Mind-boggling diversity found in Guanacaste wasps

An inventory of wild-caught caterpillars, its food plants and parasites, has been going on for more than 34 years in the Área de Conservación Guanacaste, a protected section of approximately 1,200 square kilometers in northwestern Costa Rica. As a result, more than 10,000 species of moths and butterflies are estimated to live there.

Their caterpillars are in turn attacked by many parasitic wasps, also numbering thousands of species. However, most of those wasps have never been described and remain unknown.

For the past few years researchers from Canada, Costa Rica and the United States have been studying intensively one of these groups of parasitoids: the Microgastrinae wasps, named that way because most of the species have a short abdomen. These small wasps (1 to 5 millimeters long) are one of the most common and diverse groups of parasites recovered from caterpillars anywhere.

The authors of this study, published in the open access journal ZooKeys, analyzed more than 4,000 specimens of just one single genus of microgastrine parasitoid wasps from the conservation area: Apanteles, previously known from only three species in Costa Rica. The results are astonishing: 186 new species were found just in the conservation area. That is more diversity than all the species of Apanteles previously described from the New World. It also represents 20 percent of the world fauna, in less than 0.001 percent of the terrestrial area of the planet.

“What this study shows is how much we have underestimated the actual diversity of parasitoid wasps, and how much we still have to learn about them” said José Fernández-Triana, a researcher from Canada and one of the authors of the paper. “When other areas of the planet are as well collected and studied as ACG has been, the number of new species of parasitoid wasps to be discovered will be mind-boggling.”

The study also found that most of the wasp species (90 percent) only parasitized one or just a few species of moths or butterflies, suggesting that the Microgastrinae parasitoid wasps are more specialized than previously suspected.

All the new species are described through an innovative approach that integrates morphological, molecular and biological data, computer-generated descriptions, and high-quality illustrations for every single species.

The combination of techniques allowed the researchers to speed up the process of describing new species, without reducing the quality of the paper.

Images of the cocoons that the wasps spin when emerging from the parasitized caterpillar were also included whenever possible, to encourage more studies on caterpillars and their parasitoids.

“We hope that this paper lays a foundation for similar studies on other tropical areas of the world”, said Fernández-Triana. “In fact, most of the new species were named after the local persons in Costa Rica who actually collected the caterpillars in the field and reared the wasps used in this study. It is an excellent way to acknowledge and honor their valuable contribution, and we expect that in the future more citizens feel engaged to contribute to Science in similar ways.”

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