Assessing the Efficacy of Sodium Alginate and Polyacrylamide as Spray Adjuvants Combined with Bifenthrin and Imidacloprid against Lygus lineolaris and Piezodorus guildinii

Abstract

The tarnished plant bug, Lygus lineolaris, and the red-banded stink bug, Piezodorus guildinii, pose significant economic threats to cotton and soybean crops in the mid-southern USA. However, the efficacy of insecticide spraying is comparatively low, and adjuvants play a crucial role in optimizing insecticide performance. This study evaluated the impact of two adjuvants, sodium alginate (SA) and polyacrylamide (PAM), on enhancing the efficacy of bifenthrin and imidacloprid via laboratory spray bioassays. Both SA and PAM demonstrated insignificant variation in LC50 values with formulated bifenthrin and imidacloprid. However, SA and PAM exhibited synergistic effects with two technical-grade insecticides. High concentrations of PAM increased the efficacy of bifenthrin by 1.50- and 1.70-fold for L. lineolaris and P. guildinii, respectively. Conversely, no enhancement effect was observed for the SA–technical-grade bifenthrin combination against either insect pests. Additionally, both SA and PAM enhanced the effectiveness of imidacloprid in P. guildinii by up to 2.68- and 2.73-fold, respectively. While a high concentration of PAM had a 1.45-fold synergistic effect on technical-grade imidacloprid, no enhancement effect was observed for the SA/imidacloprid combination in L. lineolaris. This study explored the synergistic impact of SA and PAM on the efficacy of technical-grade and formulated bifenthrin and imidacloprid, providing valuable insights into optimizing pest control strategies in agriculture.