Emerging Fungal Disease Affecting Food Security
Fisher et al. , reported that EIDs aused by fugi are major threats to the worlds food security. This can be dated back to 19th century where a species of fungi caused a great famine. Fungi have been notorious for their ability to cause diseases in plants thereby leading to crop loss both I the pas and n recent times. For example Phythophthora infestans caused a great famine in Ireland in the 19th century and recently Puccinia graminis strain Ug99 which has capacity of causing 100 % yield loss in wheat thereby affecting food security.
However, fungi do not only cause in plants, hey also cause loss in animals important to food security. For example Aphanomyces invadans causes epizootic ulceratic syndrome in Tilapia fish which is a source of animal protein to man According to Stukenbrock and Mc Donald? ? ? , pathogens have existed in the wild before the advent of agriculture i. e. domestication of crops. Modification of the ecosystem via irrigation, fertilizer application, tillage etc has led to emergence of pathogens capable of adapting to this changes. Thus thisbrings to fore the genetic selection of pathogens that can tolerate our modern agro-ecosystem. Moreover, density and cultivation of our food crops has enabled the emergence of more virulent pahogens.
Significantly, about 1 million people died in Ireland between 1846-1851; years which the famine was believed to be intense. Though, there are other pathogens ( such as bacteria, viruses, nematodes and insects) that cause crop loss. Nonetheless, fungi account for 70-80 % of the total crop loss. (David moore et al) Despite the fact that fungi cause great food loss which could be devastating, they have been reported to cause just 4 % of extinctions caused by infectious diseases. Based on the data provided by PROMEd and Healh Map( disease monitoring programmes), it appears that fungi account for 3. 5 % and 7 % respectively of the overall fungal infectious disease threats leading to loss of biodiversity. However, the data showed that there is an increase in the fungal alerts of EIDs over the years sampled ( healthMap 18; 2007 and 46 in 2011; Promed 11; 1995 and 106 n 2011). The presence of effective dispersal stages and ability to tolerate different environmental conditions and/or host accrues a high level of infectivity and virulence in pathogenic fungi and oomycetes.
For instance, the spore of puccinia graminis; the implicatinf organism for wheat stem rust overwinters o straw stubbles in order to complete its lifecycle and then infect wheat plant. The pathogen does not pose great food security threat in recen times as a result of breeding of several resistant cultivars. However, a great loss could occur with the emergence of strains which these cultivars could be susceptible to (APS) Moreover, fungi could have broad host range, with each host differing in its susceptibility to the pathogen. Host with low susceptibility tend to incubate high load of inoculum in its system and pose a great risk to highly susceptible potential host in its community or distant community where it is transported via biotic factors such as animals, abiotic factors such as air and water and anthropogenic ctivities such as trade. Increased in geographical range of fungal infectious diseases is somewhat linked to trade.
A worthy of note example is the introduction of phytophthora infestans into Ireland from south America through trade. The inherent nature of many fungal pathogenic fungi to undergo genetic recombination, hybridization and horizontal gene transfer.
