The Shields Lab · Towson University
We study the chemical senses insects use to find food and avoid harm, and we test plant-derived repellents against crop pests such as spotted-wing drosophila.
Interactive model
Fruit flies gather on a blueberry cluster. Release methyl benzoate, or its analog E4MOB, and watch how far the plume pushes them back. It is a teaching model of the push in a push-pull system, not lab data.
Simulation · fruit flies and methyl benzoateMove the cursor to release methyl benzoate, then hold still to watch the flies through the ×3 lens. Click to hang a dispenser on the branch.Tap to hang a dispenser on the branch.
E4MOB is ethyl 4-methoxybenzoate, one of the methyl benzoate analogs the lab tests. Fly numbers and compound strengths are illustrative, not lab data.
The lab works on the senses insects use to choose food and avoid harm: taste cells on a caterpillar’s mouthparts, odor receptors on a moth’s antenna, and the avoidance a single plant volatile can set off in a fruit fly. Current projects screen analogs of methyl benzoate against spotted-wing drosophila, an invasive pest of soft fruit, and essential oils against the house cricket.
Current projects
Each project pairs a behavior people care about, a crop pest avoiding a plant or a caterpillar refusing a leaf, with the sensory cells that drive it.
Program 1 · Drosophila suzukii
Methyl benzoate keeps spotted-wing drosophila away, but only at high doses, and flies vary in how they respond. We screen analogs that change the ester group, a ring substituent, or both. Several work at lower doses.
Program 2 · Acheta domesticus
We screened 27 essential oils on house crickets in an open arena with a treated bottle they could walk into, and counted how many went in.
Program 3 · Lymantria dispar
Tip recordings from spongy moth caterpillars found that a deterrent taste cell, already known to fire for caffeine and nicotine, also fires for DEET, IR3535 and picaridin.
essential oils screened against the house cricket
Heinbockel et al. 2026, Insects 17: 106plant volatiles tested on single moth olfactory sensilla
Shields and Hildebrand 2001types of antennal sensilla described in Manduca sexta
Shields and Hildebrand 1999a, bestimated yearly U.S. small-fruit losses to spotted-wing drosophila
Northeast SARE LNE22-455RFrom molecule to field
Five steps, each from the lab’s own papers and talks, show how a plant volatile could protect a crop. Scroll to move through them.
01
Methyl benzoate is a small volatile that many plants make, and an FDA-approved food additive. Spotted-wing drosophila, an invasive pest of soft fruit, avoid it.
Gale et al. 2024, Insects 15: 47.
02
Insects smell with sensilla, hollow hairs on the antenna. Odor molecules pass through pores in the sensillum wall and reach the dendrites of receptor neurons inside. Dr. Shields’s electron microscopy described eight types of sensilla on the antenna of the female tobacco hornworm moth.
Shields and Hildebrand 1999a, b, Canadian Journal of Zoology. The drawing is not to scale.
03
A receptor neuron reports an odor as a train of action potentials. Recordings from one of those eight types, made while testing 102 plant volatiles, sorted these sensilla into three functional types.
Shields and Hildebrand 2001, J. Comp. Physiol. A 186: 1135–1151. The trace is an illustration, not a recording.
04
In the lab’s assay, 24 female flies are released along an open glass tube with the test compound at one end and solvent at the other, and the flies on each side are counted. The dose that repels half of them is the RD50. Several analogs of methyl benzoate repelled flies more strongly at lower doses.
Heinbockel and Shields, NCUR 2026.
05
In a field trial in highbush blueberry with Rutgers University and the USDA, methyl benzoate dispensers reduced infestation when fly pressure was very high. They were tested as the “push” of a push-pull system, which pairs a repellent on the crop with lure traps that pull the pest away. The traps alone did not give comparable protection, and adding them did not improve on the dispensers’ effect.
Gale, Ferguson, Rodriguez-Saona, Shields and Zhang 2024, Insects 15: 47.
Peer-reviewed
Peer-reviewed work from the lab, with links to the full text. Lab members appear as authors on every paper.
Essential oils as biofriendly alternatives to synthetic insect repellents
Insects 17(6): 575Selected essential oils act as repellents against the house cricket, Acheta domesticus
Insects 17(1): 106Evaluation of a push-pull strategy for spotted-wing drosophila management in highbush blueberry
Insects 15(1): 47April 15, 2026 · Richmond, Virginia
Torben Heinbockel presented the methyl benzoate analog screen as a talk and the house cricket study as a poster at the National Conference on Undergraduate Research.
Talk: session 172, Environmental Science and Sustainability, presentation 908 · Poster 1203 · Greater Richmond Convention Center
Also at NCUR 2026 · poster 1203
Behavioral olfactory responses of crickets to essential oils
The house cricket study, by Torben Heinbockel and Dr. Shields, in poster session 011.
2025 to 2026
Short answers, with sources
The Shields Lab at Towson University studies insect taste and smell: how insects detect plant compounds with sensory cells on their mouthparts and antennae, and how those signals steer feeding and avoidance. The lab also tests plant-derived repellents against insect pests, including spotted-wing drosophila and the house cricket.
Spotted-wing drosophila, Drosophila suzukii, is an invasive fruit fly. Unlike most fruit flies, the female has a serrated ovipositor that cuts into ripe and ripening berries to lay eggs, so infested fruit can look ready to pick. U.S. losses in small fruit are estimated at $718 million a year (Northeast SARE project LNE22-455R).
Methyl benzoate is a volatile made by many plants and an FDA-approved food additive, and spotted-wing drosophila avoid it. In a highbush blueberry field trial, methyl benzoate dispensers reduced infestation when fly pressure was very high (Gale et al. 2024). It works only at high doses, so the lab screens structural analogs; several repelled flies more strongly at lower doses (Heinbockel and Shields, NCUR 2026).
In a screen of 27 essential oils, house crickets were strongly repelled by nearly half of them. Four strong repellents, peppermint, rosemary, cinnamon and lemongrass oils, were then tested at several doses and repelled more strongly at higher doses, while the synthetic repellents DEET and IR3535 had no significant effect (Heinbockel et al. 2026, Insects 17: 106).
Spongy moth caterpillars taste with styloconic sensilla on their mouthparts. Tip recordings had shown that a deterrent cell in the medial sensillum fires for caffeine and nicotine; the lab then found that the same cell also fires for DEET, IR3535 and picaridin, the first report of insect repellents detected by a caterpillar’s taste cells (Sanford et al. 2014, PLoS ONE).
Email Dr. Shields at vshields@towson.edu with your major and year, the projects that interest you, and how many hours a week you can give. Undergraduate, master’s and pre-college students have run projects in the lab and presented them at national meetings.
Students in the lab run their own projects, from rearing insects to presenting at national and regional meetings, including ABRCMS, NCUR, the Society for Neuroscience and SICB.
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