By DOUG SCHMITZ

Iowa Correspondent

AMES, Iowa — Iowa State University (ISU) researchers last month received a $670,675 grant funded by the USDA’s National Institute of Food and Agriculture Pollinator Health Program to advance the understanding of monarch butterfly ecology.

Over the last 20 years, the monarch butterfly population has experienced an 80 percent decline in North America, with surveys of the 2017-2018 overwintering generation of monarchs indicating the numbers are still less than half of the size needed to ensure a sustainable population.

The U.S. Fish and Wildlife Service has until June of 2019 to determine whether the monarch should be listed under the Endangered Species Act.

“This project’s goal is to support development of practical, science-based strategies for increasing habitat of the monarch butterfly in combination with crop and livestock production in Iowa and the upper Midwest,” said Steve Bradbury, ISU professor of environmental toxicology in the departments of natural resource ecology and management, and entomology, who lead the study.

“This will require fundamental knowledge of monarch population responses to the quality and spatial arrangements of breeding habitat within agroecosystems,” he added.

Formed in 2015 in response to monarch population declines, the Iowa Monarch Conservation Consortium (IMCC) – a group of more than 45 collaborators, including agricultural and conservation organizations, agribusiness and utility companies, county associations, universities, and state and federal agencies – seeks to demonstrate how voluntary efforts can support species recovery and avoid the need to list the monarch as an endangered species.

Bradbury said such a listing could lead to significant regulatory and management burdens for farmers, livestock producers and other private landowners.

As an integral part of the study, ISU researchers will use indoor and field studies to develop landscape-scale models of monarch movement and population responses.

Bradbury said he and his research team plan to use female butterflies tethered to instruments in a large facility used by ISU sports teams, and radio telemetry in the field, to measure the ability of monarchs to perceive and move to milkweed and flowering plants.

“Recent research demonstrates that an ‘all hands on deck’ approach is necessary for successful monarch conservation,” said Joe Colletti, interim endowed dean of the ISU College of Agriculture and Life Sciences. “The dominance of agriculture within Iowa means that agricultural land must be a part of the solution.

“This means that consortium members are looking at all options on agricultural and non-agricultural lands for adding habitat, including augmenting existing conservation practices, establishing habitat patches in underutilized, grass-dominated areas, and adding habitat in urban locations such as parks, industrial and school properties,” he added.

Moreover, while milkweed is the only plant monarchs lay eggs on and the only source of food for the young, adult monarchs rely on nectar from flowering plants for food, Bradbury said.

“Our current model results indicate we need to better understand the perceptual range of the monarch to improve our ability to predict how different arrangements of habitat patches in the landscape influence population responses,” he said.

According to Bradbury, perceptual range is the distance at which monarchs detect milkweed or nectar plants in the landscape. It can be estimated from observations on how a monarch orients its flight towards a resource, like milkweeds. Monarch’s flight patterns can be observed through the radio telemetry studies that will also help researchers evaluate the model they are refining.

Currently, ISU researchers are coordinating their studies with U.S. Geological Survey researchers, who are developing a conservation model for the entire U.S. Bradbury said the ISU model will be at a finer scale and will be applicable to summer breeding monarchs in the North Central states.

According to the Midwest Association of Fish and Wildlife Agencies, the Mid-America strategy draft describes how the North Central states in the monarch’s northern breeding grounds will collectively establish 1.3 billion new milkweed stems over the next 20 years.

Chuck Gipp, director of the Iowa Department of Natural Resources, said Iowa’s strategy estimates 127 to 188 million new stems will be established within the state.

“Iowa falls entirely within the monarch’s northern breeding core,” he said. “This means that every patch of milkweed habitat added in Iowa counts, and Iowa is perfectly situated to lead the way in conservation efforts for the monarch butterfly. The recovery cannot succeed without Iowa.”

Bradbury said the project will determine how pesticides used in crop fields may influence monarch survival and reproduction in habitat located near field borders. Current monarch conservation recommendations call for habitat setbacks of 125 feet from fields on which pesticides are used.

He said this setback includes about 80 percent of roadsides and about 40 percent of non-crop fields in Iowa, eliminating a lot of land that could be used to establish new habitat.

In addition, the researchers will study how herbicides affect the quality of milkweeds and how insecticides impact monarch caterpillars at varying distances from field edges.

“Through this research, we will be able to determine if summer monarch populations have a greater rate of increase if we plant habitat near crop fields, even if some milkweed and some monarchs get exposed to pesticides sometimes, as compared to a conservation plan where no new habitat is established near field borders,” Bradbury said.

He added the model he and his researchers develop will support conservation planning at county, state and regional scales.

In March, the IMCC released its updated conservation strategy, which guides the implementation and documentation of a voluntary, statewide effort based on the best available science, he said.

Iowa Agriculture Secretary Mike Naig said the updated IMCC strategy has set a goal of establishing an estimated 480,000 to 830,000 acres exclusively devoted to monarch butterfly habitat in Iowa by 2038.

“The consortium has worked collaboratively with diverse stakeholders to develop a comprehensive plan to expand habitat on our agricultural land, urban areas, roadsides and other public land,” he said. “We appreciate the many partners that have been involved and are encouraged by the work already underway.”