Curative Activity of Neonicotinoids on Spotted Wing Drosophila (Drosophila suzukii Mats.) in Blueberry

Adulticidal and ovicidal activity of selected neonicotinoids (IRAC 4A) toward Drosophila suzukii (Mats.) were determined through field and laboratory bioassays.  Low and high rates of Provado 1.6F and Scorpion 35SL were applied to blueberries using a Potter spray tower.  Females were allowed to oviposit, total eggs counted, and fruit checked for larvae after five days. Adulticidal effects were low; however berries treated with Scorpion exhibited fewer eggs and larvae than controls.  Separately, efficacies of field-aged residues were determined by sampling highbush ‘Elliot' blueberries treated with Provado and Scorpion.  Two adult male and female pairs were isolated with each berry and allowed to oviposit for 72 hours.  Eggs were counted and percent hatch calculated after three weeks.  Percent hatch was lower than untreated fruit 3 and 5 days after treatment.  To further investigate, sixty blueberries were dipped in field rates of four neonicotinoids, Actara 25WG, Assail 30SG, Provado 1.6F, and Scorpion 35SL, and air dried.  For six days at 24 hour intervals, ten replicates consisting of a single adult and a berry were placed into 2 oz cup arenas, representing six different aged residues.  After two weeks, Scorpion treated berries were found to have much lower infestation rates than the other treatments or controls.  Adulticidal effects were low for all treatments.  Eggs were observed inserted beneath the epicarp in uninfested and infested berries.  Deteriorated, discolored flesh was indicative of larval infestation while uninfested flesh remained firm and green.  Future investigations will involve ovicidal effects and efficacy of early season pyrethroid-neonicotinoid mixes.