Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/3/2002
Publication Date: 6/1/2002
Citation: Interpretive Summary: The tarnished plant bug is a serious pest of cotton grown in the Mid- South. It is controlled in cotton exclusively with insecticides and populations with high levels of resistance to pyrethroid insecticides can be found throughout the Mississippi River Delta in Arkansas, Louisiana, and Mississippi. Fortunately, plant bug populations with high levels of insecticide resistance are still susceptible to acephate (Orthene) an organophosphorus insecticide. The effectiveness of acephate against resistant plant bugs has made it a very important and widely used insecticide for plant bug control in cotton. Because of this importance, resistance to acephate in plant bugs was monitored using a glass-vial bioassay in 1998-2000 at twenty locations in the Delta. The highest resistance found was 4.6-fold (as compared to susceptible plant bugs), and at most locations resistance was only 2-fold or less in all three years. These resistance levels will make acephate less effective than it originally was but are not high enough to result in control failures in the field. Acephate should still be an effective insecticide for control of tarnished plant bugs in cotton in the Delta.
Technical Abstract: Tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois), were collected from weeds in the fall of 1998, 1999, and 2000 at twenty locations in the Mississippi River Delta of Arkansas, Louisiana, and Mississippi and tested with a glass-vial bioassay for tolerance to acephate. The same twenty collection locations were used each of the three years. Plant bug populations with high levels of resistance to acephate were not found. The highest resistance found was 4.6-fold, and, at most locations in all three years, resistance was 2-fold or less. The overall trend from 1998 to 2000 was for slowly increasing tolerance to acephate. Tarnished plant bug populations at 18 to 20 test locations in 2000 had higher tolerance than was found in populations tested from the locations in 1998. However, the increase in tolerance was significant in plant bugs from only 7 of the 18 test locations. Acephate should still be an effective insecticide for control of tarnished plant bugs in cotton in the Mississippi River Delta.