Ladybug landscapes: phenological patterns of Coccinellids and their aphid prey across southern Wisconsin

Background/Question/Methods

The simplification of crop fields, farms, and agricultural landscapes is associated with decreased biodiversity and ecosystem services, such as natural pest control provided by arthropod natural enemies. While diversification may improve conservation and pest control outcomes in some cases, ecological predictions are often weak and habitat management (especially at large scales) remains an unpopular strategy. One reason for this may be that diversity per se is not necessarily beneficial to natural enemies if it is not supplementing otherwise limiting resources. A related issue is that the timing of resources availability is rarely taken into account when considering how best to support beneficial insects. In this study, we investigate how temporal patterns of prey availability vary across different crop and-non crop habitats over the course of the growing season, and how this variation affects lady beetle abundance and diversity at the landscape scale. In 2019 and 2021 we sampled aphids, lady beetles, and other generalist predators in agricultural landscapes across southern Wisconsin using sweep nets and yellow sticky card traps.

Results/Conclusions

We encountered 17 species of lady beetles across all years and habitat types. The most common species were native and non-native generalists associated with cropland (e.g. C. maculata, H. axyridis). Aphid and lady beetle abundance varied by landcover type and time of year, indicating the potential for spatio-temporal heterogeneity to contribute to either resource gaps or bridges across the growing season. Preliminary analyses indicate that such resource-based metrics may be better predictors of generalist predator populations than landcover alone. These results will help inform the design of more sustainable agricultural landscapes and promote insect conservation and biological control by natural enemies.