Effect of Biodiversity Changes in Disease Risk: Exploring Disease Emergence in a Plant-Virus System

Abstract

The effect of biodiversity on the ability of parasites to infect their host and cause disease (i.e. disease risk) is a major question in pathology, which is central to understand the emergence of infectious diseases, and to develop strategies for their management. Two hypotheses, which can be considered as extremes of a continuum, relate biodiversity to disease risk: One states that biodiversity is positively correlated with disease risk (Amplification Effect), and the second predicts a negative correlation between biodiversity and disease risk (Dilution Effect). Which of them applies better to different host-parasite systems is still a source of debate, due to limited experimental or empirical data. This is especially the case for viral diseases of plants. To address this subject, we have monitored for three years the prevalence of several viruses, and virus-associated symptoms, in populations of wild pepper (chiltepin) under different levels of human management. For each population, we also measured the habitat species diversity, host plant genetic diversity and host plant density. Results indicate that disease and infection risk increased with the level of human management, which was associated with decreased species diversity and host genetic diversity, and with increased host plant density. Importantly, species diversity of the habitat was the primary predictor of disease risk for wild chiltepin populations. This changed in managed populations where host genetic diversity was the primary predictor. Host density was generally a poorer predictor of disease and infection risk. These results support the dilution effect hypothesis, and underline the relevance of different ecological factors in determining disease/infection risk in host plant populations under different levels of anthropic influence. These results are relevant for managing plant diseases and for establishing conservation policies for endangered plant species.

Host and parasite diversity jointly control disease risk in complex communities

“…Although an increasing number of studies have reported negative correlations between host diversity and disease risk (29,38,39), the hidden effects of concurrent changes in parasite communities have rarely been explored (19,31,40). Future studies examining the biodiversity-disease relationship should focus more heavily on the relative importance of multiple components of biodiversity (and how they covary) in driving observed patterns in disease risk (41)(42)(43), including the direct and indirect effects of hosts, nonhosts (e.g., predators and competitors), parasites, as well as other microorganisms.…”

Landscape heterogeneity shapes host‐parasite interactions and results in apparent plant–virus codivergence

“…We have recently reported (Pagán et al . ) that higher levels of human management of chiltepin are associated with higher prevalence of plants showing symptoms of viral infection. A large fraction of symptomatic plants were infected by begomoviruses, specifically by Pepper golden mosaic (PepGMV) and Pepper huasteco yellow vein virus (PHYVV).…”

Plant Virus Ecology: A Glimpse of Recent Accomplishments

“…Molecular ecology research shows that the genomic sequence of viruses acquire signatures which describe their histories that help in understanding the ecological patterns and evolutionary processes. These patterns can be understood if natural host range is known (Traore et al, 2009 (Pagan et al, 2012). A bright future of plant virus ecology is ahead because the combination of molecular and traditional approaches in the discipline are being brought together to collect the details of virus genetic variations and epidemic breakouts which were impossible in the previous years (Jones, 2014a).…”