Diversity and Spatial Distribution of Predacious Dolichopodidae (Insecta: Diptera) on Organic Vegetable Fields and Adjacent Habitats in Brazil

Abstract

Adults of the fly family Dolichopodidae (Diptera) are general predators on small soft-bodied invertebrates, and often are abundant in agroecosystems. However, information about their diversity and spatial distribution in agricultural landscapes are scarce. Using structured sampling, we identified the species of Dolichopodidae associated with organic vegetable crops, fallow, agroforestry, and native vegetation in the Federal District of Brazil, and evaluate their richness and abundance. We collected 70 species Dolichopodidae distributed in 17 genera and 9 subfamilies. Of these, some 80% of the specimens belong to the following 5 taxa: Chrysotus spectabilis (Loew), Thrypticus violaceous Van Duzee, Condylostylus depressus (Aldrich), Condylostylus "caudatus group" females, and Condylostylus erectus Becker (all Diptera: Dolichopodidae). Habitats with vegetable crops harbored a higher abundance and number of species (diversity α), with a gradual reduction towards more forested environments of native vegetation. This is an inverse gradient with the general patterns of community studies with other taxa. We also verified the importance of less disturbed habitats over time in the agricultural landscape, such as agroforestry and native vegetation, as complementary habitats for the maintenance and conservation of dolichopodid species in particular, a scenario to be tested for other insect groups.

First records of Condylostylus depressus (Aldrich, 1901) and Condylostylus electus (Walker, 1852) (Diptera, Dolichopodidae) in coconut plantations in state of Pará, Brazil

“…Condylostylus was the most abundant genus in Citrus orchards from Vero Beach, Florida, USA, and the individuals were observed displaying predatory activity, thus reinforcing the evidence of their natural enemy role in agroecosystems (Cicero et al 2017). Harterreiten-Souza et al (2020) demonstrated that Condylostylus species are more abundant in agricultural crops than in agroecosystems. Further, the same authors recorded 16 species of Condylostylus in greenery crops from Federal District (Midwestern Brazil), which ranked second in abundance among the Dolichopodidae genera.…”

“…Most dolichopodids are predators and frequently occur in large numbers in crop fields. They control populations of slender-bodied insects, including whiteflies, thrips, mites and aphids, considered severe and recurrent pests in Brazilian agriculture (Ulrich 2004;Bickel 2009;Harterreiten-Souza et al 2020).…”

“…Condylostylus Bigot, 1859 currently comprises 260 valid species, from which 78 have been recorded in Brazil (Grichanov 2017;Capellari 2021;Harterreiten-Souza et al 2020). The genus is distinguished by the following combination of characters: vertical seta inserted in a tubercle, two pairs of well-developed scutellar setae, and M 1 often sharply recurved basad (Bickel 2009).…”

“…The genus is distinguished by the following combination of characters: vertical seta inserted in a tubercle, two pairs of well-developed scutellar setae, and M 1 often sharply recurved basad (Bickel 2009). Species of Condylostylus are abundant and utilized in the biological control of conventional and organic crops in Brazil (see Seffrin et al 2006;Togni et al 2010;Harterreiten-Souza et al 2020).…”

“…Specimens were photographed with a Leica MC170 HD camera, attached on a Leica M165C stereomicroscope, and the multiple images were stacked and combined using Leica Application Suite V4.11. Distribution map was made using the software Qgis 2.18.28 based on data from IBGE (2019), Capellari (2021) and Harterreiten-Souza et al (2020).…”