Lacewings

Predatory Flies

Ladybird Beetles

Parasitic Wasps

Predatory Bugs

TEMPERATURE

DROUGHT

SOY

LONGITUDE

LATITUDE

OTHER AGRICULTURE

GRASSLAND

FOREST

Soybean generalist predator community responses to landscape composition, drought, and temperature stress in the Midwest US

Kaitlin Stack Whitney1, Timothy D. Meehan1, Krista Hamilton2, Claudio Gratton1

 1 Department of Entomology, University of Wisconsin-Madison 2 Wisconsin Department of Agriculture, Trade, & Consumer Protection

Acknowledgments: Thanks to Caitlin Bergstrom, Collin Schwantes, Amanda Rudie, Chase Fritz, Liz Wood, Jade Kochanski, Forrest Howk, Tony Theis,

Emily Carnahan, and Byungsoo Khang for fieldwork and identification help.

Funded by USDA NIFA Grant #2011-67009-30022.

Kaitlin Stack Whitney whitney3@wisc.edu

IntroductionNoncrop habitat in landscapes are positively correlated with natural enemy abundance and diversity in agroecosystems

Yet previous studies don’t include temperature and rainfall, abiotic factors that strongly impact natural enemy survival, foraging, and plant-insect interactions

The goal of our study was thus to examine how including temperature and drought stress could change interpretations of landscape composition relationships with agroecosystem insect communities in soybean.

Hypotheses

Discussion

Drought and temperature stress were consistently the strongest factors determining community composition and presence/absence of soybean natural enemies in WI

Yet at sites where natural enemies were present, landscape factors significantly affected abundance

No support for previous findings that ladybird beetles are positively correlated with grassland, but overall support for our hypothesis that agricultural lands support generalist predators by providing crop and prey resources throughout the growing season

Methods

Results

Conclusions

Our study demonstrates the importance of including abiotic factors when examining relationships between landscape composition and natural enemy communities in agroecosystems.

We also demonstrate the importance of considering impacts on multiple taxa, as each exhibited different responses to landscape and abiotic variables.

Understanding the relationships between soybean natural enemies with changes in temperature and drought stress will be increasingly important when considering future climate scenarios.

Figure 1. NMDS biplot illustrating where soy natural enemy community scores fit along environmental gradients. Fixed effects in blue had significant relationships with community composition using PERMANOVA (p<0.05).

Table 1 (below). Individual taxa presence/ absence and abundance relationships with abiotic and landscape variables were tested using regression analysis. +/- indicate significant relationships (p<0.05). Red signs indicate presence/absence analysis; green signs indicate abundance analysis.

More natural enemies with more agriculture and grasslands, given their ability to prey switch and use crop-derived resources.

More natural enemies with more soy via prey aggregation.

Increased drought and temperature stress will reduce soybean plant health, in turn decreasing the quantity and quality of prey available for soybean natural enemies.

Natural enemies were collected at 580 unique soybean fields in Wisconsin using sweep samples (100 sweep effort) between 2010 and 2013

Drought stress was determined at each site using weekly data from the United States Drought Monitor

Temperature was measured using cumulative growing degree days at each site for the specific sampling date

Landscape composition was determined in a 1.5km radius circle area around each soybean field using the USDA Cropland Data Layer and ArcGIS Statistical analyses were done in R using nonmetric multidimensional scaling and permutational multivariate analysis

TaxaPredatory flies

Ladybird beetles

Predatory bugs

Lacewings

Parasitic wasps

Drought

TempForest

Other Ag

Grassland

SoyLatitude

Longitude

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