Transmission mode predicts coinfection patterns of insect-specific viruses in field populations of the Queensland fruit fly.

Insect-specific viruses (ISVs) can affect insect health and fitness, but can also interact with other insect-associated microorganisms. Despite this, ISVs are often studied in isolation from each other, in laboratory populations. Consequently, their diversity, prevalence and associations with other viruses in field populations are less known, yet these parameters are important to understanding virus epidemiology. To help address this knowledge gap, we assessed the diversity, prevalence and coinfections of three ISVs (horizontally transmitted cripavirus, biparentally transmitted sigmavirus and maternally transmitted iflavirus) in 29 field populations of Queensland fruit fly, Australia's most significant horticultural pest, in the context of their different transmission modes. We detected new virus variant diversity. In contrast to the very high virus prevalence in laboratory populations, 46.8% of 293 field flies carried one virus and 4.8% had two viruses. Cripavirus and sigmavirus occurred in all regions, while iflavirus was restricted to subtropical and tropical regions. Cripavirus was most prevalent (37.5%), followed by sigmavirus (13.7%) and iflavirus (4.4%). Cripavirus coinfected some flies with either one of the two vertically transmitted viruses. However, sigmavirus did not coinfect individuals with iflavirus. Three different modelling approaches detected negative association patterns between sigmavirus and iflavirus, consistent with the absence of such coinfections in laboratory populations. This may be linked with their maternal transmission and the ineffective paternal transmission of sigmavirus. Furthermore, we found that, unlike sigmavirus and iflavirus, cripavirus load was higher in laboratory than field flies. Laboratory and mass-rearing conditions may increase ISV prevalence and load due to increased transmission opportunities. We conclude that a combination of field and laboratory studies is needed to uncover ISV interactions and further our understanding of ISV epidemiology.

Vertical and horizontal gene transfer shaped plant colonization and biomass degradation in the fungal genus Armillaria.

The fungal genus Armillaria contains necrotrophic pathogens and some of the largest terrestrial organisms that cause tremendous losses in diverse ecosystems, yet how they evolved pathogenicity in a clade of dominantly non-pathogenic wood degraders remains elusive. Here we show that Armillaria species, in addition to gene duplications and de novo gene origins, acquired at least 1,025 genes via 124 horizontal gene transfer events, primarily from Ascomycota. Horizontal gene transfer might have affected plant biomass degrading and virulence abilities of Armillaria, and provides an explanation for their unusual, soft rot-like wood decay strategy. Combined multi-species expression data revealed extensive regulation of horizontally acquired and wood-decay related genes, putative virulence factors and two novel conserved pathogenicity-induced small secreted proteins, which induced necrosis in planta. Overall, this study details how evolution knitted together horizontally and vertically inherited genes in complex adaptive traits of plant biomass degradation and pathogenicity in important fungal pathogens.

Validation of reference-assisted assembly using existing and novel Heliothine genomes.

Chloridea subflexa and Chloridea virescens are a pair of closely related noctuid species exhibiting pheromone-based sexual isolation and divergent host plant preferences. We produced a novel Illumina short read C. subflexa genome assembly and an improved C. virescens genome assembly, which offer opportunities to study the genomic basis for evolutionarily important traits in this lepidopteran family with few genomic resources. We then examined the feasibility of reference-assisted assembly, an approach that leverages existing high quality genomic resources for genome improvement in closely related taxa and applied it to our Heliothine genomes. Our work demonstrates that reference-assisted assembly has the potential to enhance contiguity and completeness of existing insect genomic resources with minimal additional laboratory costs. We conclude by discussing both the potential and pitfalls of reference-assisted assembly according to the intended downstream assembly application.

Assessing Differences between Clinical Isolates of Aspergillus fumigatus from Cases of Proven Invasive Aspergillosis and Colonizing Isolates with Respect to Phenotype (Virulence in Tenebrio molitor Larvae) and Genotype.

The fungus Aspergillus fumigatus, the cause of invasive aspergillosis (IA), is a serious risk to transplant patients and those with respiratory diseases. Host immune suppression is considered the most important factor for the development of IA. Less is known about the importance of fungal virulence in the development of IA including the significance of variation between isolates. In this study, isolates of A. fumigatus from cases diagnosed as having proven IA or colonisation (no evidence of IA) were compared in assays to measure isolate virulence. These assays included the measurement of radial growth and protease production on agar, sensitivity to UV light and oxidative stressors, and virulence in Tenebrio molitor (mealworm) larvae. These assays did not reveal obvious differences in virulence between the two groups of isolates; this provided the impetus to conduct genomic analysis. Whole genome sequencing and analysis did not allow grouping into coloniser or IA isolates. However, focused analysis of single nucleotide polymorphisms revealed variation in three putative genes: AFUA_5G09420 (ccg-8), AFUA_4G00330, and AFUA_4G00350. These are known to be responsive to azole exposure, and ccg-8 deletion leads to azole hypersensitivity in other fungi. A. fumigatus virulence is challenging, but the findings of this study indicate that further research into the response to oxidative stress and azole exposure are required to understand the development of IA.

Horticultural innovation by viral-induced gene regulation of carotenogenesis.

Multipartite viral vectors provide a simple, inexpensive and effective biotechnological tool to transiently manipulate (i.e. reduce or increase) gene expression in planta and characterise the function of genetic traits. The development of virus-induced gene regulation (VIGR) systems usually involve the targeted silencing or overexpression of genes involved in pigment biosynthesis or degradation in plastids, thereby providing rapid visual assessment of success in establishing RNA- or DNA-based VIGR systems in planta. Carotenoids pigments provide plant tissues with an array of yellow, orange, and pinkish-red colours. VIGR-induced transient manipulation of carotenoid-related gene expression has advanced our understanding of carotenoid biosynthesis, regulation, accumulation and degradation, as well as plastid signalling processes. In this review, we describe mechanisms of VIGR, the importance of carotenoids as visual markers of technology development, and knowledge gained through manipulating carotenogenesis in model plants as well as horticultural crops not always amenable to transgenic approaches. We outline how VIGR can be utilised in plants to fast-track the characterisation of gene function(s), accelerate fruit tree breeding programs, edit genomes, and biofortify plant products enriched in carotenoid micronutrients for horticultural innovation.

Mediterranean fruit fly genes exhibit different expression patterns between heat and cold treatments.

Invasive Tephritid fruit flies are a global threat to both agriculture and horticulture industries. Biosecurity has played a critical role in reducing their damage but becomes more and more challenging after several key chemical pesticides were banned or withdrawn for health or environmental reasons. This has led to non-chemical approaches including heat and cold treatments being broadly utilized to get rid of fruit fly infestation. However, the molecular mechanisms to kill the flies underlying these stressors are not clear yet. This knowledge will certainly help refine current post-harvest treatment strategies and develop more efficient, cost-effective and environmentally friendly approaches for fruit fly management. Previously, the molecular response of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) to heat was examined thoroughly, in which 31 key genes were identified with significant changes in expression levels and their high-resolution expression timeline was constructed across 11 timepoints. However, whether these candidate genes respond to cold in the same way was unknown. Here, a temperature bioassay was conducted and the expression profiles of these genes were investigated across the same 11 timepoints using cold treatment. The results showed that most of candidate genes exhibited divergent expression profiles compared to heat treatment, suggesting that the fly molecular response to cold may be different from those to heat. This study provides new knowledge of Tephritid fruit fly response to cold at a molecular level, which could aid in improving current fruit fly management and facilitate the development of new strategies to control this serious horticultural insect pest.

Characterization of sensory neuron membrane proteins (SNMPs) in cotton bollworm Helicoverpa armigera (Lepidoptera: Noctuidae).

Sensory neuron membrane proteins (SNMPs) play a critical role in insect chemosensory system. Previously, three SNMPs were identified, characterized and functionally investigated in a lepidopteran model insect, Bombyx mori. However, whether these results are consistent across other lepidopteran species are unknown. Here genome and transcriptome data analysis, expression profiling, quantitative real-time PCR (qRT-PCR) and the yeast hybridization system were utilized to examine snmp genes of Helicoverpa armigera, one of the most destructive lepidopteran pests in cropping areas. In silico expression and qRT-PCR analyses showed that, just as the B. mori snmp genes, H. armigera snmp1 (Harmsnmp1) is specifically expressed in adult antennae. Harmsnmp2 is broadly expressed in multiple tissues including adult antennae, tarsi, larval antennae and mouthparts. Harmsnmp3 is specifically expressed in larval midguts. Further RNAseq analysis suggested that the expression levels of Harmsnmp2 and Harmsnmp3 differed significantly depending on the plant species on which the larvae fed, indicating they may be involved in plant-feeding behaviours. Yeast hybridization results revealed a protein-protein interaction between HarmSNMP1 and the sex pheromone receptor, HarmOR13. This study demonstrated that SNMPs may share same functions and mechanisms in different lepidopteran species, which improved our understanding of insect snmp genes and their functions in lepidopterans.

Prior exposure of Arabidopsis seedlings to mechanical stress heightens jasmonic acid-mediated defense against necrotrophic pathogens.

BACKGROUND: Prolonged mechanical stress (MS) causes thigmomorphogenesis, a stress acclimation response associated with increased disease resistance. What remains unclear is if; 1) plants pre-exposed to a short period of repetitive MS can prime defence responses upon subsequent challenge with necrotrophic pathogens, 2) MS mediates plant immunity via jasmonic acid (JA) signalling, and 3) a short period of repetitive MS can cause long-term changes in gene expression resembling a stress-induced memory. To address these points, 10-days old juvenile Arabidopsis seedlings were mechanically stressed for 7-days using a soft brush and subsequently challenged with the necrotrophic pathogens, Alternaria brassicicola, and Botrytis cinerea. Here we assessed how MS impacted structural cell wall appositions, disease symptoms and altered gene expression in response to infection. RESULTS: The MS-treated plants exhibited enhanced cell wall appositions and jasmonic acid (JA) accumulation that correlated with a reduction in disease progression compared to unstressed plants. The expression of genes involved in JA signalling, callose deposition, peroxidase and phytoalexin biosynthesis and reactive oxygen species detoxification were hyper-induced 4-days post-infection in MS-treated plants. The loss-of-function in JA signalling mediated by the JA-insensitive coronatine-insensitive 1 (coi1) mutant impaired the hyper-induction of defense gene expression and promoted pathogen proliferation in MS-treated plants subject to infection. The basal expression level of PATHOGENESIS-RELATED GENE 1 and PLANT DEFENSIN 1.2 defense marker genes were constitutively upregulated in rosette leaves for 5-days post-MS, as well as in naïve cauline leaves that differentiated from the inflorescence meristem well after ceasing MS. CONCLUSION: This study reveals that exposure of juvenile Arabidopsis plants to a short repetitive period of MS can alter gene expression and prime plant resistance upon subsequent challenge with necrotrophic pathogens via the JA-mediated COI1 signalling pathway. MS may facilitate a stress-induced memory to modulate the plant's response to future stress encounters. These data advance our understanding of how MS primes plant immunity against necrotrophic pathogens and how that could be utilised in sustainable agricultural practices.

Separating two tightly linked species-defining phenotypes in Bactrocera with hybrid recombinant analysis.

BACKGROUND: Bactrocera tryoni and Bactrocera neohumeralis mate asynchronously; the former mates exclusively around dusk while the latter mates during the day. The two species also differ in the colour of the post-pronotal lobe (callus), which is predominantly yellow in B. tryoni and brown in B. neohumeralis. We have examined the genetic relationship between the two characters in hybrids, backcrosses and multigeneration hybrid progeny. RESULTS: Our analysis of the mating time of the parental species revealed that while B. tryoni mate exclusively at dusk, B. neohumeralis females pair with B. neohumeralis males during the day and with B. tryoni males at dusk. We found considerable variance in mating time and callus colour among hybrid backcross individuals of both sexes but there was a strong although not invariant trend for callus colour to co-segregate with mating time in both sexes. To genetically separate these two phenotypes we allowed the interspecific F1 hybrids to propagate for 25 generations (F25) without selection for mating time or callus colour, finding that the advanced hybrid population had moved towards B. tryoni phenotypes for both traits. Selection for day mating in replicate lines at F25 resulted in significant phenotypic shifts in both traits towards B. neohumeralis phenotypes in F26. However, we were unable to completely recover the mating time profile of B. neohumeralis and relaxation of selection for day mating led to a shift back towards dusk mating, but not yellow callus colour, by F35. CONCLUSION: We conclude that the inheritance of the two major species-defining traits is separable but tightly linked and involves more than one gene in each case. It also appears that laboratory conditions select for the B. tryoni phenotypes for mating time. We discuss our findings in relation to speciation theory and the likely effects of domestication during the generation of mass release strains for sterile insect control programmes.

Molecular Response of the Mediterranean Fruit Fly (Diptera: Tephritidae) to Heat.

Tephritid fruit flies are highly successful invaders and some-such as the Mediterranean fruit fly, Ceratitis capitata (Wiedemann)-are able to adapt to a large range of crops. Biosecurity controls require that shipments of produce are ensured to be pest-free, which is increasingly difficult due to the ban of key pesticides. Instead, stress-based strategies including controlled atmosphere, temperature, and irradiation can be used to eradicate flies inside products. However, unlike pesticide science, we do not yet have a robust scientific approach to measure cost-effectively whether a sufficiently lethal stress has been delivered and understand what this stress does to the biology of the pest. The latter is crucial as it would enable a combination of stresses targeting multiple molecular pathways and thus allow for lower doses of each to achieve higher lethality and reduce the development of resistance. Using heat as an example, this is the first study investigating the molecular stress response to heat in Tephritidae. Using a novel setup delivering measured doses of heat on C. capitata larvae and a high-density 11 timepoint gene expression experiment, we identified key components of lethal heat-stress response. While unraveling the complete molecular mechanism of fruit fly response to lethal stress would be a long-term project, this work curates and develops 31 potential biomarkers to assess whether sufficient lethal stress has been delivered. Further, as these protocols are straightforward and less expensive than other-omic approaches, our studies and approach will assist other researchers working on stress response.

De novo assembly of the olive fruit fly (Bactrocera oleae) genome with linked-reads and long-read technologies minimizes gaps and provides exceptional Y chromosome assembly.

BACKGROUND: The olive fruit fly, Bactrocera oleae, is the most important pest in the olive fruit agribusiness industry. This is because female flies lay their eggs in the unripe fruits and upon hatching the larvae feed on the fruits thus destroying them. The lack of a high-quality genome and other genomic and transcriptomic data has hindered progress in understanding the fly's biology and proposing alternative control methods to pesticide use. RESULTS: Genomic DNA was sequenced from male and female Demokritos strain flies, maintained in the laboratory for over 45 years. We used short-, mate-pair-, and long-read sequencing technologies to generate a combined male-female genome assembly (GenBank accession GCA_001188975.2). Genomic DNA sequencing from male insects using 10x Genomics linked-reads technology followed by mate-pair and long-read scaffolding and gap-closing generated a highly contiguous 489 Mb genome with a scaffold N50 of 4.69 Mb and L50 of 30 scaffolds (GenBank accession GCA_001188975.4). RNA-seq data generated from 12 tissues and/or developmental stages allowed for genome annotation. Short reads from both males and females and the chromosome quotient method enabled identification of Y-chromosome scaffolds which were extensively validated by PCR. CONCLUSIONS: The high-quality genome generated represents a critical tool in olive fruit fly research. We provide an extensive RNA-seq data set, and genome annotation, critical towards gaining an insight into the biology of the olive fruit fly. In addition, elucidation of Y-chromosome sequences will advance our understanding of the Y-chromosome's organization, function and evolution and is poised to provide avenues for sterile insect technique approaches.

A phylogenomics approach to characterizing sensory neuron membrane proteins (SNMPs) in Lepidoptera.

Sensory neuron membrane proteins (SNMPs) play a critical role in the insect olfactory system but there is a deficit of functional studies beyond Drosophila. Here, we use a combination of available genome sequences, manual curation, genome and transcriptome data, phylogenetics, expression profiling and gene knockdown to investigate SNMP superfamily in various insect species with a focus on Lepidoptera. We curated 81 genes from 36 insect species and identified a novel lepidopteran SNMP gene family, SNMP3. Phylogenetic analysis shows that lepidopteran SNMP3, but not the previously annotated lepidopteran SNMP2, is the true homologue of the dipteran SNMP2. Digital expression, microarray and qPCR analyses show that the lepidopteran SNMP1 is specifically expressed in adult antennae. SNMP2 is widely expressed in multiple tissues while SNMP3 is specifically expressed in the larval midgut. Microarray analysis suggest SNMP3 may be involved in the silkworm immunity response to virus and bacterial infections. We functionally characterized SNMP1 in the silkworm using RNA interference (RNAi) and behavioral assays. Our results suggested that Bombyx mori SNMP1 is a functional orthologue of the Drosophila melanogaster SNMP1 and plays a critical role in pheromone detection. Split-ubiquitin yeast hybridization study shows that BmorSNMP1 has a protein-protein interaction with the pheromone receptor (BmorOR1), and the co-receptor (BmorOrco). Concluding, we propose a novel molecular model in which BmorOrco, BmorSNMP1 and BmorOR1 form a heteromer in the detection of the silkworm sex pheromone bombykol.

The transcriptomic responses of C4 grasses to subambient CO2 and low light are largely species specific and only refined by photosynthetic subtype.

Three subtypes of C4 photosynthesis exist (NADP-ME, NAD-ME and PEPCK), each known to be beneficial under specific environmental conditions. However, the influence of photosynthetic subtype on transcriptomic plasticity, as well as the genes underpinning this variability, remain largely unknown. Here, we comprehensively investigate the responses of six C4 grass species, spanning all three C4 subtypes, to two controlled environmental stresses: low light (200 µmol m-2  sec-1 ) and glacial CO2 (subambient; 180 ppm). We identify a susceptibility within NADP-ME species to glacial CO2 . Notably, although glacial CO2 phenotypes could be tied to C4 subtype, biochemical and transcriptomic responses to glacial CO2 were largely species specific. Nevertheless, we were able to identify subtype specific subsets of significantly differentially expressed transcripts which link resource acquisition and allocation to NADP-ME species susceptibility to glacial CO2 . Here, low light phenotypes were comparable across species with no clear subtype response, while again, transcriptomic responses to low light were largely species specific. However, numerous functional similarities were noted within the transcriptomic responses to low light, suggesting these responses are functionally relatively conserved. Additionally, PEPCK species exhibited heightened regulation of transcripts related to metabolism in response to both stresses, likely tied to their C4 metabolic pathway. These results highlight the influence that both species and subtype can have on plant responses to abiotic stress, building on our mechanistic understanding of acclimation within C4 grasses and highlighting avenues for future crop improvements.

The draft genome of Actinia tenebrosa reveals insights into toxin evolution.

Sea anemones have a wide array of toxic compounds (peptide toxins found in their venom) which have potential uses as therapeutics. To date, the majority of studies characterizing toxins in sea anemones have been restricted to species from the superfamily, Actinioidea. No highly complete draft genomes are currently available for this superfamily, however, highlighting our limited understanding of the genes encoding toxins in this important group. Here we have sequenced, assembled, and annotated a draft genome for Actinia tenebrosa. The genome is estimated to be approximately 255 megabases, with 31,556 protein-coding genes. Quality metrics revealed that this draft genome matches the quality and completeness of other model cnidarian genomes, including Nematostella, Hydra, and Acropora. Phylogenomic analyses revealed strong conservation of the Cnidaria and Hexacorallia core-gene set. However, we found that lineage-specific gene families have undergone significant expansion events compared with shared gene families. Enrichment analysis performed for both gene ontologies, and protein domains revealed that genes encoding toxins contribute to a significant proportion of the lineage-specific genes and gene families. The results make clear that the draft genome of A. tenebrosa will provide insight into the evolution of toxins and lineage-specific genes, and provide an important resource for the discovery of novel biological compounds.

Investigating the NAD-ME biochemical pathway within C4 grasses using transcript and amino acid variation in C4 photosynthetic genes.

Expanding knowledge of the C4 photosynthetic pathway can provide key information to aid biological improvements to crop photosynthesis and yield. While the C4 NADP-ME pathway is well characterised, there is increasing agricultural and bioengineering interest in the comparably understudied NAD-ME and PEPCK pathways. Within this study, a systematic identification of key differences across species has allowed us to investigate the evolution of C4-recruited genes in one C3 and eleven C4 grasses (Poaceae) spanning two independent origins of C4 photosynthesis. We present evidence for C4-specific paralogs of NAD-malic enzyme 2, MPC1 and MPC2 (mitochondrial pyruvate carriers) via increased transcript abundance and associated rates of evolution, implicating them as genes recruited to perform C4 photosynthesis within NAD-ME and PEPCK subtypes. We then investigate the localisation of AspAT across subtypes, using novel and published evidence to place AspAT3 in both the cytosol and peroxisome. Finally, these findings are integrated with transcript abundance of previously identified C4 genes to provide an updated model for C4 grass NAD-ME and PEPCK photosynthesis. This updated model allows us to develop on the current understanding of NAD-ME and PEPCK photosynthesis in grasses, bolstering our efforts to understand the evolutionary 'path to C4' and improve C4 photosynthesis.

Draft Genome Sequence of the Fungus Lecanicillium psalliotae Strain HWLR35, Isolated from a Wheat Leaf Infected with Leaf Rust (Caused by Puccinia triticina).

Lecanicillium psalliotae is an entomopathogenic, mycoparasitical, and nematophagous fungus known to produce antibiotic and antifungal compounds. Here, we report the first 36-Mb draft genome sequence of L. psalliotae strain HWLR35. The draft genome contains 197 scaffolds and is predicted to have 11,009 protein-coding genes.

Contemporary evolution of a Lepidopteran species, Heliothis virescens, in response to modern agricultural practices.

Adaptation to human-induced environmental change has the potential to profoundly influence the genomic architecture of affected species. This is particularly true in agricultural ecosystems, where anthropogenic selection pressure is strong. Heliothis virescens primarily feeds on cotton in its larval stages, and US populations have been declining since the widespread planting of transgenic cotton, which endogenously expresses proteins derived from Bacillus thuringiensis (Bt). No physiological adaptation to Bt toxin has been found in the field, so adaptation in this altered environment could involve (i) shifts in host plant selection mechanisms to avoid cotton, (ii) changes in detoxification mechanisms required for cotton-feeding vs. feeding on other hosts or (iii) loss of resistance to previously used management practices including insecticides. Here, we begin to address whether such changes occurred in H. virescens populations between 1997 and 2012, as Bt-cotton cultivation spread through the agricultural landscape. For our study, we produced an H. virescens genome assembly and used this in concert with a ddRAD-seq-enabled genome scan to identify loci with significant allele frequency changes over the 15-year period. Genetic changes at a previously described H. virescens insecticide target of selection were detectable in our genome scan and increased our confidence in this methodology. Additional loci were also detected as being under selection, and we quantified the selection strength required to elicit observed allele frequency changes at each locus. Potential contributions of genes near loci under selection to adaptive phenotypes in the H. virescens cotton system are discussed.

Complex modular architecture around a simple toolkit of wing pattern genes.

Identifying the genomic changes that control morphological variation and understanding how they generate diversity is a major goal of evolutionary biology. In Heliconius butterflies, a small number of genes control the development of diverse wing color patterns. Here, we used full genome sequencing of individuals across the Heliconius erato radiation and closely related species to characterize genomic variation associated with wing pattern diversity. We show that variation around color pattern genes is highly modular, with narrow genomic intervals associated with specific differences in color and pattern. This modular architecture explains the diversity of color patterns and provides a flexible mechanism for rapid morphological diversification.

The whole genome sequence of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), reveals insights into the biology and adaptive evolution of a highly invasive pest species.

BACKGROUND: The Mediterranean fruit fly (medfly), Ceratitis capitata, is a major destructive insect pest due to its broad host range, which includes hundreds of fruits and vegetables. It exhibits a unique ability to invade and adapt to ecological niches throughout tropical and subtropical regions of the world, though medfly infestations have been prevented and controlled by the sterile insect technique (SIT) as part of integrated pest management programs (IPMs). The genetic analysis and manipulation of medfly has been subject to intensive study in an effort to improve SIT efficacy and other aspects of IPM control. RESULTS: The 479 Mb medfly genome is sequenced from adult flies from lines inbred for 20 generations. A high-quality assembly is achieved having a contig N50 of 45.7 kb and scaffold N50 of 4.06 Mb. In-depth curation of more than 1800 messenger RNAs shows specific gene expansions that can be related to invasiveness and host adaptation, including gene families for chemoreception, toxin and insecticide metabolism, cuticle proteins, opsins, and aquaporins. We identify genes relevant to IPM control, including those required to improve SIT. CONCLUSIONS: The medfly genome sequence provides critical insights into the biology of one of the most serious and widespread agricultural pests. This knowledge should significantly advance the means of controlling the size and invasive potential of medfly populations. Its close relationship to Drosophila, and other insect species important to agriculture and human health, will further comparative functional and structural studies of insect genomes that should broaden our understanding of gene family evolution.