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Title: Toxicity of selected insecticides and insecticide mixtures in a glass-vial bioassay to southern green stink bug (Hemiptera: Pentatomidae) from central Texas

Author
item LOPEZ, JUAN DE DIOS - Retired ARS Employee
item Latheef, Mohamed - Ab
item Hoffmann, Wesley

Submitted to: Crop Protection Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/25/2013
Publication Date: 12/8/2013
Citation: Lopez, J., Latheef, M.A., Hoffmann, W.C. 2013. Toxicity of selected insecticides and insecticide mixtures in a glass-vial bioassay to southern green stink bug (Hemiptera: Pentatomidae) from central Texas. Crop Protection Journal. 38(4):571-578.

Interpretive Summary: Southern green stinkbugs are a re-emergent pest in many food and fiber crops in the Southern United States requiring significant expenditures by farmers to control these pests. Studies were conducted to assess the toxicity of currently available insecticides and to develop baseline mortality data to monitor resistance of the insect to insecticides. Toxicity studies for selected organophosphate and synthetic pyrethroid insecticides via glass-vial bioassays showed that commercial formulations were less toxic than technical materials and lack synergism when multiple active compounds were present in the formulations. These studies establish baselines of toxicity of a number of compounds used to control adult southern green stinkbug and will be used to monitor resistance in naturally occurring populations.

Technical Abstract: Among the phytophagous pentatomids, the southern green stink bug (SGSB), Nezara viridula (L.) is cosmopolitan in distribution, and feeds on important food and fiber crops. With the introduction of transgenic cultivars and concomitant reduction of pesticide applications against heliothine insects, SGSB has resurged as one of the serious pests in the US Cotton Belt. It induces abscission of bolls, reduces seed cotton yield, gin-turnout and fiber quality. Also, it vectors bacterial and fungal pathogens causing necrosis of the locule and rotting of the bolls. Control options are largely dependent upon and limited to the use of insecticides. Data are needed to assess the toxicity of currently available insecticides and to develop baseline mortality data to monitor resistance of the insect to insecticides in Central Texas. We studied the toxicity of selected organophosphate and synthetic pyrethroid insecticides by glass vial bioassay to adult SGSB captured in blacklight traps in Central Texas. Dicrotophos was 6-fold more toxic to SGSB than acephate. The toxicity of acephate and chlorpyrifos was comparable. The order of toxicity of synthetic pyrethroids to SGSB was '-cyhalothrin >zeta-cypermethrin >'-cyhalothrin >cypermethrin >bifenthrin. Mixtures of technical grade active ingredients were 4- to 7.5-fold more toxic to SGSB compared to commercially-formulated pesticides. The dampened efficacy of the commercial formulations suggests that the mixtures of the technical grade active ingredients failed to potentiate, probably because of lack of additivity or synergism in the composition of active ingredients used in the formulations. The inert and other ingredients used in the formulations may have played a part as well.