Banker Plant Efficacy to Boost Natural Predators for Management of Field Populations of Scirtothrips dorsalis Hood (Thysanoptera Thripidae) in Strawberries

Abstract

Since 2015, Scirtothrips dorsalis Hood has emerged as the main pest of strawberries in Florida. Given the limited management options, there is a recognized need to expand on the management strategies for this pest. Therefore, we explored the possibility of using banker plants to recruit naturally occurring predators of thrips into strawberry fields to suppress S. dorsalis. The study began in the 2021-2022 strawberry season where five banker plants were screened to determine which ones could consistently attract thrips predators by flowering throughout the strawberry season. Capsicum annum L. (ornamental pepper) and Lobularia maritima L. (sweet alyssum) were selected for further evaluation. In the 2022-2023 strawberry season, using a randomized complete block design we assessed the capability of these banker plants to attract thrips predators into the strawberry field. In addition, we examined how the banker plant distance from the strawberry plants influenced the S. dorsalis pest suppression. Our results showed that strawberries located within 3.7 m of ornamental pepper plants had less leaf damage from S. dorsalis compared with those farther away, which may result from the repellent effect of the ornamental peppers. Additionally, Geocoris spp. and Orius spp. were identified as the main thrips predators in the system, although in relatively low numbers. Therefore, these results highlight the potential of incorporating ornamental pepper as a banker plant in strawberry production. Additional applications of this research are explored below.

Keywords: Fragaria x ananassa; biological control; flowering plants; integrated pest management; thrips.

Figure 1

Field experimental design of the 2021–2022 banker plant screening study.

Figure 2

Field experimental design of the 2022–2023 banker plant evaluation study.

Figure 3

The damage ratings of plants located closer to or farther away from the banker plants. Damage ratings that differ significantly based on linear contrasts (Tukey p < 0.05) are indicated by different letters on the bars. A score of 1 represents less than 10% bronzing and reddening of leaf veins and petioles, a score of 2 corresponds to 20–39% damage, a score of 3 to 40–50% damage, and a score of 4 to 60–70% damage. Damage exceeding 80% is assigned the highest score of 5.

Figure 4

Total fruit count of strawberry plants in plots closer to and farther away from banker plant strips. Fruit counts that differ based on linear contrasts (Tukey p < 0.05) are differentiated by different letters on bars.

Figure 5

The number of S. dorsalis predators captured on yellow sticky cards placed in the banker plants and strawberry plots during the 2021–2022 strawberry season. Comparisons were made within each treatment. The number of predators showing significant differences based on linear contrasts (Tukey p < 0.05) are indicated by different letters on the bars.

Figure 6

Number of S. dorsalis found on strawberry leaves in plots adjacent to all treatments in the 2022–2023 strawberry season. Contrasts that differ significantly (Tukey p < 0.05) are indicated by different letters on bars.

Figure 7

Strawberry leaf damage ratings among treatments at each distance from the banker plants. Bars with different letters indicate significant differences (Tukey p < 0.05) within each panel. A score of 1 indicates less than 10% bronzing and reddening of veins and petioles, 2 corresponds to 20–39% damage, 3 to 40–50%, 4 to 60–70%, and 5 represents over 80% damage.

Figure 8

Average marketable yield of strawberries (g) per treatment during the 2022–2023 season. Marketable yield estimates (g) that show significant differences (Tukey p < 0.05) are indicated by different letters on the bars.