About

Ian MacRae is a professor in the Department of Entomology at the University of Minnesota. He has worked as an applied entomologist for over 40 years, conducting research on insects within natural and agricultural systems. His research primarily focuses on Integrated Pest Management (IPM), the spatio-temporal distribution of insect pests, and the application of various tools to investigate these topics. MacRae maintains an extensive extension program, facilitating stakeholder involvement in multiple research projects, and works closely with stakeholders on issues related to small grains, oilseed crops, sugar beets, soybeans, wild rice, and potatoes. Located at the UMN North Central Research & Outreach Center near Crookston, he conducts most of his teaching there, offering both in-person and distance courses. His current research efforts include managing pests in cropping systems of northwest Minnesota, with particular emphasis on the Colorado Potato Beetle and aphid vectors of Potato Virus Y in seed production areas. MacRae's outreach work involves providing educational materials and presentations to stakeholders, emphasizing the importance of direct collaboration with those who benefit from his research. His contributions have been recognized through various awards, including the Entomological Society of America Plant-Insect Ecosystems Integrated Pest Management Team Award in 2018 and the University of Minnesota Extension Dean’s Award for Distinguished Team in 2014.

Research topics

• Biology
• Computer Science
• Agroforestry
• Ecology
• Agronomy
• Botany
• Artificial Intelligence

Selected publications

• Influence of Spatial Scale on Landscape Effects Important to Arthropod Management

  CABI eBooks · 2024-08-22

  book-chapterSenior author

  The development and expansion of efficient spatial technologies and geostatistical analysis capabilities over the last few decades has enabled a dramatic increase in spatial landscape research. The knowledge gained from this research in large-scale agroecosystems impacts implementation of integrated pest management (IPM) programs across four spatial scales: (i) intrafield, (ii) local landscape, (iii) regional, and (iv) continental. Understanding the variability and interactions across these agroecological landscape scales can increase management options to encompass wider impacts from mobile pest and beneficial insects. IPM programs implemented by farmers and other managers have largely been applied uniformly at the field level. However, management of pest insects with clear and predictable intrafield spatial distributions may become more efficient through site-specific applications. The makeup of local landscapes surrounding fields directly affects the dynamics of field populations of pests, natural enemies, and pollinators, and this impact will expand considerations for managing local landscapes. Beyond the local landscape (i.e. regional landscape), longer range movement by pests and natural enemies and their interactions with crop and non-crop habitats can dramatically influence pest risk potential, natural enemy prevalence, and management itself. Finally, continental-scale migration of pests can contribute significantly to risk assessment important for IPM program development and implementation. Case studies are presented illustrating the incorporation of improved spatial understanding into the development and implementation of IPM programs. Increasingly, sustainability of large-scale crop production systems will be enhanced by farm-level IPM decisions that account for local, regional, and continental landscape interactions. The success of future IPM programs will depend on better understanding these broader ecological interactions to enhance the prediction of agroecosystem services across all spatial scales and increase overall effectiveness of landscape services and economic and environmental resilience.

  PublisherDOI

• Landscapes with higher crop diversity have lower aphid species richness but higher plant virus prevalence

  Journal of Applied Ecology · 2024-05-21 · 6 citations

  articleOpen access

  Abstract Diversifying agricultural systems by growing more than one crop species in an area can decrease pest and disease pressure and increase crop yields. However, there is a lack of information on how crop diversity at larger spatial scales influences pest and disease pressure. Here, we investigated how landscape‐scale crop diversity affects aphid vector communities and prevalence of non‐persistently transmitted potato virus Y (PVY). To test the influence of landscape‐scale crop diversity on PVY prevalence and aphid communities, we conducted a field study during the 2020 and 2021 field seasons in the San Luis Valley, Colorado, where we quantified aphid communities and PVY incidence at multiple sites. We then determined the association between aphid species richness and abundance and PVY incidence with landscape variables (crop diversity metrics and percentage cover of crop species) within 1, 2 and 3 km buffers from study sites. Higher crop diversity (measured as Shannon Diversity Index) led to decreased aphid species richness at a 3 km buffer in the 2021 field season. We only detected a positive association between percentage of alfalfa crop cover and aphid species richness in 2020 and aphid abundance in 2021 within a 1 km buffer. Higher crop diversity led to increased PVY incidence at a 2 km buffer in 2021 and 3 km buffer in 2020 and 2021. At a 3 km buffer in 2021, we found a positive influence of crop species richness on PVY incidence and a negative influence of crop species evenness on PVY incidence. Also in 2021, we found a positive influence of percentage of potato (virus host) on PVY incidence and a negative influence of percentage of barley (virus non‐host) on PVY incidence. Synthesis and applications . In summary, we found that landscape‐scale crop diversity impacts plant virus prevalence at spatial scales of >1 km. This suggests that potato growers could reduce PVY prevalence by geographically isolating potato fields from other potato or other PVY hosts. Crop diversity had a negative influence on aphid vector communities, so growers could reduce risk of virus spread by aphid vectors by using certified potato seed in a diversified landscape.

  PublisherOA PDFDOI

• Influence of Spatial Scale on Landscape Effects Important to Arthropod Management

  CABI eBooks · 2024-08-23

  book-chapterSenior author

  The development and expansion of efficient spatial technologies and geostatistical analysis capabilities over the last few decades has enabled a dramatic increase in spatial landscape research. The knowledge gained from this research in large-scale agroecosystems impacts implementation of integrated pest management (IPM) programs across four spatial scales: (i) intrafield, (ii) local landscape, (iii) regional, and (iv) continental. Understanding the variability and interactions across these agroecological landscape scales can increase management options to encompass wider impacts from mobile pest and beneficial insects. IPM programs implemented by farmers and other managers have largely been applied uniformly at the field level. However, management of pest insects with clear and predictable intrafield spatial distributions may become more efficient through site-specific applications. The makeup of local landscapes surrounding fields directly affects the dynamics of field populations of pests, natural enemies, and pollinators, and this impact will expand considerations for managing local landscapes. Beyond the local landscape (i.e. regional landscape), longer range movement by pests and natural enemies and their interactions with crop and non-crop habitats can dramatically influence pest risk potential, natural enemy prevalence, and management itself. Finally, continental-scale migration of pests can contribute significantly to risk assessment important for IPM program development and implementation. Case studies are presented illustrating the incorporation of improved spatial understanding into the development and implementation of IPM programs. Increasingly, sustainability of large-scale crop production systems will be enhanced by farm-level IPM decisions that account for local, regional, and continental landscape interactions. The success of future IPM programs will depend on better understanding these broader ecological interactions to enhance the prediction of agroecosystem services across all spatial scales and increase overall effectiveness of landscape services and economic and environmental resilience.

  PublisherDOI

• Economic-threshold-based classification of soybean aphid, Aphis glycines, infestations in commercial soybean fields using Sentinel-2 satellite data

  Crop Protection · 2023-12-12 · 5 citations

  articleOpen access
  PublisherOA PDFDOI

• Effects of feeding injury from Popillia japonica (Coleoptera: Scarabaeidae) on soybean spectral reflectance and yield

  Frontiers in Insect Science · 2022-10-20 · 6 citations

  articleOpen access

  Remote sensing has been shown to be a promising technology for the detection and monitoring of plant stresses including insect feeding. Popillia japonica Newman, is an invasive insect species in the United States, and a pest of concern to soybean, Glycine max (L.) Merr., in the upper Midwest. To investigate the effects of P. japonica feeding injury (i.e., defoliation) on soybean canopy spectral reflectance and yield, field trials with plots of caged soybean plants were established during the summers of 2020 and 2021. In each year, field-collected P. japonica adults were released into some of the caged plots, creating a gradient of infestation levels and resulting injury. Estimates of injury caused by P. japonica , ground-based hyperspectral readings, total yield, and yield components were obtained from the caged plots. Injury was greatest in the upper canopy of soybean in plots infested with P. japonica . Overall mean canopy injury (i.e., across lower, middle, and upper canopy) ranged from 0.23 to 6.26%, which is representative of injury levels observed in soybean fields in the Midwest United States. Feeding injury from P. japonica tended to reduce measures of soybean canopy reflectance in near infra-red wavelengths (~700 to 1000 nm). These results indicate that remote sensing has potential for detection of injury from P. japonica and could facilitate scouting for this pest. Effects of P. japonica injury on total yield were not observed, but a reduction in seed size was detected in one of the two years. The threat to soybean yield posed by P. japonica alone appears minimal, but this pest adds to the guild of other defoliating insects in soybean whose combined effects could threaten yield. The results of this research will guide refinement of management recommendations for this pest in soybean and hold relevance for other cropping systems.

  PublisherOA PDFDOI

• Linear Support Vector Machine Classification of Plant Stress From Soybean Aphid (Hemiptera: Aphididae) Using Hyperspectral Reflectance

  Journal of Economic Entomology · 2022 · 22 citations

  • Artificial Intelligence
  • Biology
  • Computer Science

  Spectral remote sensing has the potential to improve scouting and management of soybean aphid (Aphis glycines Matsumura), which can cause yield losses of over 40% in the North Central Region of the United States. We used linear support vector machines (SVMs) to determine 1) whether hyperspectral samples could be classified into treat/no-treat classes based on the economic threshold (250 aphids per plant) and 2) how many wavelengths or features are needed to generate an accurate model without overfitting the data. A range of aphid infestation levels on soybean was created using caged field plots in 2013, 2014, 2017, and 2018 in Minnesota and in 2017 and 2018 in Iowa. Hyperspectral measurements of soybean canopies in each plot were recorded with a spectroradiometer. SVM training and testing were performed using 15 combinations of normalized canopy reflectance at wavelengths of 720, 750, 780, and 1,010 nm. Pairwise Bonferroni-adjusted t-tests of Cohen's kappa values showed four wavelength combinations were optimal, namely model 1 (780 nm), model 2 (780 and 1,010 nm), model 3 (780, 1,010, and 720 nm), and model 4 (780, 1,010, 720, and 750 nm). Model 2 showed the best overall performance, with an accuracy of 89.4%, a sensitivity of 81.2%, and a specificity of 91.6%. The findings from this experiment provide the first documentation of successful classification of remotely sensed spectral data of soybean aphid-induced stress into threshold-based classes.

  PublisherDOI

• Floral Plantings in Large-Scale Commercial Agroecosystems Support Both Pollinators and Arthropod Predators

  Insects · 2021 · 13 citations

  • Biology
  • Ecology
  • Agroforestry

  Beneficial insect populations and the services that they provide are in decline, largely due to agricultural land use and practices. Establishing perennial floral plantings in the unused margins of crop fields can help conserve beneficial pollinators and predators in commercial agroecosystems. We assessed the impacts of floral plantings on both pollinators and arthropod predators when established adjacent to conventionally managed commercial potato fields. Floral plantings significantly increased the abundance of pollinators within floral margins compared with unmanaged margins. Increased floral cover within margins led to significantly greater pollinator abundance as well. The overall abundance of arthropod predators was also significantly increased in floral plantings, although it was unrelated to the amount of floral cover. Within adjacent potato crops, the presence of floral plantings in field margins had no effect on the abundance of pollinators or predators, although higher floral cover in margins did marginally increase in-crop pollinator abundance. Establishing floral plantings of this kind on a large scale in commercial agroecosystems can help conserve both pollinators and predators, but may not increase ecosystem services in nearby crops.

  PublisherOA PDFDOI

• Notes on UAS and Remote Sensing of Insect Damage

  American Journal of Potato Research · 2021-01-05 · 3 citations

  article1st authorCorresponding
  PublisherDOI

• Wildflower plantings in commercial agroecosystems promote generalist predators of Colorado potato beetle

  Biological Control · 2020 · 13 citations

  Senior authorCorresponding
  • Biology
  • Agronomy
  • Agroforestry
  PublisherDOI

• Implementation of a Diagnostic-Concentration Bioassay for Detection of Susceptibility to Pyrethroids in Soybean Aphid (Hemiptera: Aphididae)

  Journal of Economic Entomology · 2019-12-12 · 20 citations

  article

  Soybean aphid, Aphis glycines Matsumura, remains the most economically damaging arthropod pest of soybean in the midwestern United States and southern Canada. Foliar applications of a limited number of insecticide modes of action have been the primary management tactic, and pyrethroid resistance was documented recently with full concentration-response leaf-dip and glass-vial bioassays. Full concentration-response bioassays can be cumbersome, and a more efficient assessment tool was needed. In this study, we implemented a diagnostic-concentration glass-vial bioassay using bifenthrin and λ-cyhalothrin. Bioassays were conducted with field-collected soybean aphid populations to assess the geographic extent and severity of resistance to pyrethroids. In 2017, 10 of 18 and 11 of 21 field populations tested with bifenthrin and λ-cyhalothrin, respectively, had mean proportion mortalities less than the susceptible laboratory population. In 2018, 17 of 23 and 13 of 23 field populations tested with bifenthrin and λ-cyhalothrin, respectively, had mean proportion mortalities less than the susceptible laboratory population. Populations collected after reported field failures of a pyrethroid insecticide generally had mean proportion mortalities less than the susceptible laboratory population. In both years, there was a strong correlation between chemistries, which suggests cross-resistance between these insecticides. The diagnostic-concentration glass-vial bioassays reported here will provide the foundation for an insecticide resistance monitoring program with the ability to determine practical levels and geographic extent of insecticide resistance.

  PublisherDOI

Frequent coauthors

• David W. Ragsdale

  11 shared

• Robert L. Koch

  University of Minnesota

  9 shared

• Edward B. Radcliffe

  9 shared

• Erin W. Hodgson

  Iowa State University

  9 shared

• Phillip Glogoza

  University of Minnesota

  8 shared

• B. A. Croft

  7 shared

• Soizik Laguette

  University of North Dakota

  6 shared

• Neville Winchester

  University of Victoria

  6 shared

Labs

• Ian MacRae LabPI

Education

• PhD, Entomology

  Oregon State University

  1994

• MS, Biology

  University of Victoria

  1988

• B.Sc., Biology

  University of Prince Edward Island

  1980

Awards & honors

• Plant-Insect Ecosystems Integrated Pest Management Team Awar…
• University of Minnesota Extension Dean’s Award for Distingui…
• Entomological Society of America Outstanding Service, Subjec…
• Integrated Pest Management Team Award (presented to Soybean…