READING AND LISTENING.

Reading:

The yellow crazy ant is one of the world’s most destructive invasive species (species that are not native to an area but rather introduced to it). It has spread to many regions of Earth and caused great damage to native ecosystems. In recent decades, the crazy ant has invaded part of a unique palm forest on one of the Seychelles Islands off the coast of Africa. Some strategies are being considered to stop the ant from spreading farther and damaging the unique ecosystem of the palm forest.

One of the strategies proposed to stop the ants is to use traps containing a low concentration of chemicals that are toxic to the ants. These ant traps have been successfully used in other locations, such as an island near Australia, where up to 99 percent of the invasive ant population has been killed by traps.

Another strategy would be to cut down broad-leaved trees, which are the ants’ favorite habitat. Broad-leaved trees host a type of insect that provides food (a sugary substance) for the yellow crazy ants. The broad-leaved trees are not native to the palm forest; they were introduced there recently. Removing the trees would not damage the palm forest ecosystem, but it would reduce the extent of the habitat preferred by the invasive ants, which might reduce their population.

Finally, it has been noted that ant populations are significantly denser near areas with human activity. Recently, a sharp increase in yellow crazy ants has been observed at one edge of the palm forest where a new visitor center was built, which suggests that more ants were transported to the area with construction material used for the center and that the ants have been eating food left behind by visitors there. Limiting human activity near the palm forest could help reduce ant populations.

Listening:

Unfortunately, the suggestions you read about are unlikely to work in this case.

First of all, using toxic and traps would cause some unintended harm. You see, these traps do not differentiate between the yellow crazy ants and other native species of ants. That means that the native ants can be harmed by the traps. The island near Australia you read about does not have any native ants. So no unintended harm was done there. But in the palm forest on the Seychelles Islands, there are native ant species present that we want to protect. And these ants would certainly be killed by the toxic traps.

Second, cutting down broad-leaved trees might not solve the problem. You see, yellow crazy ants can thrive in several different kinds of habitats. Yes, they thrive in a habitat with broad-leaved trees. However, they also do well in habitats like open areas with increased sunlight. The trouble is if we cut down the broad-leaved trees, we would create areas of increased sunlight inside the palm forest. So in other words, if we cut down broad-leaved trees, we might destroy one type of habitat that the ants like, but we’ll be creating a new habitat that is also very friendly to the yellow crazy ants. So we won’t get rid of the ants that way.

Finally, limiting human activity around the forest might slow down the ant spread a little, but it might lead to a serious economic problem. You see, the islands’ palm forest is the region’s main tourist attraction, and the unique trees and animals that live in the palm forest attract not just tourists, but also scientists who conduct studies on the region’s rare species. In fact, tourism and visits from scientists are the most important sources of income for the local people. Therefore, trying to limit human presence around the forest would negatively affect the economy of the whole region.

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