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February 22, 2007

Invasive Armies Are A Pestiferous Problem

Hawaii seems to have a history of being colonized... by invasive species.

When I was young, I used to value the lives of all animals equally. On rainy days, when I was walking home from the bus stop, I would pick worms out of puddles and deposit them on safe ground. I would let an ant crawl onto my finger and deposit it out of harms way. Those were teh days...Then I went off to college, and while living in the dorms my attitude towards my little six legged friends, the ants, changed considerably.

Our apartment had a full kitchen and we lived on the top floor. The people who lived below us had less than desirably cleanliness. At first, it was just the occassional scout ant. We'd pick them up and take them out on the back porch and release them. Then one day, we came home ad our entire carpet was covered with them. Nothing was safe, anything remotely scented was crawling with the little buggers. From then on, the gloves were off. It was four young women against an army of ants and we vowed to win, even if it meant killing them one at a time.

Long story short, we first tried to be eco-friendly, and even ant friendly. We encouraged them to leave by removing all food sources. We had to keep ALL our food (cereal, bread, spices) in the fridge for safe-keeping for more than a semester but it made no difference with the idiots living below us. Finally, we had to resort to more stringent methods of ant eradication.

After one especially bad evening in which we all, more or less, ate ants, we decided to show no more mercy. After all, they hadn't. They had even foudn their way into our refrigerator. All chemical eradication methods (we found the uni-supplied glass cleaner worked better than most stuff) were used in the battle, stomping for good measure. Despite the exterminators and all manner of ant-proofing chemicals and home remedies, the problem never did go away entirely. We finally just moved off-campus. By the end of that year, each and every one of us, kindly souls that we were, showed not an ounce of regret for squishing an ant with a thumb (and generally did so with some relish). Smushing them was not nearly as disgusting as ingesting them, after all.

Still, it's good to remember that ants generally serve a very useful purpose. They aerate the soil and eat other creepy crawlies, as well as acting as a food source for other animals, including humans (ant eating is a delicacy). We've also been able to axploit the amazing working power of ants in our agricultural processes. For example, the wonderful African red tea, Rooibos, is cultivated using ants. The seeds of the Rooibos (red bush) plant are very, very small. Like grain of sand small. So instead of having laborers try to collect them, farmers employ ants that collect the seeds and return them to their colonies, where they are harvested.

According to Wikipedia, ants make up almost a quarter of the Earth's animal biomass and there are not many ant-free places left in the world, just perpetually cold remote places like Antarctica. One place that doesn't have native ants is the Hawaiian Islands. It was just remote enough not to have them show up on their own.

Not until people showed up, anyway. One especially destructive ant species, the Argentine ant, arrived in Honolulu on goods shipped from California during the Great Depression after causing quite a bit of citrus crop damage on the mainland. This ant tends to chase other ants out and preys on pest-eating and pollenating insects (the kind farmers like) as well as on the crops and seeds themselves.

Nowadays almost four dozen ant species have moved in on the Hawaiian Islands and are causing significant troubles with the local wildlife. Because the islands are so remote, the native plants and animals have evolved differently from much of the rest of the world. There are virtually no social insects native to the islands, and so the strengths of the complex social hierarchy of ant colonies often overwhelm the native locals.

The native insect population that has long acted as the pollinators for the native flora, and has not developed adaptations to avoid being eaten by ants (like tasting bad or flying or having hard exo-skeletons) and so the ants munch away undeterred on them and on the native plants and plant seeds as well.

The Argentine ant has a long history of causing trouble when it is introduced into new ecosystems. Because it is able to survive and thrive at high elevations, the Argentine ant is one of the few ant species that can climb up into the fragile volcano ecosystems, such as Haleakala National Park on Maui. Scientists are finding that the ant colonies established here are having a negative impact on the local insects, arthropods especially. The Argentine loves to eat young bees so you can see out that might negatively impact pollenators throughout the world. This disrupts the whole food chain, causing indirect effects on more native fauna that relies on these native bugs and plants for its food and other uses like nesting materials for animals like the endangered Palila, a large Hawaiian honeycreeper.

On Maui this past week, we saw very few birds but we saw quite a lot of ants and a couple mongooses. It's become apparent that the native bird populations are being attacked from a variety of angles, but almost all problems can be attributed to invasive species - whether its humans stealing their habitat, troubles of mongoose eating their eggs, or ants disrupting their food sources.

Posted by sorsha at February 22, 2007 1:19 PM