A team of Purdue University researchers is developing what it calls the "next generation" of insecticides to control disease-carrying insects such as mosquitos, ticks and tsetse flies, which are developing resistance to traditional insecticides. While most Hoosiers likely view the pests as a nuisance, the insects are a critical human health threat in underdeveloped regions. The researchers believe they have the building blocks to make a new class of insecticides that is more effective, healthier for humans and better for the environment.
Catherine Hill, one of the researchers leading the project and Purdue College of Agriculture associate professor, says there hasn't been much industry effort to develop new insecticides, mostly because the pests harm third world populations, spreading diseases such as malaria and Lyme disease.
The greatest need is in Africa, where the World Health Organization says malaria kills nearly 3,000 children each day in Sub Saharan Africa. The continent accounts for 90 percent of malaria deaths worldwide, but the disease is also a concern in parts of Southeast Asia. Hill believes the U.S. and European markets would benefit from improved insecticides as well.
"[Insecticides currently on the market] use old chemistries that have been around for a very long time—some of them for decades," says Hill. "Many of them are not only neurotoxic to insects, they're also neurotoxic to humans and other animals and can concentrate in the environment. They're not particularly good for our health or safe for the environment."
Hill says the fact that disease-carrying insects are developing resistance to traditional insecticides underscores the need for a new approach—and she believes her lab may have found it. The team's method focuses on insects' DNA.
"The DNA of an insect is different than the DNA of a human or a dog, for example," says Hill. "We're trying to exploit that difference, and design very specific chemistries that affect the insect and not a human, for instance."
More specifically, their approach involves receptors—or molecular targets—involved with the insects' feeding process, which is the taking of a "blood meal" from a human or animal. The researchers are striving to develop a chemistry that disrupts the feeding receptors, and in turn, disrupts the transmission of disease.
"Many of these receptors are located in the central nervous system of the insect—the brain of the insect," says Val Watts, Purdue professor of medicinal chemistry and molecular pharmacology. "So they become neurotoxic. If you kill the insect by targeting these receptors, they can no longer transmit disease, because they're dead."
Watts' area of research shows the chemical compounds would have selectivity for specific insects, making genome-focused insecticides safer for humans and animals, such as companion pets like dogs and cats.
"Some of the compounds we've identified that are selective for the mosquito over the human are also selective for the mosquito over the tick," says Watts. "That suggests we can get selectivity within other insects; the idea would be we could target mosquitos without hitting honeybees."
The team has been studying the compounds for three years and is now exploring several routes for commercialization. The school's Office of Technology Commercialization has filed a provisional patent and is looking for partners to further develop the product, including chemical and agricultural biotech companies, as well as small pharmaceutical firms.
"We're also thinking about starting our own company to capture some of the intellectual property that's being generated," says Hill. "We're really interested in starting some activities in the not for profit arena, where we'd be developing and helping deliver some products into the third world, where many of these insects transmit diseases to people who don't have the money to pay for these products."
Noting they're "at the very tip of the iceberg," the researchers say the creation of a "next generation" insecticide product will, realistically, take another 10 to 15 years.
"You're looking for that one perfect chemistry—that needle in a haystack; it's a huge undertaking to try to identify the chemistry that has all of the properties you want," says Hill. "It takes a lot of time, money and highly skilled people. We're looking at how we keep investing in this very promising research and drive it forward."
Hill says the team will continue sifting through the "haystack"—searching for discoveries that could save Hoosiers from annoying mosquito bites, and more importantly, thousands of lives from a deadly disease.