Alternate Methods of Whitefly Control

Don’t bombard cotton pests withinsecticide; supplementing chemical sprays with biological control methods is abetter approach.

That’s the advice of entomologists with theU.S.Arid-Land Agricultural Research Center and theUniversity of Arizona. The center is anew facility of the Agricultural Research Service (ARS), the U.S. Department of Agriculture’s primaryscientific research agency.

The silverleaf whitefly is a serious cotton pest. In the 1990s, at the peakof their population explosion, whiteflies were destroying millions ofdollars’ worth of U.S. crops every year. ARS entomologistsStevenNaranjo andJamesHagler contributed to a national effort to reduce the whitefly population.

Now they advocate a combination of preventative action, biological controland selective insecticides as the most effective, environmentally-friendlyresponse to whitefly invasions.

Naranjo and University of Arizona researcher Peter Ellsworth analyzed thefactors contributing to whitefly mortality. They identified the most commoncauses of death, including predatory insects and weather-induced dislodgment.This led them to recommend conserving natural predators for effective whiteflycontrol.

To discern which insects are natural whitefly predators, Hagler developed anassay that tests insect gut contents for evidence of whitefly consumption.Using this method, he and Naranjo quantified predation frequency for 18whitefly predators, many of which had been unidentified previously.

The researchers recommend complementing biological control with commercialinsect growth regulators like buprofezin and pyriproxyfen. Their studies showthat growth regulators tend to conserve natural predators, while conventionalinsecticides can be indiscriminate, eliminating predator and prey alike.

The scientists’ research has enabled them to make specificrecommendations for improving whitefly population management. Their work ispart of a growing knowledge base that has helped decrease insecticide use forwhitefly control by about 85 percent since 1995.

Readmore about the research in the April issue of Agricultural Researchmagazine.