Drosophilidae Research Articles

Pore-forming toxin-like proteins in the anti-parasitoid immune response of Drosophila.

Species of the ananassae subgroup of Drosophilidae are highly resistant to parasitoid wasp infections. We have previously shown that the genes encoding Cytolethal Distending Toxin B (CdtB) and the Apoptosis Inducing Protein of 56 kDa (AIP56) were horizontally transferred to these fly species from prokaryotes and are now instrumental in the anti-parasitoid immune defense of Drosophila ananassae. Here we describe a new family of genes, which encode proteins with Hemolysin E domains, heretofore only identified in prokaryotes. Hemolysin E proteins are pore-forming toxins, important virulence factors of bacteria. Bioinformatical, transcriptional and protein expressional studies were used. The hemolysin E-like genes have a scattered distribution among the genomes of species belonging to several different monophyletic lineages in the family Drosophilidae. We detected structural homology with the bacterial Hemolysin E toxins and showed that the origin of the D. ananassae hemolysin E-like genes (hl1-38) is consistent with prokaryotic horizontal gene transfer. These genes encode humoral factors, secreted into the hemolymph by the fat body and hemocytes. Their expression is induced solely by parasitoid infection and the proteins bind to the developing parasitoids. Hemolysin E-like proteins acquired by horizontal gene transfer and expressed by the primary immune organs may contribute to the elimination of parasitoids, as novel humoral factors in Drosophila innate immunity.

Investigations on the determination, distribution and population change of Drosophilidae (Diptera) species in cherry and peach fields in Tokat (Türkiye) province

In this study, the presence and prevalence of Drosophilidae species were studied in cherry and peach plantations of Tokat province in 2021-2022. In addition, the population of the species belonging to the family was monitored for two years in one peach and cherry plantations in central district of Tokat. According to the results, 10 species were recorded in the central district of Tokat, 9 species in Erbaa, 8 species in Turhal and 6 species in Pazar. Drosophila subobscura Collin, 1936 was the most common species in cherry and peach fields in central district of Tokat in 2021 and 2022. In Erbaa, D. subobscura was the most common species in cherry fields in 2021 and D. hydeii Sturtevant, 1921 and Scamptomyza pallida (Zetterstedt, 1847) took the first place in terms of prevalence in peach fields. In 2022, the most common species in cherry and peach fields was D. subobscura. While D. hydei was the most common species in cherry and peach plantations in Turhal in 2021, D. immigrans Sturtevant, 1921 in cherry fields, and D. subobscura in peach fields were common in 2022. In the cherry fields in Pazar, the common species was D. immigrans in 2021 and D. subobscura in 2022. D. suzukii (Matsumura, 1931), one of the important species in the family, was recorded in cherry and peach plantations in central district of Tokat and Erbaa, and in peach plantations in Turhal. D. suzukii was seen for the first time on 25.08.2021 in the cherry fields of Tokat Centre in 2021, while it could not be detected in the peach fields. In 2022, the first adult detection in cherry areas was made on 29.08.2022 and in peach areas on 08.08.2022. This study is the first detailed study on Drosophilidae family in Tokat (Türkiye) province.

Fluctuating Asymmetry Spotted Wing Drosophila (Diptera: Drosophilidae) Exposed to Sublethal Doses of Acetamiprid and Nicotine.

Long-term exposure to low concentrations of toxic substances can cause several adverse consequences ranging from molecular to morphological. Sublethal doses may also lead to increased tolerance in the offspring of surviving individuals. One of the consequences of such stress is deviations from the ideal body symmetry during development, reflected by increased levels of fluctuating asymmetry (FA). This research aimed to verify FA in the wing veins of insects belonging to the Drosophilidae family-Drosophila suzukii, a fruit pest controlled by the insecticide acetamiprid, a neonicotinoid. To determine whether FA varied depending on insecticides present in the diet, multigenerational cultures of D. suzukii were carried out on media supplemented with different concentrations (below the LC50) of two insecticides. Nicotine was used as a positive control. Fecundity decreased, the number of insects decreased, and breeding did not continue beyond the tenth generation. However, the FA level at different concentrations was similar, and high FA values were observed even at lower acetamiprid concentrations. We did not see significant changes in FA levels in subsequent generations. D. suzukii proved extremely sensitive to acetamiprid, and FA is a good index of this sensitivity.

Alpha‐amanitin tolerance of adult flies of mycophagous and nonmycophagous species in Drosophilidae

AbstractMushrooms produce a great variety of defense chemical compounds to protect themselves from fungivores. Alpha‐amanitin is one of such compounds found in some Amanita mushrooms. The present study focuses on the effect of α‐amanitin on adult survival in 17 drosophilid species including mycophagous ones from the subgenus Drosophila and the genus Hirtodrosophila and nonmycophagous ones of the subgenera Drosophila, Siphlodora and Sophophora. The results showed that all the essential fungivores and some partially mycophagous species from different lineages are tolerant to this lethal toxin at a concentration of 50 μg/mL, suggesting that the α‐amanitin tolerance may have been acquired more or less independently of the evolution of mycophagy in the family Drosophilidae.

Single-fly genome assemblies fill major phylogenomic gaps across the Drosophilidae Tree of Life.

Long-read sequencing is driving rapid progress in genome assembly across all major groups of life, including species of the family Drosophilidae, a longtime model system for genetics, genomics, and evolution. We previously developed a cost-effective hybrid Oxford Nanopore (ONT) long-read and Illumina short-read sequencing approach and used it to assemble 101 drosophilid genomes from laboratory cultures, greatly increasing the number of genome assemblies for this taxonomic group. The next major challenge is to address the laboratory culture bias in taxon sampling by sequencing genomes of species that cannot easily be reared in the lab. Here, we build upon our previous methods to perform amplification-free ONT sequencing of single wild flies obtained either directly from the field or from ethanol-preserved specimens in museum collections, greatly improving the representation of lesser studied drosophilid taxa in whole-genome data. Using Illumina Novaseq X Plus and ONT P2 sequencers with R10.4.1 chemistry, we set a new benchmark for inexpensive hybrid genome assembly at US $150 per genome while assembling genomes from as little as 35 ng of genomic DNA from a single fly. We present 183 new genome assemblies for 179 species as a resource for drosophilid systematics, phylogenetics, and comparative genomics. Of these genomes, 62 are from pooled lab strains and 121 from single adult flies. Despite the sample limitations of working with small insects, most single-fly diploid assemblies are comparable in contiguity (>1 Mb contig N50), completeness (>98% complete dipteran BUSCOs), and accuracy (>QV40 genome-wide with ONT R10.4.1) to assemblies from inbred lines. We present a well-resolved multi-locus phylogeny for 360 drosophilid and 4 outgroup species encompassing all publicly available (as of August 2023) genomes for this group. Finally, we present a Progressive Cactus whole-genome, reference-free alignment built from a subset of 298 suitably high-quality drosophilid genomes. The new assemblies and alignment, along with updated laboratory protocols and computational pipelines, are released as an open resource and as a tool for studying evolution at the scale of an entire insect family.

Insights into the evolution of herbivory from a leaf-mining fly.

Herbivorous insects and their host plants comprise most known species on Earth. Illuminating how herbivory repeatedly evolved in insects from non-herbivorous lineages is critical to understanding how this biodiversity is created and maintained. We characterized the trophic niche of Scaptomyza flava, a representative of a lineage nested within the Drosophila that transitioned to herbivory ~10-15 million years ago. We used natural history studies to determine if S. flava is a true herbivore or a cryptic microbe-feeder, given that the ancestral character state for the family Drosophilidae is likely microbe-feeding. Specifically, we quantified oviposition substrate choice and larval viability across food-types, trophic-related morphological traits, and nitrogen isotope and sterol profiles across putatively herbivorous and non-herbivorous drosophilids. The results of these studies show that S. flava is an obligate herbivore of living plants. Paired with its genetic model host, Arabidopsis thaliana, S. flava is a novel and powerful system for exploring mechanisms underlying the evolution of herbivory, a complex trait that enabled the exceptional diversification of insects.

Patterns and Population Dynamics of Inversion Polymorphism in different Species of Drosophila

The structural and numerical aberrations are known to occur in different species of plants and animals including humans. Paracentic inversions in Drosophila, pericentric inversions in grasshoppers, trananslocations in Oenothera lamarckian and polyploidy in plants have been studied in detail. The genus Drosophiala is an interesting biological model which belongs to the family Drosophilidae (Class-Insecta and Order-Diptera) characterised by rich species diversity at global level and also in India. More than 1500 species have been rereported at global levl and about 150 species from India. Inversions were detected about hundred years ago in Drosophila melanogaster through their suppressive effects on recombination by Sturtevant. Inversion polymorphism caused due to paracentic inversions have been studied in a lage number of species and about 100 species have been found to be chromosomally polymorphic. Inversions polymorphism has been studied in detail in certain species with respect to the patterns and population dynamics of inversion polymorphis. In this article, briefly the patterns and population dynamics of inversion polymorphism have been described in certain species. In several cases, it has been found that inversions are adaptive. But the precise selective mechanisms that maintain them polymorphic in naturlal populations remains poorly uderstood and it has been suggested by molecular evolutionary biologists that recent advances in the area of population genomics, modelling and functional genetics promise to geatly improve our uderstanging of this long standing and fundamental problem in the near future.

Diptera Pests Occurring on Vegetable Crops in Poland

Abstract In Poland, the share of Diptera in the species composition of the harmful entomofauna occurring on vegetable crops ranges from 20 to 25%. They occur on all vegetables grown in Poland (over 80 species and botanical varieties). Since the systematic registration of pests inhabiting crops in Poland in 1919, over 70 species of flies have been listed as pests of vegetable plants. Species from three families dominate in terms of population and numbers: Anthomyiidae with 12 species (Delia radicum, on early and late cultivars of cruciferous vegetables, mainly broccoli, cauliflower, white cabbage, kohlrabi, and radishes; Delia platura occurs annually on bean and cucumber; Delia antiqua on onion and garlic; and Pegomya hyoscyami on beetroot), Cecidomyiidae with 10 species (two species dominate, Contarinia nasturtii and Dasineura napi, on cruciferous vegetables), and Agromyzidae with 23 species (Liriomyza bryoniae on cucumbers, tomatoes, and peppers, and Phytomyza gymnostoma on leeks). Short-term, gradational occurrence of some dominant species was found, including Botanophila gnava (lettuce), Chamaepsila rosae (carrot, parsley), Delia platura (asparagus, bean), Delia radicum (broccoli, cauliflower, kohlrabi, radishes, white cabbage), Phytomyza gymnostoma (leek), Oscinella frit (corn), and Suillia lurida (garlic). However, they did not affect the level of plant production in the following years of cultivation. Apart from phytophagous species, taxa with a different trophic structure are common. These are copro-, necro-, sapro-, and zoophagous species. The most numerous were flies from the Drosophilidae family (Drosophila busckii, Drosophila limbata, Scaptomyza pallida, Fanniidae (Fannia canicularis, Fannia scalaris), Heleomyzidae (Tephrochlamys tarsalis), and Muscidae (Muscina levida, Muscina stabulans, Phaonia trimaculata). Natural enemies of insects play an important role in vegetable agrocenoses. Species belonging to the order of Coleoptera beetles (Carabidae and Staphylinidae), Syrphidae, Tachinidae, and Muscidae, mainly Phaonia trimaculata larvae, play the most important role in reducing the number of Diptera. In addition, the number of phytophages is limited by other organisms, e.g., Diplopoda, Nematoda, Arachnida, and pathogens of viral, bacterial, and fungal origin.

Molecular Identification of Three Species of Leaf Miners from the Order Diptera on Brassicaceae Crops in Basra Governorate

The leafminer (Order: Diptera) is an insect that can be found throughout the Middle East and many other parts of the world. It feeds on a range of plants. It was discovered on several Brassicaceae family leaves in Iraq. In this study, the leafminer samples were collected from the Agricultural Experimental Station – the University of Basrah campus. These samples were microscopically analysed and morphologically characterized to distinguish leafminer genera. Our results revealed that the Agromyzidae family included two species Liriomyza sativae, and Chromatomyia horticola. While the Drosophilidae family involved Scaptomyza flava. These three genera belong to the 420 bases pair. For both intra- and interspecific variation, the mitochondrial region’s COX area has been thoroughly investigated. The results of all these studies combine to create a sizable collection of sequencing data for the Agromyzidae and Drosophilidae families.

Skeleton phylogeny reconstructed with transcriptomes for the tribe Drosophilini (Diptera: Drosophilidae)

The family Drosophilidae is one of the most important model systems in evolutionary biology. Thanks to advances in high-throughput sequencing technology, a number of molecular phylogenetic analyses have been undertaken by using large data sets of many genes and many species sampled across this family. Especially, recent analyses using genome sequences have depicted the family-wide skeleton phylogeny with high confidence. However, the taxon sampling is still insufficient for minor lineages and non-Drosophila genera. In this study, we carried out phylogenetic analyses using a large number of transcriptome-based nucleotide sequences, focusing on the largest, core tribe Drosophilini in the Drosophilidae. In our analyses, some noise factors against phylogenetic reconstruction were taken into account by removing putative paralogy from the datasets and examining the effects of missing data, i.e. gene occupancy and site coverage, and incomplete lineage sorting. The inferred phylogeny has newly resolved the following phylogenetic positions/relationships at the genomic scale: (i) the monophyly of the subgenus Siphlodora including Zaprionus flavofasciatus to be transferred therein; (ii) the paraphyly of the robusta and melanica species groups within a clade comprised of the robusta, melanica and quadrisetata groups and Z. flavofasciatus; (iii) Drosophila curviceps (representing the curviceps group), D. annulipes (the quadrilineata subgroup of the immigrans group) and D. maculinotata clustered into a clade sister to the Idiomyia + Scaptomyza clade, forming together the expanded Hawaiian drosophilid lineage; (iv) Dichaetophora tenuicauda (representing the lineage comprised of the Zygothrica genus group and Dichaetophora) placed as the sister to the clade of the expanded Hawaiian drosophilid lineage and Siphlodora; and (v) relationships of the subgenus Drosophila and the genus Zaprionus as follows: (Zaprionus, (the quadrilineata subgroup, ((D. sternopleuralis, the immigrans group proper), (the quinaria radiation, the tripunctata radiation)))). These results are to be incorporated into the so-far published phylogenomic tree as a backbone (constraint) tree for grafting much more species based on sequences of a limited number of genes. Such a comprehensive, highly confident phylogenetic tree with extensive and dense taxon sampling will provide an essential framework for comparative studies of the Drosophilidae.

Detecting natural selection in trait-trait coevolution

No phenotypic trait evolves independently of all other traits, but the cause of trait-trait coevolution is poorly understood. While the coevolution could arise simply from pleiotropic mutations that simultaneously affect the traits concerned, it could also result from multivariate natural selection favoring certain trait relationships. To gain a general mechanistic understanding of trait-trait coevolution, we examine the evolution of 220 cell morphology traits across 16 natural strains of the yeast Saccharomyces cerevisiae and the evolution of 24 wing morphology traits across 110 fly species of the family Drosophilidae, along with the variations of these traits among gene deletion or mutation accumulation lines (a.k.a. mutants). For numerous trait pairs, the phenotypic correlation among evolutionary lineages differs significantly from that among mutants. Specifically, we find hundreds of cases where the evolutionary correlation between traits is strengthened or reversed relative to the mutational correlation, which, according to our population genetic simulation, is likely caused by multivariate selection. Furthermore, we detect selection for enhanced modularity of the yeast traits analyzed. Together, these results demonstrate that trait-trait coevolution is shaped by natural selection and suggest that the pleiotropic structure of mutation is not optimal. Because the morphological traits analyzed here are chosen largely because of their measurability and thereby are not expected to be biased with regard to natural selection, our conclusion is likely general.

A review of the entomofauna associated with decaying cacti in New World deserts

Abstract Cactus species are well represented in arid and semiarid environments, where they sometimes even dominate the landscape, forming true cactus forests. In this review, we summarize for the first time the importance of cactus species as a wood resource for a neglected saproxylic (dead wood-dependent) entomofauna associated with decomposing and decomposed tissues in arid and semiarid environments. The complex decomposition process of cactus species is discussed in depth. We provide a checklist of the entomofauna living in decaying and decayed cacti, in which insects represented 93% of the species recorded. In particular, Coleoptera (41.5%) and Diptera (43.8%) orders together represented 85% of the insect species recorded. The family Drosophilidae made up 50% of studied Diptera species because the drosophilid–cactus–yeast complex has been widely studied during recent decades. However, we found that during the last 2 decades, there has been increasing interest in investigating the diversity of arthropods in this saproxylic habitat in Mexico, with a special focus on Syrphidae (Diptera) and Coleoptera, the former for their role in the decomposition process. Disentangling the role of the insects associated with decaying cactus is a challenge when it comes to understanding the function of xeric saprophagous insects in this environment. One frontier in this research area is to find whether decomposed stems in xeric soils would act as “islands” of fertility due to the amount of nitrogen which could be recuperated from these microecosystems. Further research is needed to understand the ecological succession of the entomofauna playing a role in the decomposition process of cactus species in semiarid environments.

Phylogenetic classification and palm-inflorescence anthophily of the Colocasiomyia zeylanica species group (Diptera: Drosophilidae), with descriptions of five new species.

The zeylanica group is one of the six species groups of the anthophilic genus Colocasiomyia de Meijere in the family Drosophilidae. In addition to two known species, five morphospecies have been recognized as members of this species group but left undescribed formally. In this study, species delimitation of these putatively new species was determined by barcoding of the mitochondrial COI (cytochrome c oxydase subunit I) gene and morphological comparison. Phylogenetic relationships within the genus Colocasiomyia were inferred by a cladistic analysis of 89 morphological characters. Based on the results of these analyses, we redefined the zeylanica species group and established two subgroups within it: the zeylanica subgroup comprised of C. zeylanica, C. nepalensis, C. pinangae sp. nov., C. besaris sp. nov. and C. luciphila sp. nov., and the oligochaeta subgroup of C. oligochaeta sp. nov. and C. grimaldii sp. nov. In addition, we briefly address the anthophilic habits of drosophilid flies using palm (Arecaceae) inflorescences, especially of the zeylanica group, compiling scattered collection records from the Oriental and Papuan regions.

Larva morphology of shore flies <i>Ephydra riparia</i> and <i>Paracoenia fumosa</i> (Diptera: Ephydridae) and adaptation of Diptera to increased salinity

Larvae of many shore fly species (family Ephydridae) are adapted to living in water with high or extremely high salinity. Little is known about the morphological and physiological foundations of such adaptation. We described the details of the morphology of third-instar larvae of two shore flies: Ephydra riparia and Paracoenia fumosa and presented the scanning electron microscopy (SEM) images. For the first time, by silver-staining and SEM, we proved that the larvae of both studied species had anal organs (AO) – specialized structures that serve an osmoregulatory function and are responsible for the transport of ions from the environment to the larval hemolymph (but not in the opposite direction). We compared the larvae morphology of the studied species with some other shore fly species from the genera Ephydra, Paracoenia, Hydrellia, and Coenia, as well as with larvae of the model species Drosophila melanogaster (family Drosophilidae). Special attention was paid to the morphology of AO, which contribute to the adaptation of larvae to increased salinity. Extremely halophilic species either do not have AO, or they are poorly developed, while moderately halophilic shore flies have more developed features connected with the permeability of the AO cuticle and active ion transport. These features are most developed in freshwater shore flies. AO activity can vary due to the shape and area of the AO, the smoothness or wrinkling of the cuticle, and the presence of nanoscale pits on it. Described variability of AO structure is probably adaptive since, at high salinity, both the permeability of the AO cuticle and the active transport of ions from the environment to the hemolymph become less beneficial or even harmful.

Effect of Celery (Apium graveolens L.) Microgreens on Drosophila melanogaster

Celery (Apium graveolens L. ; family : Apiaceae) was often used as a spice in daily food. However, this plant contains many antioxidant compounds useful for attenuating neurodegenerative disorders including Parkinson's disease. Planting celery in the form of microgreens harvested 15 days was expected to increase the content of bioactive compounds. In the current study, we intended to evaluate the neuromodulatory potential of methanol extract of celery microgreens on fruit flies (Drosophila melanogaster Meigen : family Drosophilidae ; ordo : Diptera) which were exposed to paraquat. Neuroprotective capacity was assessed by survival rate, locomotor performance, lipid peroxidation and dopamine content after being treated with 120 µg/mL extract of celery microgreens and 3.5 mM paraquat for 4 days. Phytochemical constituents from extract of celery microgreens were measured including total polyphenol content and antioxidant activity using the radicals scavenging method. Exposure of adult fruit flies to paraquat will cause a decrease in the survival and locomotor phenotype improved by extract of celery microgreens treatment. In parallel, increased malondialdehyde content from lipid peroxidation and decreased dopamine content can be improved by the presence of celery microgreens extract. Neuroprotective capacities indicate a high content of antioxidant compounds of celery microgreens extract. Our study concludes that celery microgreens exhibited to retard the effect of oxidative stress that causes Parkinson's disease.

The P-element Has Not Significant Effect on the <i>Drosophila simulans</i> Viability

Cases of horizontal transfer of transposable elements (TEs) between species are known for the Drosophilidae family. In the middle of the last century, the case of horizontal transfer of the P-element from the Drosophila willistoni to the D. melanogaster was described. A novel P-element invasion into the D. simulans genome from D. melanogaster occurred approximately 10 years ago. Currently, the P-element has spread across all D. melanogaster population and 30% of D. simulans populations in Europe, Africa and America. In this paper, we investigated the presence of the P-element in D. simulans lines caught in different years in three Asian populations (Tashkent, Nalchik and Sakhalin Island). We also examined the physiological characteristics (cytotype, lifespan, fecundity and locomotor activity) of D. simulans lines with and without the P-element to determine the significance of this new mobile element in the genome. The P-element was found in lines isolated from nature after 2012. The number of P-element copies per genome (two-to-three dozen according to fluorescence in situ hybridization data) was greater than in the American and comparable to the African populations. There were signs of intraspecific hybrid dysgenesis for some pairs of lines. However, in general the presence of the P-element did not adversely affect the physiological characteristics. Either adaptation to the new TE occurs very quickly, or the rate of movement of the P-element is so insignificant that its appearance in the genome remains unnoticed.

The P-Element Has Not Significant Effect on the Drosophila simulans Viability

Cases of horizontal transfer of transposable elements (TEs) between species are known for the Drosophilidae family. In the middle of the last century, the case of horizontal transfer of the P-element from the Drosophila willistoni to the D. melanogaster was described. A novel P-element invasion into the D. simulans genome from D. melanogaster occurred approximately 10 years ago. Currently, the P-element has spread across all D. melanogaster population and 30% of D. simulans populations in Europe, Africa and America. In this paper, we investigated the presence of the P-element in D. simulans lines caught in different years in three Asian populations (Tashkent, Nalchik and Sakhalin Island). We also examined the physiological characteristics (cytotype, lifespan, fecundity and locomotor activity) of D. simulans lines with and without the P-element to determine the significance of this new mobile element in the genome. The P-element was found in lines isolated from nature after 2012. The number of P-element copies per genome (two-to-three dozen according to fluorescence in situ hybridization data) was greater than in the American and comparable to the African populations. There were signs of intraspecific hybrid dysgenesis for some pairs of lines. However, in general the presence of the P-element did not adversely affect the physiological characteristics. Either adaptation to the new TE occurs very quickly, or the rate of movement of the P-element is so insignificant that its appearance in the genome remains unnoticed.

Whole mitochondrial genome phylogeny of Drosophilidae

A total of 241 mitochondrial genomes were assembled and annotated from the SRA database to reconstruct a mtDNA genome phylogeny for the genus Drosophila, the family Drosophilidae, and close relatives. The resulting mtDNA genome phylogeny is largely congruent with previous higher-level analyses of Drosophila species with the exception of the relationships between the melanogaster, montium, anannassae, saltans and obscura groups. Although relationships within these species groups are congruent between nuclear and mtDNA studies, the mtDNA genome phylogeny of the groups is different when compared to earlier studies. Monophyly of known species groups within the genus Drosophila are highly supported and, as in previous work, the genera Lordiphosa, Hirtodrosophila, Zaprionus and Scaptomya are all imbedded within the genus Drosophila. Incongruence and partitioned support analyses indicate that DNA sequences are better at resolving the phylogeny than their translated protein sequences. Such analyses also indicate that genes on the minus strand of the circular molecule (Lrrna, Srrna, ND4, ND4L and ND5) provide most of the support for the overall phylogenetic hypothesis.

Evolution and development of male-specific leg brushes in Drosophilidae.

The origin, diversification, and secondary loss of sexually dimorphic characters are common in animal evolution. In some cases, structurally and functionally similar traits have evolved independently in multiple lineages. Prominent examples of such traits include the male-specific grasping structures that develop on the front legs of many dipteran insects. In this report, we describe the evolution and development of one of these structures, the male-specific "sex brush." The sex brush is composed of densely packed, irregularly arranged modified bristles and is found in several distantly related lineages in the family Drosophilidae. Phylogenetic analysis using 250 genes from over 200 species provides modest support for a single origin of the sex brush followed by many secondary losses; however, independent origins of the sex brush cannot be ruled out completely. We show that sex brushes develop in very similar ways in all brush-bearing lineages. The dense packing of brush hairs is explained by the specification of bristle precursor cells at a near-maximum density permitted by the lateral inhibition mechanism, as well as by the reduced size of the surrounding epithelial cells. In contrast to the female and the ancestral male condition, where bristles are arranged in stereotypical, precisely spaced rows, cell migration does not contribute appreciably to the formation of the sex brush. The complex phylogenetic history of the sex brush can make it a valuable model for investigating coevolution of sex-specific morphology and mating behavior.

First record of the genus Acletoxenus (Diptera: Drosophilidae) and its predaceous species A. formosus (Leow, 1864) in Egypt, with some field observations and biological remarks

BackgroundThe genus Acletoxenus (tribe Gitonini, subfamily Steganinae, family Drosophilidae) is a small widespread genus, comprising only four species worldwide, namely: Acletoxenus indicus Malloch, 1929, A. quadristriatus Duda, 1936, A. meijerei Duda, 1924 in addition to A. formosus (Leow, 1864), the species of the present study. The larvae of Acletoxenus spp. are known as predators of whiteflies.ResultsThe genus Acletoxenus and its predaceous species A. formosus (Leow, 1864) are recorded in the present study for the first time from Egypt. This species was found associated with the immature stages of the glasshouse whitefly, Trialeurodes vaporariorum Westwood, 1856 (Hemiptera: Aleyrodidae) feeding on the castor bean plant, Ricinus communis L. which has been grown at the Plant Protection Institute, Agricultural Research Center, Giza, Egypt. The morphological diagnoses, in situ predatory behavior in the field and ex situ biological remarks in the laboratory were discussed.ConclusionThe predaceous drosophilid fly, Acletoxenus formosus (Leow, 1864), is recorded herein with its genus for the first time from Egypt as the second representative of the tribe Gitonini (subfamilies Steganinae, family Drosophilidae) in the country. The recording of this species in Egypt is of a great interest as it will encourage and lead to further research on different biological aspects. This drosophilid is a beneficial fly as its larvae are predators of immature stages of whiteflies (family Aleyrodidae) and it could be used as a potential biological control agent.