GAINESVILLE—Close to 2,000 tiny transgenic predator mites that feed on agricultural pests were released at a secured area on the University of Florida campus Thursday, marking the first time a genetically altered arthropod has been field-tested.

Professor Marjorie Hoy, an eminent scholar in entomology and nematology, recently received federal, state and campus approval to release the small, flightless mites which are natural predators of the spider mite, a well-known pest of strawberries and ornamentals.

Although the world’s scientists have already genetically enhanced some plants, animals and insects, this is the first time a scientist has received permission to test a genetically altered arthropod (invertebrate animals with segmented bodies and jointed limbs) species in the field. Hoy’s test will take approximately one year.

“This mite, Metaseiulus occidentalis, contains only a genetic marker and is not harmful to humans, plants or animals,” said Hoy of UF’s Institute of Food and Agricultural Sciences. “If the mite establishes in Florida, we’d have a beneficial predator species to help control spider mites.”

The use of predator species to control certain pests — known as biological control — is environmentally friendly because it often reduces the amount of pesticides needed, Hoy said. During the UF field tests, Hoy will study the mites in an attempt improve the efficiency of biological control agents. “This can be done most rapidly by using molecular genetic techniques.”

Hoy and her colleagues began research by inserting a bacterial gene (lacZ) into the M. occidentalis mite as a marker or tag. The gene is not active, so it does not alter the biological traits of the predator mite in any way, she said.

The lacZ marker comes from a weakened lab strain of a microorganism and has been tested repeatedly and used safely many times by other scientists, Hoy said. More than 150 generations — three years worth of reproduction — of the new genetically transformed mite were reared in a lab and studied by scientists to assure safety.

On Thursday, Hoy placed the lab-reared mites, held on small, paraffin-coated discs, into pinto bean plants at an agricultural research plot. Hoy said a good predator-prey rate was established and the new mites should suppress the spider mites on the bean plants within the next two to three weeks.

Hoy said it could be several years before scientists develop a strain of beneficial arthropod that carries a useful gene, but her research using a genetic marker is a first step in the right direction.

With the campus field tests, Hoy hopes to determine the ability of the mites to control spider mites, their dispersal rates, the distance they can travel, and the ability of scientists to mitigate, or kill the predator mites with an appropriate pesticide, if necessary.

Hoy said her study also will determine if the mites can thrive in the Florida climate, something unlikely because of the heat and humidity, she said.

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