Diversity investigation by application of DNA barcoding: a case study of lepidopteran insects in Xinjiang wild fruit forests, China

To investigate the species diversity of lepidopteran insects in Xinjiang
wild fruit forests, establish insect community monitoring systems and
determine the local species pool, we test the applicability of DNA
barcoding based on cytochrome c oxidase subunit I (COI) gene for accurate
and rapid identification of insect species. From 2017 to 2019, a total of
212 samples with ambiguous morphological identification were selected for
DNA barcoding analysis. Five sequence-based methods for species
delimitation (ABGD, BINs, GMYC, jMOTU and bPTP) were conducted for
comparison to traditional morphology-based identification. In total, 2,422
samples were recorded, representing 143 species of 110 genera in 17
families in Lepidoptera. The diversity analysis showed that the richness
indices for Noctuidae was the highest (54 species), and for Pterophoridae,
Cossidae, Limacodidae, Lasiocampidae, Pieridae and Lycaenidae were the
lowest (all with 1 species). The Shannon-Wiener species diversity index
(H') and Pielou’s evenness (J') of lepidopteran insects first
increased and then decreased across these three years, while the Simpson
diversity index showed a trend of subtracted-then-added. For
molecular-based identification, 67 lepidopteran species within 61 genera
in 14 families were identified through DNA barcoding. Neighbor Joining
(NJ) analysis showed that conspecific individuals were clustered together
and formed monophyletic groups with a high support value, except for
Lacanobia contigua (Denis & Schiffermüller, 1775) (Noctuidae:
Hadeninae). Sixty-seven morphospecies were classified into various numbers
of MOTUs based on ABGD, BINs, GMYC, jMOTU and bPTP (70, 96, 2, 71, and 71,
respectively). In Xinjiang wild fruit forests, the family with the largest
number of species is Noctuidae, followed by Geometridae, Crambidae, and
the remaining families. The highest Shannon diversity index is observed
for the family Noctuidae. Our results indicate that the distance-based
methods (ABGD and jMOTU) and character-based method (bPTP) outperform
GMYC. BINs is inclined to overestimate species diversity compared to other
methods.