Biology subjects

Mora Van Cauwelaert, E.

Publications and source records attributed to Mora Van Cauwelaert, E..

6 recordsLinked to original sources

bioRxiv2026

Predator coexistence and herbivore suppression are shaped by predator functional types in intraguild predation modules

Coexistence of multiple predators in ecological communities and their combined effects on the abundance and diversity of shared prey are often difficult to predict. In some theoretical models, predator coexistence is limited by antagonistic interactions, especially in the form of intraguild predation (IGP) that typically leads to out-competition between predators and high prey densities. However, empirical studies show that predator coexistence is common even in the presence of IGP. This discrepancy between theoretical expectations and empirical observations can be highly relevant for practical applications like using multiple natural enemies for pest suppression in agriculture. It is proposed that greater functional differences between natural enemies (i.e. predators) could reduce competition and overcome the negative effects of IGP, thereby promoting their coexistence and enhancing herbivore (i.e. prey) suppression. In this study, we theoretically explore this proposition. We develop a theoretical model based on the types of natural enemies of aphids to identify how functional differences between predators in IGP modules affect predator coexistence and herbivore suppression. We show that pairwise combinations of four functional predator types (ladybird, predatory bug, hoverfly, and parasitoid) can increase the coexistence range for different intraguild predation and competition strengths between predators (IGP symmetry), along a productivity gradient. This outcome depends on the external food input rate for the predatory bug and hoverfly types, and on their position as IG predator or IG prey. Herbivore suppression was primarily driven by IGP symmetry (i.e. the relative intraguild predation and exploitative competition strength between predators) and was especially pronounced in competitive-like modules where the IG predator was excluded for most scenarios. However, for some competitive-like IGP modules with predatory bug and hoverfly types, both predators can persist and provide a high herbivore suppression across increasing productivity. Our results can help explain experimental findings in conservation biocontrol, where coexistence between natural enemies is joined with effective herbivore suppression, and offer additional support for the role of functional diversity in reconciling theoretical predictions with experimental observations in multiple-predator communities.

ecology↗

bioRxiv2023

Harvesting trajectories in large-scale coffee plantations: ecological and management drivers and implications

CONTEXTCoffee is produced under different management systems and scales of production categorized as Syndromes of Production. The "Capitalist Syndrome" is characterized by the high use of capital and labor inputs to increase agricultural outputs. This syndrome results in practices like high planting densities that may promote the development and dispersal of plant pathogens like coffee leaf rust. The spatial arrangement of coffee trees drives the spatial movement of the harvesters, who can bear and disperse pathogens across and within plantations. In most capitalist coffee plantations, harvesters work multiple hours to maximize the daily harvest, which might increase their dispersal potential. However, their spatial movement has not yet been described, nor its relationship with the scale or management of the plantation, and even less its ecological implications for pathogens dispersal. OBJECTIVEWe describe and analyze the daily spatial movement of coffee harvesters in two large-scale capitalist plantations: an organic and a conventional plantation. METHODSUsing state-space models, we recorded and analyzed the spatial movements of harvesters. We then constructed a driver tree for harvest dynamics, which incorporated qualitative variables related to climate, coffee plants, and management aspects reported by the harvesters. RESULTS AND CONCLUSIONSOur model differentiated two kinds of movements: 1) when trees have berries, harvesters remain in the coffee rows or areas nearby (Collect state; 94-98% of the steps); 2) when not, harvesters make longer steps within the harvesting location or move to another area (Search state; 2-6% of the steps). In the organic plantation, the Search state had a longer-tailed step-length distribution than in the conventional plantation, resulting in a significantly higher visited area per worker (p<0.05). This might be related to a) a lower fruit load or percentage of trees with ripe fruits when we took the data or b) smaller harvesting locations ("pantes") per number of harvesters. Harvesting movements that explore a wider area, either by visiting more plants or by changing locations on the same day, could create more foci of CLR infection across the plantation. SIGNIFICANCEOur results highlight practices that can reduce the possible impact of human dispersal of pathogens like shorter harvesting trajectories by working fewer hours a day or avoiding harvesting at the end of the maturation season when few trees have berries and harvesters have to travel longer distances. This calls for organic coffee management that could prevent diseases, increase diversity, and guarantee just and safe conditions for workers.

ecology↗

bioRxiv2023

Interplay between harvesting, planting density and ripening time affects coffee leaf rust dispersal and infection

The relationship between the spatial structure of hosts and the individual movement of vectors is central to developing a comprehensive representation of pathogen dynamics. Here we focus on the dynamics of coffee leaf rust (CLR; Hemileia vastatrix), which is one of the principal coffee diseases around the globe. This fungus disperses between plants or regions through direct contact, water splash, or local turbulent wind conditions. Some studies have proposed that coffee harvesters can also bear CLR during harvesting. However, it is not clear how relevant these movements are for CLR dispersal and plot-level infection in plots with different planting densities. Besides, there are bidirectional interactions between the plantation characteristics (e.g. planting density and ripening synchronicity) and the movement of harvesters that might modify their dispersal potential. Overall, there is a lack of mechanistic models to represent these interactions. Here we present a computational model to explore the role of coffee ripening synchronicity in reproducing the different movement trajectories observed in the field. We then evaluate how these harvesting trajectories modify rust dispersal and change CLR infection in plots with increasing planting densities and a constant contact-mediated rust dispersal mechanism. For both synchronization scenarios, the distribution of step lengths is positively skewed. Interplant asynchronous ripening and scarcity of trees with berries generate trajectories with medium to long steps contrary to scenarios with synchronous ripening and without scarcity. The harvest dispersal significantly increases coffee plot infection (up to 15%) compared to scenarios where only local mechanisms for CLR dispersal are present. This effect is maximal for trajectories with medium to long steps from the asynchronous scenario and in plantations with medium planting densities. In particular, medium-sized steps are more likely to create new foci and networks of contact-mediated infected plants. The interaction between the proportion and the size of infected networks results in a nonlinear behavior of rust increase due to harvest. Our results aim to spur discussion on practices that could reduce the impact of harvesting and specific trajectories, in scenarios where one can benefit from asynchronous maturation of berries and shaded plantations. Some examples of practices include reducing the medium to long-distance movements during the same day, for instance, by avoiding harvesting at the end of the harvest season when trees ripening asynchronicity and CLR levels are higher.

ecology↗

bioRxiv2021

High-order interactions maintain or enhance structural robustness of a coffee agroecosystem network

The capacity of highly diverse systems to prevail has proven difficult to explain. In addition to methodological issues, the inherent complexity of ecosystems and issues like multicausality, non-linearity and context-specificity make it hard to establish general and unidirectional explanations. Nevertheless, in recent years, high order interactions have been increasingly discussed as a mechanism that benefits the functioning of highly diverse ecosystems and may add to the mechanisms that explain their persistence. Until now, this idea has been explored by means of hypothetical simulated networks. Here, we test this idea using an updated and empirically documented network for a coffee agroecosystem. We identify potentially key nodes and measure network robustness in the face of node removal with and without incorporation of high order interactions. We find that the systems robustness is either increased or unaffected by the addition of high order interactions, in contrast with randomized counterparts with similar structural characteristics. We also propose a method for representing networks with high order interactions as ordinary graphs and a method for measuring their robustness. HighlightsO_LIThe robustness of a coffee-associated ecological network is either increased or unaffected by the incorporation of high order interactions. C_LIO_LIA method is proposed for representing high order interactions in ordinary networks. C_LIO_LIA method is proposed to measure the robustness of networks with high order interactions. C_LIO_LIHigh order interactions may promote the persistence of diverse ecosystems. C_LI

ecology↗

bioRxiv2019

Landscape heterogeneity of peasant-managed agricultural matrices

In agricultural landscapes, management practices and other environmental and social factors shape complex agroecological matrices. In turn, the structure of such matrices impacts both agricultural activities and biodiversity conservation, for instance, by mediating wildlife migration between agricultural and habitat patches. One way to characterize a matrix, its potential role in biodiversity conservation, and how its descriptors change across different spatial scales, is characterizing heterogeneity metrics and systematically examining how such metrics change with grain size and landscape extent. However, these methods have rarely been applied to tropical, peasant-managed landscapes, even though this type of landscape occupies most of the agricultural surface in or near biodiversity hotspots. We focus on a peasant-managed agricultural landscape in Oaxaca, Mexico, for which we mapped and quantified the land-use classes and evaluated heterogeneity metrics. We also examined the response of heterogeneity metrics to changes in grain and extent scales. This allowed us to further understand the structure and conservation potential of the agroecological matrix in this type of landscape, to broadly compare this landscape with other agricultural landscapes in North America, and to recommend specific landscape metrics for different types of studies involving agricultural matrices. We conclude that this type of agricultural matrix is ideal to pursue joint agricultural and conservation strategies in an integrated landscape.

ecology↗

bioRxiv2018

Combined effect of matrix quality and spatial heterogeneity on biodiversity decline

The land-sparing/land-sharing debate remains an oversimplified framework to evaluate landscape management strategies that aim to reconcile food production and biodiversity conservation. Still, biodiversity-yield curves, on which the framework has relied, provide valuable qualitative information on biodiversitys sensitivity to agricultural practices, and much research has studied this relationship. But the potential effect of landscape configuration on biodiversitys response to intensification has rarely been considered; besides, studies have often taken yield as an indicator of agricultural management and have generalized conclusions from studying particular taxonomic groups. In this work we adapt a metacommunity model to analyze factors that shape biodiversitys response to agricultural intensification while addressing some of the simplifications of the land-sparing/land-sharing dichotomy. In particular, we study species richness decline in landscapes encompassing a combined gradient in matrix quality and configurational heterogeneity of habitat patches, and considering community dynamics. We found that species richness along an intensification gradient shifts from following a robust response to presenting an abrupt decline, as landscape heterogeneity increases, as stricter survival thresholds are applied to species or as habitat area is reduced. Our work highlights the interdependent effects of heterogeneity, habitat availability and matrix quality on biodiversity and contributes to a nuanced understanding of ecological and landscape factors that enable a robust response of biodiversity in the face of spatiotemporal perturbations.

ecology↗