Full length articleCOI DNA barcoding for molecular identification of the genus Aphidius (Braconidae: Aphidiinae) in South Korea, with diagnoses of two newly recorded species
Graphical abstract
Introduction
The genus Aphidius belongs to the family Braconidae which, as one of the richest insect families, have approximately 21,221 species in worldwide, and is subdivided into 1,103 genera of 45 subfamilies. Within the subfamily Aphidiinae, include 63 genera and 657 species worldwide (Yu et al., 2016). Some species, such as Aphidius ervi, A. colemani, and A. matricariae, are already used for biological pest control, as Aphidius is well known as a very effective biological control agency for aphids in agriculture which has been found almost everywhere from the world. As most species of aphids occurred in the Northern Hemisphere (Blackman and Eastop, 2000), the Aphidius was considered to be primarily as a Holarctic group (Wharton et al., 1997). As a species-rich genus with huge diversity on their hosts, Aphidius consists of 131 recorded species over the world (Rakhshani et al., 2011, Yu et al., 2016), while only 13 species have been recorded in South Korea (Hwang et al., 2018, Starý and Choi, 2000, NIBR, 2019, Yu et al., 2016).
This genus is characterized by following morphological diagnostic characters (Starý, 1967, Wharton et al., 1997). Head is transverse, as wide as or wider than mesosoma at between each side of tegulae, number of antennae segments are very variable (13 to 23). Notaulices are distinct at the ascendant part of mesoscutum (Starý, 1967). Stigma of fore wing are distinct, triangular and easily distinguished from R1. Fore wing venation has not clearly separated three submarginal cells; marginal cell opened distally and m-cu absent or nearly so and first subdiscal cell open distally in most species. Basal half of petiole is not distinctly tube-shaped, with its sternum at least partly free from median tergite, fused part not reaching level of spiracles. Propodeum is not deeply impressed medially, if apparently impressed then propodeum areolate. Areola is comparatively narrow posteriorly, its maximum width less than or equal to its maximum length (Wharton et al., 1997). Ovipositor sheaths are comparatively short, slightly curved upwards, sparsely haired (Starý, 1967).
Aphidius has an ecological characteristic as solitary koinobiont endo-parasitoids of adult and immature aphids. The hatching larvae pupation occurs therein, and after a few days the host become mummified with various shades of brown color and are often shiny (Starý, 1967). The endo-parasitoid completes its development within the mummy, emerging through an exit hole that it made in the mummy (Brodeur and McNeil, 1992, Hǻgvar and Hofsvang, 1991). In agriculture and horticulture, Aphidius colemani and A. ervi are representatively used as a commercial biocontrol agency for pest aphids world-widely (Fernandez and Nentwig, 1997, Henter and Via, 1995, Sequeira and Mackauer, 1992, Takada, 1998). However, exotic species, such as A. ervi, has caused the negative effect by competition with other native braconid species, reducing its population density (Schellhorn et al., 2002). Therefore, to resolve the ecological problem of the commercial species, it is necessary to investigate indigenous Aphidius species potential as a local biocontrol agency.
The genus Aphidius have been studied in molecular identification and phylogenetics by using several molecular markers (Derocles et al., 2012, Derocles et al., 2014, Jamhour, 2017). Using COI, 52 Aphidiinae species and 33 Aphidius species have been analyzed respectively in previous studies (Derocles et al., 2012, Jamhour, 2017). In addition, phylogenetic relationships of 29 Aphidiinae species were reconstructed using COI in combination with other mitochondrial and nuclear markers (Derocles et al., 2016). From this point of view, COI is a marker that not only is useful to resolve phylogenetic relationships but also facilitates to molecularly identify unknown species because of its richness of the reference data. Therefore, we used COI in order to perform molecular identification and to understand phylogenetic relationships in the genus Aphidius.
In recent, we surveyed Aphidius species in South Korea to confirm the previous records as well as to find the unrecorded or new species. To resolve the cryptic differences in morphology, we used a molecular identification technique based on mitochondrial COI barcode to identify the species of the genus Aphidius. In addition, dignoses and illustrations of the two newly recorded species in South Korea were provided.
Section snippets
Sample collection
We used whaling net to sweep and set up Malaise traps in various regions in South Korea and collected it every two weeks (Table 1). When parasitic aphids were found during collection, investigate the host plants and aphids, put them in insect breeding dish. After that, it was sampled after confirming coming out from mummified aphid. As a result, we collected 31 individuals of 8 species belonging to genera Aphidius. These specimens were sampled between 2014 and 2017. All collected samples are
Results and discussion
A total of 97 COI sequences (≥525 bp) were obtained from the 20 species (i.e. 19 ingroup + 1 outgroup). In the barcode analysis, we could not include A. pleotrichophori because there is no sequence deposited in GenBank. The aligned length of all the sequences was 475 bp including 343 conserved and 132 variable sites. After excluding 15 duplicate sequences generated in this study, 82 MOTU were finally analyzed in the data analysis with 74 ingroup and 8 outgroup taxa.
A phylogenetic tree was
Acknowledgements
This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2018R1D1A3B07044298). It was also supported by a grant from the National Institute of Biological Resources (NIBR201711101) and Korea Environment Industry & Technology Institute (KEITI) through Exotic Invasive Species Management Program (2018002270005), funded by Korea Ministry of Environment (MOE).
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