Non-target effects of three insecticides on the natural enemy community of grain sorghum and secondary pest outbreaks

Monday, November 14, 2022

9:24 AM – 9:36 AM PT

Location: Vancouver Convention Centre, Meeting Room 208/209

Presenting Author(s)

Danielle Gray

Graduate Assistant Researcher
Texas A&M University
College Station, Texas

Co-Author(s)

DL

Dalton Ludwick

Texas A&M AgriLife Extension
Corpus Christi, Texas
TT

Tyler Towles

Louisiana State University
Winnsboro, Louisiana
SB

Stephen Biles

Texas A&M AgriLife Extension
Port Lavaca, Texas
KC

Kate Crumley

Texas A&M AgriLife Extension
Wharton, Texas
TM

Tyler Mays

Texas A&M AgriLife Extension
Brownfield, Texas
David L. Kerns

Texas A&M University
College Station, Texas

Pyrethroid-based insecticides are among the most widely used control tactics for rice stink bug in grain sorghum in the Coastal Bend of Texas. In a 2021 study, we documented pyrethroid resistance in rice stink bug, Oebalus pugnax, in populations collected from the Coastal Bend using a glass vial bioassay with residues of a pyrethroid, lambda-cyhalothrin. To evaluate the efficacy of other insecticides which could serve as alternative control measures, we conducted field experiments in grain sorghum plots across the region with three commercial insecticides from different classes during the summer of 2022. The insecticides we evaluated were Warrior II (pyrethroid), Dimethoate 400 (organophosphate), and Tenchu (neonicotinoid). Dimethoate 400, which is not labeled for use on stink bugs, and Tenchu, which is not labeled for use in sorghum, are known to be broad-spectrum and disruptive to beneficial insects that can aid substantially in pest management. Currently, research is limited on the non-target effects of these insecticides on natural enemies in grain sorghum or the risk of secondary pest outbreaks. Understanding the non-target effects of these pesticides in a grain sorghum system before recommending them is essential to developing a successful integrated pest management program. To accomplish this, we collected data on the natural enemy community composition of sorghum aphid, Melanaphis sorghi, an important pest of grain sorghum in this region, as well as the pest itself. We conducted surveys to collect data on natural enemies and sorghum aphid populations before and after insecticide treatments.