May 4, 2000 / USDA - ARS News Service
Two of cotton's worst enemies are conceding to an environmentally friendly
insecticide called spinosad. Approved for use on more than 100
crops -- including apples, almonds, citrus, eggplant, tomatoes, cotton, and
coffee -- spinosad is poised to replace malathion, until now the most widely
used insecticide against the Mediterranean fruit fly.
Agricultural Research Service scientists in College Station, Texas, have
years of expertise developing new tactics to test this new insecticide on
commercially-grown cotton. Cotton bollworms and budworms have developed
resistance to most commonly used commercial insecticides. As a result, these
insects now infest over 75 percent of the U.S. cotton crop.
Aerial applications of spinosad were applied with a small droplet size (200
micron) and a 5-gallon spray rate. Commercial cotton treated at this level
had fewer damaging bollworm and budworm larvae compared to cotton treated
with other pesticides. Larvae found on cotton treated with standard
insecticides were more mature, suggesting that spinosad prevented small
larvae from becoming larger and more damaging. Typically, spray rates for
standard insecticides average about 2 to 3 gallons per acre.
The Texas study was conducted through a trust fund cooperative agreement
between ARS and the makers of spinosad, Dow AgroSciences LLC, of
Indianapolis, Ind. Just as important, these studies established that
spinosad is nontoxic to beneficial insects like lady beetles and pirate
bugs. More beneficial insects were found on cotton treated with spinosad,
but fewer of them survived on cotton treated with standard insecticides.
ARS is the chief research agency for the U.S. Department of Agriculture.
(posted without permission)
