DOI: 10.5061/dryad.41ns1rng4
title: Data from: The success of a habitat specialist biological control agent in the face of disturbance

description: A field study was conducted in alfalfa fields in the Arlington
 Agricultural Research Station, Dane County, Wisconsin, USA. Three fields
 were studied. Each field was divided into three sections and in each
 section a one of three treatments was implemented:
 1.       Control –
 harvesting normally, once a month (medium disturbance)
 2.       Insecticide
 – harvesting as in the control + implementing insecticide spray
 (permethrin insecticide Pounce 32 EC (8 oz/ac)) immediately after harvest
 (high disturbance)
 3.       Strips –
 harvesting in strips (low disturbance) In each field and each section
 insects were collected during the summer of 2001 (exact dates are in the
 files). Insects were collected with sweep nets, the number of sweeps
 changed in according to the number of aphids in the field, and is given in
 the files for each sample. Mummies of Apidius ervi were collected by
 visual searches of three minutes.
description: The study was conducted in the Arlington Agricultural Research
 Station, Dane County, Wisconsin, USA. The disturbance
 experiment was conducted during the summer of 2001. The experiment was run
 in three fields of 3.2, 3.5, and 7.5 ha that were located between 0.6 and
 3.7 km apart. Each field was divided into three equal sections to which
 one of the following treatments was applied: control, insecticide, or
 strip. In the control, alfalfa was harvested normally. In the insecticide
 treatment, the plot was harvested normally and then the permethrin
 insecticide Pounce 32 EC (8 oz/ac) was applied. In the strip treatment,
 strips of alfalfa were left uncut during the normal harvesting event.
 These uncut strips were harvested two weeks later, when the cut parts of
 the plot had already regrown. This represents a lower degree of
 disturbance to the arthropods, because they can survive in the uncut
 strips and immigrate into the cut strips after they have started to
 regrow. In the first round of harvesting the uncut strips were meant to be
 five meters wide. This was mechanically hard to execute which resulted in
 uneven strips, some thinner than the desired five meters. In the second
 and third harvesting events, the strips were made to be the width of the
 harvester (7.3 meters), so the cut and uncut strips were the same
 width. Insects were sampled with sweep nets from May 17
 (day zero) to September 22, 2001 (day 128). Samples were taken once or
 twice a week depending on weather conditions (rain sometimes prevented
 sampling) and alfalfa height. Immediately after harvest, the alfalfa was
 too short for sampling, except for the uncut parts of the strip treatment.
 Ten samples were taken in each treatment/field on every sampling date. All
 samples were taken at least 5m away from the field edge. The number of
 sweeps per sample changed according to aphid abundance: at the extreme low
 aphid abundance, 40 sweeps were taken (which resulted in 400 sweeps per
 treatment-field), while at the extreme high abundance (more than 50 aphids
 per sweep) only one sweep was taken per sample (10 sweeps per
 treatment-field). In order to measure parasitism directly, aphids from the
 sweep samples were returned to the lab. Fifty adults (and fourth instars
 if 50 adults were not obtained) were dissected from every treatment-field
 on every sampling event to count second and third-instar parasitoid
 larvae. Finally, three 3-min sets of visual searches were conducted to
 assess <em>A. ervi</em> mummy abundances; searches were
 conducted by walking slowly through the field and recording visible
 mummies. All mummies were collected and reared in the lab in petri dishes
 to estimate hyperparasitism rate.