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Post-Harvest
Orchard Cleanup May Deter Mexican Fruit FliesBy Alfredo Flores July 12, 2002Research shows that grapefruit growers
can help reduce the danger of Mexican fruit fly infestation by removing all
fruit remaining in trees and on the ground after harvest. Lacking this fruit,
wild Mexican fruit flies will have to leave the area to find food and places to
lay their eggs, and may die trying. This finding comes from Agricultural
Research Service entomologists David Robacker and Ivich Fraser at the
Kika de la Garza Subtropical
Agricultural Research Center in Weslaco, Texas. The Mexican fruit fly plays
havoc with citrus crops in Texas, California, Florida, Mexico and Central
America. Ten-year losses from the pest in South Texas and northern Mexico alone
have been estimated at almost $7 billion from treatment costs, reduced crop
yields, export sanctions and lost markets. The damage occurs when fruit fly larvae feed on the grapefruit pulp, ruining
the fruit for human consumption. But what perplexes scientists is that
theres new evidence that these flies do not naturally recognize
grapefruit as a host. Robacker and Fraser have investigated the factors that
attract the pest to an egg-laying site. Findings of how the fly perceives and
reacts to its environment will help in developing better monitoring and control
methods. The researchers compared the responses of laboratory-raised and wild-strain
fruit flies when exposed to grapefruit. Before testing lab-raised flies,
Robacker placed grapefruit in cages with the flies for several days. Later,
those females were 400 percent more attracted to the fruit than were flies
without previous exposure. This suggests that wild-strain Mexican fruit fly adults are likely to feed
on whatevers nearby when they emerge from the ground. So quick removal of
fallen grapefruit might send the pest searching for other, less valuable
alternatives. ARS is the U.S. Department of
Agricultures chief scientific research agency. U.S. Department of Agriculture |