New kind of insecticide

Researchers at Purdue University in West Lafayette, Indiana are studying Ants to come up with new ways to get rid of them.

One of the most common house ant species might have been built for living in some of the smallest spaces in a forest, but the ants have found ways to take advantage of the comforts of city living.

Grzegorz Buczkowski, a Purdue University research assistant professor of entomology, found that odorous house ant colonies become larger and more complex as they move from forest to city and act somewhat like an invasive species. The ants live about 50 to a colony with one queen in forest settings but explode into supercolonies with more than 6 million workers and 50,000 queens in urban areas.

“This is a native species that’s doing this,” said Buczkowski, whose results are published in the early online version of the journal Biological Invasions. “Native ants are not supposed to become invasive. We don’t know of any other native ants that are outcompeting other species of native ants like these.”

Odorous house ants live in hollow acorn shells in the forest. They’re called odorous because they have a coconut- or rum-like smell when crushed. They’re considered one of the most common house ants.

In semi-natural areas that are a cross of forest and urban areas, such as a park, Buczkowski said he observed colonies of about 500 workers with a single queen. He said it’s possible that as the ants get closer to urban areas they have easier access to food, shelter and other resources.

“In the forest, they have to compete for food and nesting sites,” Buczkowski said. “In the cities, they don’t have that competition. People give them a place to nest, a place to eat.”

Buczkowski observed the ants in three different settings on and around the Purdue campus. He said it might be expected that if the odorous house ants were able to multiply into complex colonies, other ants would do the same.

But Buczkowski found no evidence that other ants had adapted to new environments and evolved into larger groups as the odorous house ants have. He said it’s possible that odorous house ants are better adapted to city environments than other ant species or that they had somehow outcompeted or dominated other species.

“This raises a lot of questions we’d like to answer,” he said.

Buczkowski said understanding why the supercolonies form could lead to better control of the pests in homes, as well as ensuring that they don’t outcompete beneficial species.

Future studies on odorous house ants will include studying the ant’s genetics and trying to understand the effects of urbanization of odorous house ants.

“They don’t sting they don’t bite, but they do have very large colonies, so you can have very large numbers, going into someone’s kitchen or even nesting outside the house. It’s more of an urban nuisance ant,” said Grzesiek Buczkowski, an entomologist at Purdue.

A hydrogel could be the answer to the pesky pest problem. It starts out as dry crystals.

“At the start we have dry bait crystals. They look like grains of rice, and it’s kind of a hard plastic material,” explained Buczkowski.

But just add water and it turns into a clear jelly-like substance that can absorb about 300 times its own weight.

Researchers add a small amount of pesticide and sugar water to the gel – ants love sugar. In tests the pesticide-laced gel killed off 94 percent of an argentine ant population in two weeks.

“The bait crystals are just a really good way to get the insecticide to the colonies,” said Buczkowski.

The gel uses a hundred times less insecticide than traditional liquid baits and a million times less than sprays, making it better for the environment. It’s also cheap and easy to use.

“We can also eliminate an invasive ant and hopefully help out the native ants,” said Buczkowski.

Any ant species could eat the bait, but argentine ants have been known to invade and eliminate native ants – which are needed for a healthy ecosystem. The native ants – or good ants – can’t compete with argentine ants for food – including the bait crystals.

More testing is needed to make sure the gel isn’t attractive to other good insects or birds. For now, it’s a real, and deadly treat for these ants.

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