Edge effects, tree cover and soil properties linked to the distribution of Diaprepes abbreviatus in a Florida citrus orchard.

Abstract

<h4>Background</h4>Diaprepes root weevil (DRW, Diaprepes abbreviatus) is a major economic pest of citrus trees in Florida and the Caribbean Basin. To identify potential drivers of local patterns of weevil abundance and tree condition, we measured relationships between DRW and edaphic properties in a Florida orchard in which half the trees were initially protected from herbivores by individual protective covers (IPCs) of fabric mesh. Weevils were monitored for 2 years in 94 plots arranged in a grid pattern. Soil samples were processed for physicochemical properties, and DNA from soil organisms was subjected to metabarcoding for ITS2 rDNA, 16S rDNA, and COI mtDNA.<h4>Results</h4>Weevils aggregated each summer along plot boundaries adjacent to a natural area of alternate hosts, consistent with an edge-biased distribution reflecting seasonal weevil migration. Fourteen months after the covers were removed, 93% of 484 prokaryote species (dominated by Bacilli, Actinobacteria, Alphaproteobacteria, and Cyanobacteria) that were most closely associated with IPC use were less abundant beneath the trees that were formerly covered than under previously uncovered trees. Soil moisture, Paenibacillus spp. diversity, and IPCs were associated with DRW patterns and tree condition including mortality.<h4>Conclusions</h4>Early season, edge-biased distribution of DRW should be exploited for monitoring and management efficacy. The relationship here between tree mortality and microbiome species deficits associated with IPCs supports the need for research to resolve the role of tree covers in potential trophic cascades that affect plant health. © 2026 Society of Chemical Industry.