Systemic activity of neonicotinoids on Drosophila suzukii in blueberry

The ovicidal and adulticidal activity of selected neonicotinoids (IRAC 4A) toward Drosophila suzukii (Matsumara 1931) were determined through field and laboratory bioassays.  Adulticide effects were low; Potter spray tower trials to determine adulticide LC₅₀ values showed a high resistance to all neonicotinoids.  However when blueberries were treated to simulate a natural environment, eggs laid in berries treated with dinotefuran and acetamiprid were less likely to hatch.  This is due to translaminar migration of the products through the exocarp, corroborated by the higher solubility of those two products compared with imidacloprid and thiamethoxam.  Further trials were designed to evaluate the translaminar and systemic effects.  Blueberries were dipped in field rates of four neonicotinoids, Actara 25WG, Assail 30SG, Provado 1.6F, and Scorpion 35SL, and air dried.  Replicates consisting of a single adult and a berry were placed into 2 oz cup arenas, every day for six days (six different aged residues).  Eggs had been counted in fruit with and without any larvae present.  Deteriorated flesh indicated larval infestation while uninfested flesh remained firm and green.  Berries treated with Scorpion were found to have much lower infestation rates than the other treatments or controls.  Adulticidal effects were low for all treatments.  Because of these results, a field trial was designed to determine efficacy of neonicotinoids as a preventative systemic control and demonstrate a method of application to blueberry crops.  Low-pressure drip line irrigation was connected to a commercial sprayer and used to chemigate blueberry plots.  At this time the trial is in progress.