Cotton growers have long faced an uphill battle against insects like aphids, caterpillars and lygus bugs. These pests reduce yields and diminish producer profitability.
But a team of Texas A&M AgriLife Research scientists say a new line of research could offer a new tool for integrated pest management, IPM, in cotton by exploiting a biological weakness shared by many plant-feeding insects.
Their strategy focuses on an unexpected target: cholesterol.
“Everybody knows cholesterol,” said Gregory Sword, Ph.D., Regents Professor and Charles R. Parencia Chair in Cotton Entomology in the Texas A&M College of Agriculture and Life Sciences Department of Entomology. “But insects need it and obtain it in a very different way than we do. Our research identified that difference as a weakness we can exploit to protect plants.”
Finding the sterol weakness in insects
Unlike humans, plant‑feeding insects cannot make their own cholesterol. Instead, they rely entirely on plants for similar compounds, called phytosterols, which pests convert into the cholesterol essential for growth and reproduction.
That dependency led Sword’s collaborators Spencer Behmer, Ph.D., and Keyan Zhu‑Salzman, Ph.D., both professors and entomologists in the Department of Entomology, to a simple but powerful idea: Change the sterols inside plants, and you change what’s available to the insect to use for nutrition.
The team partnered with a leading plant sterol expert in the U.S., Robert Grebenok, Ph.D., biology professor at Canisius University, Buffalo, New York, to explore the idea.
The team’s early work with Arabidopsis, a non‑crop model plant for genetic studies, showed the approach could work.
By altering a single gene involved in sterol production, researchers shifted the plant’s sterol blend away from “good sterols” insects use easily and toward “bad sterols” insects struggle to process, Sword said.
When insects fed on these modified plants, they did not immediately die, but Sword said they grew slower, reproduced less and failed to reach damaging population levels.
“It’s not a magic bullet that kills insects,” he said. “But you just need to keep populations below damaging thresholds. That’s the key to any successful IPM program.”
Moving the discovery into cotton
Now the AgriLife Research team is taking the concept into cotton.
With support from Cotton Incorporated and a U.S. Department of Agriculture grant, they are working with Keerti Rathore, Ph.D., an AgriLife Research plant biotechnologist and leading expert in crop transformation in the Texas A&M Department of Soil and Crop Sciences, and Mason Clark, Ph.D., assistant research scientist in the Department of Entomology, to use RNAi gene silencing and CRISPR gene editing to adjust cotton’s sterol profile by targeting a gene called Hydra1.
Early results have shown promise, Sword said. Transformed cotton plants grew normally, produced lint and seed, and are being tested for the types of sterol shifts needed to hinder pests.
What excites Sword most is the approach’s potential to work across many pest species, which directly aligns with broader strategic goals for sustainable pest management through innovative biotechnology.
“This is a weakness shared by all plant‑feeding insects … everything from aphids to caterpillars to stink bugs,” he said. “One trait could potentially protect against a whole range of different insects.”
With experimental plants already in soil and second‑generation seed in hand, the team is now beginning the painstaking work of measuring plant performance, profiling sterol chemistry and testing pest responses. If successful, the research could offer growers a new, more natural tool to protect important crops while reducing reliance on insecticides.
“We’ve gone from basic science to something that might become a real solution to pressing pest problems,” Sword said. “It’s pretty exciting to see where this could go.”
