Research & Publications

Broader research interests

A common thread in my research is the exploration of the ecological effects of human activities on the ecologies of individual organisms, populations, and communities. Within this general framework, I have pursued both applied (e.g., “What are the consequence of pesticide-contaminated soils for ground-nesting bees?”) and basic (e.g, “How does the shape of a habitat patch affect movement across patch borders?”) scientific questions. During my graduate studies with Dr. Alex Harmon-Threatt at the University of Illinois, my research has focused on the effects of xenobiotics, habitat fragmentation, and trophic interactions on insects, with a particular focus on bees.

Current research

Patterns of biodiversity in fragmented landscapes

A picture of an igneous glade, a diagram of the eastern collared lizard, spider, bee, and flower food web, and a picture of a model crab spider on a flower.

Habitat fragmentation has been recognized as one of the primary drivers of biodiversity loss. One challenge in studying the effects of habitat fragmentation is that it is often associated with habitat degradation and novel human-modified matrix habitats. I study the effects of habitat fragmentation and trophic interactions on biodiversity in naturally fragmented igneous glades in southeastern Missouri.

Utilizing efforts to reintroduce the top predator in this system, the eastern collared lizard (Crotaphytus collaris), my research aims to understand how top-down effects influence spider, bee, and flowering plant diversity. My results suggest that eastern collared lizards modify spider communities such that flower-hunting families, specifically jumping spiders, are more common in areas with the lizards. This, in turn, changes the composition of bee communities and bee foraging behavior.

With increasing concern for the conservation of pollinators – especially bees – in fragmented landscapes, conservation and restoration plans may also need to support or re-establish top-down effects. Combined with increased floral and nesting resources, such plans may be the most effective at restoring historic pollinator communities.

Habitat shape and insect movement

A diagram suggesting that a random path leaves a more complex shape (star) more often than a less complex shape (circle) and a picture of the flight-intercept traps used for this work.

Movement between habitat patches is often a key factor in determining if a species will persist in a fragmented landscape. Habitat shape may facilitate movement in areas where habitat or wildlife corridors are logistically impractical or for species that can fly, such as insects. While the importance of habitat shape has been suggested in the literature, it has been difficult to test because it is correlated with changes in habitat area and edge:center ratio.

Using a unique set of experimental glades at Washington University in St. Louis’ Tyson Research Center, I surveyed insect communities using passive flight-intercept traps in habitat patches and in the nearby matrix. More movement across edges is predicted to lead to less dissimilarity between communities in the patch and surrounding matrix.

Determining the role that habitat shape plays on organism movement will allow us to create more effective models for predicting persistence in fragmented landscapes which has important conservation implications.

Neonicotinoid contaminated nesting resources

Pictures of bee cocoons in a tissue culture plate, an adult Osmia during a walking assessment, and a cross-section of a bee brain.

Neonicotinoids are some of the most widely used insecticides. Often applied as a seed-coating, the active ingredient is incorporated into plant parts including pollen and nectar. However, much of the pesticide is never absorbed by the plant and remains in the soil. These contaminated soils may pose a risk to ground-nesting bees – the majority of bee species – that nest in active agricultural fields, natural habitats near agricultural fields, or in areas restored to prairies from agriculture.

My research represents some of the first evidence that chronic contact exposure to realistic soil concentrations of neonicotinoids during immature development can affect solitary bee development speed, longevity, mass, and adult behavior.

Other research in the Harmon-Threatt lab is expanding on this work to explore factors that may increase neonicotinoid degradation rate and the effects on broader bee communities.

Upcoming publications

Harmon-Threatt, A.N. and N.L. Anderson. In review. Species, patch, and matrix variables interact to influence bee movement in a naturally fragmented landscape.

Anderson, N.L., B.E. Chiavini,* and A.N. Harmon-Threatt. In prep. The influence of habitat shape on insect movement across patch borders.

Anderson, N.L. and A.N. Harmon-Threatt. In prep. The reintroduction of a top predator to a patchy, endemic habitat structures bee communities through top-down forces.

Chiavini, B.E.,* A.N. Harmon-Threatt, and N.L. Anderson. In prep. Changes in pollinator behavior in response to soil neonicotinoid contamination and nutrient content.

Macalindong, J.,* A.N. Harmon-Threatt, and N.L. Anderson. In prep. Changes in pollinator anti-predator behavior in areas with increased soil organic carbon.

Barie, K., N.L. Anderson, and A.N. Harmon-Threatt. In prep. Factors influencing the distribution of bees in forested habitats

Leonard, R.J., N.L. Anderson, and A.N. Harmon-Threatt. In prep. Wing Asymmetry in response to chronic contact with realistic soil concentrations of imidacloprid in solitary bees.

Available publications

Harmon, G.,* A.N. Harmon-Threatt, and N.L. Anderson. 2022. Changes in predator biomass may mask the negative effects of neonicotinoids on primary consumers in field settings. Insect Conservation and Diversity 1-8.

Anderson, N.L. and A.N. Harmon-Threatt. 2021. Chronic contact with imidacloprid during development may decrease female solitary bee foraging ability and increase male competitive ability for mates. Chemosphere 283.

Grommes, A.,* A.N. Harmon-Threatt, and N.L. Anderson. 2021. Adding essential oils to emergence tents has taxon-specific effects on trapping efficiency of ground-nesting bees. Apidologie 52, 378-387.

Anderson, N.L., K.L. Barrett, S.E. Jones, S.E., and G.E. Belovsky. 2020. Impact of abiotic factors on microbialite growth (Great Salt Lake, Utah, USA): a tank experiment. Hydrobiologia 847, 2113–2122.

Anderson, N.L. and A.N. Harmon-Threatt. 2019. Chronic contact with realistic soil concentrations of imidacloprid affects the mass, immature development speed, and adult longevity of solitary bees. Sci Rep 9, 3724 (2019).

Anderson, N.L. and A.N. Harmon-Threatt. 2016. 07. The Effects of Seed Mix Diversity on Soil Conditions and Nesting of Bees in Prairie Restorations. North American Prairie Conference Proceedings. 17.

* Undergraduate author primarily advised by NLA

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