The modern concept of DNA-based barcoding for cataloguing biodiversity was proposed in 2003 by first adopting an approximately 600 bp fragment of the mitochondrial COI gene to compare via nucleotide alignments with known sequences from specimens previously identified by taxonomists. Other standardized regions meeting barcoding criteria then are also evolving as DNA barcodes for fast, reliable and inexpensive assessment of species composition across all forms of life, including animals, plants, fungi, bacteria and other microorganisms. Consequently, global DNA barcoding campaigns have resulted in the formation of many online workbenches and databases, such as BOLD system, as barcode references, and facilitated the development of mini-barcodes and metabarcoding strategies as important extensions of barcode techniques. Here we intend to give an overview of the characteristics and features of these barcode markers and major reference libraries existing for barcoding the planet’s life, as well as to address the limitations and opportunities of DNA barcodes to an increasingly broader community of science and society.

Background: Accurate taxonomic identification is the cornerstone for monitoring, conservation and management of ecological resources. China has the highest biodiversities and the richest species assemblages in the world, but is lacking in sufficient assessment to the abundant genetic variability. DNA barcoding is a proven tool employing sequence information for rapid and unambiguous species delineation. However, the ability of barcodes to distinguish species that are archaic and distinctive evolutionary lines remains largely untested.Methods: In order to investigate the resources of terrestrial animals in China, regions from mitochondrial COI and 16S are barcoded for 395 specimens belonging to 54 selected species, many of which are indigenous representatives in danger. High success rate of PCR amplification is achieved by using universal COI and 16S primers with many numts pseudogenes co-amplified from mammalian samples.Results: Application of barcodes to flag species is generally straightforward since no COI or 16S haplotypes are shared between closely related species. Barcoding gap, species resolution and phylogenetic relationships relying on our barcode libraries are further compared using distance and tree based approaches.Conclusion: Results show that the discriminatory power of the two barcode markers could differentiate on a case-by-case basis, and also suggest a careful consideration of the nuclear numts for barcoding studies as they might provide a new understanding for evolution.

This study was conducted to systematically assess and compare the fluctuations in crude protein (CP), crude fat (CF) and mineral content of staged (larva to adult) Drosophila (fruit fly) to that of a market-purchased black soldier fly larvae (BSFL) product. Results suggested that the relative CP content by dry matter ranged from 40.11-53.73% during Drosophila development, significantly higher (P<0.001) than the 36.90% in BSFL. The relative CF was higher in BSFL (39.14%) compared to that of Drosophila (27.03-30.10%, P<0.001). Although both insects contained sufficient levels of minerals to meet the dietary requirements of most animals, Drosophila overall possessed a lower content of iron, sodium and calcium (P<0.001) with a higher gross energy than the BSFL (P<0.01). Comparative studies of amino acid (AA) and fatty acid (FA) profiles were further carried out among Drosophila larva (DL), pupa and BSFL for their economic effectiveness. The AA spectra of insect larvae generally were similar except that the DL was higher in certain AA such as lysine (P<0.01), which is an essential AA often critical for chicken growth. In contrast, the BSFL included more essential FA such as linoleic (C18:2, ω-6) and linolenic (C18:3, ω-3) acids (P<0.01). To follow up, a husbandry trial was performed by allotting 120, 1-day-old, weight-matched, Arbor Acres broilers at random into treatment groups consisting of a low-protein diet background that contained ~20% CP supplemented with 4% BSFL and 4% or 8% DL. The average daily growth (ADG) and average daily feed intake (ADFI) of broilers, compared to the control low-protein diet, were significantly improved by feeding DL diets (P<0.01), with better live and carcass weight and higher muscle pH (P<0.001), which were positively correlated with the inclusion level of DL (P<0.001). However, no differences between the control and 4% BSFL diet were observed for the performance parameters mentioned above. Moreover, all birds under our experimental setting exhibited a comparable feed conversion ratio (FCR) and were in a healthy status as indicated by the meat traits and haematological indexes within normal physiological ranges. Collectively, findings in this study provide theoretical basis for the further exploitation of Drosophila as potential dietary ingredients for feed production in order to meet the food challenge in the future.