Dual purpose: Predatory hoverflies pollinate strawberry crops and protect them against the strawberry aphid, Chaetospihon fragaefolii

Abstract

BACKGROUND: Predatory syrphids are an important functional group due to their potential for providing multiple ecosystem services. Adults feed on nectar and pollen, and can be effective pollinators, while larvae are voracious predators that can reduce aphid pressure. Still, little research has addressed their potential dual function in agroecosystems. In this study, we assessed the potential of two predatory hoverflies, Eupeodes corollae and Sphaerophoria rueppellii, for delivering concurrent pollination and biological control of Chaetospihon fragaefolii in greenhouse strawberries.RESULTS: Both hoverfly species effectively pollinated strawberry flowers of two different varieties ('Elsanta' and 'Sonsation'), resulting in an increase in high-quality marketable fruits, a reduction of fruit deformities, and higher number of seeds per fruit compared to pollinator-excluded fruits. S. ruepellii had a significantly longer flower handling time than E. corollae, which translated to a more efficient pollination expressed as higher seed numbers per fruit after a single flower visit. By contrast, flowers that were open to multiple visits were more effectively pollinated by E. corollae, suggesting that E. corollae is potentially a better cross-pollinator than S. rueppellii. In addition, both hoverfly species suppressed aphid populations in strawberry (var. 'Sonata'), with S. rueppellii and E. corollae reducing aphid populations by 49% and 62%, respectively. CONCLUSION: Predatory syrphids can concurrently contribute to pollination and biological control in strawberry in a greenhouse setting.

Crop‐pollinating Diptera have diverse diets and habitat needs in both larval and adult stages

“…We found that 61.5% of fly species were recorded living in natural habitats as larvae, with the greatest number of species being detritivores or predators associated with plants, decaying plant and organic materials, and manure/feces. Although pollinating flies with predatory larvae are beneficial in cropping systems in need of biological control services (Dunn et al, 2020;Van Oystaeyen et al, 2022), the morphological features of these flies as adults (e.g., small body size with little to no hairs to trap pollen) may make them less efficient pollinators compared to other taxa (Stavert et al, 2016). In contrast, generalist flies that are detritivores as larvae and nectarivores as adults (such as many species in the families Syrphidae, Calliphoridae, and Muscidae), make effective pollinators.…”

“…Many flies are efficient crop pollinators that are ubiquitous, occur globally, and contribute to multiple ecosystem services in agroecosystems (Dunn et al, 2020;Van Oystaeyen et al, 2022). Some fly species also compliment bee inactivity within cropping systems, as the two taxa generally visit flowers at different times of the day and have different activity patterns based on season (Brittain et al, 2013;Lee & Kang, 2018).…”

Residual behavior and risk assessment of fluopyram, acetamiprid and chlorantraniliprole used individually or in combination on strawberry

“…The indiscriminate, frequent application of pesticides frequently result in pesticide residues in crops exceeding limits, raising the dietary risk to consumers (Balkan and Yılmaz, 2022;Khazaal et al, 2022;Nougadère et al, 2012;Tang et al, 2021;Huang et al, 2021;Mehlhorn et al, 2022). Strawberries in greenhouses due to the high temperature and humidity are particularly vulnerable to pests (Botrytis cinerea, Chaetosiphon fragaefolii, Colletotrichum and Frankliniella occidentalis) and diseases (gray mold and powdery mildew) (Li et al, 2022a;Van Oystaeyen et al, 2022;Wang et al, 2022a;Yan et al, 2021). A survey in Beijing concluded that at least one residue was observed in 26.0% of strawberry samples (Li et al, 2022b).…”

The potential of the hoverfly Allograpta exotica as a biological control agent of the strawberry aphid Chaetosiphon fragaefolii

“…(2020). The literature reports various predators of C. fragaefolii , including anthocorids, primarily species belonging to the genus Orius Wolff; coccinellids, such as Coccinella undecempunctata L., 1758, Propylea quatuordecempunctata (L., 1758), Cycloneda sanguinea (L., 1763), and Eriopis connexa (Germar, 1824); neuropterans, predominantly Chrysoperla carnea (Stephens, 1836) larvae; nabids, including Nabis ferus (L., 1758), N. rugosus (L., 1758), and Himacerus mirmicoides (O.Costa, 1834); and syrphid larvae, represented by Sphaerophoria scripta (L., 1758), Episyrphus balteatus (De Geer, 1776), Eupeodes corollae (Fabricius, 1794), and S. rueppellii (Wiedemann, 1830) (Cross et al., 2001; Easterbrook et al., 2006; Francesena et al., 2019; Kovanci et al., 2007; van Oystaeyen et al., 2022). Francesena et al.…”

“…It is worth noting that no recent reports of parasitism on this aphid species have surfaced in subsequent studies conducted by Milenkovic (1994), Khan and Shah (2017), Cingolani and Greco (2018), Rondon and Cantliffe (2004), or Francesena et al (2020). The literature reports various predators of C. fragaefolii, including anthocorids, primarily species belonging to the genus Orius Wolff; coccinellids, such as Coccinella undecempunctata L., 1758, Propylea quatuordecempunctata (L., 1758) (Cross et al, 2001;Easterbrook et al, 2006;Francesena et al, 2019;Kovanci et al, 2007;van Oystaeyen et al, 2022). Francesena et al (2019) found that the predation rate of C. sanguinea, E. connexa, C. quadrifasciata and O. insidiosus on C. fragaefolii was lower than on A. gossypii, suggesting that the relative abundance of these aphid species could affect the reduction of the C. fragaefolli population in the field when both species are present simultaneously.…”