Functional insights from the GC-poor genomes of two aphid parasitoids, Aphidius ervi and Lysiphlebus fabarum.

Parasitoid wasps have fascinating life cycles and play an important role in trophic networks, yet little is known about their genome content and function. Parasitoids that infect aphids are an important group with the potential for biological control. Their success depends on adapting to develop inside aphids and overcoming both host aphid defenses and their protective endosymbionts. We present the de novo genome assemblies, detailed annotation, and comparative analysis of two closely related parasitoid wasps that target pest aphids: Aphidius ervi and Lysiphlebus fabarum (Hymenoptera: Braconidae: Aphidiinae). The genomes are small (139 and 141 Mbp) and the most AT-rich reported thus far for any arthropod (GC content: 25.8 and 23.8%). This nucleotide bias is accompanied by skewed codon usage and is stronger in genes with adult-biased expression. AT-richness may be the consequence of reduced genome size, a near absence of DNA methylation, and energy efficiency. We identify missing desaturase genes, whose absence may underlie mimicry in the cuticular hydrocarbon profile of L. fabarum. We highlight key gene groups including those underlying venom composition, chemosensory perception, and sex determination, as well as potential losses in immune pathway genes. These findings are of fundamental interest for insect evolution and biological control applications. They provide a strong foundation for further functional studies into coevolution between parasitoids and their hosts. Both genomes are available at https://bipaa.genouest.org

Data from: Cuticular hydrocarbon divergence in the jewel wasp Nasonia: Evolutionary shifts in chemical communication channels?

The data package contains eight datasets: - CSV files containing information on the GC-MS data (GC: 7890A; MS: 5975C; Agilent Technologies, Waldbronn, Germany) for all Nasonia samples, obtained with “Enhanced Chemstation”, G1701AA, Version A.03.00. Columns are identified as follows: Peak number, average retention time, peak type, peak width, peak area (integrated absolute value), start retention time, end retention time. Further description of the data generation see Materials and Methods section in the paper. - CSV files containing information on the GC-MS data (GC: 7890A; MS: 5975C; Agilent Technologies, Waldbronn, Germany) for the Trichomalopsis outgroup samples, obtained with “Enhanced Chemstation”, G1701AA, Version A.03.00. Columns are identified as follows: Peak number, average retention time, peak type, peak width, peak area (integrated absolute value), start retention time, end retention time. Further description of the data generation see Materials and Methods section in the paper. - CHC peak areas standardized with the normalization method of the function "decostand" of the community ecology R package “vegan” (Dixon, 2003), for a more detailed description see Materials and Methods section in the paper. - Functions of the linear discriminant analysis (DA) calculated from the normalized CHC data on the Nasonia samples, first three functions plotted simultaneously in Figure 1 in the paper, further details on the DA see Materials and Methods and Results, respectively. - Phylogenetic distance matrix, used in comparison with the average manhattan chemical distances between the Nasonia species based on the relative differences between their normalized CHC peak areas, performed separately for males and females (Fig. 2 and 3, respectively). The molecular distances are based on the Nasonia phylogeny, which are themselves based on the genetic divergence of a mitochondrial gene, COI sequences retrieved from NCBI, pairwise p-distances calculated with MEGA 3.0 (Werren et al., 2010) For further information, please see Materials and Methods section in the paper as well as the Tables S2 and S3, which give the average manhattan distances the phylogenetic distances were compared to. - Single results of the Mantel tests, performed five times for both male CHC divergence vs. Nasonia phylogeny and female CHC divergence versus Nasonia phylogeny, all five p values and their respective averages are given for both combinations, as well as the r value. Each single test was performed with 9999 permutations. - Raw data on the behavioral assays, focussing on N. oneida and N. giraulti males (Fig. 4). Whether a copulation has occurred or not is given in the second column for each pairing in a binary coding (1 = yes, 0 = no), and the average number of occurred copulations is given for each pairing with untreated and treated female dummies. Species affiliation and treatment of female dummies indicated in the caption of each pairing. Male species affiliation can be found in the main caption on each spread sheet. Furthermore, the male arrestment time has been recorded (third column), but those data have not been used in this study. Mating results on two further N. giraulti strains are given as well. - Relative (percentages) distribution of CHC compound classes among the species and sexes of Nasonia and the outgroup Trichomalopsis, data underlying Fig. S2

Behavioral and genetic characteristics of a new species of Nasonia

Nasonia (Hymenoptera: Pteromalidae) is a genus of parasitoid wasps, which is fast emerging as a model system for evolutionary, genetic, developmental and host–endosymbiont interaction studies. In this study, we report a new species, Nasonia oneida, distinguish its behavioral, genetic and morphological features, and characterize its pre-mating and post-mating isolation with the other Nasonia species. Phylogenetic analyses indicate that N. oneida is the sister species to Nasonia giraulti with its own uniquely distinct cuticular hydrocarbon profiles, behavioral characteristics and subtle morphological differences. An important characteristic of N. oneida is the strong mate discrimination shown by the females against all the other Nasonia species. A genetic analysis of this phenotype by interspecies hybridization indicates that this strong discriminating phenotype is recessive. A formal species description of N. oneida Raychoudhury & Desjardins is also provided.

Desiccation Resistance and Micro-Climate Adaptation: Cuticular Hydrocarbon Signatures of Different Argentine Ant Supercolonies Across California.

Cuticular hydrocarbons (CHCs), the dominant fraction of the insects' epicuticle and the primary barrier to desiccation, form the basis for a wide range of chemical signaling systems. In eusocial insects, CHCs are key mediators of nestmate recognition, and colony identity appears to be maintained through a uniform CHC profile. In the unicolonial Argentine ant Linepithema humile, an unparalleled invasive expansion has led to vast supercolonies whose nestmates can still recognize each other across thousands of miles. CHC profiles are expected to display considerable variation as they adapt to fundamentally differing environmental conditions across the Argentine ant's expanded range, yet this variation would largely conflict with the vastly extended nestmate recognition based on CHC uniformity. To shed light on these seemingly contradictory selective pressures, we attempt to decipher which CHC classes enable adaptation to such a wide array of environmental conditions and contrast them with the overall CHC profile uniformity postulated to maintain nestmate recognition. n-Alkanes and n-alkenes showed the largest adaptability to environmental conditions most closely associated with desiccation, pointing at their function for water-proofing. Trimethyl alkanes, on the other hand, were reduced in environments associated with higher desiccation stress. However, CHC patterns correlated with environmental conditions were largely overriden when taking overall CHC variation across the expanded range of L. humile into account, resulting in conserved colony-specific CHC signatures. This delivers intriguing insights into the hierarchy of CHC functionality integrating both adaptation to a wide array of different climatic conditions and the maintenance of a universally accepted chemical profile

Two new neotropical species of predaceous midges of the tribe sphaeromiini (Diptera: ceratopogonidae)

Two new Neotropical species of the tribe Sphaeromiini are described and illustrated, Mallochohelea limitrofe from Argentina and Uruguay, and Neobezzia wirthi from Argentina. The first species is only known from the female sex, being the second one described from both, female and male specimens

Identification and analyses of extra-cranial and cranial rhabdoid tumor molecular subgroups reveal tumors with cytotoxic T cell infiltration

Extra-cranial malignant rhabdoid tumors (MRTs) and cranial atypical teratoid RTs (ATRTs) are heterogeneous pediatric cancers driven primarily by SMARCB1 loss. To understand the genome-wide molecular relationships between MRTs and ATRTs, we analyze multi-omics data from 140 MRTs and 161 ATRTs. We detect similarities between the MYC subgroup of ATRTs (ATRT-MYC) and extra-cranial MRTs, including global DNA hypomethylation and overexpression of HOX genes and genes involved in mesenchymal development, distinguishing them from other ATRT subgroups that express neural-like features. We identify five DNA methylation subgroups associated with anatomical sites and SMARCB1 mutation patterns. Groups 1, 3, and 4 exhibit cytotoxic T cell infiltration and expression of immune checkpoint regulators, consistent with a potential role for immunotherapy in rhabdoid tumor patients