From ecological menace to roadside attraction: 28 years of evidence support successful biocontrol of purple loosestrife

Introduction and spread of non-native plants provide ecologists and evolutionary biologists with abundant scientific opportunities. However, land managers charged with preventing ecological impacts face financial and logistical challenges to reduce threats by introduced species.  The available toolbox (chemical, mechanical, or biological) is also rather limited.  Failure to permanently suppress introduced species by mechanical and chemical treatments may result in biocontrol programs using host-specific insect herbivores.  Regardless of the chosen method, long-term assessment of management outcomes not just on the target species, but also on associated biota, should be an essential component of management programs. However, data to assess whether management results in desirable outcomes beyond short-term reductions of the target plant are limited.  Here we use implementation of a biocontrol program targeting a widespread wetland invader, Lythrum salicaria (purple loo..., We worked at 33 sites (mix of federal, state, and private ownership) varying in size from a few hundred square meters to >10 ha across New York State.  Initially, most sites (old fields, wetlands, marshes, and impoundments) were dominated by L. salicaria, although some releases occurred where managers documented only small patches.  Water levels varied through time, reflecting natural variation in precipitation patterns, beaver activity, and intentional manipulations by wetland managers and private landowners.  We monitored each site for a period of 15 to 28 years, starting the year insects were first released.  Releases included one or several of the following species: two leaf-feeding beetles (Galerucella calmariensis and G. pusilla), a root-feeding weevil (Hylobius transversovittatus), and a flower-feeding weevil (Nanophyes marmoratus).  
At each site we established 1 to 15 1 m2 permanent quadrats spaced 5–50 m apart.  Presence of L. salicaria wa..., Excel or Text-editor
R or R studio, # From ecological menace to roadside attraction: 28 years of evidence support successful biocontrol of purple loosestrife

doi:10.5061/dryad.8pk0p2nt9

## Description of the data and file structure

Data are typically summarized by unique quadrat by time treatment combinations (i.e., data rows). Which csv file is needed for each analysis is explained within the annotations of the associated R scripts. \"NA\" represents 'missing' values in the dataset. Some important variables of note in the data files include area (region of state where site was located), month (month of data collection; either 'June' for summer monitoring or ‘Sept’ for fall monitoring), and pl.density (number of stems per permanent 1m² quadrat). Descriptions of other variables are also found in the main text in addition to the detail provided herein.

### Column descriptions by csv file:

#### dispersal\_distance\_in\_montezuma.csv

Note: this represents summary data from only a subset of the monitored site...,