DOI: 10.5061/dryad.5qfttdzcc
title: Data from: Effect of a severe cold spell on overwintering survival of an invasive forest insect pest

description: Data from a study of a servere cold event in February 2023 on the survival
 of hemlock woolly adelgid (Adelges tsugae Annand) from four populations in
 Canada. Cold temperatures can play a significant role in the range and
 impact of pest insects. Severe cold events can reduce the size of insect
 outbreaks or in some cases even cause outbreaks to end. Measuring the
 precise impact of cold events, however, can be difficult because estimates
 of insect mortality are often made at the end of the winter season. In
 late January, 2023 long-term climate models predicted a significant cold
 event to occur over eastern North America. We used this event to evaluate
 the immediate impact on hemlock woolly adelgid overwintering mortality at
 four sites on the northern edge of the insects invaded range in eastern
 North America. We observed complete mortality, partial mortality and no
 effect of the cold event that correlated with the location and strength of
 the cold event. Our data also showed lack of support for preconditioning
 of overwintering adelgids as impacting their overwintering survival
 following this severe cold event. Finally, we compared the climatic
 conditions at our sites to historical weather data. The cold event
 observed in February 2023 resulted in the coldest temperatures observed at
 these sites, including the period within which hemlock woolly adelgid
 invaded these sites, suggesting cold conditions, especially under
 anthropogenic climate forcing, may not be a limiting factor in determining
 the ultimate northern range of hemlock woolly adelgid in eastern North
 America.
description: Insects were collected from infested trees at 4 sites in 2
 Canadian provinces immediately before and immeditely after a severe cold
 spell. The health and status of the insects (live/dead) was determined in
 a laboratory. The survival was then compared to observed temperature data
 extracted from Environment and Climate Change Canada weather
 stations. 
description: # Data from: Effect of a severe cold spell on overwintering survival of an
 invasive forest insect pest
 ## Description of the data
 and file structure There are 6 files in total: 1 ReadMe file, 2 data files
 and 6 associated code files (See Code/Software section). ReadMe.txt: This
 file. coldspell.csv: Records of number of hemlock woolly adelgid living
 and dead on shoots of hemlock trees collected from 4 sites in Canada,
 before and after a severe cold spell. Description of fields: -[];numeric;
 The row number for each record. -[province];text; either
 "Ontario" or "Nova Scotia"; the Canadian province
 where the site was located. -[site]; text; either "Annapolis Royal
 NS", "Mersey River NS", "Grafton ON" or
 "Wainfleet ON"'; the sites where samples were collected.
 -[col_date]; text; the date, in d/m/y format, that samples were collected.
 -[as_date]; text; the date, in d/m/y format, that samples were assessed.
 -[twig_age]; text; either 'c' or 'o''; the age of
 the twig (shoot) sampled (current year or old); not used in analysis.
 -[no_hwa]; numeric; the number of hemlock woolly adelgid found on the
 shoot -[live_hwa]; numeric; the number of live hemlock woolly adelgid
 found on the shoot. -[sht_len]; numeric; the length of the shoot, in cm;
 not used in analysis. -[comment]; text; notes made by the data collector;
 not used in analysis. -[Branch]; numeric; the branch number of that the
 sample was collected from; not sued in analysis.
 NovaScotiaHistoricalMortality.csv; Records of post-winter mortality of
 hemlock woolly adelgid recorded at sites in the Canadian province of Nova
 Scotia. Transcribed and cleaned from the original data files recorded in
 .xls spreadsheets. Description of fields: -[];numeric; The row number for
 each record. -[site]; text; various; the sites where samples were
 collected. -[year]; numeric; various; the year recorded in the raw data.
 -[mortality]; numeric; the mortality, in percentage, of hemlock woolly
 adelgid in samples taken at that site as recorded in the raw data
 -[mortality_true]; numeric; the true mortality, in percentage, of hemlock
 woolly adelgid in samples taken at that site. False '0's have
 been replaced with 'NA'. -[winter_true]; text; various; the two
 years spanned by the winter within which mortality occurred; e.g.,
 '2018-2019' is the winter that began in 2018 and ended in 2019
 and insect mortality was measured in the spring of 2019. Determined from
 notes recorded in the raw data. Sharing/Access information There are no
 other available versions of the data. ## Code/Software The data were
 analyzed using the R statistical computing environment and associated
 library packages authored for R. All analyses were done within the RStudio
 IDE. Associated files (not in repository) were used to generate figures in
 the associated manuscript. analysis_coldEventHWA.R; R statistical
 computing language script; Plots survival of hemlock woolly adelgid
 survival and observed temperatures, and conducts analysis of survival pre-
 and post-event. See comments in file for more detail. Requires
 coldspell.csv, hwaWeatherOctober22-March23.Rdata (prepared by
 GetReadAndCleanWeatherData.R, see below) and the R packages
 'tidyverse' & 'patchwork'.
 analysis_historicalNovaScotiaMortality.R; R statistical computing language
 script; Analyses and plots hemlock woolly adelgid mortality from multiple
 sites in Nova Scotia, Canada. See comments in file for more detail.
 Requires NovaScotiaHistoricalMortality.csv and the R package
 'tidyverse'. analysis_historicalWeather.R; R statistical
 computing language script; Plots winter temperatures for previous 10 years
 at 4 sites where hemlock woolly adelgid were collected. See comments in
 file for more detail. Requires
 hwaHistoricalWeatherDecember12-March23.Rdata (prepared in
 GetHistoricalWeatherData.R, see below) and the R packages
 'tidyverse' & 'patchwork'.
 computeEstimatedMortalityMcCavoy.R; R statistical computing language
 script; Computes an estimated survival of hemlock woolly adelgid using
 equation 2 from McAvoy et al. (doi: 10.3390/f8120497). See comments in
 file for more detail. Requires coldspell.csv,
 hwaWeatherOctober22-March23.Rdata (prepared by
 GetReadAndCleanWeatherData.R, see below) and the R package
 'tidyverse'. GetHistoricalWeatherData.R; R statistical computing
 language script; Fetches observed weather data from four sites in Canada
 from Environment and Climate Change Canada server. See comments in file
 for more detail. Require the R packages 'weathercan' and
 'tidyr'. GetReadAndCleanWeatherData.R R statistical computing
 language script; Fetches observed weather data from four sites in Canada
 from Environment and Climate Change Canada server. See comments in file
 for more detail. Require the R packages 'weathercan' and
 'tidyr'.