Efficacy of HOOK SWD Attract-and-Kill SPLAT for Management of Spotted-Wing Drosophila in Georgia Rabbiteye Blueberry, 2018

The objective of this trial was to determine efficacy of SPLAT (Specialized Pheromone and Lure Application Technology) HOOK SWD against spotted-wing drosophila (SWD), Drosophila suzukii in rabbiteye blueberries. This trial was conducted at a commercial blueberry farm in Pierce County. Treatments were arranged in a randomized complete block design with each treatment replicated 4 times for a total of 12 plots (2 acres per replicate). Treatments included: 1) grower commercial standard insecticide application (grower standard); 2) grower standard + HOOK SWD applied at 7-d intervals; and 3) grower standard + HOOK SWD applied at 14-d intervals. Grower standard did not receive any SPLAT application beside two applications of zeta-cypermethrin (Mustang Maxx 8EC) made by air blast sprayer. HOOK SWD was distributed according to manufacturers’ recommended rate with modifications. Briefly, HOOK SWD was applied as strips at the base of blueberry canes and on lower foliage were possible. Application was made on every other blueberry bush on the east side of every row using a 4-gal backpack sprayer equipped with a brass adjustable cone nozzle. Every plot was maintained using the standard commercial practice used for blueberry production in South Georgia.

One Scentry lure SWD trap (Great Lakes IPM, INC.) was hung in the center of each plot within a bush in each treatment replicate (n = 12 traps) to sample flies. Traps were deployed 7 d before first SPLAT treatment for a pretreatment assessment and then weekly after SPLAT application for a period of 4 wk (May 31–June 27). Fruit infestation was monitored by sampling immature SWD (larva and pupa) in ripe blueberries. A total of three 8.0-oz cups of blueberries were hand-picked 7 d before SPLAT application (May 31) and then weekly thereafter (June 7, June 14, June 21, and June 27). Same quantity of fruits was also harvested from the edges to determine edge effect. Fruit samples were incubated 6–7 d under controlled environment (24°C, RH 65%). Fruits were crushed, and salt extraction method was used to sample SWD larvae and pupae in the fruit. Total fly capture data were Log10 transformed and then analyzed by ANOVA using JMP Pro 13, but actual mean numbers were presented in the table. Where significant, means were separated by Tukey–Kramer HSD (P < 0.05). Fruit infestation was summarized as immatures and presented in the table.

The results show that there was no significant difference in the number of flies captured from traps between grower standard and SPLAT HOOK SWD treatments applied at 7- or 14-d intervals earlier in the season for sample dates May 31, June 7, June 14, and June 21 (Table 1). However, later in the season on June 27 significantly fewer flies were captured in traps from HOOK SWD applied 7-d interval treatment compared with grower standard treatment (Table 1). Generally, there was low fruit infestation in the field and only a small number of immature SWD were detected in the fruit samples collected from grower standard and grower standard + HOOK SWD applied at 14-d interval treatments. However, zero immature SWD were detected in fruit samples collected from grower standard + HOOK SWD applied at 7-d interval treatment throughout the season (Table 2). There was no observable phytotoxicity effects on foliage throughout the period of the trial.

We thank IR-4 Program for providing funding and ISCA Technologies, Inc. for donating the HOOK SWD product.