Data for: Implications of climate change for biocontrol efficacy across the northern range of the invasive plant Linaria dalmatica

The effect of insect biological control agents on invasive plant populations can vary spatially, and spatial variation in climate may drive regional variation in herbivory, and thus biocontrol efficacy. Within host plant populations, local plant abundance can also be affected by the spatial distribution of herbivores, but whether local patterns persist at larger scales is less well understood. We examined how infestation and damage of the stem-mining weevil Mecinus janthiniformis, a specialist biocontrol agent of the invasive plant Linaria dalmatica, varied with and among populations across the northern edge of the range in North America. We quantified weevil and invasive plant densities, as well as plant fecundity, stem diameter and height across sites spanning an area of ~39,000 km2 in British Columbia, Canada. We found that specialist weevils did not respond to host plant density within sites across the study region. Instead, weevil attack and load were most sensitive to among-site v..., We surveyed L. dalmatica populations across a wide swath of British Columbia, on the eastern side of the Canadian Cascade mountains in the summer of 2017, encompassing an area of approximately 39,000 km2 (Figure 1, Table A1). In consultation with local invasive plant managers and data from the British Columbia Invasive Alien Plant Program (B.C. Ministry of Forests, Lands and Natural Resource Operations, 2017), we selected sites where no active management, e.g. herbicide spray or mowing, was planned for 2017, with the goal of sampling as broadly as possible. Since L. dalmatica populations respond positively to disturbance (Sing et al., 2016), our goal was to choose sites of similar levels of disturbance, and all sites were located within 100 meters of primary or secondary roads. 39 sites were used in the analyses (those we were able to access in late summer to collect stems) and data from those sites are included here.
In the field, we surveyed stem density in 1x1 m2 plots - and counted ..., No proprietary programs required (all data in the mansucript were viewed and analyzed in R).