May 18, 2018

In Southeast Asia, a newly identified ant species has a unique defense mechanism: it explodes! When threatened, or when in the grips of an enemy insect, the new tree-dwelling ant species Colobopsis explodens bursts toxic yellow goo from its abdomen, killing or chasing off its attacker. The ant dies in the effort, but it is an effective way of defending the colony.

A worker Colobopsis explodens ant strikes a formidable defensive pose. Credit: © Alexey Kopchinskiy, Pensoft Publishers

The self-sacrifice of the Colobopsis explodens ant may sound drastic, but it is not uncommon in the insect world. Many bees die after stinging an attacker, and certain aphids, termites, and other ants also practice autothysis—the act of self-sacrifice through explosion.

Ant colonies differ enormously in size. A colony may have a dozen, hundreds, thousands, or in rare cases, even millions of members. A colony usually has one or more queens. Ant queens are females whose chief job is to lay eggs. An ant colony also includes the ant young or larvae. Male ants, who have wings, live in the colony only at certain times of the year. Their only job is to mate with young queens, who also have wings. The rest of the colony consists mostly of workers. These wingless female ants do not lay fertile eggs but instead build the nest, search for food, care for the queen and the young, and protect the colony. Unlike queens, workers commonly leave the nest and can often be seen walking about on the ground or in trees.

The small, reddish-brown Colobopsis explodens workers are the ones who give themselves up for the good of the colony. During combat, the worker ant bites down on the enemy, lifts its lower body, and contracts its muscles so hard that its skin splits open, releasing sticky, toxic fluid from its abdomen. The explosion kills the ant, but the curry-smelling goo either kills or repels the enemy. If invading insects make it past the exploding ants’ front line, the colony has a unique second line of defense—worker ants with enlarged, plug-shaped heads. These ants gather together to barricade the nest’s entrance, keeping enemies out.

Exploding ants have been known for quite some time, but Colobopsis explodens is the first new species to be discovered since the 1930’s. Scientists do not know much about exploding ants, but this new species provides the opportunity to learn more.

November 10, 2017

Last month, in October, scientists in Germany warned that flying insect populations are rapidly declining. A study published in the scientific journal PLOS One revealed that about 75 percent of the flying insects in German nature preserves have disappeared in less than 30 years. The decline in natural areas of Germany could spell doom for flying insects—and many other forms of life—around the world. Quick action is needed to stem this decline, a serious matter referred to somewhat less seriously as the “windshield phenomenon” by some biologists (meaning there are fewer dead bugs to clean off automobile windshields these days).

A recent study showed alarming reductions in populations of flying insects, a group of animals that includes bees, butterflies, dragonflies, mosquitoes, and fireflies (pictured here). Credit: WORLD BOOK photo by Don Stebbing

Scientists have described and named more than 1 1/2 million species (kinds) of animals. Of these, about 1 million are insects. Scientists discover thousands of new insect species every year, and they believe there are many more yet to be found. Insects form the basis of many thousands of food chains. About 60 percent of birds rely on insects as part of their diet, and many types of bats, fish, spiders, and other animals also rely heavily on insects. In addition, about 80 percent of wild plants rely on insects for pollination. Without insects, many of these animals and plants would die. Without those plants and animals, many other forms of life would die.

For the long-term study, scientists at the Entomological Society Krefeld set up malaise traps (tentlike traps made of fine mesh material that catches a wide variety of insects) in 63 German nature preserves over the course of 27 years. Malaise traps are generally set out for long periods and checked every 7 to 14 days. The traps were placed in grasslands, sand dunes, swamps, wastelands, and other areas where insects should have been plentiful. By measuring the weight of the insect catch—known as the biomass—from each malaise trap, researchers detected the sharp drop in flying insect numbers. The decrease from 1990 was alarming: an 82 percent decline at midsummer (when the populations should be most active), and a 76 percent decline throughout the year.

Pesticides and habitat destruction are thought to be the main culprits behind the decline. Jason R. Cryan, deputy director and chief of research and collections at the North Carolina Museum of Natural Sciences in the United States, noted that “Although the study was conducted entirely in Germany, these contributory factors are common globally, and thus we can expect that insect population declines of similar magnitude are occurring in other regions of the world.”

Earlier this year, the Entomological Society of America (ESA) published two formal position statements on endangered insect species and arthropod biodiversity. The statements mention the critical role insects play in healthy ecosystems and note that insects are often early indicators of ecological shifts. The ESA has called for enhanced research and increased conservation efforts to reduce habitat destruction and the use of pesticides.

September 14, 2017

Last month, Switzerland became the first European Union (EU) country to allow the sale of insect-based food items for human consumption. That’s right, for those of you craving a mealworm burger or a side of crickets or grasshoppers, you can now get them at the local market in Bern, Geneva, or Zürich. Long accepted as a protein-rich food in other parts of the world, eating insects is relatively new to Europeans, who—like a lot of other people—have a hard time getting over the “yuck” factor of eating bugs. Insects, however, are a logical, practical, and even tasty food choice as human populations continue to rise along with the economic and environmental cost of raising traditional crops and livestock.

Mealworms (the grubs of a type of darkling beetle) may be new to the diet of many people, but they have long been used in animal feed. Credit: © Denis Tabler, Shutterstock

In Africa, Asia, and parts of Latin America, it is common to find insects on menus or for sale in markets. In the United States, insects can be found as exotic menu items, and they are often used as food additives or dyes. U.S. companies can sell whole insects as long as the bugs are clean, wholesome, and raised specifically for human consumption. Most Food and Drug Administration (FDA) laws, however, detail limits of “unavoidable” bugs in other food. Chew on that for a minute. Anyway, in Europe, the Novel Food Regulation limits food that was not “used for human consumption to a significant degree” before 1997. This means that nontraditional food items must get special legal clearance. In May 2017, Switzerland approved crickets, grasshoppers, and mealworms as food items, and after the EU agreed, bugs hit store shelves in August.

A wide variety of prepared insects are available for snacking at this market in Thailand. Credit: © Thor Jorgen Udvang, Shutterstock

Not all insects are fit for human consumption, of course, but many provide a highly nutritional, readily available, and environmentally friendly food source. Traditional agriculture—the planting and harvesting of crops, the raising of livestock, and the transport and delivery of food items—is a heavy contributor to global warming, which in turn adversely affects traditional agriculture. To slow the impact of climate change, and to feed the world’s ever-growing human population, insect agriculture is a logical and practical choice. Aside from Switzerland’s new food items, such insects as ants, bees, beetles, caterpillars, and locusts are packed with protein, fiber, good fats, and vital minerals. Bugs require much less feed, space, and care than traditional farm animals. They also emit considerably fewer greenhouse gases than most livestock.

Insects can be quite tasty, too. After all, they are arthropods, the largest phylum (division) of the animal kingdom that also includes crabs, lobsters, and shrimp. Most animals and many people on Earth already indulge in entomophagy (insect eating). Is it about time the rest of us joined them?