Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - TROPICSAFE (Insect-borne prokaryote-associated diseases in tropical and subtropical perennial crops)

Teaser

TROPICSAFE address three economically important insect-borne prokaryote-associated diseases of perennial crops (palm, citrus and grapevine) grown in tropical and subtropical areas. During the last decades, these are the diseases most seriously affecting the worldwide trade and...

Summary

TROPICSAFE address three economically important insect-borne prokaryote-associated diseases of perennial crops (palm, citrus and grapevine) grown in tropical and subtropical areas. During the last decades, these are the diseases most seriously affecting the worldwide trade and import of products and materials from these crops, as a result of the globalization of trade and climate change. The target diseases are due to the presence of diverse ‘Candidatus Phytoplasma’ associated with “lethal yellowing” (LY) in palms and “yellows” in grapevine (GY), and ‘Candidatus Liberibacter’ associated with “huanglongbing” (HLB) in citrus. These infectious diseases were only recently described and for their effective, efficient and sustainable (economically and environmentally) management there is the need to fill important knowledge gaps. TROPICSAFE is concentrating the work on tropical and subtropical areas in Africa (Ghana, South Africa and Mozambique), America (Mexico, Chile) and the Caribbean (Guadeloupe, Jamaica, Cuba), as well as subtropical regions in Europe (Spain and Italy), in order to cover (i) diverse geographic areas, (ii) genetic variability and cultivation techniques in selected crops and their pathogens. The general objective of the project is to provide innovative tools and solutions to manage and reduce the impact of these harmful perennial crop diseases. Since the presence of these diseases is quite severe in the TROPICSAFE targeted areas, giving rise to social and economic threats, affecting first of all local agriculture and then the export of products internationally and, in particular, to the EU, the project work is an effective manner to also determine positive effects on the social and economic environment of these areas, especially the poorest ones.

Work performed

The diversity of the prokaryotes in the target Countries in the selected crops was determined by collection of samples infected by LY, HLB and GY associated pathogens in the original host plants from the selected geographical areas of the partner countries. From Africa (Ghana and Mozambique) in LY infected coconut palm ‘Candidatus Phytoplasma palmicola’-related strains were identified while in Jamaica, Cuba and in Mexico phytoplasmas in the 16SrIV group were identified. Surveys of GY in Europe, South Africa and South America allow to identify in Italy, besides the historical ‘Ca. P. solani’ (“bois noir”), ‘Ca. P. fraxini’, ‘Ca. P. asteris’ and in isolated cases “flavescence dorée” (mainly 16SrV-C), while in Spain ‘Ca. P. solani’ and ‘flavescence dorée’ (16SrV-D) phytoplasmas were identified. The presence of ‘Ca. P. asteris’ was confirmed in South Africa and in Chile the major phytoplasma detected was ‘Ca. P. pruni’. Surveys of HLB in citrus confirmed the presence of ‘Ca. Liberibacter africanus’ (South Africa) and ‘Ca. L. asiaticus’ (Guadeloupe, Cuba). Molecular identification of a number of insects and weeds harboring the targeted pathogens was also obtained. These materials are now available to the consortium for further molecular characterization aimed at providing fast and cheap tools for reliable pathogen detection. This is part of the control by strategies based on surveillance schemes and monitoring tools to obtain cost and environmental impact reduction of phytosanitary controls. The development of innovative rapid and reliable multiple and/or on-site methods for detection of these pathogens also in the insect vectors, LAMP/qPCR specific assays were initiated by primers and pipelines design. Stable cultures for some ‘Ca. P. phytoplasma’ were established and one antiserum was produced and is under testing. To develop advanced Integrated Pest Management (IPM) strategies for Trioza erytreae vector of HLB detected in Spain the parasitoid Tamarixia dryi was introduced from South Africa and, after the mandatory host range studies to confirm is released it in Canary Islands. Mgenia fuscovaria vector in South Africa of ‘Ca. P. asteris’ was evaluated for volatile responses on two grapevine cultivar indicating that management strategy should focus on combining visual and olfactory cues. Evaluation of grapevine, palm and citrus germoplasm susceptibility to the specific pathogens in the diverse areas was also initiated by the verification of pathogen presence and titre in the different environment (citrus, Guadeloupe, grapevine Italy and palm Jamaica and Mexico). The economical sustainability including social impact evaluation was evaluated before implementation of the measures by disseminating a dedicated questionnaire to all the project partners; this will obtain information to implement the cost and benefit analysis and to run the impact assessment after the new IPM will be implemented.

Final results

The project will close important scientific and technological gaps related to the epidemiological cycles of the selected diseases, which are significantly impacting on the local and general economies in the specific sectors and are all extremely difficult to eradicate with the currently available tools. A crucial point that TROPICSAFE will contribute to implement is the current lack of effective and/or low-cost detection methods to specifically identify insect vectors and alternative host plants of the pathogens in the traded commodities. This will specifically fill the gaps in the knowledge of the target pathogens in the partner countries, and consequently will allow the implementation of disease management by rendering available specific detection kits, environmentally safe molecules, and resistant plant genotypes that could reduce the disease economic impact. For LY and GY diseases the surveys will clarify the identity and diffusion of phytoplasmas in coconut palms and grapevine in the surveyed partner countries. Gaps in LY disease knowledge will be filled by studying the range of alternative host plant species in the different environments by inventorying and barcoding phytoplasmas, and vector or potential vector insect species. Moreover the possibility of cultivating some of the characterized strains of the phytoplasmas that will be detected as main associated agents to the diverse epidemic will open new avenues for the correct interpretation of molecular results on both pests and insect vectors.
HLB disease studies will focus on the ‘Ca. Liberibacter’ strain characterization in South Africa, Guadeloupe and Cuba to update the knowledge on pathogen strains associated with severe epidemics. The pathways of the HLB regional spread are related to the vectors’ host-alternation biology and will be clarified in different climatic regions. The project will also provide the use of new diagnostic tools, new information about alternative host plants that could act as reservoirs for CL (e.g. weeds) and an understanding of the overwintering ecology of vectors in different geographic regions and under different climatic conditions. One important issue will be to verify the absence of HLB in citrus in Europe. Evaluation of the economic and social sustainability of the innovations and strategies proposed to manage the three diseases (LY, HLB and GY) affecting the specific crops in the targeted countries will help to improve the social life of farmers and small farmers. The economic analysis will make sure that the economic and social effects of the innovation and strategies are evaluated not only with reference to farmers and agricultural families, but also to all the subjects that are affected by the innovation

Website & more info

More info: http://www.tropicsafe.eu/it/.