DOI: 10.5061/dryad.m905qfv9f
title: Data from: Phloem-feeding insects creat parasitoid free space for caterpillars

description: Seemingly small ecological changes can have large, ramifying effects that
 defy expectations. Such are keystone effects in
 ecosystems. Phloem-feeding insect herbivores can act as keystone
 species by altering community structure and species interactions via
 plant-mediated or ant-mediated mechanisms. Plant responses triggered by
 phloem-feeders can disrupt tri-trophic interactions induced by
 leaf-chewing herbivores, while ants that tend phloem-feeders can deter or
 prey on other arthropods. Here, we investigate how phloem-feeding
 herbivores change caterpillar-parasitoid interactions on Quercus
 alba (white oak) trees in natural forests. We factorially
 manipulated the presence of phloem-feeding insects as well as ant access
 on Q. alba branches over multiple years and sites, and measured
 parasitism rates of co-occurring caterpillars. While 19.3% of caterpillars
 were parasitized when phloem-feeders were removed, the presence of
 phloem-feeders completely suppressed parasitism of caterpillars (0%). This
 stark pattern was consistent across the diverse community of
 phloem-feeders and caterpillars. Our manipulation of ant access had no
 effect on parasitism of caterpillars, implicating a plant-mediated
 mechanism. We further assessed the mechanistic hypothesis that
 phloem-feeders suppress plant emission of caterpillar-induced volatile
 compounds, which could disrupt host location behavior by parasitoids of
 caterpillars. Phloem-feeders indeed reduced concentrations of four
 volatile compounds, consistent with the putative plant volatile-mediated
 mechanism. Given the important role of parasitoids in controlling
 herbivore populations, this keystone effect of phloem-feeders offers novel
 insight into community dynamics in forests and potentially other
 terrestrial ecosystems.
description: See Anderson et al. 2024 Current Biology "Phloem-feeding
 insects creat parasitoid free space for caterpillars" for full
 methods on data collection and experimental design. Three datasets are
 provided: 1) Volatiles.xlsx provides the volatile compounds, their
 concentration, and branch, site, and treatment information. There is a
 MetaData sheet with greater detail. 2) Parasitism.xlsx provides the
 caterpillar data organized such that each row is an individual
 caterpillar. These data were assembled from individual yearly data of
 similar format. Otherwise, no other processing was used to assemble this
 data. There is a MetaData sheet with greater detail on each of the
 columns. 3) CaterpillarRecovery.xlsx provides the sampling recovery,
 parasitsm, and initial stocking values of caterpillars. This data is
 grouped such that each row represents the summed totals for each year,
 site, phloem-feeder treatment, and ant-treatment. There is a MetaData
 sheet with greater detail on each of the columns.
description: # Phloem Feeders inhibit Caterpillar Parasitism
 [https://doi.org/10.5061/dryad.m905qfv9f](https://doi.org/10.5061/dryad.m905qfv9f) Three datasets are provided: 1) Volatiles.xlsx provides the volatile compounds, their concentration, and branch, site, and treatment information. There is a MetaData sheet with greater detail. 2) Parasitism.xlsx provides the caterpillar data organized such that each row is an individual caterpillar. These data were assembled from individual yearly data of similar format. Otherwise, no other processing was used to assemble this data. There is a MetaData sheet with greater detail on each of the columns. 3) CaterpillarRecovery.xlsx provides the sampling recovery, parasitsm, and initial stocking values of caterpillars. This data is grouped such that each row represents the summed totals for each year, site, phloem-feeder treatment, and ant-treatment. There is a MetaData sheet with greater detail on each of the columns. ## Description of the data and file structure See Anderson et al. 2024 Current Biology "Phloem-feeding insects creat parasitoid free space for caterpillars" for full methods on data collection and experimental design. Three datasets are provided: 1) Volatiles.xlsx, 2) Parasitism.xlsx, and  3) CaterpillarRecovery.xlsx. Each file contains the raw data necessary to replicate the results and tables in Anderson et al. 2024. Additionally, each file contains a separate sheet for meta data that describes in detail the contents of each column in the data. The CaterpillarRecovery.xlsx file has NAs for some rows, these are year/site combinations where there was no experimental ant treatment. Hence, for these years/sites, there are only "Ant access" rows.  ## Code/Software No novel code was used to analyze the data deposited. All analyses and figures were produced in R, version 4.2.3. Code may be requested by contacting the lead author, Michael S. Singer ([msinger@wesleyan.edu](mailto:msinger@wesleyan.edu)).