Evaluation of pyrethroids and organophosphates in insecticide mixtures for management of western corn rootworm larvae

Abstract

BACKGROUND: The western corn rootworm is an economically important pest of corn. Management tactics include pyrethroid and organophosphate insecticides, which may be applied as a mixture to protect corn roots. The goal of our study was to characterize the effects of pyrethroids and organophosphates alone and in combination on larval corn rootworm mortality and injury to corn roots. We evaluated two insecticide combinations: tebupirimphos with ⊎-cyfluthrin and chlorethoxyfos with bifenthrin. Using a soil-based, laboratory bioassay, we exposed larvae to five concentrations of the pyrethroid alone, the organophosphate alone, the combined formulation, and a water control. We calculated LC 50 values and co-toxicity factors to determine synergism or antagonism between organophosphates and pyrethroids. We also measured adult emergence and root injury in a field experiment that tested tebupirimphos alone, ⊎-cyfluthrin alone, the combined formulation, and an untreated control. RESULTS: Bioassay results indicated antagonism between the pyrethroid and organophosphate at most concentrations for both insecticide combinations. In the field experiment, tebupirimphos alone or in combination with ⊎-cyfluthrin significantly reduced adult emergence and root injury compared to the untreated controls, but ⊎-cyfluthrin alone did not differ from the untreated control for either metric. CONCLUSIONS: These results suggest that, at the concentrations tested, the pyrethroid component of pyrethroid-organophosphate mixtures may not contribute to a reduction of rootworm emergence or root injury. While these pyrethroids may confer a management benefit for other pests, such as seedcorn maggot, the concentrations of pyrethroids present in current formulations of these mixtures are likely too low for effective rootworm management.

Can Organophosphates and Carbamates Cause Synergisms by Inhibiting Esterases Responsible for Biotransformation of Pyrethroids?

“…There were, however, no insecticide mixtures in the database with MDR values <0.5. Hence, insecticide mixtures including esterase-inhibiting insecticides can cause synergy, but additivity seems to be just as frequent, while severe antagony seems to be rare, though occurring. ,,,,, …”

The roles of the biochemical and molecular changes in resistance of Tetranychus urticae populations selected with spiromesifen+abamectin mixture </p >

“…Rex Consortium (2013) reported that combining molecules usually outcompete other resistance management strategies, such as responsive alternation, periodic application, or mosaic, because it ensures ‘multiple intragenerational killing’. Mixed formulations are used to control species that cause economic damage in agricultural areas and vector insects such as Aedes aegypti (Pennetier et al 2008; Ngufor et al 2016; Barros et al 2019; St. Clair et al 2020; Alsay & Ay 2022).…”

Myricetin Inhibits Photodegradation of Profenofos in Water: Pathways and Mechanisms

“…Profenofos is an organophosphorus insecticide and is used to control pests on vegetables, fruits, and grain crops [1][2][3][4]. However, only a small fraction of profenofos can be absorbed by pests, while most of the rest drifts to the environment and is often detected in agricultural water.…”