Acephate Resistance in Populations of the Tarnished Plant Bug (Heteroptera: Miridae) From the Mississippi River Delta

Abstract

A monitoring program that used a glass-vial bioassay to detect acephate resistance in populations of the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois) (Heteroptera: Miridae), was carried out with weed-collected populations from 20 sites in the delta of Arkansas, Louisiana, and Mississippi. Additional results from field tests using recommended rates of formulated acephate in cotton showed that plant bug populations with resistance ratio (RR50) values > 3.0 for acephate (from the glass-vial bioassay) would be difficult to control in the field. Over a 4-yr-period from 2001 through 2004, only one population tested with the glass-vial bioassay was found with an RR50 value > 3.0 for acephate, but six populations having RR50 values > 3.0 were found in the delta in 2005. In fall 2005, an additional 10 populations from the hill region (the cotton growing areas outside the delta) were tested and four of these populations had RR50 values > 3.0. The number of populations with RR50 values > 3.0 increased to five of 10 and 18 of 20 in the hills and delta, respectively, in fall 2006. Laboratory tests using resistant populations found that resistance to acephate was not sex-linked and the alleles controlling the resistance were semidominant in nature. Because of the large increase in resistant populations and the nature of the resistance found in this study, along with control problems experienced by growers in 2006, entomologists in the mid-South strongly recommended that alternation of insecticide classes in field treatments for plant bug control be used by growers in 2007. This control strategy probably helped control plant bugs in the hills of MS where plant bug pressure was low in 2007, and only one population was found in the fall with an RR50 value > 3.0. Plant bug pressure was very high in many parts of the delta in 2007, and 15 of the 20 populations tested in the fall had RR50 values > 3.0. In one field test in cotton, a population with multiple resistance was tested and not effectively controlled in treatments using recommended rates of carbamate, organophosphate, and pyrethroid insecticides. Alternation of insecticide classes may not work very well when populations are present that are resistant to three of the four main classes of cotton insecticides. New insecticides in different classes are badly needed for control of tarnished plant bugs in cotton in the mid-South.

Development of a Plant-Based Threshold for Tarnished Plant Bug (Hemiptera: Miridae) in Cotton

“…Resistance to this class was Þrst documented in 1995 (Snodgrass 1996) and was widespread in the mid-South by 1999 (Snodgrass andScott 1999, Snodgrass andScott 2000). Similarly, resistance to the organophosphate insecticide class, speciÞcally acephate, was Þrst documented in 2001 (Snodgrass and Scott 2002) and was widespread by 2008 (Snodgrass et al 2009). As would be expected, resistance to acephate confers resistance to other organophosphates and carbamates currently labeled in cotton for most tarnished plant bug populations (Snodgrass et al 2009).…”

“…Similarly, resistance to the organophosphate insecticide class, speciÞcally acephate, was Þrst documented in 2001 (Snodgrass and Scott 2002) and was widespread by 2008 (Snodgrass et al 2009). As would be expected, resistance to acephate confers resistance to other organophosphates and carbamates currently labeled in cotton for most tarnished plant bug populations (Snodgrass et al 2009). As a result, tarnished plant bugs have become difÞcult to manage with the few classes of insecticides currently labeled for their management in cotton.…”

Tarnished Plant Bug (Hemiptera: Miridae) Thresholds for Cotton Before Bloom in the Midsouth of the United States

“…A reduction in tillage has occurred with the widespread adoption of glyphosate-tolerant cotton varieties. Another change is the continuing development of insecticide resistance among tarnished plant bug populations in the Midsouth (Snodgrass 1996, Snodgrass and Scott 2002, Snodgrass and Gore 2007. All these changes alter the environment in which plant bugs feed, and therefore, potentially change the economic injury level (EIL) for this pest.…”

Impact of Planting Date and Varietal Maturity on Tarnished Plant Bug (Hemiptera: Miridae) in Cotton

“…Resistance to the pyrethroid class of insecticides was Þrst documented in Þeld populations of tarnished plant bug in Mississippi in 1992 (Snodgrass 1996). Snodgrass et al (2009) also documented resistance to acephate in Þeld populations of tarnished plant bug in Mississippi. Because of the increased input costs, an integrated approach that incorporates insecticides with other control methods is needed for sustainable management of tarnished plant bugs in the Mississippi Delta.…”