See also Google Scholar​

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Haan, N.L., Benucci, G.M.N., Fiser, C., Bonito, G., and Landis, D.A. 2023. Contrasting effects of bioenergy crops on biodiversity. Science Advances 9, eadh 7960. Open access

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• Bionergy croppping systems could become very important parts of future landscapes as we deal with climate change, but their biodiversity impacts will depend on which cropping systems are adopted, how they're managed, and where they are placed on landscapes. We sampled biodiversity very broadly (plants, insects, vertebrates, microbes) in ten bioenergy crops in a long-term experimental array. While past research has found important differences between annual and perennial crops, we found that some perennial monoculture systems are not very different from simple annual crops like corn, harboring relatively little diversity compared to systems with more plant diversity. Future bioenergy landscapes, if they are to be of conservation value, need to include plant-diverse cropping systems!

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Haan, N.L., & Landis, D.A. 2023. Pest suppression potential varies across 10 bioenergy cropping systems. Global Change Biology: Bioenergy. doi: 10.1111/gcbb.13053. Open access

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• We used plasticine sentinel caterpillar mimics to assess natural pest suppression rates in a range of bioenergy cropping systems. The frequency of attacks, and the types of organisms responsible for them, vary hugely between crops, but also change dramatically over time and differ between areas close to the ground and up in the canopy. In general, annual crops have much lower predation rates than perennial systems and rely heavily on birds and small mammals to attack herbivores. In contrast, some of the perennial systems we worked in had high predation rates and caterpillars were attacked by a mix of vertebrate and invertebrate predators.

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Haan, N.L., Iuliano, B., Gratton, C., and Landis, D.A. 2021. Designing agricultural landscapes for biodiversity services in North America. Advances in Ecological Research 64, 191-250. Link

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• We review how current landscape structure in North America arose, what we know about how landscape structure affects service-providing insects, and propose principles for how we could intentionally design agricultural landscapes to harbor biodiversity and benefit from associated ecosystem services.

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Haan, N.L., Bowers, M.D., and Bakker, J.D. 2021. Preference, performance, and chemical defense in an endangered butterfly using novel and ancestral host plants. Scientific Reports 11. doi: 10.1038/s41598-020-80413-y. Open access

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• We tested whether adopting a novel, exotic host plant caused the endangered butterfly Taylor's checkerspot to lose adaptations to its native, ancestral hosts. While this butterfly tends to prefer laying eggs on its new host plant (Plantago lanceolata), it has retained preference for, and ability to grow on, its native (Castilleja spp.) hosts. The iridoid glycoside compounds it sequesters can be totally different depending on which species, and which tissues within a species, it feeds on.

 

Bloom, E.H., Graham, K., Haan, N.L., Heck, A., Gut, L., Landis, D., Wilson, J., Zhang, Y., Milbrath, M., Szendrei, Z., and Isaacs, R. Responding to the US National Pollinator Plan: a case study in Michigan. Frontiers in Ecology and the Environment (In press)

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• Five years ago the U.S. government released a national strategy to support pollinators. We evaluate progress toward these goals and review our own efforts with wild bees, honey bees, and monarch butterflies in the Great Lakes region.

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Haan, N.L., Zhang, Y., and Landis, D.A. 2020. Predicting landscape configuration effects on agricultural pest suppression. Trends in Ecology and Evolution. Open access

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• Review article summarizing new evidence that landscape spatial configuration shapes insect communities and rates of pest suppression by natural enemies in crop fields.

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Haan, N.L., and Landis, D.A. 2020. Grassland disturbance effects on first-instar monarch butterfly survival, floral resources, and flower-visiting insects. Biological Conservation. Open access

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• Cutting back common milkweed stems causes them to regrow, and just-hatched monarch butterfly caterpillars on these stems have doubled survival. Disturbance causes a temporary gap in floral resources to pollinators but also diversifies the timing of flowering.

 

Zhang, Y., N.L. Haan, and D.A. Landis. 2020. Landscape composition and configuration have scale-dependent effects on agricultural pest suppression. Agriculture, Ecosystems and Environment. Open access

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• We tested how landscape composition and configuration affected pest suppression in crop fields across Michigan and Wisconsin. Several aspects of both dimensions were correlated with removal of crop pests, with specific results depending on which state, and which spatial scales, were being considered.

 

Myers, A.T., N.L. Haan, and D.A. Landis. 2020. Video surveillance reveals a diverse and largely nocturnal community of monarch butterfly egg predators. Journal of Insect Conservation. Open access
 

• We caught a diverse group of predators red-handed feeding on eggs and immature monarch butterflies. The biggest surprise here was most predation occurred at night!

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Hermann, S.L., Blackledge, C., Haan, N.L., Myers, A.T., and Landis, D.A. 2019. Predators of monarch butterfly eggs and neonate larvae are more diverse than previously recognized. Scientific Reports. Open access

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• We tested 75 insect and spider taxa to see if they eat monarch eggs or caterpillars, and found all sorts of things will eat monarchs! Spiders, grasshoppers, tree crickets, lady beetles, ants, stink bugs, mirid bugs...

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Haan, N.L. and Landis, D.A. 2019. Grassland disturbance increases monarch butterfly oviposition and decreases arthropod predator abundance. Biological Conservation. Link

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• Cutting back milkweed stems causes them to regrow a few weeks later, and these new stems are much more attractive to monarch butterflies as they lay eggs, and harbor fewer of the arthropod predators that eat monarchs.

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Haan, N.L. and Landis, D.A. 2019. The importance of shifting disturbance regimes in monarch butterfly decline and recovery. Frontiers in Ecology and Evolution. Open access

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• Perspective article in which we outline the hypothesis that monarch butterflies historically benefited from the mechanical cultivation patterns that were common in corn and soybean fields until the 1990s, and that we can use disturbance in grassland settings to enhance monarch butterfly habitat.

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Haan, N.L., Bakker, J.D., and M.D. Linders. 2018. Instar-specific effects of host plants on survival of endangered butterfly larvae. Ecological Entomology 43,742-753. Link

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• Larvae of the endangered butterfly Taylor's checkerspot (Euphydryas editha taylori) survive at higher rates on their non-native host plant Plantago lanceolata and can die in early instars if one of their native Castilleja hosts begins to senesce.

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Haan, N.L., J.D. Bakker, and M.D. Bowers. 2017. Hemiparasites can transmit indirect effects from their host plants to herbivores. Ecology 99,399-410. Link

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• Plants in the genus Castilleja form parasitic connections to other plants and can transmit indirect effects from these host plants to caterpillars. The identity of the host plant parasitized by Castilleja changes how big caterpillars grow, the chemicals they sequester from Castilleja, and ultimately how likely they are to survive.

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Dunwiddie, P.W., N.L. Haan, M.J. Linders, J.D. Bakker, C. Fimbel, T.B. Thomas. 2016. Intertwined fates: opportunities and challenges in the linked recovery of two rare species. Natural Areas Journal 36,207-215. Open access

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• We outline the conservation challenges that come up when two rare species interact -- in this case the endangered butterfly Taylor's checkerspot (Euphydryas editha taylori) and the threatened plant golden paintbrush (Castilleja levisecta).

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Haan, N.L., M.R. Hunter, and M.D. Hunter. 2012. Investigating predictors of plant establishment during roadside restoration. Restoration Ecology 20, 315-321. Link

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• We planted native species on highway interchanges to see which soil conditions the plants are more likely to successfully establish in. We found the sandier the site, the higher the survival.

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