| The brown leg mite Aleuroglyphus ovatus (Troupeau) is an economically important pest of stored food products with a worldwide distribution. In addition to the damage it causes to stored products, A. ovatus is also an important environmental allergen to humans, causing IgE-mediated allergic reactions, asthma, and acariasis. This mite is often difficult to control, because their small individual, reproductive capacity, short life cycles. Moreover, intensive use of chemical acaricides for pest control has facilitated resistance ability in storge mites. Previous studies have focus on bionomics, physiology, biochemistry, and control measures in grain storge systems. However, dynamic of population and population genetic structure of A. ovatus have not been clarified. Mitogenomic studies of storage mites have been conducted to derive useful mitochondrial genetic marker in population genetic structure. However, only 2 Astigmata mitogenomes has been completely sequenced belong to storage mites and has not yet been reported for any other Acaridae mitogenome. In this study, we analyzed the seasonal dynamics and the spatial distribution pattern of A. ovatus in flour, sequenced the complete mitgenome of A. ovatus and provided a comparison to other Astigmata mites, and analyzed the genetic structure of the A. ovatus populations, which may be useful to plan appropriate strategies for the control in storage mites.The main results of this study are as follows:1. Samples from flour of four localities were collected in Wuhu, examined and counted for A. ovatus in every months. Dispersion pattern target, Taylor power method and Iwao m*/x regression analysis were used for analyzing the spatial distribution pattern of A. ovatus in the flour warehouse. The results indicated that there were two peaking periods in July and September respectively and the spatial distribution pattern of A. ovatus was assembled.2. We determined the mitogenome and mitogenomic structures for A. ovatus. It was 14,328 bp long, and consisted of 37 coding genes including 13 protein-coding genes,2 ribosomal RNA genes, and 22 transfer RNA genes. This is the first description of the complete mitogenome of a species in the Acaridae (Acari:Sarcoptiformes). The mitgenome has several features:The mtDNA gene order for A. ovatus is distinctly different from the representative ground pattern for arthropod mitogenome, a series of gene rearrangements have occurred. Most inferred tRNA genes of A. ovatus are extremely truncated (48-62 bp), lack stem-loops on either the T-or D-arm (except the trnK), and are unable to fold into the canonical tRNA cloverleaf structure. The largest non-coding region (378 bp) contained several conserved sequences involved in the regulation of mitogenome replication, including one core sequence (ACAT) associated with termination of the J-strand replication and several hypothetical stem-loop structures.3. Among 7 A. ovatus population, the genetic diversity and population differentiation were investigated using the mitochondrial rrnL-trnw-IGS-nadl gene and ITS sequence. The main results are:In the rrnL-trnw-IGS-nadl dataset, an 820bp fragment were aligned and analyzed from 68 A. ovatus individuals. Totally,17 haplotypes were detected In the ITS1-5.8S rRNA-ITS2 dataset, an 1157bp fragment were aligned and analyzed from 68 A. ovatus individuals. Totally,47 haplotypes were detected AMOVA showed that there are highly significant genetic differentiation among S JZ populations and other six populations (P< 0.01). Among SQ populations and other five populations, significant genetic differentiation also found (P< 0.05). However, there was no significant genetic differentiation among most other five populations (P> 0.05). Spatial structure analysis (Mantel tests) showed no significant correlation between genetic and geographical distance (P> 0.05). The haplotype phylogenetic tree and network showed that all these haplotypes from the same localicity didn’t cluster together. These results suggested that significant genetic differentiation occurred among A. ovatus individuals, and most of the genetic differentiation occurred within populations.4. The genetic diversity and population differentiation among different months and habitats for A. ovatus population were also investigated using the mitochondrial rrnL-trnw-IGS-nadl gene and ITS sequence. In contrast to the haplotype diversity and nucleotide diversity result inferred from the rrnL-trmv-IGS-nadl dataset and ITS dataset are at different levels. AMOVA showed that there are no significant genetic differentiations among different months and hosts populations (P> 0.05). The haplotype phylogenetic tree and network showed that all these haplotypes from the same month or habitats didn’t cluster together. |
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