ARS | Publication request: SEASONAL CHANGES IN PYRETHROID RESISTANCE IN TARNISHED PLANT BUG POPULATIONS OVER A TWO-YEAR PERIOD IN THE MISSISSIPPI RIVER DELTA

Submitted to: Mississippi Insect Control Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: November 11, 1996
Publication Date: N/A

Technical Abstract: Pyrethroid resistance in populations of the tarnished plant bug found in the Mississippi River Delta of Arkansas, Louisiana, and Mississippi was monitored by exposing at least 50 adults per test population to a discriminating dose of 15 ug of permethrin. Plant bugs were collected at the same locations (in most cases) in the spring and fall of 1995 and 1996, and a total of 71 or 72 collection locations were used. In the spring of 1995, 42% of the plant bug populations tested were susceptible (>90% mortality) as compared to 45% in the spring of 1996. In the fall of 1995, 15% of the test populations were susceptible as compared to only 10% in the fall of 1996. Only one plant bug population was found during the spring of each year that was highly resistant (<30% mortality) to permethrin. During the fall of 1995 and 1996, 18 and 18.3%, respectively, of the plant bug populations tested with permethrin were highly resistant. These results showed that pyrethroid resistance was widespread in plant bug populations in both years in the Delta, with the highest levels of resistance occurring in the fall after the cotton growing season. Plant bugs in the Delta produce three to four generations on weeds during September-October and in April-May of the following year. As shown in this study, the production of these generations away from cotton (and the selection pressure that pyrethroid use in cotton exerts on plant bug populations) allowed resistance in them to decline. However, pyrethroids should not be used in cotton for plant bug control in May and June, since over half of the plant bug populations tested in the spring of both years had pyrethroid resistance.