This study examined the effect of different field edge habitats on predatory insect populations in soybean fields. Researchers sampled 18 soybean fields with either wooded ("complex") or grassy ("simple") edge habitats every 2-3 weeks from June to August. They found that multicolored Asian lady beetle populations increased over 100% from simple edge habitats to field interiors, but decreased 60% from complex edges to interiors. Lacewing populations were not affected by edge type and were highest on edges regardless of type, decreasing 70% into fields. All predatory insect species reached maximum numbers in late August.

1. Field Edge Habitat Effect on Soybean Insect Predators
Alan Sundermeier, Extension Educator, Ohio State University
Dan Pavuk, Department of Biological Sciences, Bowling Green State University
Introduction Discussion
Edge habitats adjacent to annual row crop The most abundant predatory arthropod collected by
agroecosystems have the potential to provide sweep net was Orius insidiosus (Hemiptera:
resources and refugia for a wide diversity of Anthocoridae). Although 2007 had been predicted to
beneficial insects.his study, our major objective be a year when soybean aphid populations would be
was to document predatory insects that may have extremely large, this did not happen in northwestern
potential for regulation of the soybean aphid, in Ohio. Low numbers of aphids were detected in
Insidious flower bug, Orius Multicolored Asian ladybird
soybean field having two different types of edge many fields, but numbers did not approach the
insidiosus (Hemiptera: beetle, Harmonia axyridis
habitats. economic threshold of 250 aphids/plant.
Anthocoridae) (Coleoptera: Coccinellidae)
Soybean field with Soybean field with
complex edge simple edge
Abstract
Damsel bug, Nabis sp.
(Hemiptera: Nabidae)
Edge habitats adjacent to soybean fields have the potential to
provide resources and refuge for a wide diversity of beneficial
insects, such as pollinators, predators, and parasitoids.
Conservation biological control is an approach that focuses on
various ways of providing natural enemies of crop pests the
Predatory Arthropods 2007 necessary resources to allow them to persist and increase
their populations in proximity to crop fields. In this study, our
Total Number of Arthropods
Methodology 180 major objective was to document predatory insects that may
Coccinellidae have the potential for regulation of the soybean aphid. Data
160
was collected from Northwest Oho soybean fields that had
Eighteen soybean fields were selected for 140 Orius insidiosus edge habitats which consisted of a wooded area (complex)
sampling during the 2007 growing season. Nine 120 Nabis spp compared to an edge habitat that consisted of grass species
fields had edge habitats that consisted of a wooded 100 (simple). Fields were samples every two weeks from June
area (“complex” soybean field), and nine fields had 80 Other Predators
through August by using a sweep net to capture insects
edge habitats made up of herbaceous species
60 present. In each soybean field, three locations were sampled,
(“simple” soybean field). The soybean fields were the edge of the field, 50 feet into the field, and 150 feet into the
40
sampled every 2-3 weeks from mid-June through field. Multicolored Asian ladybird beetles (MALB) populations
mid-August. Arthropods were sampled using a 38 20
0 increased 116% from a low near simple edge habitats to the
cm sweep net. In order to assess the natural center of soybean fields. However in a complex edge habitat,
Simple Soybean
Complex Soybean
Simple Soybean
Complex Soybean
Simple Soybean
Complex Soybean
enemy assemblages present in soybean fields MALB populations decreased 60% from a high near edge
infested with the soybean aphid, we sampled the habitat compared to center of field. Lacewing populations
edge of each field, as well as 15 and 45 meters were not effected by type of edge habitat. More lacewing was
into each field. Three-10 sweep samples were found on edge habitat regardless of type. Lacewing
taken at each location in each soybean field. population decreased 70% as counts were taken at interior
Sweep net samples were placed in clear plastic field locations. All species of predatory insect populations
freezer bags and frozen and sorted at later dates. reached maximum numbers in late August.
June July August