Ergeben sich Anhaltspunkte für einen Verlust von Biodiversität in der langjährigen Überwachung von Schaderregern?

Die Krefelder Studie zeigte 2017 einen Rückgang der Masse von fliegenden Insekten um etwa 75% innerhalb von 27 Jahren in einem geschützten Gebiet (HALLMANN et al. 2017). Um die Rolle der Landwirtschaft besser zu verstehen, wären Vergleichsdaten von ungeschützten landwirtschaftlichen Flächen hilfreich. Die Richtlinie 2009/128/EH des Europäischen Parlamentes und des Rates verlangt die Überwachung der Schaderreger in den wichtigsten Kulturpflanzen der Mitgliedsstaaten. Diese oft langjährigen Monitoringdaten von Agrarflächen können für Trendanalysen inklusive Tests auf einen potentiellen Verlust von Biodiversität im Bereich der Schädlinge und Krankheiten genutzt werden. Das Luxemburger Monitoring zeigte im Zeitraum 2007-2017 eine zunehmende Rolle von Gelbrost und eine abnehmende Rolle von Braunrost im Winterweizen. Bei Fusarium-Symptomen und Mehltau im Winterweizen sowie der Anzahl von Stängelrüsslern (gefangen mittels Gelbschalen im Winterraps) wurden sehr starke Schwankungen zwischen den Jahren beobachtet, ohne dass ein Trend in Richtung Aussterben einer Art gezeigt werden konnte. Septoria Blattdürre wurde in allen Jahren in hoher Dichte spätestens gegen Ende der Weizensaison gefunden. Die höchste pro Jahr in Luxemburg gefundene Anzahl von Rapsglanzkäfern pro Haupttrieb am Winterraps nahm zwischen 2007 und 2017 geringfügig aber statistisch absicherbar zu. Es wurde eine hohe Dynamik der Schaderreger zwischen den Jahren beobachtet ohne dass ein Verschwinden einer oder mehrerer der überwachten Arten auf den beobachteten Agrarflächen nachgewiesen werden konnte (DAM et al. 2020). Literatur DAM D, PALLEZ-BARTHEL M, EL JARROUDI M, EICKERMANN M, BEYER M (2020): The debate on a loss of biodiversity: can we derive evidence from the monitoring of major plant pests and diseases in major crops? Journal of Plant Diseases and Protection 127: 811-819. https://doi.org/10.1007/s41348-020-00351-9. HALLMANN CA, SORG M, JONGEJANS E, SIEPEL H, HOFLAND N, SCHWAN H, STENMANS W, MÜLLER A, SUMSER H, HÖRREN T, GOULSON D, DE KROON H (2017): More than 75 percent decline over 27 years in total flying insect biomass in protected areas. PLoS One 12:e0185809. https://doi.org/10.1371/journal.pone.0185809

Future development of apricot blossom blight under climate change in Southern France

International audienceClimate change will have several consequences for agro-systems, one of which will concern changes to the development of pathogens. Because of the losses it causes, particularly in organic farming, Monilinia laxa is an important pathogen affecting apricot crops. This study focuses on the consequences of climate change regarding blossom and twig blight (Monilinia laxa) of apricot. To achieve this, a Climatic Index of cumulated Blight risk (CIB) was built, to obtain the weighted sum of blossom blight incidence throughout the blooming period. An epidemiological model to calculate the incidence of blossom blight during every potentially infectious episode and based on biological parameters, was calibrated using a trap pot experiment where trees were placed in orchards and subject to various meteorological conditions. The CIB derived from this model was evaluated on field data, and was shown to be a robust and useful tool to predict the effects of climate change on the development of apricot blight. Then, using the CIB with a phenological model to predict blooming periods in the future, we estimated the risks of apricot blight until 2100 on four contrasted apricot cultivars and in three geographical zones under climate change scenarios RCP 4.5 and 8.5. This study revealed different effects of climate change depending on the cultivar and altitude. Apricot trees would bloom earlier (up to a difference of 50 days between 1950 and 2100) under climate change. Under the combined effects of these shifts of blooming period and changing climatic conditions, late cultivars such as Bergarouge might see a reduction in the risk of blossom blight (down to 31%) because of warmer but dryer blooming periods. Other varieties (e.g.: Bergeron) could experience an increase in this risk by up to 27% with a shift of the blooming period towards rainier conditions at the highest altitudes. The results of this study could be used to anticipate future changes as well as be used at present as a decision-support tool for farmers

Enhancing septoria leaf blotch forecasts in winter wheat I: the efect of temperature on the temporal distance between critical rainfall periods and the breaking of the control threshold

peer reviewedIn integrated pest management (IPM), pests are controlled when the costs of control correspond with the damage caused by a pest on a monetary scale, implying that low pest levels are left uncontrolled. Several forecast models have been developed in plant pathology to warn farmers before an epidemic occurs to allow timely control. Most of these models do not predict a control threshold (pest level at which action needs to be taken to prevent economic losses at the farm level) directly making an application in precision agriculture where pesticides and other inputs shall be used precisely where and when they are needed, difcult. Here, we quantifed the temporal distance between critical rainfall periods and the breaking of the control threshold of Z. tritici on winter wheat, as afected by temperature based on data from 52 feld experiments carried out in Luxembourg between 2005 and 2016. The highest frequency of hours with rain (≥0.1 mm/h) was observed approximately at 300 h before epidemic outbreaks at about 13 °C, at 350 h at 11.5 °C and at about 475 h at about 7.5 °C. A Q10 value of 2.8 was estimated. The knowledge generated here will be used to construct a model that directly forecasts the time at which the control threshold will be reached and thus, when fungicide use is needed according to the standards of IPM with direct applicability in precision agriculture.Sentinell

The debate on a loss of biodiversity: can we derive evidence from the monitoring of major plant pests and diseases in major crops?

The European commission directive EC 128/2009 calls for monitoring pests and pathogens of major crops. The monitoring data may be analysed for trends over time, including tests for a potential loss of biodiversity in the domain of plant pests and pathogens. The monitoring programs carried out in Luxembourg since 2007 provided evidence for an increasing role of yellow rust and a decreasing role of brown rust on winter wheat. Vast inter-annual variability was observed at the level of Fusarium head blight and mildew symptoms on winter wheat as well as at the level of Ceutorhynchus counts in oilseed rape, but no trend towards extinction could be demonstrated. Septoria leaf blotch was present in winter wheat at high levels towards the end of all seasons. The maximum number of Brassicogethes aeneus individuals found per main stem and season on oilseed rape increased slightly but significantly between 2007 and 2017. Substantial evidence for highly dynamic changes in the pest populations was found, but no evidence for the vanishing of the monitored species could be demonstrated.Sentinell