No Mistaking this Bug with New Insect ID
Technique By Jan
Suszkiw September 9, 2009
Misidentifying boll weevils caught in pheromone traps could be easier
to avoid, thanks to a new DNA fingerprinting method devised by
Agricultural Research Service (ARS)
scientists and their collaborators.
Boll weevils-long-snouted, 2/10-inch-long beetles that damage cotton's
lint-producing bolls-are familiar foes to growers. Indeed, since first being
discovered in southern Texas in 1892, the boll weevil, Anthonomus
grandis, has caused billions of dollars in losses to U.S. cotton. An
eradication program that began in 1978 has eliminated the pest from 87 percent
of the 15 million acres of American cotton.
Trapping, aided by the use of chemical insect attractants called
pheromones, is a key component of the program that can tell where, when, and to
what degree boll weevils are present, including those re-invading zones
previously cleared of the pest. Field scouts checking pheromone traps sometimes
encounter other weevil species, or pieces of trapped weevils that have been
partially eaten by insect predators like ants, raising the risk of
misidentification. That, in turn, can lead to unnecessary and costly
insecticide spraying, according to entomologist
Sappington, in the ARS
Insects and Crop Genetics Research Unit at Ames, Iowa.
Capitalizing on findings from earlier population genetics studies of
the boll weevil, Sappington and colleagues devised a method that uses
microsatellite molecular markers to distinguish between the boll weevil and
other related species, including pepper, cranberry and pecan weevils.
This characteristic DNA fingerprint, observed on a standard
electrophoretic gel, appear as three separate bands, forming a unique
barcode-like arrangement of DNA that's specific to boll weevils. These bands
are of a specific size and are not shown by non-target weevil species. In
tests, the method also identified boll weevils from partial remains, including
legs and wings, and yielded results in two days.
Sappington coauthored a paper describing the method in the Journal of Economic
Entomology, along with colleagues from
Rutgers University in Chatsworth, N.J.,
Oklahoma State University at
Stillwater and the Seoul National
University in South Korea.
ARS is the principal intramural scientific research agency of the
U.S. Department of