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. 2024 Aug 12;117(4):1572-1581.
doi: 10.1093/jee/toae103.

Hover fly (Diptera: Syrphidae) diversity and seasonality in North Georgia apple and peach orchards

Kenneth W McCravy  1   2 , C Scott Clem  1 , Jordan B Bailey  3 , Sabrina A Elgar  1 , Brett R Blaauw  1
Affiliations

Hover fly (Diptera: Syrphidae) diversity and seasonality in North Georgia apple and peach orchards

Kenneth W McCravy et al. J Econ Entomol. .

Abstract

Crop pollination and natural biological control provided by beneficial insects have an economic worth of hundreds of billions of dollars annually. Apple and peach production in North Georgia are economically important industries that benefit from these ecological services. Hover flies are dual ecosystem service providers that have been relatively understudied in orchard ecosystems. We investigated the diversity and seasonal activity of hover flies in apple and peach orchards at 2 sites in North Georgia from March to October 2020 and 2021. Bowl traps were used to sample hover flies in orchard edge and interior habitats. The aphidophagous species Toxomerus geminatus (Say) (Diptera: Syrphidae) and Toxomerus marginatus (Say) (Diptera: Syrphidae) comprised 86.6% of the total hover flies collected. Apple orchards yielded the greatest hover fly presence, species richness, and Toxomerus spp. abundance. Hover fly richness and diversity were greatest during postbloom, but Toxomerus spp. abundance was greatest during the bloom period. No differences in presence, richness, diversity, or Toxomerus spp. abundance were found between edge and interior habitats. Toxomerus geminatus and T. marginatus were dominant from March through August, with T. geminatus being more abundant than T. marginatus in March, early April, and August. October sampling produced the greatest hover fly richness. Our results suggest that hover flies are abundant in North Georgia orchards and exhibit substantial spatial and temporal variation in richness and diversity. Expanded studies incorporating additional sampling efforts and methods are needed to further characterize the hover fly fauna and their impact on North Georgia apple and peach orchards.

Keywords: bowl trap; ecosystem service; natural enemy; pollinator; seasonal phenology.

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Figures

Graphical Abstract
Graphical Abstract
Fig. 1.
Fig. 1.
A) Orchard arrangement and layout of bowl traps in apple and peach orchards at 2 sites in Fannin and Gilmer Counties, Georgia, USA, in March–October 2020 and 2021. B) Setup of bowl traps used in the study.
Fig. 2.
Fig. 2.
Mean (±SE) per trap set of A) presence, B) species richness, and C) diversity (based on the Shannon diversity index) of hover flies in apple and peach orchards at 2 sites in Fannin and Gilmer Counties, Georgia, USA, in March–October 2020 and 2021. *Difference significant (P < 0.05).
Fig. 3.
Fig. 3.
Mean (±SE) per trap set of A) presence, B) species richness, and C) diversity (based on the Shannon diversity index) of hover flies during bloom and postbloom periods in apple and peach orchards at 2 sites in Fannin and Gilmer Counties, Georgia, USA, in March–October 2020 and 2021. **Difference significant (P < 0.01).
Fig. 4.
Fig. 4.
Mean (±SE) per trap set of A) presence, B) species richness, and C) diversity (based on the Shannon diversity index) of hover flies in edge and interior habitats in apple and peach orchards at 2 sites in Fannin and Gilmer Counties, Georgia, USA, in March–October 2020 and 2021.
Fig. 5.
Fig. 5.
Mean (±SE) per trap set of Toxomerus spp. abundance in relation to A) crop species, B) bloom vs. postbloom periods, and C) edge vs. interior habitats in apple and peach orchards at 2 sites in Fannin and Gilmer Counties, Georgia, USA, in March–October 2020 and 2021. *Difference significant (P < 0.05).
See this image and copyright information in PMC

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