We report here genome sequences and comparative analyses of three closely related parasitoid wasps: Nasonia vitripennis, N. giraulti, and N. longicornis. Parasitoids are important regulators of arthropod populations, including major agricultural pests and disease vectors, and Nasonia is an emerging genetic model, particularly for evolutionary and developmental genetics. Key findings include the identification of a functional DNA methylation tool kit; hymenopteran-specific genes including diverse venoms; lateral gene transfers among Pox viruses, Wolbachia, and Nasonia; and the rapid evolution of genes involved in nuclear-mitochondrial interactions that are implicated in speciation. Newly developed genome resources advance Nasonia for genetic research, accelerate mapping and cloning of quantitative trait loci, and will ultimately provide tools and knowledge for further increasing the utility of parasitoids as pest insect-control agents.

Here we report the genome sequence of the honeybee Apis mellifera, a key model for social behaviour and essential to global ecology through pollination. Compared with other sequenced insect genomes, the A. mellifera genome has high A+T and CpG contents, lacks major transposon families, evolves more slowly, and is more similar to vertebrates for circadian rhythm, RNA interference and DNA methylation genes, among others. Furthermore, A. mellifera has fewer genes for innate immunity, detoxification enzymes, cuticle-forming proteins and gustatory receptors, more genes for odorant receptors, and novel genes for nectar and pollen utilization, consistent with its ecology and social organization. Compared to Drosophila, genes in early developmental pathways differ in Apis, whereas similarities exist for functions that differ markedly, such as sex determination, brain function and behaviour. Population genetics suggests a novel African origin for the species A. mellifera and insights into whether Africanized bees spread throughout the New World via hybridization or displacement.

Neuropeptides and protein hormones are ancient molecules that mediate cell-to-cell communication. The whole genome sequence from the red flour beetle Tribolium castaneum, along with those from other insect species, provides an opportunity to study the evolution of the genes encoding neuropeptide and protein hormones. We identified 41 of these genes in the Tribolium genome by using a combination of bioinformatic and peptidomic approaches. These genes encode >80 mature neuropeptides and protein hormones, 49 peptides of which were experimentally identified by peptidomics of the central nervous system and other neuroendocrine organs. Twenty-three genes have orthologs in Drosophila melanogaster: Sixteen genes in five different groups are likely the result of recent gene expansions during beetle evolution. These five groups contain peptides related to antidiuretic factor-b (ADF-b), CRF-like diuretic hormone (DH37 and DH47 of Tribolium), adipokinetic hormone (AKH), eclosion hormone, and insulin-like peptide. In addition, we found a gene encoding an arginine-vasopressin-like (AVPL) peptide and one for its receptor. Both genes occur only in Tribolium and not in other holometabolous insects with a sequenced genome. The presence of many additional osmoregulatory peptides in Tribolium agrees well with its ability to live in very dry surroundings. In contrast to these extra genes, there are at least nine neuropeptide genes missing in Tribolium, including the genes encoding the prepropeptides for corazonin, kinin, and allatostatin-A. The cognate receptor genes for these three peptides also appear to be absent in the Tribolium genome. Our analysis of Tribolium indicates that, during insect evolution, genes for neuropeptides and protein hormones are often duplicated or lost.[Supplemental material is available online at www.genome.org.] Multicellular organisms use signaling molecules for cell-to-cell communication. Important among these signaling molecules are peptides and protein hormones which are produced in endocrine cells or neurons as larger precursors. These precursors (prepropeptides) are cleaved and further modified to yield mature peptides that are secreted into the extracellular environment. Peptides exert their action by binding to membrane receptors, mostly being G-protein coupled receptors (GPCRs), although some of them are receptor tyrosine kinases.Studies of a number of insect species have provided invaluable information for understanding the function and the evolution of neuropeptides. Earlier studies on insect neuropeptides have used large physiological model species (i.e., locust, cockroach, and moth), and these have provided the groundwork for identifying the active signaling molecules. Further characterization of the functions of neuropeptides has been provided by recent genetic studies in Drosophila melanogaster, examining the genetic null mutants and cell ablations of specific peptidergic cells (McNabb et al. 1997;Park et al. 2002aPark et al. , 2003Kim and Rulifson 2004;Isabel et al. 2005;Kim et al. 2006)....

G protein-coupled receptor (GPCR) genes are large gene families in every animal, sometimes making up to 1-2% of the animal's genome. Of all insect GPCRs, the neurohormone (neuropeptide, protein hormone, biogenic amine) GPCRs are especially important, because they, together with their ligands, occupy a high hierarchic position in the physiology of insects and steer crucial processes such as development, reproduction, and behavior. In this paper, we give a review of our current knowledge on Drosophila melanogaster GPCRs and use this information to annotate the neurohormone GPCR genes present in the recently sequenced genome from the honey bee Apis mellifera. We found 35 neuropeptide receptor genes in the honey bee (44 in Drosophila) and two genes, coding for leucine-rich repeats-containing protein hormone GPCRs (4 in Drosophila). In addition, the honey bee has 19 biogenic amine receptor genes (21 in Drosophila). The larger numbers of neurohormone receptors in Drosophila are probably due to gene duplications that occurred during recent evolution of the fly. Our analyses also yielded the likely ligands for 40 of the 56 honey bee neurohormone GPCRs identified in this study. In addition, we made some interesting observations on neurohormone GPCR evolution and the evolution and co-evolution of their ligands. For neuropeptide and protein hormone GPCRs, there appears to be a general co-evolution between receptors and their ligands. This is in contrast to biogenic amine GPCRs, where evolutionarily unrelated GPCRs often bind to the same biogenic amine, suggesting frequent ligand exchanges ("ligand hops") during GPCR evolution.

Neuropeptides and their G protein-coupled receptors (GPCRs) play a central role in the physiology of insects. One large family of insect neuropeptides are the adipokinetic hormones (AKHs), which mobilize lipids and carbohydrates from the insect fat body. Other peptides are the corazonins that are structurally related to the AKHs but represent a different neuropeptide signaling system. We have previously cloned an orphan GPCR from the malaria mosquito Anopheles gambiae that was structurally intermediate between the A. gambiae AKH and corazonin GPCRs. Using functional expression of the receptor in cells in cell culture, we have now identified the ligand for this orphan receptor as being pQVTFSRDWNAamide, a neuropeptide that is structurally intermediate between AKH and corazonin and that we therefore named ACP (AKH/corazonin-related peptide). ACP does not activate the A. gambiae AKH and corazonin receptors and, vice versa, AKH and corazonin do not activate the ACP receptor, showing that the ACP/ receptor couple is an independent and so far unknown peptidergic signaling system. Because ACP is structurally intermediate between AKH and corazonin and the ACP receptor between the AKH and corazonin receptors, this is a prominent example of receptor/ligand co-evolution, probably originating from receptor and ligand gene duplications followed by mutations and evolutionary selection, thereby yielding three independent hormonal systems. The ACP signaling system occurs in the mosquitoes A. gambiae, Aedes aegypti, and Culex pipiens (Diptera), the silkworm Bombyx mori (Lepidoptera), the red flour beetle Tribolium castaneum (Coleoptera), the parasitic wasp Nasonia vitripennis (Hymenoptera), and the bug Rhodnius prolixus (Hemiptera). However, the ACP system is not present in 12 Drosophila species (Diptera), the honeybee Apis mellifera (Hymenoptera), the pea aphid Acyrthosiphon pisum (Hemiptera), the body louse Pediculus humanus (Phthiraptera), and the crustacean Daphnia pulex, indicating that it has been lost several times during arthropod evolution. In particular, this frequent loss of hormonal systems is unique for arthropods compared with vertebrates.