ARE ESSENTIAL OILS EFFECTIVE AGAINST BUGS? – The Waynedale Information

0
411

Bed bugs hide in dark, invisible rooms and multiply quickly, making them difficult to control. This work has become even more difficult in recent years as the pests have developed resistance to the insecticides that have long been used to eradicate them from homes, hotel rooms, and other spaces.

Plant-based essential oils are generally deadly to bed bugs, but it has been unclear how to use them most effectively. Purdue University entomologist Ameya Gondhalekar and his former Ph.D. Student Sudip Gaire discovered how essential oil compounds affect the physiology of bed bugs and how they can improve the lethality of pyrethroids, a class of commercial and household insecticides.

Their results were published in two articles in the journal Pesticide Biochemistry and Physiology – one last year and one in March this year.

“We have seen that we can kill resistant bed bugs with traditional pyrethroid insecticides, but we have to use ever larger amounts. Applying them at these levels is a problem, ”said Gondhalekar, Scientific Associate Professor of Entomology. “Our results show that essential oils can kill bed bugs, but the combination of essential oils and pyrethroid insecticides has a synergistic effect.”

Gaire and Gondhalekar first tested the pyrethroid insecticide deltamethrin and a range of essential oil compounds on non-resistant bed bugs and a resistant Knoxville bed bug strain. A single dose of deltamethrin that was supposed to kill 25% of the beetles killed that many non-resistant bed bugs, but it took 70,000 times more to kill 25% of the Knoxville tribe.

“Deltamethrin is so ineffective on the Knoxville bed bug strain that you have almost no control in the field, even in large doses,” said Gaire.

The active ingredients in essential oils – thymol from thyme, carvacrol from oregano and thyme, eugenol from clove and others – work equally against resistant and non-resistant insects. A dose that was supposed to kill 25% killed so many of each type.

Gondhalekar said bugs’ nervous systems normally open and close sodium channels to pass signals through neurons. Deltamethrin binds to these sodium channels and holds them open so the neurons cannot stop firing. This repeated firing quickly depletes the beetle’s energy and kills it.

But resistant bed bugs have several mechanisms to resist pyrethroids, including overactive levels of an enzyme called cytochrome P450, which breaks down deltamethrin. The essential oil compounds, Gaire and Gondhalekar reported, bind to and deactivate this enzyme, allowing deltamethrin to do its job in the bed bug’s nervous system.

Gaire and Gondhalekar combined a single dose of deltamethrin with a single dose of essential oil compounds, which are expected to kill 25 to 50 percent of resistant bed bugs. Instead, it killed more than 90 percent of resistant bed bugs.

“When we treated the resistant Knoxville bed bugs with various essential oils and tested them for cytochrome P450, we found that these enzymes were inhibited,” said Gaire. “The essential oil compounds were able to neutralize these enzymes so that the deltamethrin can do its job.”

Gondhalekar’s laboratory will continue to research potential formulations of essential oils containing pyrethroid insecticides and test them in the laboratory and in the field to maximize pest control. Purdue University’s AgSEED program, the Center for Urban and Industrial Pest Management, and the Bilsland Dissertation Fellowship supported this research as part of Gaire’s dissertation.

The Waynedale News Agents The Waynedale News AgentsLatest posts from The Waynedale News Staff (See everything)