My interest in the history of entomology and evolutionary thought dates to graduate school, when I began research on Benjamin D. Walsh (1808-1869), an entomologist and correspondent of Charles Darwin. My work has focused on elucidation of Walsh’s impact on entomological science and his original contributions to Darwinian theory. At a time when most entomologists labored in taxonomic work without pondering the utilitarian side of their science, Walsh aggressively promoted the application of sound entomological research to mitigate farmers’ problems with pestiferous insects. The first two periodicals in America devoted to applied entomology were edited or co-edited by Walsh. His appointment as first state entomologist of Illinois, an office nearly without precedence, predated the first professorship in American entomology. Remarkably, Walsh also championed Darwin’s revolutionary theory of species origin and posited phytophagic speciation, credited as the theoretical progenitor of sympatric speciation. Prominent researchers recognize Walsh for wrestling with the species concept and note his foresight regarding cryptic species. Darwin valued Walsh’s observations and cited him in later editions of the Origin of Species as well as Descent of Man and Variations of Animals and Plants under Domestication.
In my undergraduate courses, many designed for honors students and non-majors, I target information and scientific literacy, critical thinking, teamwork, communication, and quantitative reasoning. These skills are broadly applicable across professional careers and vital for navigating life in the modern world. I have developed a number of pedagogies and activities, some of which are published with former graduate students. My graduate courses have focused on Darwin and evolutionary thought, professional preparedness, and insect physiology (my former area of research).
The long term goals of my lab are to understand the ecology of major insect pest groups of ornamentals and vegetables produced in controlled environments and to develop ecologically based management practices that will reduce our dependence on pesticides and have less adverse effects on the environment. With this in mind, the core objectives of my research program will be (1) to advance our understanding of ecological principles and how they are driving the population trends observed for major insect pest groups of ornamentals and vegetables produced in controlled environments and their natural enemies, (2) apply these ecological principles to develop management practices for insect pests, and (3) develop IPM solutions for ornamental and vegetables that can be applied not only in controlled environments but elsewhere. Current projects examine the effects of physical and cultural controls on life history traits of selected pests of plants grown in controlled environments. In addition, I am exploring the effect of the level of initial insect infestation on overall distribution as well as the relationship between soil health, plant defenses and insect biodemography.
Research in our laboratory focuses primarily on molecular mechanisms involved in insect overwintering. For most insects, seasonal changes in daylength provide the environmental signal that winter is coming. This, in turn, prompts preparative steps that eventually lead to a developmental arrest (diapause) as well as enhanced cold tolerance. Our interests range from the use of clock genes to perceive these environmental signals through to the endocrine and molecular events that result in expression of the diapause phenotype. Currently, our model systems for diapause studies include flesh flies (Sarcophaga crassipalpis and S. bullata which both have a pupal diapause), members of the Heliothis/Helicoverpa complex of agricultural pests, which all have a pupal diapause), the Asian tiger mosquito (dengue vector Aedes albopictus which has an embryonic diapause), and the Northern house mosquito (West Nile virus vector Culex pipiens, which diapauses as an adult). In addition, we are engaged in research in Antarctica, where we are examining how a midge, Belgica antarctica, survives in this hostile environment. Our laboratory has also maintained a long-term interest in reproductive physiology of the tsetse fly, vector of African sleeping sickness.
The Gardiner Lab studies the ecology of urban greenspaces. Much of our work focuses on the ecological and conservation value of vacant land. This work takes place in Cleveland, Ohio – a city managing more than 27,000 vacant lots created as a result of protracted economic decline, home foreclosure, and population loss. Researchers in the lab examine how the landscape composition and legacy as well as local plant community and management of vacant lots influences their conservation value for arthropods, studies focused from the tree canopy to soil communities.
My current appointment to the Kellogg Endowed Chair in Agricultural Ecosystems Management includes work with scientist in many disciplines devoted to simultaneous ecological, economic and social improvements in agricultural ecosystems. Agroecosystems include people and the land, and more than just a single field or farm but entire landscapes including many farms and neighboring communities. Managing agroecosystems means finding ways for many farmers and their neighbors to work together. Our work generally takes a holistic approach to creating knowledge and positive change in several interrelated areas: watersheds, the science and practice of protecting water quality by farmers and their neighbors; food systems, particularly as a means of creating more connections between farms and neighboring communities and building local economies; and energy, both in terms of farm energy efficiency and conservation and sustainable energy production.
Discovering Balance on Ohio Farms: Applying ecological principles to balance clean water and fertile soil, strong supportive communities and prosperous farms; Conducting research and developing solutions through collaboration among many disciplines; Creating opportunities to reinvigorate Ohio's diverse agricultural community. Supporting the wise use of energy and resources for the profitable production and marketing of wholesome food and agricultural products for all Ohioans. This balance creates sustainable agricultural systems.
Insect pollinators are vital for the production of many fruits, nuts and vegetables, including apples, blueberries, almonds, tomatoes and pumpkins. These crops are also vulnerable to pests and diseases, which are often controlled through the use of pesticides. However, pesticides may be toxic to insect pollinators, setting up a conflict between the need for pollination and the need for pest and disease control. In our lab we are seeking to understand how to protect pollinators from the pesticides and other toxins they encounter. The managed European honey bee, Apis mellifera, serves as a model pollinator for toxicological testing. While the honey bee is the most economically important pollinator in the U.S. and serves as an excellent model species, we are also interested in understanding pesticide toxicity in other pollinating insects as well.
Many of us intuitively recognize that our mosquito problems are seasonal; there are times of the year when mosquitoes are abundant and we cannot go outside without getting bitten (e.g. late spring and summer), while there are other times when we enjoy a reprieve from mosquito bites (e.g. late fall and winter). I am interested in how precisely mosquitoes are able to tell what time of year it is and appropriately respond to their environment. Members of my lab group study how circadian clock genes might allow mosquitoes to measure day length to determine the time of year; how male mosquitoes change their accessory gland proteins to influence female behavior and physiology; and whether mosquitoes in urban environments are active for longer periods during the year and/or bite humans more frequently. We use a variety of molecular, genetic and physiological techniques to investigate these questions. Our ultimate goal is to uncover specific ways to manipulate seasonal responses in insects so that we can more effectively control them.
My overall goal is to understand how insect pests adapt to rapidly changing selection pressures in agroecosystems such as host-shifting to important crops or resistance to management tactics. A lack of understanding of how insect pests adapt limits the effectiveness and sustainability of insect management, and threatens agricultural production. Specifically, my research focuses on characterizing the genetic basis for insect pest adaptation and how these adaptive traits spread across the landscape. Our research methods range across scales, from molecular to ecosystems, and include genome sequencing, gene expression, molecular marker analysis, and migration and gene flow estimation across a species distribution. Understanding and demonstrating how insects adapt, as well as communicating research-based insect management recommendations, delays the evolution of resistance or emergence of pests and ensures safer and more productive food supply.
Our research program encompass both basic and applied aspects of areas: 1) the role of soil communities in plant health and susceptibility to herbivory, disease, and plant competition in biological farming systems, and 2) identification and behavioral characterization of plant secondary compounds and arthropod semiochemicals that mediate host finding and other behaviors.
My research investigates the molecular mechanisms of fluid secretion by the renal (Malpighian) tubules of mosquitoes (Aedes aegypti and Anopheles gambiae). Aedes mosquitoes are one of the most important vectors for spreading the viral-based illnesses of yellow fever and dengue fever to humans, whereas Anophelesmosquitoes are the primary vectors of malaria. Malpighian tubules are the kidneys of insects. Our kidneys filter our blood to produce a urine, but the Malpighian tubules of insects must actively secrete fluid to produce a urine. I am interested in elucidating how mosquitoes produce urine, because it is vital to their survival after consuming a human blood meal. That is, the Malpighian tubules excrete the excess fluid and salts absorbed from the blood they ingest. If we can identify key genes/proteins involved with urine production by mosquito Malpighian tubules, then we may be able to interfere with this process via genetic disruption or pharmacological agents, thereby making it less likely for a mosquito to bite another person and spread disease.
Our lab is broadly interested in understanding the factors that influence variation in susceptibilty to pathogen infection and transmission of infectious disease. We study how insects interact with harmful and helpful microbes and the ecological and evolutionary forces shaping insect immune defense. As vector biologists, we are also interested in finding ways to use this information to improve our ability to prevent the spread of vector-borne diseases. We primarly study Aedes aegypti, the mosquito vector of dengue and Zika virus. We are currently focusing on two major research areas:
1. The factors determining the formation and maintenance of the mosquito microbiome. The mosquito midgut microbiome is an important determinant of vector borne disease transmission, but it varies between species, location, and even between individuals in the same population. It also varies across developmental stages and as a result of changes in diet. We are interested in better understanding the environmental, physiological, and genetic factors that shape bacterial populations in the mosquito gut. We are currently studying the impact of larval nutrition on adult microbiome formation. Our approach is multifacetd, combining high throughput methods (e.g. bacterial 16S high-throughput sequencing, transcriptomics) and targeted molecular techniques (e.g. RNAi and qPCR) to quantitatively assess organism and population-level phenotypes.
2. The impact of the microbiome on mosquito capacity to transmit pathogens? The bacteria associated with mosquitoes can have important implications for their susceptibility to infection by pathogens like dengue virus. We are interested in taking this further, and investigating how the microbiome impacts life history traits critical for disease transmission. We study this at the level of individual organisms as well as populations, asking how the microbiome impacts the life history of a single mosquito and the extent to which the microbiome could influence variation in pathogen transmission.
The Tilmon lab performs research and extension on the ecology and management of insects in agronomic crops including corn and soybean. Projects span the discplines of ecology, evolution, and behavior.
In our lab we work on the biology and management of vegetable and fruit pests. Our work also involves educating growers and extension agents on how to implement integrated pest management in fruit and vegetable crops both on commercial farms and in home gardens, and providing timely information on pests as the season progresses. Our research includes evaluating insect monitoring techniques, assessing the relationship between pest population levels and timing of control applications and manipulating chemical and cultural practices to enhance the impact of natural enemies.