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hydei Sturtevant Drosophila hydei Sturtevant, 1921: 101. Drosophila (Drosophila) hydei: Carson et al. 1983: 241 [records]; Peck et al. 1998: 228 [introduced species]; Causton et al. 2006: 133 [introduced species]. Distribution. Introduced. Cosmopolitan; Galápagos: Isabela, Santa Cruz. Remarks. Adults of this species were most common in humid highlands (Carson et al. 1983)., Published as part of Sinclair, Bradley J., 2023, An annotated checklist of the Diptera of the Galápagos Archipelago (Ecuador), pp. 1-102 in Zootaxa 5283 (1) on page 55, DOI: 10.11646/zootaxa.5283.1.1, http://zenodo.org/record/7912667, {"references":["Sturtevant, A. H. (1921) The North American species of Drosophila. Carnegie Institution of Washington Publication, No. 301, 1 - 150. https: // doi. org / 10.5962 / bhl. title. 10480","Carson, H. L., Val, F. C. & Wheeler, M. R. (1983) Drosophilidae of the Galapagos Islands, with descriptions of two new species. International Journal of Entomology, 25 (4), 239 - 248.","Peck, S. B., Heraty, J., Landry, B. & Sinclair, B. J. (1998) Introduced insect fauna of an oceanic archipelago: the Galapagos Islands, Ecuador. American Entomologist, 44 (4), 218 - 237. https: // doi. org / 10.1093 / ae / 44.4.218","Causton, C. E., Peck, S. B., Sinclair, B. J., Roque-Albelo, L., Hodgson, C. J. & Landry, B. (2006) Alien insects: threats and implications for conservation of Galapagos Islands. Annals of Entomological Society of America, 99 (1), 121 - 143. https: // doi. org / 10.1603 / 0013 - 8746 (2006) 099 [0121: AITAIF] 2.0. CO; 2"]}

Drosophila hydei Sturtevant, 1921 Synonyms: Drosophila marmoria Hutton, 1901; Drosophila hydei yucatanensis Spencer, 1940; Drosophila setosa Dobzhansky and Pavan, 1943 Distribution: Adventive: Hawaii, Maui, Molokai, Lanai, Oahu, Kauai. Extralimital: Cosmopolitan Additional References: Heed (1968); Momma (1968); Sturtevant (1921); Swezey (1952), Published as part of Rampasso, Augusto Santos & O'Grady, Patrick Michael, 2022, Distribution and Taxonomy of Endemic and Introduced Drosophilidae in Hawaii, pp. 1-80 in Zootaxa 5106 (1) on page 11, DOI: 10.11646/zootaxa.5106.1.1, http://zenodo.org/record/6336841, {"references":["Sturtevant, A. H. (1921) The North American species of Drosophila. Carnegie Institution of Washington Publication, 301, 1 - 150. https: // doi. org / 10.5962 / bhl. title. 33564","Hutton, F. W. (1901) Synopsis of the Diptera brachycera of New Zealand. Transactions and Proceedings of the New Zealand Institute, 33, 1 - 95.","Spencer, W. P. (1940) Subspecies, hybrids and speciation in Drosophila hydei and Drosophila virilis. American Naturalist, 74, 157 - 179. https: // doi. org / 10.1086 / 280882","Dobzhansky, T. & Pavan, C. (1943) Studies on Brazilian species of Drosophila. Boletim. Faculdade de Filosofia, Ciencias e Letras, Universidade de Sao Paulo, 36, 7 - 72.","Heed, W. B. (1968) Ecology of the Hawaiian Drosophila. The University of Texas Publications, 6818, 387 - 419.","Momma, E. (1968) Domestic Drosophila in Hawaii. Drosophila Information Service, 43, 168.","Swezey, O. H. (1952) Note: Insects from decaying blossoms. Proceedings of the Hawaiian Entomological Society, 14, 357."]}

Spiroplasma are a group of Mollicutes whose members include plant pathogens, insect pathogens, and endosymbionts of animals. Spiroplasma phenotypes have been repeatedly observed to be spontaneously lost in Drosophila cultures, and several studies have documented a high genomic turnover in Spiroplasma symbionts and plant pathogens. These observations suggest that Spiroplasma evolves quickly in comparison to other insect symbionts. Here, we systematically assess evolutionary rates and patterns of Spiroplasma poulsonii, a natural symbiont of Drosophila. We analysed genomic evolution of sHy within flies, and sMel within in vitro culture over several years. We observed that S. poulsonii substitution rates are among the highest reported for any bacteria, and around two orders of magnitude higher compared with other inherited arthropod endosymbionts. The absence of mismatch repair loci mutS and mutL is conserved across Spiroplasma and likely contributes to elevated substitution rates. Further, the closely related strains sMel and sHy (>99.5% sequence identity in shared loci) show extensive structural genomic differences, which potentially indicates a higher degree of host adaptation in sHy, a protective symbiont of Drosophila hydei. Finally, comparison across diverse Spiroplasma lineages confirms previous reports of dynamic evolution of toxins, and identifies loci similar to the male-killing toxin Spaid in several Spiroplasma lineages and other endosymbionts. Overall, our results highlight the peculiar nature of Spiroplasma genome evolution, which may explain unusual features of its evolutionary ecology.

The outcome of natural enemy attack in insects has commonly been found to be influenced by the presence of protective symbionts in the host. The degree to which protection functions in natural populations, however, will depend on the robustness of the phenotype to variation in the abiotic environment. We studied the impact of a key environmental parameter – temperature – on the efficacy of the protective effect of the symbiont Spiroplasma on its host Drosophila hydei, against attack by the parasitoid wasp Leptopilina heterotoma. In addition, we investigated the thermal sensitivity of the symbiont’s vertical transmission, which may be a key determinant of the ability of the symbiont to persist. We found that vertical transmission was more robust than previously considered, with Spiroplasma being maintained at 25 °C, 18 °C and with 18/15 °C diurnal cycles, with rates of segregational loss only increasing at 15 °C. Protection against wasp attack was ablated before symbiont transmission was lost, with the symbiont failing to rescue the fly host at 18 °C. We conclude that the presence of a protective symbiosis in natural populations cannot be simply inferred from presence of a symbiont whose protective capacity has been tested under narrow controlled conditions. More broadly, we argue that the thermal environment is likely to represent an important determinant of the evolutionary ecology of defensive symbioses in natural environments, potentially driving seasonal, latitudinal and altitudinal variation in symbiont frequency, and modulating the strength of selection for symbiotic protective systems compared to defensive systems encoded in the nuclear genomes.

Maternally-transmitted endosymbiotic bacteria are ubiquitous in insects. Among other influential phenotypes, many heritable symbionts of arthropods are notorious for manipulating host reproduction through one of four reproductive syndromes, which are generally exerted during early developmental stages of the host: male feminization; parthenogenesis induction; male killing; and cytoplasmic incompatibility (CI). Major advances have been achieved in understanding mechanisms and identifying symbiont factors involved in reproductive manipulation, particularly male killing and cytoplasmic incompatibility. Nonetheless, whether cytoplasmically-transmitted bacteria influence the maternally-loaded components of the egg or early embryo has not been examined. In the present study, we investigated whether heritable endosymbionts that cause different reproductive phenotypes in Drosophila melanogaster influence the mRNA transcriptome of early embryos. We used mRNA-seq to evaluate differential expression in Drosophila embryos lacking endosymbionts (control) to those harbouring the male-killing Spiroplasma poulsonii strain MSRO-Br, the CI-inducing Wolbachia strain wMel, or Spiroplasma poulsonii strain Hyd1; a strain that lacks a reproductive phenotype and is naturally associated with Drosophila hydei. We found no consistent evidence of influence of symbiont on mRNA composition of early embryos, suggesting that the reproductive manipulation mechanism does not involve alteration of maternally-loaded transcripts. In addition, we capitalized on several available mRNA-seq datasets derived from Spiroplasma-infected Drosophila melanogaster embryos, to search for signals of depurination of rRNA, consistent with the activity of Ribosome Inactivating Proteins (RIPs) encoded by Spiroplasma poulsonii. We found small but statistically significant signals of depurination of Drosophila rRNA in the Spiroplasma treatments (both strains), but not in the symbiont-free control or Wolbachia treatment, consistent with the action of RIPs. The depurination signal was slightly stronger in the treatment with the male-killing strain. This result supports a recent report that RIP-induced damage contributes to male embryo death.

Most flying animals produce aerodynamic forces by flapping their wings back and forth with a complex wingbeat pattern. The fluid dynamics that underlies this motion has been divided into separate aerodynamic mechanisms of which rotational lift, that results from fast wing pitch rotations, is particularly important for flight control and manoeuvrability. This rotational force mechanism has been modelled using Kutta–Joukowski theory, which combines the forward stroke motion of the wing with the fast pitch motion to compute forces. Recent studies, however, suggest that hovering insects can produce rotational forces at stroke reversal, without a forward motion of the wing. We have conducted a broad numerical parametric study over a range of wing morphologies and wing kinematics to show that rotational force production depends on two mechanisms: (i) conventional Kutta–Joukowski-based rotational forces, and (ii) a rotational force mechanism that enables insects with an offset of the pitch-axis relative to the wing's chordwise symmetry axis to generate rotational forces in the absence of forward wing motion. Because flying animals produce control actions frequently near stroke reversal, this pitch-axis-offset dependent aerodynamic mechanism may be particularly important for understanding control and manoeuvrability in natural flyers.

Rare carnivorous plants representing the genus Sarracenia are perceived as very interesting to scientists involved in various fields of botany, ethnobotany, entomology, phytochemistry and others. Such high interest is caused mainly by the unique capacity of Sarracenia spp. to attract insects. Therefore, an attempt to develop a protocol for micropropagation of the Sarracenia alata (Alph.Wood) Alph.Wood, commonly named yellow trumpets, and to identify the specific chemical composition of volatile compounds of this plant in vitro and ex vivo was undertaken. Thus, the chemical volatile compounds excreted by the studied plant to attract insects were recognized with the application of the headspace solid-phase microextraction (HS-SPME) coupled with the GC-MS technique. As the major volatile compounds (Z)-3-hexen-1-ol (16.48% ± 0.31), (E)-3-hexen-1-ol acetate (19.99% ± 0.01) and β-caryophyllene (11.30% ± 0.27) were identified. Further, both the chemical assumed to be responsible for attracting insects, i.e., pyridine (3.10% ± 0.07), and whole plants were used in in vivo bioassays with two insect species, namely Drosophila hydei and Acyrthosiphon pisum. The obtained results bring a new perspective on the possibilities of cultivating rare carnivorous plants in vitro since they are regarded as a valuable source of bioactive volatile compounds, as including ones with repellent or attractant activity.

Antennal sensilla and compound eyes of fruit flies, Drosophila melanogaster (Meigen), Drosophila suzukii (Matsumura), Drosophila immigrans (Sturtevant), and Drosophila hydei (Sturtevant) (all Diptera: Drosophilidae), were observed with stereoscopic microscopy and scanning electron microscopy. The results showed that the antenna consists of 3 segments: a proximal scape, a pedicel, and a flagellum composed of a funiculus and a dendritic arista. Six morphologically distinct types of sensilla were observed on the antenna: chaetica, microtrichia, trichoid (Tr I, Tr II), basiconic, clavate, and coeloconic (Co I, Co II). Basiconic sensilla were significantly shorter than other sensilla in the funiculus of D. melanogaster. The number of clavate sensillae was less than other sensilla in the funiculus of D. melanogaster and D. immigrans, but was greater in D. suzukii and D. hydei. Moreover, coeloconic sensilla were absent in D. suzukii and D. hydei. The length and abundance of the chaetica sensilla on the compound eyes were different significantly among the 4 species. Drosophila hydei had chaotic sensilla with the greatest length and abundance; they were lowest for D. suzukii. Based on the previous literature, the possible functions of these sensilla are discussed. We inferred that fruit flies may regulate their behaviors according to the information detected by these sensilla.

Drosophila (Drosophila) hydei Sturtevant, 1921 Drosophila hydei Sturtevant, 1921: 101. Holotype, male. USA (Florida: Lakeland) (MCZ). Distribution: Cosmopolitan. Egyptian localities: Coastal Strip: Alexandria. Dates of collection: March to October (B��chli et al. 1982 and Yassin & Abou-Youssef 2004)., Published as part of El-Hawagry, Magdi S., Zatwarnicki, Tadeusz & Ebrahim, Ayman M., 2018, Catalogue of the Egyptian Ephydroidea (Diptera: Schizophora: Acalyptratae), pp. 201-246 in Zootaxa 4444 (3) on page 235, DOI: 10.11646/zootaxa.4444.3.1, http://zenodo.org/record/1309626, {"references":["Sturtevant, A. H. (1921) The North American Species of Drosophila. Carnegie Institute of Washington Publication, 301, 1 - 150. https: // doi. org / 10.5962 / bhl. title. 33564","Yassin, A. & Abou-Youssef, A. Y. (2004) A new front for a global invasive drosophilid: the colonization of the Northern- Western desert of Egypt by Zaprionus indianus Gupta, 1970. Drosophila Information Service, 87, 67 - 68."]}

Background and Aims The first documented observation of pollination in Pleurothallidinae was that of Endre ́s, who noticed that the ‘viscid sepals’ of Specklinia endotrachys were visited by a ‘small fly’. Chase would later iden- tify the visiting flies as being members of the genus Drosophila. This study documents and describes how species of the S. endotrachys complex are pollinated by different Drosophila species. Methods Specimens of Specklinia and Drosophila were collected in the field in Costa Rica and preserved in the JBL and L herbaria. Flies were photographed, filmed and observed for several days during a 2-year period and were identified by a combination of non-invasive DNA barcoding and anatomical surveys. Tissue samples of the sepals, petals and labellum of Specklinia species were observed and documented by SEM, LM and TEM. Electroantennogram experiments were carried out on Drosophila hydei using the known aggregation pheromones ethyl tiglate, methyl tiglate and isopropyl tiglate. Floral compounds were analysed by gas chromatography–mass spectometry using those same pheromones as standards. Key Results Flowers of S. endotrachys, S. pfavii, S. remotiflora and S. spectabilis are visited and pollinated by several different but closely related Drosophila species. The flies are arrested by aggregation pheromones, including ethyl tiglate, methyl tiglate and isopropyl tiglate, released by the flowers, and to which at least D. hydei is very sen- sitive. Visible nectar drops on the adaxial surface of sepals are secreted by nectar-secreting stomata, encouraging male and female Drosophila to linger on the flowers for several hours at a time. The flies frequently show courtship behaviour, occasionally copulating. Several different Drosophila species can be found on a single Specklinia species. Conclusions Species of the S. endotrachys group share a similar pollination syndrome. There seem to be no spe- cies-specific relationships between the orchids and the flies. It is not expected that Specklinia species will hybridize naturally as their populations do not overlap geographically. The combination of pheromone attraction and nectar feeding is likely to be a generalized pollination syndrome in Pleurothallidinae. Ministerio del Ambiente y Energía/[]/MINAE/Costa Rica Sistema Nacional de Áreas de Conservación/[]/SINAC/Costa Rica Universidad de Costa Rica/[814-B1-239]/UCR/Costa Rica Universidad de Costa Rica/[814-B3-075]/UCR/Costa Rica UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Jardín Botánico Lankester (JBL)

Maternally transmitted endosymbionts of insects are ubiquitous in nature and play diverse roles in the ecology and evolution of their hosts. To persist in host lineages, many symbionts manipulate host reproduction to their advantage (e.g. cytoplasmic incompatibility and male-killing), or confer fitness benefits to their hosts (e.g. metabolic provisioning and defense against natural enemies). Recent studies suggest that strains of the bacterial genus Spiroplasma protect their host (flies in the genus Drosophila ) against parasitoid attack. The Spiroplasma -conferred protection is partial and flies surviving a wasp attack have reduced adult longevity and fecundity. Therefore, it is unclear whether protection against wasps alone can counter Spiroplasma loss by imperfect maternal transmission and any possible fitness costs to harboring Spiroplasma . To address this question, we conducted a population cage study comparing Spiroplasma frequencies over time (host generations) under conditions of high wasp pressure and no wasp pressure. A dramatic increase of Spiroplasma prevalence was observed under high wasp pressure. In contrast, Spiroplasma prevalence in the absence of wasps did not change significantly over time; a pattern consistent with random drift. Thus, the defensive mechanism may contribute to the high prevalence of Spiroplasma in host populations despite imperfect vertical transmission.

Parasites reduce host fitness via perturbations to host energy allocation, growth, survival, and reproduction. Here, we investigate the independent effects of parasite exposure and infection on host metabolic rate. Our study focuses on Drosophila hydei and a naturally occurring ectoparasitic mite, Macrocheles muscaedomesticae. We use flow-through respirometry to measure the metabolic rate of flies during the period of exposure (preinfection) and during mite attachment. Flies were exposed to mites either indirectly (through a mesh screen) or directly, allowing for physical contact between the fly and the mite. We predicted that fly metabolic rate would increase with the level of parasite exposure: unexposed flies < flies with indirect exposure to mites < flies with direct contact with mites < flies actively infected with mites. As expected, flies indirectly exposed to but not in direct contact with mites produced 70% more CO2 than unexposed flies. Flies in direct contact with mites produced 35% mor...

In the cosmopolitan fruit fly Drosophila hydei Sturtevant, 1921 (Diptera: Drosophilidae), the relative abundance of males is significantly higher than females, but the physiological basis of such sex-specific differences are largely unknown. For wild populations of D. hydei, we found seasonal changes (summer versus autumn) in desiccation-related traits, but the desiccation tolerance of males was higher than that of females in all seasons. For desiccation-related traits, we tested whether thermal developmental acclimation at three temperatures (17, 21, and 28 °C) matched seasonal changes observed under wild conditions. Male flies showed significantly higher trait values for desiccation resistance, cuticular lipid mass, hemolymph content, carbohydrate content, and dehydration tolerance compared with females when reared at lower or higher temperatures despite the lack of significant sex-specific differences in the total body-water content of flies reared at a particular growth temperature. We observed plastic changes in the amount of cuticular lipids consistent with corresponding differences in the rate of water loss. Treatment of cuticular surface with organic solvent (hexane) supported the role of cuticular lipids in affecting transcuticular water loss. We found significant thermal plastic effects for desiccation-related traits of D. hydei, but the sexual dimorphism was in the opposite direction, i.e., males were more desiccation resistant than females in D. hydei, whereas the reverse is true for many other Drosophila species. Our results suggest that sex-specific differences in the level of desiccation resistance in D. hydei are good predictors of relative abundance levels of male and female flies under wild conditions.

In recent years, fruit flies (Drosophila spp.: Drosophilidae) have become an increasingly serious problem for cherry production in northern China. In this study, we examined the species composition and dynamics of fruit flies in cherry orchards using lure-baited traps placed at different heights, and in 3 different cherry cultivars, from Apr through Sep 2014 to 2016 in Qingdao, Shandong Province, China. The total number of fruit flies increased from yr to yr. Four species were captured: Drosophila melanogaster Meigen, Drosophila suzukii Matsumura, Drosophila hydei Sturtevant, and Drosophila immigrans Sturtevant (all Diptera: Drosophilidae). The dominant species was D. melanogaster, with 66.7% of the total captured, followed by D. suzukii (29.7%). Drosophila hydei and D. immigrans accounted for only 3.0 and 0.6%, respectively, and for these last 2 species, no peak period in abundance was observed. In general, Drosophila spp. appeared in Apr, and peaked around mid-Jul. Over the 3 yr span of the study, peak fruit fly abundance occurred later each yr, being at the end of Jun in 2014, and in the middle of Jul in 2015 and 2016. There were significant differences in the number of Drosophila species among cherry cultivars, as well as in the number of Drosophila trapped at different heights. The cultivar maturing in the middle of the season (cv. ‘Van') attracted the most fruit flies. The optimal height for trap placement was at 1 m above ground level, which is recommended as a standard height for Drosophila spp. population monitoring.

Drosophila hydei is more abundant under colder and drier montane habitats in the western Himalayas as compared to Drosophila repleta, but the mechanistic basis of such climatic adaptation is largely unknown. In this study of two closely related Drosophila species, D. hydei and D. repleta, we examined the role of dehydration tolerance on survival under desiccating conditions. Water loss before succumbing to death (dehydration tolerance) is much higher in D. hydei (~ 74%) than D. repleta (~ 48%). Total surface lipids and percent melanisation did not differ significantly in these two species. Thus, species-specific water loss tolerance capacities are significantly correlated with varying levels of desiccation resistance. Patterns of rate of water loss do not account for contrasting levels of desiccation resistance in these two species. These differences in dehydration tolerance impact desiccation resistance and might explain their distribution pattern – why D. hydei is more abundant than D. repleta in dry ha...

A bacterium belonging to the genus Spiroplasma, an endosymbiont of the fly Drosophila hydei, is vertically transmitted through host egg cytoplasm. To infer vertical transmission rates of Spiroplasma in natural populations of D. hydei, the infection status of Spiroplasma was examined for offspring produced by Spiroplasma-positive females that were collected in two geographical populations. In both populations, nearly half of the broods consisted of only infected offspring. Infection frequencies of the rest of the broods ranged from 0.364 to 0.975. Quantitative PCR demonstrated that the Spiroplasma titers in the whole body of wild-caught females were highly variable (1.81 × 106–5.60 × 108 cells per insect). Contrary to our expectations, however, the Spiroplasma titers did not account for the variation in infection frequencies among offspring (i.e., vertical transmission rates). These results suggest that the spatial distribution of Spiroplasma, particularly in somatic tissues and germ tissues, is highly variable among host individuals, which may be caused by environmental stochasticity or some unknown effects.

Some members of the genus Spiroplasma are vertically transmitted endosymbionts of insects. Among them, Spiroplasma sp. Dhd, a member of the Spiroplasma poulsonii clade, is highly prevalent among worldwide populations of Drosophila hydei. Here we found that 53 out of 3,763 wild-caught D. hydei (1.4 %) were ectoparasitized by the mite that belong to the genus Macrocheles. Many of the ectoparasitized flies (79 %) had a single mite, but some flies had up to five mites. Among 59 mites subjected to Spiroplasma-specific PCR, 15 individuals were found to be positive. Infection status of Spiroplasma in flies and the associated mites were incongruent. Partial nucleotide sequences of the Spiroplasma P58 gene suggest that some of the mites are infected with a Spiroplasma, which is identical or closely related to Spiroplasma sp. Dhd. This finding provides a potential route of horizontal Spiroplasma transmission between D. hydei individuals in natural populations. In addition, a Spiroplasma strain that does not form a monophyletic group with S. poulsonii was also found from a mite individual.

While numerous insect studies have demonstrated the effects environmental conditions, genetic variation and other factors have on thermal resistance, often showing patterns consistent with adaptive plasticity and local adaptation, few experiments have considered the effects of multiple factors simultaneously. Here however, we have investigated the impact of sex, rearing conditions, hardening, population, and laboratory rearing period on adult heat resistance in stocks of Drosophila hydei, a cosmopolitan species that occurs across a range of climatic zones. We show that population and putative laboratory adaptation effects are larger than those associated with rearing temperature and hardening, although there was also a notable interaction between hardening and sex, in that females showed a cost of hardening that was not present in males. In separate experiments, we found that environmental effects across a generation were small and similar in magnitude to those within a generation. These findings suggest multiple sources of variation on heat resistance and place potential genetic versus environmental sources in context.

SUMMARYHeterogeneities in parasite infection among conspecific hosts often manifest as sex- or size-biased infections, which are typically attributed to differential host susceptibility and exposure. Since parasite fitness is often tied to host quality, host preference by parasites is likely to be under strong selection. We test the hypothesis that host preference is sufficient to generate variability in infection rate among conspecifics. Specifically, we ask whether the miteMacrocheles muscaedomesticaeis able to discriminate betweenDrosophila hydeihosts of different sex and size, while explicitly accounting for the potential confounding effects of these two factors. Our results indicate a preference for female hosts, but this preference appears to be driven by size and not sexper se. When differences in body size were controlled for, the sex-biased infection disappeared, while mites presented with the choice of two female flies of disparate sizes were more likely to select the larger host. Across the distribution of fly body weight in this study, mites preferentially attached to flies of intermediate size. This study provides evidence that mite choice for certain host types can play an important role in parasite transmission, even in the absence of differential susceptibility or exposure among hosts.

This article presents the results of a study investigating the biological activity of triphenyltin chloride (TPhT) and two metalloorganic compounds, triphenyllead chloride (TPhL) and triphenylmethane chloride (TPhC), in their interaction with model membranes and the living organisms of fruit flies Drosophila hydei. The study of model membranes (sonicated liposomes) was conducted using the electron spin resonance (ESR) spin probe technique, whereas the experiment on fruit flies involved investigating their viability on media containing the studied compounds. The test results clearly demonstrate that TPhT affects fruit flies more actively than TPhL (complete lethality after 7 days of culture with a TPhT-containing medium). No toxic effect of TPhC on fruit flies was shown. The results of the biological experiment were reflected in the physical experiment involving an ESR study of liposomes: TPhT activity manifested itself as a considerable increase in fluidity of the central region of the liposome lipid bilayer.

In this study, a static magnetic field influence on development and viability in two different species, Drosophila melanogaster and Drosophila hydei, was investigated. Both species completed development (egg--adult), in and out of the static magnetic field induced by double horseshoe magnet. Treated vials with eggs were placed in the gap between magnetic poles (47 mm) and exposed to the average magnetic induction of 60 mT, while control ones were kept far enough from magnetic field source. We found that exposure to the static magnetic field reduced development time in both species, but statistical significance was found only for D. hydei. Furthermore, we found that the average viability of both Drosophila species exposed to the magnetic field was significantly weaker compared to control ones. These results indicate that 60 mT static magnetic field could be considered as a potential stressor, influencing on different levels the embryonic and post-embryonic development of individuals. Ministry of Education and Science Development, Republic of Serbia [173012, 173027]

A maternally-inherited spiroplasma endosymbiont of Drosophila hydei does not exert apparent phenotypes on both sexes of its host and is prevalent in natural populations of D. hydei. Our previous experiments using a laboratory stock of D. hydei revealed that low temperatures (such as 15°C and 18°C) dramatically lower the vertical transmission rates of this spiroplasma. Therefore, we hypothesized that, in temperate regions, the infection frequencies may decrease in cool seasons but increase in the summer season. To clarify the temporal population dynamics of the spiroplasma infection, D. hydei were collected from two Japanese populations in 2006–2008 from May to early August, representing the only period when a number of D. hydei are collectable in Japan, and examined for spiroplasma infection. Within each year, the frequency of spiroplasma infection fluctuated considerably in both populations. Consistent with our hypothesis, the infection frequency showed an increasing trend in both populations in 2007. However, the data in 2006 and 2008 did not show consistent patterns of increase. The population dynamics of spiroplasma infection may be affected but not critically determined by temperature. Moreover, despite the fluctuation within each year, the infection frequencies seemed to be stable across the years. The frequencies of spiroplasma infection in D. hydei populations may be stabilized by multiple factors. One of these factors may involve a context-dependent positive effect of spiroplasma on the fitness of D. hydei, as was recently observed in laboratory experiments.

Studies on the effects of perfluorooctane sulfonic acid (PFOS) exposure on terrestrial invertebrates are very scarce. Here, we quantified the effects of PFOS on the number of offspring for two generations of Drosophila hydei Sturtevant 1921 (Diptera: Drosophilidae) reared in the laboratory. The first generation was exposed to a range of PFOS concentrations from 5 to 5,000 ng/ml and a control through their diet. For the second generation, offspring of the 50 ng/ml PFOS treatment and the control were further reared in a PFOS-free environment. For the first generation, the number of offspring decreased with increasing levels of PFOS contamination. Although the second generation was not exposed to PFOS, we still observed a reduction in the number of offspring when the parental flies were exposed to 50 ng/ml PFOS. The results of the current study indicate that the sensitivity to PFOS of D. hydei is several magnitudes higher than of the other terrestrial invertebrate species tested so far. This sensitivity falls within the concentration range detected in its natural food.

Maternally transmitted endosymbionts of the genus Spiroplasma infecting several species of Drosophila are known to cause selective death of male offspring (male killing). The male-killing trait is considered to be advantageous for maternally transmitted endosymbionts. However, a non-male-killing spiroplasma is present in Japanese populations of Drosophila hydei at high frequencies (23-66%). This spiroplasma is phylogenetically closely related to the male-killing spiroplasma infecting other Drosophila species. It is unknown why this spiroplasma is maintained in its host populations despite its inability to cause male killing. We examined the susceptibilities of the spiroplasma in D. hydei to four different temperatures (28, 25, 18, and 15 degrees C). Diagnostic PCR revealed that vertical transmission of the spiroplasma was nearly perfect at 28 and 25 degrees C, partially suppressed at 18 degrees C, and completely blocked at 15 degrees C. Furthermore, quantitative PCR demonstrated that offspring treated at 18 degrees C exhibited dramatically lower densities of spiroplasma (i.e., approximately one-tenth) compared to offspring treated at 28 and 25 degrees C. Considering the low temperatures during winter in Japan, some unknown advantageous effects of the spiroplasma that compensate for the failure of vertical transmission are suggested to act in natural populations of D. hydei.

The suitability of whole mount electron microscopy for the localization of gene activity in polytene chromosomes was tested by heat shock induction in Drosophila hydei. The heat shock response of salivary glands is found out to be detrimental to surface spreading properties of salivary gland material. The major heat shock band in division 81 is determined to be 81C2. The heat shock puff is covered by amorphous material probably representing transcription complexes that partly obscure the underlying structures. After 5 min heat shock treatment, spherical particles are observed on the puff site. Successful mapping of this region, which consists of very thin bands including a developmental puff, suggests that whole mount electron microscopy is the method of choice for routine localization of gene activity in polytene chromosome systems.

Alanen, M. 1986. Drosophila hydei polytene chromosomes: Investigation of the chromosome ends by whole mount electron microscopy.-Hereditas 104: 85–89. Lund, Sweden. ISSN 0018–0661. Received March 11, 1985 Whole mount electron microscopy reveals structural differences between chromatin in the proximal ends and the distal ends of polytene chromosome arms of Drosophila hydei. The chromocenter appears as an indeterminate fusion product of proximal chromosome ends with no superstructure evident. The telomeric area, which is formed by the contact of distal chromosome ends, consists of structures resembling the structural units forming the polytene chromosome bands.