Investigation of an algae-derived polymer as a pollinator-friendly pesticide adjuvant

Chemical applications in croplands can be a major source of pesticide exposure to pollinators, including off-target drift. Adjuvants are added to pesticides to improve spray characteristics. The major goal of this study was to identify the possibility of using sodium alginate (SA) as a drift-reducing pesticide adjuvant that is less/nontoxic to honeybees than polyacrylamide (PAM) an industry standard. The toxicity bioassay experiments were carried out with six- to eight-day-old, caged honeybee workers. Each cage contained 20 honeybees. Caged bees were treated with adjuvant, insecticide, adjuvant + insecticide, and a water only as a control, using a modified Potter Spray Tower. The insecticides imidacloprid and bifenthrin were used at three different concentrations (LC₂₅, LC₅₀, and LC₇₅). Two different concentrations of the adjuvants SA and PAM were tested. The 48-hour mortality results were recorded. Our results indicate noticeable reductions in bee killing when SA is used as an insecticide adjuvant instead of PAM.