The complete mitochondrial genome of Anoplocnemis curvipes F. (Coreinea, Coreidae, Heteroptera), a pest of fresh cowpea pods

Open Access Journal; Published online: 18 July 2017The complete 16,345-bp mitochondrial genome of the agriculturally destructive pod sucking pest, the giant coreid bug, Anoplocnemis curvipes (Hemiptera: Coreidae), was assembled from paired-end Illumina HiSeq 2500 reads. The A. curvipes mitochondrial genome consists of 13 protein coding genes (PCGs), 22 tRNAs, 2 rRNAs and a control region in the order and orientation typical among insects. PCG initiation codons (ATG, ATC, ATT and ATA) with termination codon (TAA) are used with the exception of TAG stop codons by Cytb and ND3. All tRNA genes fold into predicted cloverleaf secondary structures having requisite triplets on the anticodon loop, apart from tRNA-Ser1 (AGN) whose dihydrouridine (DHU) arm forms a simple loop. The phylogenetic analysis of hemipteran mitogenomes clusters to the family level and supports the monophyly of the five superfamilies in Pentatomomorpha of Hemiptera. The Coreoidea and Pyrrhocoroidea are sister groups, while Coreidae and Alydidae are sister groups to Rhopalidae. These analyses provide insight to mitogenomics and evolutionary relationships among pentatomoid insects

Development of reference transcriptomes for the major field insect pests of cowpea: a toolbox for insect pest management approaches in West Africa

Cowpea is a widely cultivated and major nutritional source of protein for many people that live in West Africa. Annual yields and longevity of grain storage is greatly reduced by feeding damage caused by a complex of insect pests that include the pod sucking bugs, Anoplocnemis curvipes Fabricius (Hemiptera: Coreidae) and Clavigralla tomentosicollis Stål (Hemiptera: Coreidae); as well as phloem-feeding cowpea aphids, Aphis craccivora Koch (Hemiptera: Aphididae) and flower thrips, Megalurothrips sjostedti Trybom (Thysanoptera: Thripidae). Efforts to control these pests remain a challenge and there is a need to understand the structure and movement of these pest populations in order to facilitate the development of integrated pest management strategies (IPM). Molecular tools have the potential to help facilitate a better understanding of pest populations. Towards this goal, we used 454 pyrosequencing technology to generate 319,126, 176,262, 320,722 and 227,882 raw reads from A. curvipes, A. craccivora, C. tomentosicollis and M. sjostedti, respectively. The reads were de novo assembled into 11,687, 7,647,10,652 and 7,348 transcripts for A. curvipes, A. craccivora, C. tomentosicollis and M. sjostedti, respectively.Functional annotation of the resulting transcripts identified genes putatively involved in insecticide resistance, pathogen defense and immunity. Additionally, sequences that matched the primary aphid endosymbiont, Buchneraaphidicola, were identified among A. craccivora transcripts. Furthermore, 742, 97, 607 and 180 single nucleotide polymorphisms (SNPs) were respectively predicted among A. curvipes, A. craccivora, C. tomentosicollis and M.sjostedti transcripts, and will likely be valuable tools for future molecular genetic marker development. These results demonstrate that Roche 454-based transcriptome sequencing could be useful for the development of genomic resources for cowpea pest insects in West Africa

Genome Sequence of the Wheat Stem Sawfly, Cephus cinctus, Representing an Early-Branching Lineage of the Hymenoptera, Illuminates Evolution of Hymenopteran Chemoreceptors.

The wheat stem sawfly, Cephus cinctus, is a major pest of wheat and key ecological player in the grasslands of western North America. It also represents the distinctive Cephoidea superfamily of sawflies (Symphyta) that appeared early during the hymenopteran radiation, but after three early-branching eusymphytan superfamilies that form the base of the order Hymenoptera. We present a high-quality draft genome assembly of 162 Mb in 1,976 scaffolds with a scaffold N50 of 622 kb. Automated gene annotation identified 11,210 protein-coding gene models and 1,307 noncoding RNA models. Thirteen percent of the assembly consists of ∼58,000 transposable elements partitioned equally between Class-I and Class-II elements. Orthology analysis reveals that 86% of Cephus proteins have identifiable orthologs in other insects. Phylogenomic analysis of conserved subsets of these proteins supports the placement of the Cephoidea between the Eusymphyta and the parasitic woodwasp superfamily Orussoidea. Manual annotation and phylogenetic analysis of families of odorant, gustatory, and ionotropic receptors, plus odorant-binding proteins, shows that Cephus has representatives for most conserved and expanded gene lineages in the Apocrita (wasps, ants, and bees). Cephus has also maintained several insect gene lineages that have been lost from the Apocrita, most prominently the carbon dioxide receptor subfamily. Furthermore, Cephus encodes a few small lineage-specific chemoreceptor gene family expansions that might be involved in adaptations to new grasses including wheat. These comparative analyses identify gene family members likely to have been present in the hymenopteran ancestor and provide a new perspective on the evolution of the chemosensory gene repertoire

The spatial genetic differentiation of the legume pod borer, Maruca vitrata F. (Lepidoptera: Crambidae) populations in West Africa

The legume pod borer, Maruca vitrata, is an endemic insect pest that causes significant yield loss to the cowpea crop in West Africa. The application of population genetic tools is important in the management of insect pests but such data on M. vitrata is lacking. We applied a set of six microsatellite markers to assess the population structure of M. vitrata collected at five sites from Burkina Faso, Niger and Nigeria. Observed polymorphisms ranged from one (marker 3393) to eight (marker 32008) alleles per locus. Observed and expected heterozygosities ranged from 0.0 to 0.8 and 0.0 to 0.6, respectively. Three of the loci in samples from Nigeria and Burkina Faso deviated significantly from Hardy-Weinberg Equilibrium (HWE), whereas no loci deviated significantly in samples from Niger. Analysis of molecular variance (AMOVA) indicated that 67.3% level of the genetic variation was within individuals compared to 17.3% among populations. A global estimate of FST=0.1 (ENA corrected FST=0.1) was significant (P≤0.05) and corroborated by pairwise FST values that were significant among all possible comparisons. A significant correlation was predicted between genetic divergence and geographic distance between subpopulations (R2=0.6, P=0.04), and cluster analysis by the program STRUCTURE predicted that co-ancestry of genotypes were indicative of three distinct populations. The spatial genetic variance among M. vitrata in West Africa may be due to limited gene flow, south-north seasonal movement pattern or other reproductive barriers. This information is important for the cultural, chemical and biological control strategies for managing M. vitrata

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Genetic Differentiation among Maruca vitrata F. (Lepidoptera: Crambidae) Populations on Cultivated Cowpea and Wild Host Plants: Implications for Insect Resistance Management and Biological Control Strategies

Maruca vitrata Fabricius (Lepidoptera: Crambidae) is a polyphagous insect pest that feeds on a variety of leguminous plantsin the tropics and subtropics. The contribution of host-associated genetic variation on population structure wasinvestigated using analysis of mitochondrial cytochrome oxidase 1 (cox1) sequence and microsatellite marker data from M.vitrata collected from cultivated cowpea (Vigna unguiculata L. Walp.), and alternative host plants Pueraria phaseoloides(Roxb.) Benth. var. javanica (Benth.) Baker, Loncocarpus sericeus (Poir), and Tephrosia candida (Roxb.). Analyses ofmicrosatellite data revealed a significant global FST estimate of 0.05 (P#0.001). The program STRUCTURE estimated 2genotypic clusters (co-ancestries) on the four host plants across 3 geographic locations, but little geographic variation waspredicted among genotypes from different geographic locations using analysis of molecular variance (AMOVA; amonggroup variation 20.68%) or F-statistics (FSTLoc =20.01; P = 0.62). These results were corroborated by mitochondrialhaplotype data (QSTLoc = 0.05; P = 0.92). In contrast, genotypes obtained from different host plants showed low butsignificant levels of genetic variation (FSTHost = 0.04; P = 0.01), which accounted for 4.08% of the total genetic variation, butwas not congruent with mitochondrial haplotype analyses (QSTHost = 0.06; P = 0.27). Variation among host plants at a locationand host plants among locations showed no consistent evidence for M. vitrata population subdivision. These resultssuggest that host plants do not significantly influence the genetic structure of M. vitrata, and this has implications forbiocontrol agent releases as well as insecticide resistance management (IRM) for M. vitrata in West Africa.C

The mitogenome of the brown pod-sucking bug Clavigralla tomentosicollis Stäl (Hemiptera: Coreidae)

Published online: 16 July 2017The brown pod-sucking bug, Clavigralla tomentosicollis Stäl (Hemiptera: Coreidae), causes significant damage to cultivated cowpea, Vigna unguiculata Walp, a staple crop in sub-Saharan Africa. C. tomentosicollis pierce and suck sap from cowpea pods, resulting in reduced grain yield and quality. The complete, 16,089 bp mitogenome of C. tomentosicollis encodes 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), two ribosomal RNAs (rRNAs) and an A + T rich control region, with gene order and orientation identical to that of the insect ancestral gene order. The initiation and termination codons for the PCGs used standard ATN codons and TAA or TAG codons respectively. All predicted tRNAs fold into a clover-leaf secondary structures with the exception of tRNA-Ser (AGN) with a semi-loop dihydrouridine arm. The 1509 bps A + T rich region contains a single 89 bp tandem repeat unit duplicated 3.7 times. When compared with other published Coreoidea mitogenomes, C. tomentosicollis was also highly A − T skewed, and similar in both size and A − T%; however, its longer tandem repeat within the A + T rich region was unique. The C. tomentosicollis mitogenome can serve as a foundation to combine molecular marker data with pest monitoring strategies to better understand the population dynamics of this species