Discovery of Africa moth species important for agriculture, controlling invasive plants

December 20, 2012

GAINESVILLE, Fla. — In the rain forests of the Congo, where mammals and birds are hunted to near-extinction, an impenetrable sound of buzzing insects blankets the atmosphere.

Because it is a fairly inaccessible region with political unrest, much of the Congo’s insect biodiversity remains largely undiscovered. In a new monographic book published this week in Zootaxa, researchers at the University of Florida and the Royal Museum of Central Africa in Belgium provide insect biodiversity information for this area in Central Africa that increasingly undergoes habitat destruction.

Focusing on a group of leaf-mining moths, researchers name 41 new species, nearly doubling the number previously known from the region. Leaf miners occur worldwide and the biodiversity research is important because some species are agricultural pests, while others help control unwanted invasive plant species. Some are also known to delay plant aging.

“When we began this project, we had no idea how many species would be out there,” said co-author Akito Kawahara, assistant curator of Lepidoptera at the Florida Museum of Natural History on the UF campus. “In a two-week field trip, we discovered nearly 50 potentially new species, which is really surprising. There is still an enormous amount of life out there that we know very little of.”

Lead author Jurate DePrins has been working on leaf miners in the Congo for nearly 10 years and was joined by Kawahara about five years ago. As the name suggests, the small moths burrow within leaves as larvae, making them particularly difficult to find. Adult moths measure only about 2 to 5 millimeters in length, but they can be extraordinarily beautiful with colorful markings and metallic scales, Kawahara said.

“The caterpillars are completely flat so they can live inside the thin leaf,” Kawahara said. “If you think of a regular caterpillar and then you squished it and shrunk it, that’s what they look like.”

After collecting caterpillars in the wild, researchers raise the larvae to adulthood on-site, a process that takes less than a week for some species.

“It’s so hard to tell what’s actually happening because they’re so small and they get overlooked, but if you look at what is happening inside a leaf under a microscope, it’s just an incredible world,” Kawahara said. “You’ll see a tiny wasp larva living within a caterpillar, and another, even smaller wasp larva living inside that larger wasp larva that is inside the moth larva. It really opens your eyes to this incredible, unknown world and makes you think, ‘What is going on here?’ It’s truly amazing.”

Leaf-mining moths have unusual survival strategies, poorly understood by researchers, Kawahara said. Relatives of the new species are known to make “green islands,” patches of green leaves found in a pile of brown leaves. When leaves fall from trees and turn brown, the caterpillars preserve the leaves they live in and keep them green.

“Some of these caterpillars actually have the ability to control plant tissue and prevent aging in the plant,” Kawahara said. “Now we’re trying to actually understand the mechanism behind how they actually do it.”

Lithocolletinae, the group that the authors focused on, is one of the oldest-known subfamilies in Lepidoptera, first described by Carl Linnaeus in 1758. The only book describing its species in Africa was published in 1961.

“This is really one of the first major revisions on species level of any of the African members of this large family,” said Donald Davis, a research entomologist at the National Museum of Natural History, Smithsonian Institution. “Any of their discoveries is going to be important because it greatly increases what we previously knew, how little we knew.”

While many large organisms are being studied, not many researchers focus on the smaller organisms, Davis said. Information about Lithocolletinae is needed to understand which species may be agricultural pests or used to control invasive plants.

“It’s an unknown fauna and so they’ve made a major step to start telling us something about this biota,” Davis said. “Because the moths are herbivores, they have both beneficial and detrimental benefits. It’s one of the things we get a lot of questions about.”