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Repercusión del Cambio Climá9co en la Sanidad Vegetal Impacto del Cambio Climá9co en los Insectos Vectores de Patógenos de Plantas Alberto Fereres [email protected] Ins$tuto de Ciencias Agrarias. ICA, Consejo Superior de Inves$gaciones Cien$ficas. Madrid 38 Jornadas de Productos Fitosanitarios. Ins9tuto Químico de Sarriá. Barcelona, 25 Octubre, 2016 -­‐  Greenhouse Gases: Since the start of the industrial era in 1750, the global average concentra<on of carbon dioxide (CO2) in the atmosphere has increased by 41%, methane by 160%, and nitrous oxide by 20%. -­‐  Atmospheric CO2 levels are currently about 400 μmol mol-­‐1 and CO2 levels are forecast to rise to 650 μmol mol-­‐1 by the year 2100 (IPPC, 2014). -­‐  Direct Consequences of Climate Change: Increased temperature, UV radia9on, drought and wind speeds, altered rainfall paQerns (escenario mas op<mista) VIRUS AND BATERIAL DISEASES ARE ONE OF THE MOST YIELD-­‐LIMITING FACTORS IN MANY PARTS OF THE WORLD FACTORS INVOLVED IN SPREAD INSECT VECTORS Aphids, Whiteflies, Thrips NATURAL ENEMIES ABIOTIC FACTORS Tº, RH, CO2 RAINFALL, RADIATION HOST PLANTS Natural & managed ecosystems Parasitoids, Predators & Entomopathogens Insects drive the emergence of exis9ng or new plant-­‐pathogens under the following circumstances: 1.  An insect species with higher vector propensity enters into a new region increasing the incidence and severity of a plant pathogen 2.  An insect species introduc<on with differen9al feeding habits than the exis<ng vector popula<on. 3.  A vector species, beQer adapted to a wider host plant range expands into a new habitat enhancing pathogen spread. 4.  Excep9onal weather condi9ons may facilitate long-­‐distance migra9on and introduc<ons of a vector species into new regions 5.  Mutualis<c rela<onships between a given plant virus and its insect vector Causes of increasing emerging insect-­‐transmiQed diseases Fereres. 2015. Current Opinion in Virology 2015, 10, 42-­‐46. 1.  Unprecedented global movement (both inten<onal and uninten<onal) of plants and arthropods resul<ng from human transport and interna<onal trade 2.  There are changes in agricultural prac9ces itself, including the development of new biofuel crops, which are selected to increase biomass with the risk of becoming more suscep<ble to vectors or ac<ng as an extensive monoculture reservoir of plant viruses 3.  Interac9ons between insect vectors and their pathogens can be antagonis<c, neutral or mutualis<c, but increasing evidence suggests that many of these interac<ons can favour the spread and emergence of plant viruses. 4.  Climate change will alter species distribu9ons (including regions where crops are planted) a.  Poleward shigs of 612 crop pests and pathogens averaged 27 kms/
decade since the 1960s (Bebber et al. Nature Clim. Change 2013, 3, 985-­‐988)-­‐ b.  Greater wind speeds over the oceans have been observed over a 23-­‐yr period (Young et al. Science 2011, 332, 451-­‐455), which in turn may promote long-­‐distance dispersion of insect vectors of plant pathogens An average poleward shig of 2.7±0.8 km/year since 1960, but with significant varia<on in trends among taxonomic groups. Hemipterans and Thysanopteras are the orders that show the highest mean la9tudinal shig (Bebber et al. 2013) Bebber, D.P.; Ramotowski, M.A.T.; Gurr, S.J. Crop pests and pathogens move polewards in a warming world. Nature Clim. Change 2013, 3, 985-­‐988. •  Predicted expansion north of Bemisia tabaci in the Mediterranean under global warming scenarios Gilolli, G., Pasquali, S., Parisi, S., Winter, S., 2014. Modelling the poten<al distribu<on of Bemisia tabaci in Europe in light of the climate change scenario. Pest Manag. Sci. 70, 1611–1623. -­‐  An addi9onal five genera9ons of aphids/year are predicted with a 2ºC increase -­‐  Aphid flights will occur earlier with global warming (8 days earlier in the next 50 years) Bell, J.R., Alderson, L., Izera, D., Kruger, T., Parker, S., Pickup, J., Shortall, C.R., Taylor, M.S., Verrier, P., Harrington, R., 2015. Long-­‐term phenological trends, species accumula<on rates, aphid traits, and climate: five decades of change in migra<ng aphids. J. Anim. Ecol. 84, 21–34. Figure from ANN SANDERSON, SHEILA COLLA. OQawa, Canada Bumblebee popula9ons shrink as they cannot colonize northern habitats but are disappearing from Southern la9tudes in America and Europe •  Greater wind speeds over the oceans have been observed over a 23-­‐yr period (Young et al. Science 2011, 332, 451-­‐455), which in turn may promote long-­‐distance dispersion of insect vectors of plant pathogens •  During the past two decades there has been a consistent trend toward increasing wind speeds Effects of eCO2 on Virus Vectors and Virus Diseases •  eCO2 influences: 1.  The nutri9ous value of leaves to virus vectors: eg: aphids and whiteflies tend to compensate the higher C:N rate by increasing phloem sap uptake, but aphids generally reduce their intrinsic growth rate under eCO2 (Dader et al., 2016; Trebicki et al. 2016) 2.  The paQerns of gene expression of defense signaling routes against both vectors and viruses usually increase host plant resistance against virus infec9on (Zhang et al., 2015) that may reduce the incidence of virus diseases -­‐ Dader et al., 2016. Dáder, B.; Fereres, A.; Moreno, A.; Trębicki, P. Scien@fic Reports 2016, 6:19120 -­‐ Trębicki, P.; Vandegeer, R.K.; Bosque-­‐Pérez, N.A.; Powell, K.S.; Dader, B.; Freeman, A.J.; Yen, A.L.; Fitzgerald, G.J.; Luck, J.E.. Scien@fic Reports 2016, 6 22785. -­‐ Zhang, S., Li, X., Sun, Z., Shsao, S., Hu, L., Ye, M., Zhou, Y., Xia, X., Yu, J., Shia, K., 2015. J. Exp. Bot. 66 (7), 1951–1963. Aphid preda<on may be more efficient under eCO2 because aphids become less sensi<ve to alarm pheromone Hentley & Jones. J Chem Ecol (2014) 40:1110–1114 •  Escape responses to ladybirds was reduced by >50 % arer aphids had been reared on plants grown under eCO2 •  Ladybird preda<on will become more efficient under eCO2. -­‐ eCO2 reduces host plant quality, making aphids to engage in more intense and sustained feeding ac9vity Harmonia axyridis Amphorophora idaei CLIMATE CHANGE & PLANT PATHOGEN EPIDEMICS
Overall Outcomes and Conclusions
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Poleward shirs of >600 crop pest and pathogens averaged 27 kms/decade since the 1960s. Hemipterans are moving at a rate of 13.7 kms/year. Bemisia tabaci is expected to move northwards in the Mediterranean countries (-­‐) eCO2 reduces disease severity and modulate plant defense responses to various virus diseases (+) The variable responses of insect vectors to eCO2 are plant-­‐mediated effects causing in many cases a reduc<on in the intrinsic growth rate of aphids and enhanced preda9on by natural enemies (+) Some other vector pest species may adapt to the lower C:N ra<o and perform well (eg. B. tabaci) Warmer winters can increase epidemics in regions with temperate climates by increasing overwintering virus and vector survival and increasing the number of genera<ons/year (-­‐) HoQer, drier summers will decrease virus epidemics in rainfed crops in regions with Mediterranean climates by decreasing virus and vector over-­‐
summering (+) Greater wind speeds may promote long-­‐distance dispersion of insect vectors of plant pathogens (-­‐) FUTURE RESEARCH NEEDS •  Influence on virus mul9plica9on inside vectors and on virus transmission efficiencies achieved by insect vectors including aphids, whiteflies, thrips, mites, nematodes and fungal vectors. •  Effects of increased or decreased rainfall, and the extreme weather parameters such as drought, flooding, rela<ve humidity, and increased wind speeds on spread of virus diseases. •  Field experiments inves9ga9ng the effects of diverse climate change parameters on viruses, vectors, and plant hosts in field situa9ons, including in FACE facili<es, open-­‐top chambers, heated and rainfall-­‐
adjusted plots in regions with high temperatures or where flood or drought condi<ons occur. •  More experiments that address climate change scenarios where several parameters change simultaneously and con9nuously are needed to make reliable predic<ons ACKNOWLEDGEMENTS Insect Vectors of Plant Pathogens Team Ins9tute of Agricultural Sciences. Madrid, Spain. Spanish Research Council. CSIC 3rd. Hemipteran-­‐Plant-­‐Interac9ons Symposium (HPIS 2017) at Madrid, Spain SAVE THE DATE: 4-­‐8 June, 2017 hQp://www.hpis2017.csic.es