Evaluation of pyrethroids efficacy against ambrosia beetles using Fuji apple bolts

Pyrethroid based insecticides such as ζ-cypermethrin, (Mustang® Maxx), λ-cyhalothrin (Warrior®II with Zeon® Technology); and two insecticides with dual mode of action; imidacloprid + β-cyfluthrin (Leverage® 360) and ζ -cypermethrin + bifenthrin (Hero®) were applied to Fuji apple (Malus domesticaI) bolts to manage ambrosia beetle attacks in early spring of 2020. Hero®, Mustang®Max, Warrior®II and deltamethrin impregnated netting were tested in container-grown Gala apple and eastern redbud (Cercis canadensis) trees in late spring. Ambrosia beetle attack was induced using 95% ethanol injection in bolts and aqueous ethanol (2.5% ethanol) irrigation to trees. Experiments were set up at the edge of a wooden lot. Apple bolts were removed 7, 14 and 21 d after insecticide application, whereas trees were evaluated at day 3 and 7 and 14 d. None of the insecticides tested had an effective deterrent action against ambrosia beetle attacks to apple (bolts and trees) neither redbud trees.  Pyrethroid-treated netting entirely protected trees from AB attacks.