Museum scientist takes on bugs of the Southern Hemisphere: leads team aiming to study 5,000 species of plant-eating bugs

Natural History, May, 2004

Bugs "down under" will take center stage in a new collaborative five-year project between scientists at the American Museum of Natural History and colleagues at other prominent research institutions. Funded by the National Science Foundation (NSF), the $3 million initiative will involve collecting and compiling global biodiversity information on plant-feeding insects of-the family Miridae, with a focus on the Australian and South African species of these bugs. Randall T. Schuh, Curator and Chair of the Museum's Division of Invertebrate Zoology, is coleading the project with Gerry Cassis, head of the Centre for Biodiversity and Conservation Research at the Australian Museum. Teams of entomologists led by Drs. Schuh and Cassis will oversee this multipronged effort together with Thomas J. Henry of the U.S. Department of Agriculture's Systematic Entomology Laboratory and Michael D. Schwartz of Agriculture and Agri-Food Canada, also leading specialists on these insects.

The project's goal is to create a world taxonomy and database for these bugs that feed by sucking the juices from host plants. Because the biodiversity of all life is generally better known in the Northern Hemisphere than in the Southern, this project will focus on the tremendous plant and insect biodiversity concentrated in the Southern Hemisphere, especially in Australia and South Africa.

"Australia's insect biota is virtually unknown to many entomologists outside that country," said Dr. Schuh. "To understand the world's insect biota, you have to understand Australia's insect biota. Prior to 1995, one might have concluded that Australia had a very limited fauna. But with the collecting that Dr. Cassis and I have done in the past seven years, we are finally getting a decent representation of these creatures. Now, with this grant project, the broad outlines of the Australian and Southern Hemisphere biota overall will be well known."

Dr. Cassis calls this project "the research opportunity of a lifetime," and believes it will make a spectacular contribution to the international understanding of biodiversity. "The Miridae, a family of sap-sucking insects, is one of the most diverse groups of life on the planet," he says. "These bugs--some barely bigger than a pinhead--were here before the dinosaurs, and have not only survived, but have flourished to the point where you find them everywhere."

Insects are estimated to comprise 75 percent of Earth's biodiversity at the species level. Plant bugs, including the Miridae, represent a tremendous amount of that biodiversity.

Data for the plant bugs project, which also involves scientists from Canada, Colombia, Germany, Russia, and the United States, will consist of about 550,000 specimens already in museums and another 100,000 specimens--mainly of the relatively unknown insect biota of Southern Hemisphere locations like Australia, Chile, South Africa, and parts of Asia--to be acquired through 15 to 20 field expeditions such as the 2002 Constantine S. Niarchos Expedition to Australia. The investigators plan to ramp up collection efforts extensively in these locations, as they have been poorly sampled in the past.

All told, the specimens studied will represent more than 5,000 species with nearly 25 percent of them to be described as new. (For comparison, most individual taxonomists are lucky to describe 30 new species in a year.) About 800 of the species collected will come from Australia, where there is a high degree of insect endemism, or insects that live only on this continent. The scientists also will note the species of plants on which each of-the collected insects is found to create a database that indicates the host plants for each group of bugs.

Drs. Schuh and Cassis are renowned experts on plant bugs and have collaborated for several years in collecting and studying them. With this grant, they can increase their description and analytic efforts to an "industrial" scale, involving more than a dozen entomologists. Analysis of-family-group relations among the greatly expanded inventory of species resulting from this project will involve use of the Museum's cluster supercomputer to search for the simplest family tree to describe all these bug species' evolutionary transitions from the tree's base to its farthest reaches. The supercomputer, one of the fastest in the world, is used Museumwide to analyze complex arrays of biological data and arrive at the best tree formation among many possible trees that could describe the evolutionary relationships among groups of species.

On the plant side, the project will double the number of known bug hosts to about 6,000, and boost the number of bug species with known hosts to more than 4,000. With this large body of information, theories of host association can be tested with the aim of understanding whether bugs have coevolved with their plant hosts, whether host affiliation is the result of ecological association, or whether the evolution of host associations is driven by chemicals in plants.