Biology subjects

Blomme, G.

Publications and source records attributed to Blomme, G..

4 recordsLinked to original sources

bioRxiv2025

Pathogen and pest communities in food security crops across climate gradients: Anticipating future challenges in the Great Lakes region of Africa

CONTEXTTropical cropping systems must adapt to the current and future geographic distribution of pathogen and pest communities. An important research gap is how climate change may shift the distribution of pathogens and pests in tropical lowlands and highlands. OBJECTIVEWe evaluated the current geographic risk of 27 pathogens and pests in the production of four food security crops (banana, cassava, potato, and sweetpotato) in the Great Lakes region of Africa, and the potential future risk under climate change. Models for each pathogen and pest indicate the potential for changes in geographic distribution, with model fit indicating the potential for decision support systems to facilitate management. METHODSFirst, cropland connectivity analysis identified locations likely important in the spread of crop-specific pathogens and pests, such as locations in Rwanda and Burundi. Second, we surveyed the 27 economically important pathogens and pests in Rwanda and Burundi, mapping the distribution of each across climate gradients and quantifying patterns of association. Third, we used machine learning to develop models of each species as a function of environmental variables, including host landscape variables. We also evaluated the increase in temperature across altitudes under future climate change scenarios in this region. RESULTS AND CONCLUSIONSAmong the ten machine-learning algorithms evaluated, random forests and support vector machines generally performed best for predicting severity and infestation. Host landscape variables were useful predictors for some species. Based on climate matching, 44% of the pathogens and pests could become more common with warmer temperatures at higher altitudes, while 17% may become less common. SIGNIFICANCEThis study indicates adaptation priorities for crop health in a region with multiple challenges to agricultural sustainability. The models developed here also indicate which species may have more potential and relevance for future development of pathogen and pest forecasts.

ecology↗

bioRxiv2021

Spread of Xanthomonas vasicola pv. musacearum within banana mats: implications for Xanthomonas wilt management

Xanthomonas wilt (XW) of banana caused by Xanthomonas vasicola pv. musacearum (Xvm) does not spread to all plants physically interconnected through the rhizome when one or a few are diseased. However, the factors behind this incomplete systemic spread of Xvm are not fully known yet could inform XW management. This study explored the effect of Xvm inoculum amounts, number and size of suckers, sucker positioning on mother plant corms and other mother plant corm attributes on sucker colonization. A shorter (p <0.05) incubation period (17.9 vs 21.1 days) and higher (p<.001) cumulative number of symptomatic leaves (5.2 vs 1.6 leaves) was observed when all (high inoculum) compared to two leaves (low inoculum) were inoculated. Xvm was recovered in corms at 29 days post inoculation (dpi) in both treatments with no differences (p >0.05) in proportions of corms with Xvm between the treatments. However, Xvm was recovered earlier and at a higher frequency in suckers when all leaves were inoculated. Lower Xvm recoveries occurred in the lower corm sections to which most suckers were attached relative to the middle and upper corm sections. Xvm incidence in corms increased with the number of attached maiden suckers, and the dpi while it declined with increasing mother plant and corm height. Thus, Xvm spread within mats is influenced by the amount of inoculum and the physiological stage (e.g., height) of the plant and attached suckers. The position of suckers, predominantly at the bottom of corms also protects them from infection. Measures that reduce Xvm inoculum build-up in mats are thus crucial for minimizing within mat XW spread.

pathology↗

bioRxiv2020

The Distribution of Enset Pests and Pathogens and a Genomic Survey of Enset Xanthomonas Wilt

Mapping the distribution of crop pests and pathogens is essential to safeguard food security and sustainable livelihoods. However, these data are unavailable for many neglected and underutilised crops, particularly in developing countries. In Ethiopia, the worlds largest historic recipient of food aid, the indigenous banana relative enset (Ensete ventricosum) is threatened by multiple pests and pathogens whilst providing the staple starch source for 20 million people. Foremost among these is Xanthomonas Wilt of enset (EXW), caused by Xanthomonas vasicola pv. musacearum (Xvm), a globally important disease of bananas (Musa sp.) that likely originated in enset. Here we collate 1069 farm surveys to map the distribution and relative prevalence of enset pests and pathogens across the entire enset growing region. We find that EXW is the most frequently encountered pathogen, and that farmers consistently ranked EXW as the most significant constraint on enset agriculture. Our surveys also showed that corm rot, and the pests root mealybug, mole rat and porcupine are all virtually ubiquitous. Finally, we apply genotyping-by-sequencing to the detection of Xvm and demonstrate that it is present even in asymptomatic domesticated and wild enset samples, suggesting that management of plants displaying symptoms alone may not be sufficient to reduce disease transmission. Holistic understanding of pests and pathogen distributions in enset may have significant benefits for both food security in Ethiopia, and preventing proliferation in related crops such as banana across central and east Africa.

ecology↗

bioRxiv2017

Global cropland connectivity: A risk factor for invasion and saturation by emerging pathogens and pests

The geographic pattern of cropland is an important risk factor for invasion and saturation by crop-specific pathogens and arthropods. Understanding cropland networks supports smart pest sampling and mitigation strategies. We evaluate global networks of cropland connectivity for key vegetatively-propagated crops (banana and plantain, cassava, potato, sweetpotato, and yam) important for food security in the tropics. For each crop, potential movement between geographic location pairs was evaluated using a gravity model, with associated uncertainty quantification. The highly-linked hub and bridge locations in cropland connectivity risk maps are likely priorities for surveillance and management, and for tracing intra-region movement of pathogens and pests. Important locations are identified beyond those locations that simply have high crop density. Cropland connectivity risk maps provide a new risk component for integration with other factors - such as climatic suitability, genetic resistance, and trade routes - to inform Pest Risk Assessment and mitigation.

ecology↗