The effect of border sprays and between‐row soil tillage on Drosophila suzukii in organic blackberry production

Abstract

Drosophila suzukii (Matsumura) is a major pest of soft‐skinned fruit. Females have an enlarged serrated ovipositor that is used to cut into ripening fruit and lay their eggs. Larvae develop inside infested fruit, rendering fruit unmarketable. Previous research has indicated that D. suzukii can move from adjacent woodlands into cultivated fields. Furthermore, multiple generations can occur in a single season as a result of fallen, infested fruit in the fields. Our hypothesis was that border sprays and soil tillage of field aisles can reduce D. suzukii presence in commercial blackberry fields (Rubus spp.). To test our hypothesis, we conducted split‐plot field trials in organic blackberry fields for 3 and 4 weeks in 2014 and 2015, respectively. Treatments were border sprays (whole plot, pyrethrins + azadirachtin) and tillage (subplot, ~15 cm). We evaluated adult D. suzukii in both years and berry infestation and natural enemies in 2015 only. We found that plots with border treatments had fewer D. suzukii (larvae and adults) than plots without border sprays. Tilling the soil between rows of blackberry bushes did not have a significant effect on adult captures or larval infestation of fruit. Natural enemies were unaffected by the border spray and tillage treatments. Our results confirmed our hypothesis that border sprays can be utilized to reduce populations of D. suzukii in organic blackberry fields, while maintaining populations of natural enemies. However, the effect of soil tillage is unclear and requires further investigation. Additional research should investigate the timing of border sprays and their effect on high infestations of D. suzukii as well as quantify fruit fall and depth of burial to reduce D. suzukii emergence using soil tillage.

Phenotypic Plasticity Promotes Overwintering Survival in A Globally Invasive Crop Pest, Drosophila suzukii

“…Similar migration could occur in D. suzukii allowing it to avoid the most extreme low temperatures in a given area. Indeed, there is evidence that D. suzukii moves between crop land and adjacent wooded areas during peak field season [ 71 , 72 , 73 , 74 , 75 ]. Similarly, there is reason to believe that these insects may overwinter in habitats such as leaf litter [ 20 , 25 , 76 ], which provides thermal insulation and keeps ground temperatures within a few degrees of freezing throughout the winter [ 59 , 77 , 78 ].…”

Spotted wing drosophila (Drosophila suzukii) utilization and dispersal from the wild host Asian bush honeysuckle (Lonicera spp.)

“…Using cultural control techniques on farms in combination with chemical control represents a realistic way of reducing the expansive population pressure on a local scale (Prokopy & Kogan, ). Increasingly, research and management techniques for this pest are focused in this direction (Iglesias & Liburd, ; Leach et al ., ; Wallingford et al ., ) with recognition that successful control of this pest will require use of diverse approaches (Asplen et al ., ).…”

Infestation and timing of use of non-crop plants by Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) in the Okanagan Basin, Canada

“…If trap counts reflect host plant use, then the abundance and proximity of non-crop plants will be important in managing D. suzukii. Knowledge of the use of hosts by D. suzukii will aid in realistic consideration or dismissal of management strategies such as vegetation reduction or "sanitation", extra-crop or peripheral treatment (Iglesias and Liburd 2017;Klick et al 2016), mass-trapping or sterile insect technique, proposed by some authors (e.g., Cini et al 2012;Haye et al 2016).…”