Public Release: 

Natural Pest Control Shows Economic Promise For Citrus Industry

University of Wyoming


Sept. 9, 1996 -- An obscure wasp species found by a University of Wyoming researcher in Costa Rica shows promise for controlling a damaging citrus crop pest and ultimately may translate to lower prices for some orange juices marketed in the United States.

The wasp was the focus of research conducted by Nina Zitani, a UW entomology graduate student from Moorestown, N.J. She spent the last two summers in Costa Rica's Guanacaste Conservation Area (GCA), where she investigated the basic biology of certain parasitic wasps that attack caterpillars. The new wasp species had not previously been described in scientific literature, says her adviser Scott Shaw, a professor of entomology in the UW Department of Plant, Soil and Insect Sciences who also has conducted research in the GCA.

"Our improved knowledge of this tropical forest insect may ultimately impact American breakfast tables and pocketbooks," Shaw says.

Zitani says it is important to understand how parasitic insects can be used for natural insect control. She says she collected samples from the forest and reared a certain type of wasp found in swallowtail butterflies. That type of butterfly is a pest to citrus tree leaves, Zitani says. Shaw says the feeding can lead to defoliation and less fruit production, often resulting in expenses for chemical pesticides.

"The wasps often eat caterpillars that are pests of crops, so it is important to identify the wasp species," Zitani says, adding that she was able to identify the type of wasp that parasitizes the butterfly.

Zitani says the research is vital to understanding natural insect control. Her primary task was to search the forest for various types of leaf-feeding caterpillars, then to raise the insects in captivity to see what wasps emerged. Female wasps lay their eggs inside caterpillars, which usually die before turning into moths or butterflies.

"The fact that the wasp attacks swallowtail caterpillars is of interest. It is the first record of a wasp in this group attacking this butterfly family group anywhere in the Americas," Shaw says. "That it attacks a citrus-feeder suggests its economic potential."

Some local research in Costa Rica indicates that the cost of orange production can be reduced by using natural biological controls rather than synthetic chemical pesticides, he says.

Zitani and Shaw are preparing a journal article describing and naming the new wasp -- outlining its biology -- that they expect to publish early next year in the "Journal of Hymenoptera Research."

Shaw and other scientists are conducting a biological inventory in the GCA to learn and catalog all forms of life occupying the area. The GCA, similar to a United States national park, is left as much as possible in its natural state, free from pesticide use. Shaw says Zitani's research is considered a contribution to that project.

GCA is a 427-mile tropical forest preserve in northwestern Costa Rica. Its diverse ecology includes beaches and marine habitat along the Pacific coast, inland through various stages of regenerating tropical dry forests and across three volcanic mountain peaks covered by tropical wet forests. Zitani conducted most of her research in tropical rain forests.

Her research is supported by several agencies, including the UW Department of PSIS, College of Agriculture Research Office, the UW Graduate School, the National Biodiversity Institute (INBio) in Costa Rica and GCA. She has applied for a Sigma Xi research grant to continue her studies.


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