Complete mitochondrial genome of the meadow moth, Loxostege sticticalis (Lepidoptera: Pyraloidea: Crambidae), compared to other Pyraloidea moths

Abstract

The mitochondrial genome (mitogenome) is an important topic for comparative and evolutionary genomics, as well as phylogenetic and population genetics. However, there are limited data regarding the mitochondrial genome available of Pyraloidea, one of the largest superfamilies in Lepidoptera. In this report, we present the complete mitogenome of the meadow moth, Loxostege sticticalis L. (Lepidoptera: Pyraloidea: Crambidae), which is a serious economic pest of both crops and weeds worldwide, thereby enhancing the available genomic information for Pyraloidea. This circular genome is 15,218bp in length, containing 13 protein-coding genes (PCGs), two rRNA genes (rRNAs), and 22 tRNA genes (tRNAs), with a typical gene orientation and order comparable to other sequenced Pyraloidea insects. The genome composition of the major strand exhibits highly AT bias (80.82%), with a slightly positive AT skew indicating the occurrence of more As than Ts. The L. sticticalis mitogenome has a total of 130bp of intergenic spacer sequences spread over 15 regions, ranging in size from 1 to 48bp, of which only two are common among the 23 total Pyraloidea moths that have data collected on the mitogenome (one is located between tRNAGln and ND2 with variation change in length and a limited sequence conservation, and the other is located between tRNASer(UCN) and ND1 with a conserved 6bp motif ‘ATACTA’). The A + T-rich region of 331bp in the genome is comprised of non-repetitive sequences but contains an ATAGN motif followed by a poly-T stretch of 17bp, a microsatellite-like (TA)11 element preceded by an ATTTA motif, and a poly-A stretch upstream tRNAMet. These conserved structures identified in the A + T-rich region are presented in all of the sequenced Pyraloidea species. We provide a mitogenome-based phylogeny of Pyraloidea species, in which L. sticticalis shares close ancestry to Ostrinia species with substantial evidence. Our phylogenetic analyses strongly divide Crambidae into two sister lineages, one consisting of Pyraustinae and Spilomelinae, while the other contains Crambinae, Acentropinae, Scopariinae, Schoenobiinae and Glaphyriinae. The mitogenome dataset also supports the basal split between Pyraustinae and Spilomelinae.