A Treasure Trove of Parasitic Wasps

For the last three decades, scientists in the Area de Conservacion Guanacaste (ACG), a roughly 1000-square-kilometer chunk of forest in northwestern Costa Rica, have been inventorying and rearing hundreds of thousands of caterpillars. With the help of local apprentices, they comb the forests for the critters, pluck them from plants and the ground, and then string them up in plastic bags in a barn. Then, they watch and wait while the caterpillars pupate to see what emerges. 

Sometimes, it’s a moth or a butterfly, exactly as it should be. Other times, though, it’s a wasp whose mother laid her eggs in the caterpillar before the researchers put it in its bag. After hatching, the wasp larvae devour their host from the inside out and emerge from the corpse.

There are plenty of parasitoid wasps like this out there (some of which we’ve covered before), and last month the researchers announced that there are plenty more where those came from. Their latest paper describes and names almost 200 new species of the wasp genus Apanteles—which until recently had only three known species! Clearly, the team says, scientists have been underestimating the diversity of parasitoid wasps and, as more and more parts of the world are as well-cataloged as the ACG, the total number of species could be mind-boggling. 

Each of these new wasps is only about as long as a fingernail, and most of them are very choosy when it comes to their caterpillar hosts. The researchers found that around 90 percent of the species parasitize just a few (or even a single) type of caterpillar, suggesting the subfamily they come from is more specialized than anyone knew.

As I wrote at The Week, parasites are not a very popular conservation cause, but many of them are ecologically important. By turning caterpillars and other insects into zombies and living nurseries and then killing them, Apanteles and other parasitoid wasps provide free pest control. In some parts of the world, people release swarms of them to control problem insects. The researchers in the ACG hope that by getting local people involved in their studies, they can show Costa Ricans the value of these wasps and have more allies for protecting their habitat. As a thank you to their many local lay assistants in the field, the team named many of the new species after them—resulting in beautifully tongue-twisting Latin-Latin American hybrid names like Apanteles jorgehernandezi, A. monicachavarriae, A. raulsolorsanoi, A. robertoespinozai, and A. yolandarojasae. 

Primary photo courtesy the Frost Museum flickr page; cc.