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Q&A: the Buzz on Mosquitoes and Metropolises in Southern Arizona

By Stephanie Doster | Oct. 23, 2009

Emerging Earth

A team of University of Arizona researchers has received a $299,891 National Science Foundation/US Department of Agriculture–Forest Service grant to study mosquito disease vectors in Arizona cities. Uniting entomology, land cover analysis, climate/insect modeling, and institutional ethnography, the project will examine the relationship between institutions and insects in the growing greater-Arizona cities stretching from Phoenix and Casa Grande to Marana, Tucson, and Green Valley—an area encompassing 5.3 million people. Paul Robbins, the project’s principal investigator (PI) and professor in the School of Geography and Development, discussed the team’s research and goals in an October 12 interview. The co-PIs are John Paul Jones, Andrew Comrie, and Willem van Leeuwen from the School of Geography and Development, and Elizabeth Willott of the Department of Entomology. The project, ULTRA-Ex: Ecological Hazards in Southwestern Metropolises: The Case of Mosquito Disease Vectors, began September 15 and will run through February 2012.

Q: What basic problem does this project aim to address?
Robbins: Mosquitoes and the diseases they carry blanket whole regions—sometimes whole states or whole countries—but many mosquitoes can breed in water bodies the size of a paper cup. The resolution of that problem—the geographic scale, the size of that unit—is totally mismatched. You have states and governments that have to govern the scale of a whole city. Public health officials are set up at the county level. The mosquito operates at the paper cup level. That is an inevitable contradiction that generates the entire project. How can we predict where the paper cups are going to be? Where is that micro-habitat that the bug favors or doesn’t favor distributed in a complex place like a city that has culverts, drains, parks, and people who are watering their lawns, like in Phoenix? Micro-ecologies vary. This project will help determine how we can improve our understanding and management of urban environmental problems.

Q: What role does remote-sensing play?

Robbins: The project asks how can we envision the city using remote sensing—in this case a high resolution satellite image of a city. How can we turn that picture—a picture the human eye can see—into something that looks like what the mosquito sees? How does the mosquito see? That’s where our experts come in. They try to project what that landscape looks like to the mosquito. What does that mosquito like? Lush vegetation in a low-lying, cooler space with a little bit of water. How do you turn that optic, the bug’s way of seeing (it actually transduces, technically, and doesn’t “see”) and connect it with a picture we can take from space? Then the social scientists have to understand how the government itself, the state, sees the bug, and from what we’ve learned from previous work, this varies enormously. So the state sees differently, the bug sees differently, and then the satellite image sees differently. If we’re going to manage the health problem, how are we going to get everyone on the same page? How can you create a vision that captures all of that?

Q: How do you plan to create one vision?
Robbins: We will synthesize data from direct sampling of mosquito populations, high resolution urban-scale modeling, surveys, and what the public—for example, managers, citizens, and developers—know about the ecological mosquito system. The idea is to produce maps that show the hazard from the bug’s point of view—where bugs like to be—generated through a very complex spatial modeling system. What kinds of thinking does that generate from different areas of the public? From poor neighborhoods, from rich neighborhoods, from people who have lawns and irrigation and people who don’t? From state agencies charged with health versus those charged with managing the water supply? Those maps area supposed to generate a different way of seeing.

Q: What is the ultimate result?
Robbins: A change in the way we manage that is more sensitive to how the bug sees, more sensitive to how communities see, and more sensitive to the way cities are planned because it’s the very morphology of cities—the shape of the cities—that generates bugs… We need to develop a little more public understanding and we think creating maps for a meeting with the public can do that. We would go as far as to say this is a model approach for managing all kinds of urban ecological hazards; this is a test case. If we can get this right, we can do the same thing for fire in a peri-urban environment, the same thing for invasive species like buffelgrass, or for urban wildlife. These are the concerns people in southwestern cities have and they are serious concerns. The problem is people right now can’t envision these ecological processes in space, where they live. If they can do that, then you’ve mobilized the science in some meaningful way.

Q: What roles do the five scientists play in the research?
Robbins: I’m the ring leader—and an institutional analyst—but J.P. Jones is really our institutional analysis guy. Andrew Comrie will put these bugs through a climate-based population model and vary the rainfall and temperature. Willem van Leeuwen is going to take remote sensing and integrate it with data from trapping the insects and from microclimate data at trap sites to generate a spatial version of the model. Elizabeth Willott is our insect person who will oversee the mosquito trapping. You put the traps in at night and see how many bugs you have in the morning and a data logger measures humidity and temperature at that very specific location. We’ll use all of that information to try to paint a picture of the whole city based on this data. It’s pretty ambitious.

Q: What set this project in motion?
Robbins: West Nile virus, initially… Now dengue, a potentially fatal disease, is right over the border in Sonora, which shares our climatological conditions. There were a couple of cases in the state last year but they probably came from outside the country and were brought here. So the real practical applications of this are non-trivial in a changing environmental context.

Q: What are the implications of climate change for mosquitoes?
In southern Arizona, what you’re seeing under some scenarios of warming is an increased length of the mosquito season. Generally you worry about them in the rainy season, but we’re seeing that expand out to fall and spring, and that makes a big difference because it provides a much longer breeding season and a longer presence for bugs to transfer disease. It also means state agencies could fundamentally have to change the funding for vector control and the organization of state activities, so this has pretty big implications.

Even a small change can be a big difference in the health situation. Temperature spikes that exceed 100 degrees F tend to kill off certain species, so in the middle of summer you’d think you’d have a dip in the population. But the city has all kinds of nice, cool places where mosquitoes can survive those hot days and recolonize. If we know that, we can design the city differently and take care of our yards differently so we could, I hate to say it, take advantage of those heat spikes to bring down disease rates, in theory. The kicker is we are still trying to understand what’s going to happen to the monsoon under global change. It’s a really complicated system. We also don’t know how much mosquito habitats vary in a big system like a city. In someone’s neighborhood, if you have one residence with an abandoned pool and some overhanging trees, that’s the breeding site for the whole area. It doesn’t matter what everyone else is doing or what the temperature is.

Q: How does this project build on past research?
Robbins: The climate change and health people like Andrew Comrie and many other excellent scientists on campus are really getting better at building models that connect these kinds of problems to climate, and that led them to the mosquito. Elizabeth Willott’s work on wetlands brought her to the mosquito. Our modelers are interested in trying to micro-model the ecology of the city using high resolution products. The perfect case for that becomes the mosquito. For social scientists who were funded previously to do studies on how these institutions think, mosquitoes are a clear articulation of that. I think what is interesting is this is a case where four different scientific problems found an object that could unite them. I think fire and other hazards could do that, too.

Q: This grant falls under the Urban Long-Term Research Area (ULTRA) program for enhancing urban sustainability. What do you envision for an ULTRA?
Robbins: The idea moving forward is to have an Urban Long-Term Research Area in Tucson or in the greater southern Arizona region and to use this approach for different types of hazards. The goal would be to get a better mapped, public education grasp on things that make living in this region complicated or even sometimes dangerous. The project calls for getting these kinds of practitioners, who speak very different languages, to produce a coherent set of observations and models that are socially and scientifically useful. If we prove we can do that, we’ll submit proposals to sustain this for the long-term—to monitor mosquitoes and other hazards and human ecological impacts over the next 25 years as the climate changes, and map fire as the fire regime changes and invasives as the desert changes. The long-term is the fun part—the city could be a social ecological lab and I think everyone on campus is excited about the prospect of that.