Invasive Ants in Hawaiʻi
As the most isolated island chain on Earth, for most of its existence, Hawaiʻi was too distant for many plants and animals to colonize. But as humans entered the picture, new species were being introduced to the islands at a rate like never before. Although plants and vertebrates were brought intentionally by humans, insects were mostly accidental travelers, stowing away on other cargo. Humans like to move stuff, and sometimes, that stuff carries ants!
Hawai’i evolved with no native ant species and now there are 60+ species that call Hawaiʻi home. The more aggressive species in particular can have significant impacts on the environment, by reducing biodiversity (they chase other insects away), harming native animals like birds and sea turtles, and increasing the number of plant pests, like aphids and mealybugs. As most home gardeners already know, ants and plant pests go hand-in-hand. Certain families of Hemipteran insects produce honeydew, a sugary substance high in carbohydrates. Many species of ants “farm” these insects, including aphids, mealybugs, whitefly, and other garden nuisances. As the population of these pests increases, so does the amount of sooty mold and plant disease.
Photo Credit (L-R): Zach Pezzillo, BIISC
Little Fire Ants and Hawaii Ant Lab
When little fire ants made it to Hawai’i, there were no protocols in place for treatment. To combat this new invasive ant, the Hawaiʻi Ant Lab (HAL) was founded in 2009. This team of researchers and technicians began testing various products to target LFA, making sure that the baits were attractive enough for the ants to pick up, but deadly enough to accomplish the goal. One immediate challenge was using granular bait products in east Hawaii’s notoriously damp environments, full of heavy vegetation- the products didn’t reach high up into the trees where ants were making colonies, and they quickly decomposed in wet conditions, becoming ineffective. HAL researchers created an innovative solution: a goopy “gel mix” that combined attractive oil and protein with pesticides. It was water resistant and able to be sprayed high into the trees where the LFA were living. They continue to test ways to improve the gel bait, and just last year published a recipe that could be used with Advion WDG, a new product easily available online.
HAL also tested dozens of granular products, ruling out those that weren’t effective or attractive to LFA and sharing their findings with Big Island residents. It’s not just working with ants, either – adding pesticides to the approved list in Hawai’i means a lot of red tape, and HAL does the paperwork too! They collaborate with manufacturers and the HDOA’s pesticides branch to navigate regulatory hurdles, applying for special licenses and making products available to Hawai’i consumers.
The HAL team also surveys the mulch piles for LFA at the Hilo, Kealakehe, and Puʻuanahulu green waste facilities on Hawaiʻi Island to mitigate the risk of spreading LFA through the movement of mulch. As LFA expanded its range across Hawai’i, so has HAL. On all the islands where LFA populations have been discovered, HAL staff have collaborated with HDOA and ISC personnel to survey, map, treat, and monitor populations.
Hawaiʻi Ant Lab is based in Hilo, Hawaiʻi with two other locations in Kailua-Kona and Oʻahu.
Invasive Ants on the Horizon
While little fire ants are a literal pain, there are even worse ants out there! The Hawaiʻi Ant Lab is a part of the Hawaiʻi Invasive Species Council’s Port of Entry/Exit Pest Monitoring Program, which surveys our ports for highly invasive insects that are spreading around the world. Two species in particular that HAL is looking out for are the red imported fire ant (Solenopsis invicta) and the tawny crazy ant (Nylanderia fulva).
Solenopsis invicta (red imported fire ant, or RIFA) are larger reddish ants that act aggressively when their nests are disturbed. Unlike LFA, they like to build their nests in the ground by making large dirt mounds. RIFA has been spreading across the southern US stinging thousands of people and livestock along the way and has caused deadly reactions in humans and pets. They have been recorded spreading in potting media, sod, soil, and used electronic equipment. Besides stinging people and animals, RIFA will also chew on crop plants, damaging them and reducing yields.
Nylanderia fulva (Tawny crazy ant) is a small, fast-moving ant that is spreading quickly through the United States. Similar to LFA, they breed quickly and produce multiple queens, creating large supercolonies. While they don’t sting, they excrete formic acid, which can be very damaging to wildlife. In badly infested areas they have killed chickens and blind cattle. They also can destroy and short-circuit electrical equipment. Tawny crazy ants are easily transported by mistake because they will make their nests in almost anything.
Photos by (L-R): Steven W (cc), Michael Bentley (cc)
These are just a few of the ants that have Hawaiʻi Ant Lab’s attention. Help us detect new ant species by collecting ant samples on your property and sending them in to get identified. Ants are small and require a microscope to properly ID, so take advantage of the free identification services available at BIISC and HAL. Request your FREE ant collection kit today from www.stoptheant.org.
Learn more about ants by visiting the Hawaii Ant Lab website and follow them on social media:
