Host phylogenetic diversity predicts the global extent and composition of tree pests

Abstract

Tree pests cause billions of dollars of damage annually; yet, we know little about what limits their regional composition and distribution. Here, we model the co‐occurrence of 4510 pests and 981 tree host genera spread across 233 countries. We show the composition of tree pests is primarily driven by the phylogenetic composition of host trees, whereas effects of climate and geography tend to be more minor. Pests that utilise many hosts tend to be more widespread; however, most pests do not fill the geographic range of their hosts—indicating that many pests could expand their extents if able to overcome barriers limiting their current distribution. Our results suggest that the establishment of pests in new regions may be largely dictated by the presence of suitable host trees, but more work is needed to fully understand the influences climate has on the distributions of individual pest species.

A global analysis of tree pests and emerging pest threats

“…Warmer climates may also be associated with more favorable environmental conditions for pests, additional pest lifecycles, and greater host stress, each of which could increase the likelihood and impacts of pest establishments. Likewise the continued introduction of trees to new regions (accidentally or intentionally) similarly expands the potential range of many pests as host composition is the primary driver of tree pest composition globally ( 33 ). Future work integrating effects of global change on pest distributions could help refine projections of invasion risks over the next few decades.…”

Non‐native tree pests have a broader host range than native pests and differentially impact host lineages

“…However, the relationship between dispersal and host specificity in plant pathogens remains underexplored. Some insect pests have both wide host range and high dispersal capacity (Beck & Kitching, 2007), and there may be a more general positive relationship between host range and geographical extent (Gougherty & Davies, 2022; Poulin et al, 2011). Third, non‐native pathogens might initially colonise a few very abundant hosts, and perhaps only expand their host range slowly over time, parallel to the lag in geographical expansion commonly observed following the initial establishment of non‐native species (Crooks et al, 1999).…”

“…The relationship between phylogenetic distance and ecological or functional similarity is not always straightforward, even when traits are phylogenetically conserved (Cadotte et al, 2017), and convergent evolution can result in phylogenetically distant species being functionally similar (Mayfield & Levine, 2010; Webb et al, 2002). Nonetheless, many pests show phylogenetic conservatism in their host range such that they preferentially associate with closely related host taxa (Gilbert et al, 2012; Gilbert & Webb, 2007; Parker et al, 2015; Ssebuliba & Davies, 2021), and empirical data provide strong evidence that host phylogeny strongly structures pest distributions, at least at broad spatial scales (Gougherty & Davies, 2022). Pests with a broad phylogenetic host range may be more likely to establish in a novel host community, and tree communities that are closely related to a pests' native hosts may be more invadable (Gougherty & Davies, 2021).…”

Precipitation's complicated role in driving the abundance of an emerging disease vector in an urban, arid landscape

“…The ability to examine highly localized and variable conditions that precede ecological events and the distributions of seasonal phenological phenomena Park et al 2021) will have broad applicability across ecological questions and ecosystems. Kriging may become a valuable planning tool for many organismal-environment problems, including predicting outbreaks of tree-killing beetles (Gougherty & Davies 2021), understanding drivers of arthropod declines (Dornelas & Daskalova 2020), anticipating changes to water bodies after precipitation (Haines 1981;Lipp et al 2001); and making more granular predictions of effects of global change on organisms such as amphibians (Walls et al 2013;Catenazzi 2015), those dependent on specialized interaction partners (Kearns et al 1998;Kiers et al 2010), and rare and biogeographically limited species (Lyons et al 2005;Enquist et al 2019). Pearson's correlation coefficient calculated on repeatedly subsampled data reveals a weak positive correlation between logarithmically transformed female counts and unbinned precipitation data (r (df>500)=0.22;) that is nevertheless statistically significant (p<0.001), because the relationship is approximately linear.…”