Whiteflies can be biologically controlled in Florida greenhouse tomatoes, according to a new University of Florida study, which helps reduce the need for pesticide applications.

Biological control, or biocontrol, is the mitigation of pests using natural means rather than synthetic ones.

Florida is the country’s top producer of fresh tomatoes, and sales of the state’s crop for 2009-2010 exceeded $402 million.

Lance Osborne, an entomology professor and associate director of UF’s Mid-Florida Research and Education Center in Apopka, led the study that found that papaya plants can be used to host a wasp that attacks silverleaf whiteflies, an insect that is a major pest of tomatoes. The findings are published in the current issue of the journal Biological Control.

“The major issues involved with this whitefly are its ability to transmit viruses and to become resistant to most pesticides,” Osborne said. “This pest is very prone to developing resistance, so 100 percent reliance on pesticides equates to resistance. It equates to almost disaster.”

“We’re trying to reduce the use of pesticides so we don’t develop a super strain of whitefly that’s resistant to everything,” he said.

Whiteflies feed on tomato leaves and transmit diseases, including tomato yellow leaf curl virus. By introducing papaya plants with wasps into the greenhouse before any pest whiteflies are detected, the wasps act as sentries and attack any whiteflies that might become established in the crop.

Wasps have been used before to control whiteflies in greenhouse production systems, but those sold commercially tended to be expensive and ineffective.