The Chappell lab works to develop models to be used in agricultural disease and pest management. We are interested in forecasting, optimization, and decision support. This interest leads us through many agroecosystems, in which we study epidemiological processes. We model these processes to provide understanding and output useful for crop protection.

• Temporal dynamics of plant disease inoculum. Many crop pathogens have non-crop hosts. Many fungal and bacterial plant pathogens can be free-living. In addition to processes affecting epidemics in crops, non-pathogenic processes affect inoculum dynamics. Pathogens may live as saprobes in the absence of living hosts. We are modeling the temporal dynamics of soilborne fungal pathogens to learn what processes govern those dynamics, and to advance forecasting methods.

• Vector phenology and behavior. Many crop pathogens are transmitted by insects. Weather-driven models of pest and vector insect development are a cornerstone of agricultural disease forecasting. We are incorporating insect behavior into existing model frameworks to account for behavioral regulation of environmental experience, and to understand how behavioral processes including dispersal and feeding combine into vector transmission.

• Context of disease/pest management. Researchers focus on individual pest and disease threats to develop deep understanding of each. Growers must protect crops from many threats simultaneously and do so within logistical constraints. A current lab project funded through the NIFA Food and Agriculture Cyberinformatics and Tools initiative aims to harmonize decision support models, moving toward optimizing crop protection instead of optimizing responses to interconnected threats as though they were separate.

• Resistance evolution. Crop protection involves the use of chemicals to kill or otherwise negatively affect pathogens and pests, both of which can evolve resistance to chemicals. Some crop protection strategies are better than others in terms of encouraging resistance evolution, and many competing factors are relevant to these strategies. As we develop decision support that can affect pest management practices, we use simulation to study potential consequences for resistance management.

Chappell TM, Ward RV, DePolt KT, Roberts PM, Greene JK, Kennedy GG (2020) Cotton Thrips Infestation Predictor: A practical tool for predicting tobacco thrips (Frankliniella fusca) infestation of cotton seedlings in the southeastern United States. Pest Manag. Sci. http://doi.org/10.1002/ps.5954

Chappell TM, Codod CB, Williams BW, Kemerait RC, Culbreath AK, Kennedy GG (2020) Adding Epidemiologically Important Meteorological Data to Peanut Rx, the Risk Assessment Framework for Spotted Wilt of Peanut. Phytopathology 110:1199-1207. http://doi.org/10.1094/PHYTO-11-19-0438-R

Davis II RL, Greene JK, Dou F, Jo YK, Chappell TM (2020) A Practical Application of Unsupervised Machine Learning for Analyzing Plant Image Data Collected Using Unmanned Aircraft Systems. Agronomy 10:633. http://doi.org/10.3390/agronomy10050633

Ben-Mahmoud S, Anderson T, Chappell TM, Smeda JR, Mutschler MA, Kennedy GG, De Jong DM, Ullman DE (2019) A thrips vector of tomato spotted wilt virus responds to tomato acylsugar chemical diversity with reduced oviposition and virus inoculation. Sci. Rep.http://doi.org/10.1038/s41598-019-53473-y

Magarey RD, Klammer SSH, Chappell TM, Trexler CM, Pallipparambil GR, Hain EF (2019) Perspective: Eco-efficiency as a strategy for optimizing the sustainability of pest management. Pest Manag. Sci. http://doi.org/10.1002/ps.5560

Chappell TM, Magarey RD, Kurtz R, Trexler CM, Pallipparambil GR, Hain EF (2019) Perspective: Service‐based business models to incentivize the efficient use of pesticides in crop protection. Pest Manag. Sci. http://doi.org/10.1002/ps.5523

Magarey RD, Chappell TM, Trexler CM, Pallipparambil GR, Hain EF (2019) Social Ecological System tools for improving crop pest management. J. Integrated Pest Manag. http://doi.org/10.1093/jipm/pmz004

Chappell TM, Huseth AS, Kennedy GG (2019) Stability of neonicotinoid sensitivity in Frankliniella fusca populations found in agroecosystems of the southeastern United States. Pest Manag. Sci. http://doi.org/10.1002/ps.5319

Ben-Mahmoud S, Smeda JR, Chappell TM, Stafford-Banks C, Kaplinsky CH, Anderson T, Mutschler MA, Kennedy GG, Ullman DE (2018) Acylsugar amount and fatty acid profile differentially suppress oviposition by western flower thrips, Frankliniella occidentalis, on tomato and interspecific hybrid flowers. PLOS ONE, 13(7). http://doi.org/10.1371/journal.pone.0201583

Chappell TM and Kennedy GG (2018) Estimating the effectiveness of imidacloprid when used to suppress transmission of Tomato spotted wilt orthotospovirus in commercial agriculture.  J. Econ. Entom. http://doi.org/10.1093/jee/toy164

Huseth AS, Chappell TM, Chitturi A, Jacobson AL, Kennedy GG (2018) Insecticide Resistance Signals Negative Consequences of Widespread Neonicotinoid Use on Multiple Field Crops in the U.S. Cotton Belt. Environ. Sci. Technol. 52(4): 2314–2322. http://doi.org/10.1021/acs.est.7b06015

Smeda JR, Schilmiller AL, Anderson T, Ben-Mahmoud S, Ullman DE, Chappell TM, Kessler A, Mutschler MA (2018) Combination of Acylglucose QTL reveals additive and epistatic genetic interactions and impacts insect oviposition and virus infection. Mol. Breeding, 38: 3. http://doi.org/10.1007/s11032-017-0756-z

Knowles LL, Chappell TM, Marquez EJ, Cohn TJ (2016) Tests of the Role of Sexual Selection in Genitalic Divergence with Multiple Hybrid Clines. J. Orthoptera Res., 25(2):75-82. http://doi.org/10.1665/034.025.0206

Chappell TM and Rausher MD (2016) Host range evolution in Coleosporium ipomoeae, a plant pathogen with multiple hosts. Proc. Nat. Acad. Sci., 113(19): 5346-5351. http://doi.org/10.1073/pnas.1522997113

Leckie BM, D’Ambrosio DA, Chappell TM, Halitschke R, De Jong DM, Kessler A, Kennedy GG, Mutschler MA (2016) Differential and synergistic functionality of acylsugars in suppressing oviposition by insect herbivores PLOS ONE, 11(4). http://doi.org/10.1371/journal.pone.0153345

Huseth AS, Chappell TM, Langdon K, Morsello SC, Martin S, Greene JK, Herbert A, Jacobson AL, Reay-Jones FPF, Reed T, Reisig DD, Roberts PM, Smith R, Kennedy GG (2016) Frankliniella fusca resistance to neonicotinoid insecticides: an emerging challenge for cotton pest management in the Eastern United States. Pest Manag. Sci., 72: 1934-1945. http://doi.org/10.1002/ps.4232

Kennedy SR, Schultz EM, Chappell TM, Kohrn B, Knowels GM, Herr AJ (2015) Volatility of mutator phenotypes at single cell resolution. PLOS Genet., 11(4). http://doi.org/10.1371/journal.pgen.1005151

Chappell TM, Kennedy GG, Walgenbach JF (2014) Predicting codling moth (Cydia pomonella) phenology in North Carolina based on temperature and improved generation turnover estimates. Pest Manag. Sci., 71: 1425-1432.  http://doi.org/10.1002/ps.3947

Chappell TM, Beaudoin AL, Kennedy GG (2013) Interacting Virus Abundance and Transmission Intensity Underlie Tomato Spotted Wilt Virus Incidence: An Example Weather-Based Model for Cultivated Tobacco. PLOS ONE, 8(8). http://doi.org/10.1371/journal.pone.0073321

Chappell TM and Rausher MD (2011) Genetics of resistance to the rust fungus Coleosporium ipomoeae in three species of morning glory (Ipomoea). PLOS ONE, 6(12). http://doi.org/10.1371/journal.pone.0028875