Scouting ecological drivers of natural enemies in citrus orchards: implications for biological control in the Corsican agricultural landscape

CARRIE, E.; MARGRIS, L.; CARLUT, E.; Frank, E.; CANARD, E.; PLANTEGENEST, M.; SANGUIN, H.; Julhia, L.; RAVIGNE, V.; SOUBEYRAND, S.

doi:10.64898/2026.05.27.727191

bioRxiv · 10.64898/2026.05.27.727191

Scouting ecological drivers of natural enemies in citrus orchards: implications for biological control in the Corsican agricultural landscape

CARRIE, E.·MARGRIS, L.·CARLUT, E.·Frank, E.·CANARD, E.·PLANTEGENEST, M.·SANGUIN, H.·Julhia, L.·RAVIGNE, V.·SOUBEYRAND, S.

View original source ↗Export metadata ↓

Abstract

O_LIEffective pest control requires a better understanding of natural enemy ecology, particularly how their distribution responds to landscape structure and local management. Agricultural intensification has simplified landscapes, reducing biodiversity and constraining pest control. Landscape-scale surveys are therefore needed to identify strategies that support natural enemies in agricultural systems. C_LIO_LIFrom 2021 to 2022, over three seasons, we surveyed 25 clementine orchards across a gradient of landscape complexity in Corsica. We modelled the tree-level occurrence of four natural enemy species in relation to ecological context across multiple spatial and temporal scales. Site-level evenness, reflecting differences in species occurrence frequencies, was also estimated to assess how natural enemy assemblages vary across local management and landscape gradients. C_LIO_LIClimate and local management were the primary drivers of species occurrence, with additional contributions from landscape factors. Species displayed distinct responses, while model performance increased with the number of sampled trees, plateauing at around half of the sampling effort. C_LIO_LISite-level evenness was higher in organic orchards than in conventional orchards. In conventional orchards, it responded to landscape structure in a scale-dependent manner, increasing at the larger scale with the heterogeneity and spatial continuity of semi-natural habitats. C_LIO_LISynthesis and applications. Organic farming enhances natural enemy presence and diversity in Corsican citrus orchards, while the naturalness and complexity of surrounding landscape can mitigate species scarcity in conventional orchards. We recommend continued long-term monitoring of arthropod communities in these systems, prioritizing the number of sampling sites and years while reducing the number of trees sampled per site to optimize effort. C_LI

Explore related subjects

ecology Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

CARRIE, E., MARGRIS, L., CARLUT, E., Frank, E., CANARD, E., PLANTEGENEST, M., SANGUIN, H., Julhia, L., RAVIGNE, V., SOUBEYRAND, S.. 2026-06-01. Scouting ecological drivers of natural enemies in citrus orchards: implications for biological control in the Corsican agricultural landscape. https://doi.org/10.64898/2026.05.27.727191

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Species-composition distributions under competition, ecological drift and immigration

Understanding how species interactions, ecological drift, and immigration jointly shape community composition is a central goal of community ecology. These processes determine not only average community composition, but also how often different community states occur. Here, we ask how competition reshapes the neutral distribution of community composition generated by drift and immigration. We analyze a stochastic two-species competition model with immigration and derive the stationary distribution of relative species composition near neutrality. The stationary distribution shows when communities are usually balanced and when they are instead dominated by one species. Species dominance can become common even when the corresponding deterministic model predicts stable coexistence, particularly in smaller communities. Balanced and dominance states can also occur together, producing a trimodal distribution. Competitive asymmetry further biases the distribution toward the competitively favored species. Thus, the interplay between competition, ecological drift, and immigration determines not only how much community composition varies, but also which community states are most likely to be observed. Our results provide an analytical bridge between neutral and competition theory and a framework for interpreting variation in community composition.

ecology↗

bioRxiv2026

Floristic composition, phenology, and conservation value of four peat bogs in Bucovina, with the presence of Betula nana

This paper presents a comparative analysis of the floristic composition and site characteristics of four peat bogs in Bucovina, Romania: Poiana Stampei, Romanesti, Saru Dornei, and Gaina-Lucina. The research was based on phytosociological releves on 25 msq plots and direct field phenological observations, on six field visits from May to August 2026. Vegetation was characterised using the Braun Blanquet method, and floristic similarity between sites was assessed with the Sorensen and Bray Curtis indices. All four plots shared a common core of taxa characteristic of peatland vegetation: Sphagnum spp., Carex rostrata, Drosera rotundifolia, Eriophorum vaginatum, and Vaccinium species. Species richness was 13 taxa at Poiana Stampei, Romanesti, and Saru Dornei, and 12 at Gaina-Lucina. Romanesti and Saru Dornei showed the highest floristic similarity (descriptive values, not statistically tested, given a single releve per site), while Gaina-Lucina differed most markedly, not through species richness, which was similar across sites, but through species identity and through the presence of Betula nana, a glacial relict absent from the other sites. The results provide a descriptive basis for future research on the floristic composition and conservation of these habitats.

ecology↗

bioRxiv2026

Long-Term Surveillance Reveals Establishment of Aedes albopictus in Eastern Nebraska, USA

Aedes albopictus (Skuse), the Asian tiger mosquito, is a highly competent arboviral vector whose range has expanded substantially across the United States over the past four decades. Despite predictive models placing Nebraska within the species' climatically suitable range, its establishment status in the state has remained poorly characterized. Here, we report results from a nine-year mosquito surveillance program (2017-2025) conducted across 44 Nebraska counties in collaboration with the Nebraska Department of Health and Human Services. Ae. albopictus was detected in five counties, with sustained, annually increasing populations documented in Richardson, Douglas, and Lancaster counties. Richardson County recorded continuous detections during 2017-2025, with proportional representation rising to 60.50% of collected mosquitoes by 2025. In Douglas and Lancaster counties, temporal advancement of first seasonal detection in 2024 and 2025 provide evidence consistent with successful overwintering rather than annual reintroduction. A cumulative degree-day model predicted adult emergence in mid-May across all county-year combinations, consistently preceding trap deployment by two to seven weeks and revealing a systematic early-season surveillance gap. Generalized linear mixed-effects models indicated that trap-level detection persistence, rather than urban location, was the primary predictor of yearly Ae. albopictus positivity, suggesting that current invasion dynamics are driven by focal source populations. These findings provide strong evidence for the establishment of Ae. albopictus in eastern Nebraska and highlight the need for earlier seasonal surveillance and standardized criteria to define establishment in northward-expanding vector populations.

ecology↗