greater relative growth rate. Overall, interactions with FAW are detrimental for stemborer species and may be an important factor to explain the invasive success of S. frugiperda. Such knowledge is essential to understand the mechanisms behind ecological interactions between pests with overlapping niches in the field and in designing successful integrated pest management strategies.