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United States Department of Agriculture

Agricultural Research Service

Title: Using genetic markers and population assignment techniques to infer origin of boll weevils (Coleoptera: Curculionidae) unexpectedly captured near an eradication zone in Mexico

Authors
item Kim, Kyung
item Cano-Rios, Pedro - INIFAP, MEXICO
item Sappington, Thomas

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 6, 2006
Publication Date: August 1, 2006
Citation: Kim, K.S., Cano-Rios, P., Sappington, T.W. 2006. Using genetic markers and population assignment techniques to infer origin of boll weevils (Coleoptera: Curculionidae) unexpectedly captured near an eradication zone in Mexico. Environmental Entomology. 35:813-826.

Interpretive Summary: The boll weevil is an insect pest of cotton, which originally invaded the U.S. from Mexico a little over a century ago. Tremendous effort and resources are being invested in eradicating the weevil from the U.S. and northern Mexico, and the threat of weevils re-entering an eradication zone is of great concern. Several boll weevils were captured in 2004 in an eradication zone near Tlahualilo, Durango, Mexico, an area where boll weevils had not been captured for about 10 years. To identify the most likely origin of individual boll weevils captured in this area, we used a molecular technique called "microsatellite analysis" to study variation in DNA from weevils collected in four other populations from northern Mexico and a population from southern Texas. Our results suggest that the boll weevils captured in the eradication zone near Tlahualilo were already present, but at a low level that was not detectable in previous years, but that this area also is receiving migrants from a cotton growing region approximately 200 km to the north, near Rosales, Chihuahua. The results will guide decisions by U.S. and Mexican eradication personnel regarding how best to eliminate the boll weevils from this area, where they had not expected to find any. In addition, this study demonstrates that the use of microsatellites and population assignment techniques will be of value in determining the most likely origins of boll weevils reintroduced to eradication zones in the U.S. and Mexico.

Technical Abstract: Several boll weevils were captured in pheromone traps in 2004 in an eradication zone near Tlahualilo, Durango, Mexico, an area where boll weevils had not been captured for about 10 years. It is possible that the boll weevils were from an endemic population normally too low in numbers to be detected, or that they represented an influx of migrants or their descendents. To identify the most likely origin of individual boll weevils captured in this area, we characterized microsatellite variation in boll weevils sampled in four other populations from northern Mexico and a population from southern Texas. Both indirect measures of gene flow and individual assignment tests were employed to evaluate interpopulation movement. Analyses suggest that the boll weevils captured in the eradication zone near Tlahualilo were primarily from an endemic low-level population, but that this area also is receiving immigrants from a cotton growing region approximately 200 km to the north, near Rosales, Chihuahua. This study demonstrates that the use of microsatellites and population assignment techniques will be of value in determining the most likely origins of boll weevils reintroduced to eradication zones in the U.S. and Mexico. Population assignment strategies based on genetic markers hold promise for replacing conventional, but inherently difficult and limited, mark-recapture studies of insect dispersal.

Last Modified: 11/22/2014