SUPPRESSION OF TARNISHED PLANT BUGS (HETEROPTERA: MIRIDAE) IN COTTON BY CONTROL OF EARLY SEASON WILD HOST PLANTS WITH HERBICIDES

Authors: Snodgrass, Gordon; SCOTT, WILLIAM - USDA RETIRED; Abel, Craig; ROBBINS, JAMES - MISS STATE UNI.; Gore, Jeffrey; HARDEE, DICK - USDA RETIRED

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/27/2005
Publication Date: 6/1/2005
Citation: Snodgrass, G.L., Scott, W.P., Abel, C.A., Robbins, J.T., Gore, J., Hardee, D.D. 2005. Suppression of tarnished plant bugs (heteroptera: miridae) in cotton by control of early season wild host plants with herbicides. Environmental Entomology. 35:1417-1422. 2006

Interpretive Summary: The tarnished plant bug has become the most damaging pest of cotton grown in the Mississippi River Delta of AR, LA, and MS. Its elevation in pest status was caused by reduced insecticide use due to the widespread adoption of transgenic cotton for effective control of lepidopterous pests of cotton, and eradication of boll weevils from most areas in the mid-South. Plant bugs are controlled in cotton exclusively with insecticides. In the Delta there is widespread resistance to pyrethroid insecticides along with varying levels of tolerance to most of the organophosphate and carbamate insecticides recommended for control of plant bugs in cotton. High populations are difficult to control and require multiple insecticide applications. Non-insecticidal control measures are needed to help manage plant bugs and reduce their damage and control costs. In the current study, a non-insecticidal control method for plant bugs was evaluated over a period of three years. A single herbicide application which controlled broadleaf wild host plants was made in March or April in marginal areas near fields, ditches, and roads in nine-square-mile areas of the Delta. Control of the broadleaf weeds was found to prevent population buildups of plant bugs in the marginal areas. Cotton grown in the treated areas was found to have 45.5 and 47.5% fewer numbers of plant bug nymphs and adults, respectively, than were found in cotton grown in untreated areas during June and July over the three years of the study. The average net savings in plant bug control costs was $35,477 for growers in the treated areas during the three years of the study. Suppression of plant bugs in cotton by control of their early season wild hosts was found to be an effective method of reducing plant bug numbers and control costs in cotton.

Technical Abstract: Broadleaf weeds found in marginal areas by fields, roads, and ditches were controlled with the herbicides Trimec7 or Strike 3TM in 23 km2 areas of the Mississippi Delta in March or April of 1999, 2000, and 2001. These weeds can serve as early season food and reproductive hosts for tarnished plant bugs, and population buildups can occur on these weeds prior to movement of plant bugs into cotton. Cotton fields in the treated sites and in untreated 23 km2 sites were sampled for tarnished plant bugs weekly during June and July of all three years. Overall mean numbers of tarnished plant bug adults and nymphs were significantly lower in cotton in the treated areas. The average reductions in overall mean numbers of plant bugs were 45.5 and 47% for adults and nymphs, respectively, for the three-year period. Grower costs for insecticides used to control plant bugs were lower in cotton in the treated test sites in all three years. The average net savings in plant bug control costs was estimated at $35,477 per year for growers in the treated areas over the three years of the study. Elimination of broadleaf weeds was found to be an effective method for reducing numbers of plant bugs in cotton. However, it did not reduce numbers of tarnished plant bugs in any year to a level in cotton where additional control with insecticides was not needed. KEY WORDS tarnished plant bug, Lygus lineolaris, cotton, early season wild host plant