Fly Feeding Research Articles

Bugs on Drugs: A Drosophila melanogaster Gut Model to Study In Vivo Antibiotic Tolerance of E. coli.

With an antibiotic crisis upon us, we need to boost antibiotic development and improve antibiotics’ efficacy. Crucial is knowing how to efficiently kill bacteria, especially in more complex in vivo conditions. Indeed, many bacteria harbor antibiotic-tolerant persisters, variants that survive exposure to our most potent antibiotics and catalyze resistance development. However, persistence is often only studied in vitro as we lack flexible in vivo models. Here, I explored the potential of using Drosophila melanogaster as a model for antimicrobial research, combining methods in Drosophila with microbiology techniques: assessing fly development and feeding, generating germ-free or bacteria-associated Drosophila and in situ microscopy. Adult flies tolerate antibiotics at high doses, although germ-free larvae show impaired development. Orally presented E. coli associates with Drosophila and mostly resides in the crop. E. coli shows an overall high antibiotic tolerance in vivo potentially resulting from heterogeneity in growth rates. The hipA7 high-persistence mutant displays an increased antibiotic survival while the expected low persistence of ΔrelAΔspoT and ΔrpoS mutants cannot be confirmed in vivo. In conclusion, a Drosophila model for in vivo antibiotic tolerance research shows high potential and offers a flexible system to test findings from in vitro assays in a broader, more complex condition.

Insecticidal, Repellent and Antifeedant Activity of Essential Oils from Blepharocalyx cruckshanksii (Hook. & Arn.) Nied. Leaves and Pilgerodendron uviferum (D. Don) Florin Heartwood against Horn Flies, Haematobia irritans (Diptera: Muscidae).

Haematobia irritans is a cosmopolitan obligate blood-feeding ectoparasite of cattle and is the major global pest of livestock production. Currently, H. irritans management is largely dependent on broad-spectrum pesticides, which has led to the development of insecticide resistance. Thus, alternative control methods are needed. Essential oils have been studied as an alternative due to their wide spectrum of biological activities against insects. Thus, the main aim of this study was to evaluate the insecticidal, repellent and antifeedant activity of the essential oils from Blepharocalyx cruckshanksii leaves and Pilgerodendron uviferum heartwood against horn flies in laboratory conditions. The composition of the essential oils was analyzed using gas chromatography coupled to mass spectrometry. Accordingly, α-pinene (36.50%) and limonene (20.50%) were the principal components of the B. cruckchanksii essential oil, and δ-cadinol (24.16%), cubenol (22.64%), 15-copaenol (15.46%) and δ-cadinene (10.81%) were the most abundant compounds in the P. uviferum essential oil. Mortality of flies and feeding behavior were evaluated by non-choice tests, and olfactory response was evaluated using a Y-tube olfactometer. Both essential oils were toxic to horn flies, with LC50 values for B. cruckchanksii essential oil of 3.58 µL L−1 air at 4 h, and for P. uviferum essential oil of 9.41 µL L−1 air and 1.02 µL L−1 air at 1 and 4 h, respectively. Moreover, the essential oils exhibited spatial repellency in the olfactometer using only 10 µg of each oil, and these significantly reduced the horn fly feeding at all doses evaluated. Although further laboratory and field studies related to the insectistatic and insecticide properties of these essential oils against H. irritans are necessary, B. cruckshanksii leaves and P. uviferum heartwood essential oils are promising candidates for horn fly management.

Identification of anti-horn fly vaccine antigen candidates using a reverse vaccinology approach

BackgroundThe horn fly, Haematobia irritans irritans, causes significant production losses to the cattle industry. Horn fly control relies on insecticides; however, alternative control methods such as vaccines are needed due to the fly's capacity to quickly develop resistance to insecticides, and the pressure for eco-friendly options.MethodsWe used a reverse vaccinology approach comprising three vaccine prediction and 11 annotation tools to evaluate and rank 79,542 translated open reading frames (ORFs) from the horn fly's transcriptome, and selected 10 transcript ORFs as vaccine candidates for expression in Pichia pastoris. The expression of the 10 selected transcripts and the proteins that they encoded were investigated in adult flies by reverse transcription polymerase chain reaction (RT-PCR) and mass spectrometry, respectively. Then, we evaluated the immunogenicity of a vaccine candidate in an immunization trial and the antigen’s effects on horn fly mortality and fecundity in an in vitro feeding assay.ResultsSix of the ten vaccine candidate antigens were successfully expressed in P. pastoris. RT-PCR confirmed the expression of all six ORFs in adult fly RNA. One of the vaccine candidate antigens, BI-HS009, was expressed in sufficient quantity for immunogenicity and efficacy trials. The IgG titers of animals vaccinated with BI-HS009 plus adjuvant were significantly higher than those of animals vaccinated with buffer plus adjuvant only from days 42 to 112, with a peak on day 56. Progeny of horn flies feeding upon blood from animals vaccinated with BI-HS009 plus adjuvant collected on day 56 had 63% lower pupariation rate and 57% lower adult emergence than the control group (ANOVA: F(1, 6) = 8.221, P = 0.028 and F(1, 6) = 8.299, P = 0.028, respectively).ConclusionsThe reverse vaccinology approach streamlined the discovery process by prioritizing possible vaccine antigen candidates. Through a thoughtful process of selection and in vivo and in vitro evaluations, we were able to identify a promising antigen for an anti-horn fly vaccine.Graphical abstract

Mapping of a novel major effect Hessian fly field partial-resistance locus in southern soft red winter wheat line LA03136E71.

Hessian fly resistance has centralized around resistance loci that are biotype specific. We show that field resistance is evident and controlled by a single locus on chromosome 7D. Hessian flies (Mayetiola destructor Say) infest and feed upon wheat (Triticum aestivum L) resulting in significant yield loss. Genetically resistant cultivars are the most effective method of Hessian fly management. Wheat breeders in the southern USA have observed cultivars exhibiting a "field resistance" to Hessian fly that is not detectable by greenhouse assay. The resistant breeding line "LA03136E71" and susceptible cultivar "Shirley" were crossed to develop a population of 200 random F4:5 lines using single seed descent. The population was evaluated in a total of five locations in North Carolina during the 2019, 2020, and 2021 seasons. A subsample of each plot was evaluated for the total number of tillers, number of infested tillers, and total number of larvae/pupae. From these data, the percent infested tillers, number of larvae/pupae per tiller, and the number of larvae/pupae per infested tiller were estimated. In all within and across environment combinations for all traits recorded, the genotype effect was significant (p<0.05). Interval mapping identified a single large effect QTL distally on the short arm of chromosome 7D for all environment-trait combinations. This locus was identified on a chromosome where no other Hessian fly resistance/tolerance QTL has been previously identified. This novel Hessian fly partial-resistance QTL is termed QHft.nc-7D. Fine mapping must be conducted in this region to narrow down the causal agents responsible for this trait, and investigation into the mode of action is highly suggested.

Drosophila females receive male substrate-borne signals through specific leg neurons during courtship

SummarySubstrate-borne vibratory signals are thought to be one of the most ancient and taxonomically widespread communication signals among animal species, including Drosophila flies.1, 2, 3, 4, 5, 6, 7, 8, 9 During courtship, the male Drosophila abdomen tremulates (as defined in Busnel et al.10) to generate vibrations in the courting substrate.8,9 These vibrations coincide with nearby females becoming immobile, a behavior that facilitates mounting and copulation.8,11, 12, 13 It was unknown how the Drosophila female detects these substrate-borne vibratory signals. Here, we confirm that the immobility response of the female to the tremulations is not dependent on any air-borne cue. We show that substrate-borne communication is used by wild Drosophila and that the vibrations propagate through those natural substrates (e.g., fruits) where flies feed and court. We examine transmission of the signals through a variety of substrates and describe how each of these substrates modifies the vibratory signal during propagation and affects the female response. Moreover, we identify the main sensory structures and neurons that receive the vibrations in the female legs, as well as the mechanically gated ion channels Nanchung and Piezo (but not Trpγ) that mediate sensitivity to the vibrations. Together, our results show that Drosophila flies, like many other arthropods, use substrate-borne communication as a natural means of communication, strengthening the idea that this mode of signal transfer is heavily used and reliable in the wild.3,4,7 Our findings also reveal the cellular and molecular mechanisms underlying the vibration-sensing modality necessary for this communication.

PAHs in feed coals and fly ashes from coal-fired thermal power plants in Bulgaria

The first thorough study of PAHs in feed coals and FAs from combustion in six Bulgarian TPPs was done. Since coal-derived FAs are applied to many targets, it is imperative to enhance the knowledge for their geochemical composition and environmental impact. The gap of information on PAHs in feed coals and coal-derived FAs has outlined the aim of the study: (i) to compare by geochemical proxy PAHs in feed coals and FAs generated in six Bulgarian TPPs; (ii) to track the changes in PAHs compositions with feed coal ranks and in different ESP rows; and (iii) to estimate the potential toxicity of FAs (if any). Extractable organic matter (EOM) was prepared. PAHs were isolated in aromatic fractions and quantified in μg/kg. The total PAHs for lignite feed coal are in the range 400–530 μg/kg and for FAs 0.30–12.60 μg/kg: for subbituminous feed coal, they are 4000 μg/kg, and for FAs, 1.10–32.50 μg/kg. For bituminous feed coals, they are - 860 μg/kg and 9305 μg/kg, and for FAs from both TPPs, they are several times lower, from 69.4 μg/kg to 103.3 μg/kg, for the five ESP rows of Varna TPP and from 100.4 to 182.20 μg/kg, for the three rows of ESPs of Russe TPP. The EOM for low rank feed coals is strongly dominated by coal biomarkers, i.e., perylene and phenyl substituted PAHs. Therefore, calculations and ratios based on PAHs compositions are done only for bituminous feed coals and their FAs. Combustion has resulted in a regular shift to lighter PAHs compared to the signature PAHs of feed coals. PAHs distributions in FAs are dominated by phenanthrene. Distribution profiles according to the number of aromatic cycles (R) in PAHs are dominated by three-ring (3R) PAHs > four-ring (4R) PAHs. Only in the last row of ESP from the Varna TPP is there evidence for the presence of heavier PAH, five-ring (5R) benzo[g,h,i]fluoranthene, trapped by the finest particulate matter. Relatively low PAHs concentrations determined for FAs are compared with the values for PAHs in soils according to the Bulgarian regulation.

Initiation of compatible wheat-Hessian fly interactions triggers the expression of a novel UDP-glycosyltransferase, MdesUGT1, in virulent Hessian fly larvae

Insect UDP-glycosyltransferases (UGTs) play an important role in detoxification of substrates such as plant allelochemicals, and cuticle formation by the process of glucosidation. Hessian fly (Mayetiola destructor), belonging to the order Diptera (Family: Cecidomyiidae), is a destructive pest of host wheat causing significant economic losses. In the current study, using the assembled genome, we identified thirteen genes in M. destructor that belong to the family of UGTs (MdesUGT). Expression profiling revealed differential expression of MdesUGT genes in Hessian fly feeding instars. Further, we report the molecular cloning of MdesUGT1, designated as UGT301F1, from M. destructor. Characterization of the MdesUGT1 amino acid sequence revealed a conserved signature motif and sugar donor-binding domains characteristic of UGT proteins. Further expression analysis revealed dramatic increase in transcript accumulation of MdesUGT1 in the first and second feeding instars during compatible interactions (susceptible wheat, virulent larvae) but lacked significant upregulation during incompatible wheat Hessian fly interactions. Similar increase in MdesUGT1 transcripts was also observed during interactions of Hessian fly with nonhost, Brachypodium distachyon. These findings suggest the possible early involvement of MdesUGT1 in detoxification of plant toxins, and subsequent role in cuticular formation, thus contributing to the growth and development of this dipteran insect pest. Identification and characterization of insect UGTs could provide valuable insights into the detoxification and growth inhibitory mechanisms and facilitate future plant pest management strategies.

Influence of Dopamine on Fluorescent Advanced Glycation End Products Formation Using Drosophila melanogaster.

Non-enzymatic glycation and covalent modification of proteins leads to Advanced Glycation End products (AGEs). AGEs are biomarkers of aging and neurodegenerative disease, and can be induced by impaired neuronal signaling. The objective of this study was to investigate if manipulation of dopamine (DA) in vitro using the model protein, bovine serum albumin (BSA), and in vivo using the model organism Drosophila melanogaster, influences fluorescent AGEs (fAGEs) formation as an indicator of dopamine-induced oxidation events. DA inhibited fAGEs-BSA synthesis in vitro, suggesting an anti-oxidative effect, which was not observed when flies were fed DA. Feeding flies cocaine and methamphetamine led to increased fAGEs formation. Mutants lacking the dopaminergic transporter or the D1-type showed further elevation of fAGEs accumulation, indicating that the long-term perturbation in DA function leads to higher production of fAGEs. To confirm that DA has oxidative properties in vivo, we fed flies antioxidant quercetin (QUE) together with methamphetamine. QUE significantly decreased methamphetamine-induced fAGEs formation suggesting that the perturbation of DA function in vivo leads to increased oxidation. These findings present arguments for the use of fAGEs as a biomarker of DA-associated neurodegenerative changes and for assessment of antioxidant interventions such as QUE treatment.

A closed-loop optogenetic screen for neurons controlling feeding in Drosophila.

Feeding is an essential part of animal life that is greatly impacted by the sense of taste. Although the characterization of taste-detection at the periphery has been extensive, higher order taste and feeding circuits are still being elucidated. Here, we use an automated closed-loop optogenetic activation screen to detect novel taste and feeding neurons in Drosophila melanogaster. Out of 122 Janelia FlyLight Project GAL4 lines preselected based on expression pattern, we identify six lines that acutely promote feeding and 35 lines that inhibit it. As proof of principle, we follow up on R70C07-GAL4, which labels neurons that strongly inhibit feeding. Using split-GAL4 lines to isolate subsets of the R70C07-GAL4 population, we find both appetitive and aversive neurons. Furthermore, we show that R70C07-GAL4 labels putative second-order taste interneurons that contact both sweet and bitter sensory neurons. These results serve as a resource for further functional dissection of fly feeding circuits.

Preference and detrimental effects of high fat, sugar, and salt diet in wild-caught Drosophila simulans are reversed by flight exercise.

High saturated fat, sugar, and salt contents are a staple of a Western diet (WD), contributing to obesity, metabolic syndrome, and a plethora of other health risks. However, the combinatorial effects of these ingredients have not been fully evaluated. Here, using the wild‐caught Drosophila simulans, we show that a diet enriched with saturated fat, sugar, and salt is more detrimental than each ingredient separately, resulting in a significantly decreased lifespan, locomotor activity, sleep, reproductive function, and mitochondrial function. These detrimental effects were more pronounced in female than in male flies. Adding regular flight exercise to flies on the WD markedly negated the adverse effects of a WD. At the molecular level, the WD significantly increased levels of triglycerides and caused mitochondrial dysfunction, while exercise counterbalanced these effects. Interestingly, fruit flies developed a preference for the WD after pre‐exposure, which was averted by flight exercise. The results demonstrate that regular aerobic exercise can mitigate adverse dietary effects on fly mitochondrial function, physiology, and feeding behavior. Our data establish Drosophila simulans as a novel model of diet‐exercise interaction that bears a strong similarity to the pathophysiology of obesity and eating disorders in humans.

Some Protein Supplements as Alternatives of Standard Protein Hydrolysate in Mediterranean Fruit Fly, Ceratitis capitata (Wied) Flies Dietary Regular Diet

Insects require a diet containing a source of energy,a protein source,vitamins and certain mineral salts.The nutrients can influence the quality control parameters of the flies such as mating ability,fecundity,fertility,longevity,pupal weight and adult emergence.Yeast extract(YE)and three chemically composed protein supplements(FA),(FB) and (FC)were tested for their efficiency to provide Ceratitis capitata (Wiedemann) flies with protein as alternatives for the protein hydrolysate (PS). The shortest flies maturity period expressed in the first couple performance was related to the protein supplement (FC) 1.26, 1.01 and 1.03 days for parents, first and second generations, respectively. The highest numbers of eggs were laid by females fed on the food supplements (FB) 4.13 and (FC) 4.08 in the parents’ generation,(FB)2.81 and(PS)2.79 in the first generation and (PS) 4.29 and (FB) 4.26 in the second generations. The highest and the least egg larval recovery percentages were recorded after flies’ feeding on protein supplement (FC) 97.53% and (PS) 91.17% at the parents’ generation. The highest and the least pupal recovery percentages were observed after flies feeding on (FC) 99.17% and (PS) 90.71% while flies emergence percentages were (FC) 99.81% and (PS) 90.92%. The least male flies mortality percentages were recorded after flies fed on (YE), 12.06%, 3.20% and 3.37% at the parents, first and second generations, respectively while female flies recorded 8.09%, 6.09% and 2.11 at the same generations. Larval measurements and pupal weight of the produced individuals of the four tested protein supplements at the three generations showed non-significant differences in comparison to the standard protein-feeding source (PS).

Metabolic activation and toxicological evaluation of polychlorinated biphenyls in Drosophila melanogaster

Degradation of polychlorinated biphenyls (PCBs) is initiated by cytochrome P450 (CYP) enzymes and includes PCB oxidation to OH-metabolites, which often display a higher toxicity than their parental compounds. In search of an animal model reflecting PCB metabolism and toxicity, we tested Drosophila melanogaster, a well-known model system for genetics and human disease. Feeding Drosophila with lower chlorinated (LC) PCB congeners 28, 52 or 101 resulted in the detection of a human-like pattern of respective OH-metabolites in fly lysates. Feeding flies high PCB 28 concentrations caused lethality. Thus we silenced selected CYPs via RNA interference and analyzed the effect on PCB 28-derived metabolite formation by assaying 3-OH-2′,4,4′-trichlorobiphenyl (3-OHCB 28) and 3′-OH-4′,4,6′-trichlorobiphenyl (3′-OHCB 28) in fly lysates. We identified several drosophila CYPs (dCYPs) whose knockdown reduced PCB 28-derived OH-metabolites and suppressed PCB 28 induced lethality including dCYP1A2. Following in vitro analysis using a liver-like CYP-cocktail, containing human orthologues of dCYP1A2, we confirm human CYP1A2 as a PCB 28 metabolizing enzyme. PCB 28-induced mortality in flies was accompanied by locomotor impairment, a common phenotype of neurodegenerative disorders. Along this line, we show PCB 28-initiated caspase activation in differentiated fly neurons. This suggested the loss of neurons through apoptosis. Our findings in flies are congruent with observation in human exposed to high PCB levels. In plasma samples of PCB exposed humans, levels of the neurofilament light chain increase after LC-PCB exposure, indicating neuronal damage. In summary our findings demonstrate parallels between Drosophila and the human systems with respect to CYP mediated metabolism and PCB mediated neurotoxicity.

Impact of different Leishmania reservoirs on sand fly transmission: Perspectives from xenodiagnosis and other one health observations

Leishmania has biologically adapted to specific phlebotomine sand flies through long co-evolution. The ability of Leishmania spp. to bind to sand fly midgut allows each Leishmania species to propagate and differentiate into infectious promastigotes and be transmitted. Sand fly feeding upon a mammalian host is the first step towards being infected and a host of Leishmania. Once deposited into the skin, host susceptibility to infection vs. ability to mount a sterilizing immune response predicts which hosts could be reservoirs of different Leishmania spp. Materials, in addition to parasites, are expelled during sand fly during feeding, including salivary antigens and other factors that promote local inflammatory responses. These factors aid visceralization of infection increasing the likelihood that systemic infection is established. Any environmental factor that increases sand fly biting of a particular host increases that host’s role in Leishmania transmission. First descriptions of reservoir species were based on association with local human disease and ability to observe infected leukocytes on cytology. This approach was one pathogen for one reservoir host. Advances in sensitive molecular tools greatly increased the breadth of mammals found to host Leishmania infection. Visceralizing species of Leishmania, particularly L. infantum, are now known to have multiple mammalian hosts. L. donovani, long been described as an anthroponotic parasite, was recently identified through molecular and serologic surveys to have additional mammalian hosts. The epidemiological role of these animals as a source of parasites to additional hosts via vector transmission is not known. Current evidence suggests that dogs and other domestic animals either control infection or do not have sufficient skin parasitemia to be a source of L. donovani to P. argentipes. Further xenodiagnosis and characterization of skin parasitemia in these different hosts is required to more broadly understand which Leishmania spp. hosts can be a source of parasites to sand flies and which ones are dead-end hosts.

Dispersion of radionuclides from coal-fired brick kilns and concomitant impact on human health and the environment

Realizing the probable health implications via the exposures to radionuclides released from coal-fired brick kilns, concentrations of terrestrial radionuclides in feed coal, fly- and bottom ash collected from some major coal-fired brick kilns of Southern region in Bangladesh were measured using HPGe γ-ray spectrometry. Respective mean activity concentrations (Bq kg−1) for 226Ra, 232Th and 40K were found to be 36.3 ± 1.8, 26.2 ± 2.1 and 314 ± 18 in feed coal; 60.8 ± 3.9, 36.6 ± 3.9 and 338 ± 19 in fly ash; 54.9 ± 4.0, 39.7 ± 4.6 and 311 ± 18.0 in bottom ash samples. As a result of the combustion process, radionuclide concentration enhancements have been observed in proceeding from feed coal to fly- and bottom-ash. The calculated values of air absorbed dose-rates for fly- and bottom-ash are greater than the world average of 55 nGy/h reported by UNSCEAR, and the Lifetime Cancer Risk (LCR) approaches towards the safe limit recommended by the ICRP. As such, this does flag up a potential concern for those dwelling in nearby areas, especially for the coal workers who normally do not take any protective measures against exposure to ash dust. Multivariate statistical analysis has been used in examining for correlations between the origins of the radionuclides and their influence on the calculated radiological parameters. The measured data indicate significance for human health, also for the scientific community, and could be used for modeling studies in the region.

Transient Administration of Dopaminergic Precursor Causes Inheritable Overfeeding Behavior in Young Drosophila melanogaster Adults.

Imbalances in dopaminergic signaling during development have been indicated as part of the underlying neurobiology of several psychiatric illnesses, including schizophrenia, major depression, bipolar disorder, and food addiction. Yet, how transient manipulation of dopaminergic signaling influences long-lasting behavioral consequences, or if these modifications can induce inheritable traits, it is still not understood. In this study, we used the Drosophila melanogaster model to test if transient pharmacological activation of the dopaminergic system leads to modulations of feeding and locomotion in adult flies. We observed that transient administration of a dopaminergic precursor, levodopa, at 6 h, 3 days or 5 days post-eclosion, induced overfeeding behavior, while we did not find significant effects on locomotion. Moreover, this phenotype was inherited by the offspring of flies treated 6 h or 3 days post-eclosion, but not the offspring of those treated 5 days post-eclosion. These results indicate that transient alterations in dopaminergic signaling can produce behavioral alterations in adults, which can then be carried to descendants. These findings provide novel insights into the conditions in which environmental factors can produce transgenerational eating disorders.

Suhomyces drosophilae sp. nov., isolated from Drosophila flies feeding on a stinkhorn mushroom.

The majority of Suhomyces species have been isolated from fungus-feeding insects and particularly from the gut of beetles. In the present study, seven yeast strains were isolated from the gut of Drosophila species feeding on gleba, the spore-bearing inner mass, of a stinkhorn mushroom belonging to the family Phallaceae. Based on phenotypic, biochemical characterization and sequence analysis of the D1/D2 region of the large subunit rRNA gene and the internal transcribed spacer (ITS) region, two of these yeast strains, DGY3 and DGY4, represented a novel species of the genus Suhomyces. The novel species is closely related to an undescribed species of Candida ST-370 (DQ404513) and with Suhomyces canberraensis, wherein, the novel species differs from S. canberraensis by 40 nucleotide substitutions and three gaps (7.7 % sequence variation) in the D1/D2 region and 50 nucleotide substitutions and seven gaps (13.7 % sequence variation) in the ITS region. Several morphological and physiological differences were also observed between S. canberraensis and the strains obtained during this study. These data support the proposal of Suhomyces drosophilae as a novel species, with DGY3T as the holotype and CBS 16329T and MCC 1871T as ex-type strains.

Correction:Risk factors affecting dairy cattle protective grouping behavior, commonly known as bunching, against Stomoxys calcitrans (L.)on California dairies.

[This corrects the article DOI: 10.1371/journal.pone.0224987.].

Characterizing the microbiome of ectoparasitic louse flies feeding on migratory raptors.

Louse flies (Diptera: Hippoboscidae) are obligate ectoparasites that often cause behavioral, pathogenic, and evolutionary effects on their hosts. Interactions between ectoparasites and avian hosts, especially migrating taxa, may influence avian pathogen spread in tropical and temperate ecosystems and affect long-term survival, fitness and reproductive success. The purpose of this study was to characterize the vector-associated microbiome of ectoparasitic louse flies feeding on migrating raptors over the fall migration period. Surveys for louse flies occurred during fall migration (2015–2016) at a banding station in Pennsylvania, United States; flies were collected from seven species of migrating raptors, and we sequenced their microbial (bacteria and archaea) composition using high-throughput targeted amplicon sequencing of the 16S rRNA gene (V4 region). All louse flies collected belonged to the same species, Icosta americana. Our analysis revealed no difference in bacterial communities of louse flies retrieved from different avian host species. The louse fly microbiome was dominated by a primary endosymbiont, suggesting that louse flies maintain a core microbial structure despite receiving blood meals from different host species. Thus, our findings highlight the importance of characterizing both beneficial and potentially pathogenic endosymbionts when interpreting how vector-associated microbiomes may impact insect vectors and their avian hosts.

Drosophila Aversive Behavior toward Erwinia carotovora carotovora Is Mediated by Bitter Neurons and Leukokinin.

SummaryThe phytopathogen Erwinia carotovora carotovora (Ecc) has been used successfully to decipher some of the mechanisms that regulate the interactions between Drosophila melanogaster and bacteria, mostly following forced association between the two species. How do Drosophila normally perceive and respond to the presence of Ecc is unknown. Using a fly feeding two-choice assay and video tracking, we show that Drosophila are first attracted but then repulsed by an Ecc-contaminated solution. The initial attractive phase is dependent on the olfactory Gr63a and Gαq proteins, whereas the second repulsive phase requires a functional gustatory system. Genetic manipulations and calcium imaging indicate that bitter neurons and gustatory receptors Gr66a and Gr33a are needed for the aversive phase and that the neuropeptide leukokinin is also involved. We also demonstrate that these behaviors are independent of the NF-κB cascade that controls some of the immune, metabolic, and behavioral responses to bacteria.

Fate of cadmium in coal-fired power plants in Guizhou, Southwest China: With emphasis on updated atmospheric emissions

Coal-fired power plants (CFPPs) are important source of anthropogenic atmospheric releases of various pollutants, including cadmium (Cd). In this research, the distribution of Cd in seven CFPPs in Guizhou province, southwest China and the atmospheric Cd emissions from this source category in this province was studied. Among the boilers, one was a circulating fluidized bed boiler (CFB) and the others were pulverized coal-fired boilers (PC). All CFPPs are equipped with De-NOx, De-dust, and De-SO2 devices. Solid samples including feed fuel (coal, gangue, and coal slime), limestone, bottom ash, fly ash, gypsum, as well as stack flue gas samples were simultaneously collected and analyzed. Cd in feed coal, bottom ash, fly ash, limestone, gypsum, and stack flue gas were in the range of 0.15–0.68, 0.08–0.42, 0.43–2.03, 0.01–0.67, 0.02–0.41 mg kg−1, and 0.005–0.03 μg·Nm−3, respectively. Cd release ratio during the coal combustion in the boiler was in the range of 95.91–98.77% for PC, but only 76.94% for CFB. Cd atmospheric emission factors were in the range of 0.03–0.2 mg Cd·t−1 coal, 0.02–0.1 μg·(kW·h)−1 or 0.002–0.01 g Cd·TJ−1 for the seven CFPPs, lower values were found for CFB boiler than that of PC boilers. In 2017, the amount of Cd emitted from CFPPs in Guizhou province was estimated to be 51.4 kg y−1 (CFB: 2.4 kg y−1 and PC: 49 ± 32 kg y−1), significantly lower than previous reports.