The Genome of Rhyzopertha dominica (Fab.) (Coleoptera: Bostrichidae): Adaptation for Success.

The lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae), is a major global pest of cereal grains. Infestations are difficult to control as larvae feed inside grain kernels, and many populations are resistant to both contact insecticides and fumigants. We sequenced the genome of R. dominica to identify genes responsible for important biological functions and develop more targeted and efficacious management strategies. The genome was assembled from long read sequencing and long-range scaffolding technologies. The genome assembly is 479.1 Mb, close to the predicted genome size of 480.4 Mb by flow cytometry. This assembly is among the most contiguous beetle assemblies published to date, with 139 scaffolds, an N50 of 53.6 Mb, and L50 of 4, indicating chromosome-scale scaffolds. Predicted genes from biologically relevant groups were manually annotated using transcriptome data from adults and different larval tissues to guide annotation. The expansion of carbohydrase and serine peptidase genes suggest that they combine to enable efficient digestion of cereal proteins. A reduction in the copy number of several detoxification gene families relative to other coleopterans may reflect the low selective pressure on these genes in an insect that spends most of its life feeding internally. Chemoreceptor genes contain elevated numbers of pseudogenes for odorant receptors that also may be related to the recent ontogenetic shift of R. dominica to a diet consisting primarily of stored grains. Analysis of repetitive sequences will further define the evolution of bostrichid beetles compared to other species. The data overall contribute significantly to coleopteran genetic research.

Population genomics and phylogeography of the boll weevil, Anthonomus grandis Boheman (Coleoptera: Curculionidae), in the United States, northern Mexico, and Argentina.

The boll weevil, Anthonomus grandis Boheman (Coleoptera: Curculionidae), is an important pest of commercial cotton across the Americas. In the United States, eradication of this species is complicated by re-infestations of areas where eradication has been previously successful and by the existence of morphologically similar variants that can confound identification efforts. To date, no study has applied a high-throughput sequencing approach to better understand the population genetic structure of the boll weevil. Furthermore, only a single study has investigated genetic relationships between populations in North and South America. We used double digest restriction site-associated DNA sequencing (ddRADseq) to resolve the population genomic structure of the boll weevil in the southern United States, northern Mexico, and Argentina. Additionally, we assembled the first complete mitochondrial genome for this species and generated a preliminary whole genome assembly, both of which were used to improve the identification of informative loci. Downstream analyses revealed two main lineages-one consisting of populations found geographically west of the Sierra Madre Occidental mountain range and the second consisting of populations found to the east-were revealed, and both were sub-structured. Population geographic structure was consistent with the isolation by distance model, indicating that geogrpahic distance is likely a primary mechanism driving divergence in this species. Boll weevil populations from Argentina were found to be more closely related to the eastern lineage, suggesting a recent colonization of South America by the eastern lineage, but additional sampling across Mexico, Central America and South America is needed to further clarify their origin. Finally, we uncovered an instance of population turnover or replacement, highlighting the temporal instability of population structure.

Inheritance, distribution and genetic differentiation of a color polymorphism in Panamanian populations of the tortoise beetle, Chelymorpha alternans (Coleoptera: Chrysomelidae).

Intraspecific variation maintained in natural populations has long intrigued scientists and naturalists. One form of this variation, color polymorphisms, provide a rich opportunity to connect genotypic and phenotypic diversity within an ecological and evolutionary context. The existence of color polymorphisms in Panamanian populations of the Neotropical tortoise beetle, Chelymorpha alternans, has been suspected but never systematically explored. To characterize geographic distribution and underlying genetics we sampled a total of 3819 beetles from 28 sites across Panama, quantifying five distinct phenotypes. Two phenotypes, the "metallic" and "rufipennis" are the most widely distributed phenotypes, occurring in nearly all collecting sites. The "veraguensis" phenotype was found to be restricted to the Western end of the Isthmus and the "militaris" phenotypes restricted to sites east of the canal. Controlled matings between phenotypes and reared offspring revealed no indications of reproductive barriers, even among phenotypes which do not co-occur in nature. Color pattern phenotype is largely controlled by Mendelian assortment of four alleles competing at a single locus. A clear dominance hierarchy exists among alleles, with two being co-dominant. Genomic scans from 32 individuals revealed low levels of genetic differentiation, with a small fraction of the genome showing a high degree of divergence. The easily observed variation among populations, simple genetic architecture, and rearing capabilities, make this a promising system for investigating proximate and ultimate factors of phenotypic variation.

Thrice out of Africa: ancient and recent expansions of the honey bee, Apis mellifera.

We characterized Apis mellifera in both native and introduced ranges using 1136 single-nucleotide polymorphisms genotyped in 341 individuals. Our results indicate that A. mellifera originated in Africa and expanded into Eurasia at least twice, resulting in populations in eastern and western Europe that are geographically close but genetically distant. A third expansion in the New World has involved the near-replacement of previously introduced "European" honey bees by descendants of more recently introduced A. m. scutellata ("African" or "killer" bees). Our analyses of spatial transects and temporal series in the New World revealed differential replacement of alleles derived from eastern versus western Europe, with admixture evident in all individuals.

The discovery after 94 years of the elusive female of a myrmecolacid (Strepsiptera), and the cryptic species of Caenocholax fenyesi Pierce sensu lato.

Due to its extreme sexual dimorphism and disparate hosts, no female myrmecolacid has been matched to its conspecific male to date. Here, for the first time to our knowledge, a morphological description is given of the matched female and male myrmecolacid, Caenocholax fenyesi waloffi ssp. nov. from Veracruz, Mexico: the female parasitic in a cricket and the male parasitic in an ant. For examined segments of DNA, the male and female are identical. Male C. fenyesi Pierce sensu lato was described 94 years ago from Veracruz. The male from Texas USA, which, for the same DNA segments, shows 15% divergence from the morphologically identical male from Veracruz, is given subspecies status, and is named Caenocholax fenyesi texensis ssp. nov. The discovery of the female finally enables many interesting studies to be pursued, such as speciation in morphologically cryptic taxa, the sexes of which parasitize disparate hosts. Caenocholax fenyesi sensu lato may also be evaluated for biocontrol of the red imported fire ant, Solenopsis invicta Buren, which is a pest in the USA and Australia.