Draft mitogenomes of the invasive ant Lepisiota frauenfeldi (Mayr 1855) (Hymenoptera: Formicidae)

We present the draft mitochondrial genomes (mitogenomes) of two Lepisiota frauenfeldi (Mayr 1855) workers from two separate invasive populations detected in Western Australia (Perth OK569858) and Queensland (Brisbane OK5569859), Australia. The draft mitogenomes ranged between 16,657 and 17,090 bp and contained 37 genes (13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), and two ribosomal RNA (rRNA) genes). As with other arthropod mitogenomes, we observed high A + T content (A: 39.4–39.8%, T: 40.55–41.5%). We confirmed the species identity by molecular diagnostics based on the partial mtCOI gene that showed >99% similarity between the Australian populations and other L. frauenfeldi sequences reported to date, and in the process identified putative origins of the invasive populations as Pakistan and India for the WA and Qld incursions respectively that suggested separate introductions.

A high-throughput amplicon sequencing approach for population-wide species diversity and composition survey

Management of agricultural pests requires an understanding of pest species diversity, their interactions with beneficial insects and spatial-temporal patterns of pest abundance. Invasive and agriculturally important insect pests can build up very high populations, especially in cropping landscapes. Traditionally, sampling effort for species identification involves small sample sizes and is labour intensive. Here, we describe a multi-primer high throughput sequencing (HTS) metabarcoding method and associated analytical workflow for a rapid, intensive, high-volume survey of pest species compositions. We demonstrate our method using the taxonomically challenging Bemisia pest cryptic species complex as examples. The whiteflies Bemisia including the 'tabaci' species are agriculturally important capable of vectoring diverse plant viruses that cause diseases and crop losses. Our multi-primer metabarcoding HTS amplicon approach simultaneously process high volumes of whitefly individuals, with efficiency to detect rare (i.e., 1%) test-species, while our improved whitefly primers for metabarcoding also detected beneficial hymenopteran parasitoid species from whitefly nymphs. Field-testing our redesigned Bemisia metabarcoding primer sets across the Tanzania, Uganda and Malawi cassava cultivation landscapes, we identified the sub-Saharan Africa 1 Bemisia putative species as the dominant pest species, with other cryptic Bemisia species being detected at various abundances. We also provide evidence that Bemisia species compositions can be affected by host crops and sampling techniques that target either nymphs or adults. Our multi-primer HTS metabarcoding method incorporated two over-lapping amplicons of 472bp and 518bp that spanned the entire 657bp 3' barcoding region for Bemisia, and is particularly suitable to molecular diagnostic surveys of this highly cryptic insect pest species complex that also typically exhibited high population densities in heavy crop infestation episodes. Our approach can be adopted to understand species biodiversity across landscapes, with broad implications for improving trans-boundary biosecurity preparedness, thus contributing to molecular ecological knowledge and the development of control strategies for high-density, cryptic, pest-species complexes.

The complete mitochondrial DNA genome of Aedes vigilax (Diptera: Culicidae)

The complete mitochondrial genomes of two main clades of the medically significant saltmarsh mosquito Aedes vigilax Skuse (Diptera: Culicidae) were obtained using combined Illumina and Sanger sequencing. The two 15,877 bp circular genomes share 99.0% nucleotide identity and encode 37 genes with identical gene arrangement similar to previously published Culicidae species with a non-coding A + T rich region between rns and tRNA-Ile. Protein initiation codon is ATN apart from ND5 (GTG) and COX1 (TCG). Eight protein-coding genes encode full TAA stop codon, while five are completed by mRNA polyadenylation. Typical cloverleaf structures containing DHU and TΨC stem and loops can be inferred for all 22 tRNAs.

The complete mitochondrial DNA genomes for two lineages of Aedes notoscriptus (Diptera: Culicidae)

The complete mitochondrial genomes for two deeply divergent lineages of the urban adapted mosquito Aedes notoscriptus Skuse (Diptera: Culicidae) in Australia were sequenced using a combination of next generation Illumina and traditional Sanger sequencing. The 15,846 and 15,851 bp circular genomes share 95.0% nucleotide identity. They both have the full complement of 37 metazoan genes and identical gene arrangements to previously published Culicidae species with the one non-coding A + T rich control region present between rns and tRNA-Ile. All protein initiation codons are ATN apart from COX1 (TCG). Eight protein coding genes encode full TAA stop codons, one uses an incomplete TA and four use T. Typical cloverleaf structures containing DHU and TΨC stem and loops can be inferred for all 22 tRNAs.

Developmental expression and gene/enzyme identifications in the alpha esterase gene cluster of Drosophila melanogaster

Here we show how the 10 genes of the alpha esterase cluster of Drosophila melanogaster have diverged substantially in their expression profiles. Together with previously described sequence divergence this suggests substantial functional diversification. By peptide mass fingerprinting and in vitro gene expression we have also shown that two of the genes encode the isozymes EST9 (formerly ESTC) and EST23. EST9 is the major 'alpha staining' esterase in zymograms of gut tissues in feeding stages while orthologues of EST23 confer resistance to organophosphorus insecticides in other higher Diptera. The results for EST9 and EST23 concur with previous suggestions that the products of the alpha esterase cluster function in digestion and detoxification of xenobiotic esters. However, many of the other genes in the cluster show developmental or tissue-specific expression that seems inconsistent with such roles. Furthermore, there is generally poor correspondence between the mRNA expression patterns of the remaining eight genes and isozymes previously characterized by standard techniques of electrophoresis and staining, suggesting that the alpha cluster might only account for a small minority of the esterase isozyme profile.