Fly Strains Research Articles

The evolutionarily conserved PhLP3 is essential for sperm development in Drosophila melanogaster.

Phosducin-like proteins (PhLP) are thioredoxin domain-containing proteins that are highly conserved across unicellular and multicellular organisms. PhLP family proteins are hypothesized to function as co-chaperones in the folding of cytoskeletal proteins. Here, we present the initial molecular, biochemical, and functional characterization of CG4511 as Drosophila melanogaster PhLP3. We cloned the gene into a bacterial expression vector and produced enzymatically active recombinant PhLP3, which showed similar kinetics to previously characterized orthologues. A fly strain homozygous for a P-element insertion in the 5' UTR of the PhLP3 gene exhibited significant downregulation of PhLP3 expression. We found these male flies to be sterile. Microscopic analysis revealed altered testes morphology and impairment of spermiogenesis, leading to a lack of mature sperm. Among the most significant observations was the lack of actin cones during sperm maturation. Excision of the P-element insertion in PhLP3 restored male fertility, spermiogenesis, and seminal vesicle size. Given the high level of conservation of PhLP3, our data suggests PhLP3 may be an important regulator of sperm development across species.

Cross-resistance patterns in field strains of the sheep blowfly following laboratory-based selection pressure with dicyclanil or imidacloprid

Control of the sheep blowfly relies largely on the use of insecticides applied prophylactically in advance of expected fly activity. However, the blowfly has shown an ability to develop resistance to some of these insecticides. Recent reports of the co-occurrence of resistance to both dicyclanil and imidacloprid in in vitro bioassays with field-collected fly strains has raised the possibility that the two resistances may represent cross-resistance linked by a common mechanism. We investigated this by imposing insecticide selection pressure on larvae of two insecticide-resistant field strains over a number of generations using either dicyclanil or imidacloprid and then measuring changes in sensitivity to both the selecting chemical and the alternate chemical. Larvae selected over six generations with each chemical showed significant increases in resistance to the selecting chemical: resistance ratios at the IC50 5.5 - 8.1-fold higher for dicyclanil, and 3.1 - 3.8-fold for imidacloprid. The larvae also showed significant increases in levels of resistance towards the alternate chemical: resistance ratios 2.6 - 3.1-fold higher towards dicyclanil following selection with imidacloprid, and 2.2 - 3.2-fold higher towards imidacloprid following selection with dicyclanil. The increases in resistance to both chemicals after exposure to either suggests a common mechanism of resistance, at least in our laboratory-selected populations. Assays with the cytochrome P450 inhibitor aminobenzotriazole showed that this synergist was able to remove the increased resistance to both compounds in strains selected with either compound, suggesting that cytochrome P450 is responsible for the resistance observed to both chemicals. Our results confirm that cross-resistance exists between dicyclanil and imidacloprid in the sheep blowfly, and hence the two compounds should be considered as related entities in insecticide rotation strategies for flystrike control.

Isolation and characterization of the decreased cuticular penetration mechanism of fluralaner resistance in the house fly, Musca domestica

Decreased cuticular penetration has been documented as a mechanism of resistance in several insects, yet this mechanism remains poorly understood. Levels of resistance conferred, effects of the physicochemical properties on the manifestation of resistance and the effects of different routes of exposure are largely unknown. We recently selected a strain (FlurR) of house fly that was >11,000-fold resistance to fluralaner, and decreased cuticular penetration was one of the mechanisms of resistance (Norris et al., 2023). We sought to isolate the decreased penetration mechanism from FlurR into the background of the susceptible aabys strain, and to characterize the protection it conferred to fluralaner and other insecticides. We successfully isolated the decreased penetration mechanism and found that it conferred 7.1-fold resistance to fluralaner, and 1.4- to 4.9-fold cross-resistance to five other insecticides by topical application. Neither mass, metabolic lability, vapor pressure, nor logP explained the differences in the resistance ratios. The mechanism also conferred cross resistance by residual and feeding exposure, although at reduced levels compared to topical application. Remaining data gaps in our understanding of this mechanism are discussed.

Effect of fly ash on mechanical properties and microstructural behaviour of injected moulded recycled polypropylene composites

The global challenges of plastic waste and fly ash accumulation demand innovative recycling solutions. In Malaysia, the consumption of 11.2 million tonnes of coal annually generates approximately 2 million tonnes of fly ash, while the recycling of Polypropylene (PP) is hindered by thermo-oxidative and shear-induced degradation during mechanical recycling, resulting in reduced mechanical properties. This study addresses these issues by fabricating recycled PP composites incorporating varying fly ash contents, using a single cycle of mechanical recycling with extrusion and injection moulding methods. The composites were comprehensively tested for tensile, flexural, and compressive strengths, as well as microstructural behaviour. The results reveal a complex relationship between fly ash content and mechanical performance: while tensile strength decreases with increasing fly ash, flexural strength and strain peak at 5 % and 9 % fly ash, respectively. Compressive strength also shows a slight increase up to 7 % fly ash, indicating an optimal range for enhancing mechanical performance. Furthermore, mathematical models were proposed to predict the mechanical properties of rPP – fly ash composites, providing a valuable tool for future material design. These findings demonstrate that optimization of fly ash content can mitigate the effects of polymer degradation, offering a sustainable solution to improving the mechanical performance of this composite.

The P450-Monooxygenase Activity and CYP6D1 Expression in the Chlorfenapyr-Resistant Strain of Musca domestica L.

The house fly Musca domestica L. is one of the most common insects of veterinary and medical importance worldwide; its ability to develop resistance to a large number of insecticides is well known. Many studies support the involvement of cytochrome P-450-dependent monooxygenases (P450) in the development of resistance to pyrethroids, neonicotinoids, carbamates, and organophosphates among insects. In this paper, the monooxygenase activity and expression level of CYP6D1 were studied for the first time in a chlorfenapyr-resistant strain of house fly. Our studies demonstrated that P450 activity in adults of the susceptible strain (Lab TY) and chlorfenapyr-resistant strain (ChlA) was 1.56-4.05-fold higher than that in larvae. In females of the Lab TY and ChlA strains, this activity was 1.53- and 1.57-fold higher, respectively (p < 0.05), than that in males, and in contrast, the expression level of CYP6D1 was 21- and 8-fold lower, respectively. The monooxygenase activity did not vary between larvae of the susceptible strain Lab TY and the chlorfenapyr-resistant strain ChlA. Activity in females and males of the ChlA strain exceeded that in the Lab TY strain specimens by 1.54 (p = 0.08) and 1.83 (p < 0.05) times, respectively, with the same level of CYP6D1 expression. PCR-RFLP analysis revealed a previously undescribed mutation in the promoter region of the CYP6D1 gene in adults of the Lab TY and ChlA strains, and it did not affect the gene expression level. The obtained results show that the development of resistance to chlorfenapyr in M. domestica is accompanied by an increase in P450-monooxygenase activity without changes in CYP6D1 expression.

Topical Toxicity and Repellency Profiles of 17 Essential Oil Components against Insecticide-Resistant and Susceptible Strains of Adult Musca domestica (Diptera: Muscidae).

The house fly is a significant pest in agriculture and human health that is increasingly difficult to manage due to multiple limitations including resistance development. To explore alternative pesticides, the topical toxicity and repellency profiles of 17 essential oil components (EOCs) were evaluated against a resistant and a susceptible strain of house fly, Musca domestica L., using topical application and Y-tube olfactometers, respectively. Six of the most toxic EOCs based on the LD50 were further investigated against a susceptible strain of house fly. Thymol, (+)-pulegone, eugenol, and carvacrol were always the top four most toxic chemicals tested against the resistant house fly strain. Little to no resistance was observed to the top six EOCs based on the comparison of the results between resistant and susceptible house fly strains. P-Cymene, citronellic acid, R-(+)-limonene, linalool, γ-terpinene, estragole, and eugenol were repellent to adult house flies at certain concentrations while (-)-carvone and thymol were attractive to adult house flies. This screening of a wide variety of individual EOCs provides a stronger foundation of information for further research. This should encourage further investigation into the topical toxicity and repellency in field studies, which will provide more insight into the performance of biopesticides for house fly management and potential commercialization.

Free radical production induced by visible light in live fruit flies

Visible light triggers free radical production in alive and intact Drosophila melanogaster. We exposed fruit flies to red (613–631 nm), green (515–535 nm), and blue (455–475 nm) light while we monitored changes in unpaired electron content with an electron spin resonance spectrometer (ESR/EPR). The immediate response to light is a rapid increase in spin content lasting approximately 10 s followed by a slower, linear increase for approximately 170 s. When the light is turned off, the spin population promptly decays with a similar time course, though never fully returning to baseline. The magnitude and time course of the spin production depends on the wavelength of the light. Initially, we surmised that eumelanin might be responsible for the spin change because of its documented ability for visible light absorption and its highly stable free radical content. To explore this, we utilized different fruit fly strains with varying eumelanin content and clarified the relation of melanin types with the spin response. Our findings revealed that flies with darker cuticle have at least three-fold more unpaired electrons than flies with yellow cuticle. However, to our surprise, the increase in unpaired electron population by light was not drastically different amongst the genotypes. This suggests that light-induced free radical production may not exclusively rely on the presence of black melanin, but may instead be dependent on light effects on quinone-based cuticular polymers.

Use of the Proboscis Extension Response Assay to Evaluate the Mechanism of House Fly Behavioral Resistance to Imidacloprid.

The house fly, Musca domestica L., is a significant human and livestock pest. Experiments used female adult house flies glued onto toothpicks for controlled exposure of their tarsi alone (tarsal assay) or their tarsi and proboscis (proboscis assay) with a sucrose solution containing imidacloprid at either a low (10 µg/mL) or high (4000 µg/mL) concentration. Proboscis extension response (PER) assays were used to characterize the response of imidacloprid-susceptible and behaviorally resistant house fly strains to contact with sucrose solutions containing either a low or high concentration of imidacloprid. In each assay, 150 female flies from each fly strain were individually exposed to sucrose solutions containing either a low or high concentration of imidacloprid by deliberate contact of the fly tarsi to the test solution. The PER for each fly was subsequently recorded at 0, 2, and 10 s following the initial tarsal contact. A significant and rapid reduction in PER was observed only for the behaviorally resistant fly strain and only following contact by the flies' proboscis with the sucrose solution containing the high imidacloprid concentration. The results suggest that chemoreceptors on the fly labellum or internally on the pharyngeal taste organs are involved in the detection of imidacloprid and discrimination of the concentration, resulting in an avoidance behavior (proboscis retraction) only when imidacloprid is at sufficient concentration. Further research is needed to identify the specific receptor(s) responsible for imidacloprid detection.

The hAT family hopper transposon exists as highly similar yet discontinuous elements in the Bactrocera tephritid fly genus.

The hAT family transposable element, hopper, was originally discovered as a defective 3120-bp full-length element in a wild-type strain of the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), and subsequently a functional 3131-bp element, hopperBdwe, was isolated from a white eye mutant strain. The latter study showed that closely related elements exist in melonfly, Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae), a closely related subgenus, suggesting that hopper could have a widespread presence in the Bactrocera genus. To further understand the distribution of hopper within and beyond the B. dorsalis species complex, primer pairs from hopperBdwe and its adjacent genomic insertion site were used to survey the presence and relatedness of hopper in five species within the complex and four species beyond the complex. Based on sequence identity of a 1.94 kb internal nucleotide sequence, the closest relationships were with mutated elements from B. dorsalis s.s. and species synonymized with B. dorsalis including B. papayae, B. philippinensis and B. invadens, ranging in identity between 88.4% and 99.5%. Notably, Bactrocera carambolae (Drew & Hancock) (Diptera: Tephritidae), which is most closely related to B. dorsalis beyond the synonymized species, shared hopper identities of 97.3%-99.5%. Beyond the B. dorsalis complex, Z. cucurbitae,Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) and Bactrocera zonata (Saunders) (Diptera: Tephritidae) shared identities of 83.1%-97.1%, while hopper was absent from the Bactrocera oleae (Gmelin) (Diptera: Tephritidae) strain tested. While the functional autonomous hopperBdwe element was not detected in these species, another closely related hopper element isolated from a B. dorsalis genetic sexing strain has an uninterrupted transposase open reading frame. The discontinuous presence of hopper in the Bactrocera genus has implications for its use for genomic manipulation and understanding the phylogenetic relationship of these species.

Auxin exposure disrupts feeding behavior and fatty acid metabolism in adult Drosophila.

The ease of genetic manipulation in Drosophila melanogaster using the Gal4/UAS system has been beneficial in addressing key biological questions. Current modifications of this methodology to temporally induce transgene expression require temperature changes or exposure to exogenous compounds, both of which have been shown to have detrimental effects on physiological processes. The recently described auxin-inducible gene expression system (AGES) utilizes the plant hormone auxin to induce transgene expression and is proposed to be the least toxic compound for genetic manipulation, with no obvious effects on Drosophila development and survival in one wild-type strain. Here, we show that auxin delays larval development in another widely used fly strain, and that short- and long-term auxin exposure in adult Drosophila induces observable changes in physiology and feeding behavior. We further reveal a dosage response to adult survival upon auxin exposure, and that the recommended auxin concentration for AGES alters feeding activity. Furthermore, auxin-fed male and female flies exhibit a significant decrease in triglyceride levels and display altered transcription of fatty acid metabolism genes. Although fatty acid metabolism is disrupted, auxin does not significantly impact adult female fecundity or progeny survival, suggesting AGES may be an ideal methodology for studying limited biological processes. These results emphasize that experiments using temporal binary systems must be carefully designed and controlled to avoid confounding effects and misinterpretation of results.

Evaluation of the inheritance and dominance of behavioral resistance to imidacloprid in the house fly (Musca domestica L.) (Diptera: Muscidae).

The house fly, Musca domestica, is a cosmopolitan species known for its pestiferous nature and potential to mechanically vector numerous human and animal pathogens. Control of adult house flies often relies on insecticides formulated into food baits. However, due to the overuse of these baits, insecticide resistance has developed to all insecticide classes currently registered for use in the United States. Field populations of house flies have developed resistance to imidacloprid, the most widely used neonicotinoid insecticide for fly control, through both physiological and behavioral resistance mechanisms. In the current study, we conducted a comprehensive analysis of the inheritance and dominance of behavioral resistance to imidacloprid in a lab-selected behaviorally resistant house fly strain. Additionally, we conducted feeding preference assays to assess the feeding responses of genetic cross progeny to imidacloprid. Our results confirmed that behavioral resistance to imidacloprid is inherited as a polygenic trait, though it is inherited differently between male and female flies. We also demonstrated that feeding preference assays can be instrumental in future genetic inheritance studies as they provide direct insight into the behavior of different strains under controlled conditions that reveal, interactions between the organism and the insecticide. The findings of this study carry significant implications for pest management and underscore the need for integrated pest control approaches that consider genetic and ecological factors contributing to resistance.

Mass-Rearing Conditions Do Not Always Reduce Genetic Diversity: The Case of the Mexican Fruit Fly, Anastrepha ludens (Diptera: Tephritidae).

The application of the sterile insect technique (SIT) requires the adaptation of insects to mass-rearing conditions. It is generally accepted that this adaptation may include a reduction in genetic diversity and an associated loss of desirable characteristics for the effective performance of sterile insects in the field. Here, we compare the genetic diversity of two mass-reared strains of the Mexican fruit fly, Anastrepha ludens, and a wild (WIL) population collected near Tapachula, Mexico, using seven DNA microsatellites as molecular genetic markers. The mass-reared strains were a bisexual laboratory strain (LAB) with approximately 130 generations under mass-rearing and a genetic sexing strain, Tapachula-7 (TA7), also under mass-rearing for 100 generations. Our results revealed an overall low level of genetic differentiation (approximately 15%) among the three strains, with the LAB and WIL populations being genetically most similar and TA7 most genetically differentiated. Although there were some differences in allele frequencies between strains, our results show that overall, the adaptation to mass-rearing conditions did not reduce genetic variability compared to the wild sample in terms of heterozygosity or allelic richness, nor did it appear to alter the level of inbreeding with respect to the wild populations. These results are contrary to the general idea that mass-rearing always results in a reduction in genetic diversity. Overall, our findings can contribute to a better understanding of the impact that adaptation to mass-rearing conditions may have on the genetic make-up of strains.

Probiotic consortium modulating the gut microbiota composition and function of sterile Mediterranean fruit flies

The sterile insect technique (SIT) remains a successful approach in managing pest insects. However, the long-term mass rearing and sterilizing radiation associated with SIT have been observed to induce physiological and ecological fitness decline in target insects. This decline may be attributed to various factors, including commensal microbiota dysbiosis, selection procedures, loss of heterozygosity, and other complex interactions.. There is evidence that the bacterial symbiont of insects may play critical roles in digestion, development, reproduction, and behavior. Probiotics are an increasingly common approach for restoring the intestinal microbiota structure and fitness parameters of sterile insects, particularly in the Vienna 8 genetic sexing strain (V8-GSS) of the Mediterranean fruit fly (medfly), Ceratitis capitata. Here, we explore the influence of the previously isolated bacterial strain, Lactococcus lactis, Enterobacter sp., and Klebsiella oxytoca, administration as probiotic consortia (LEK-PC) to the larvae and/or adult diet over the course of 20 rearing generations on fitness parameters. The experiment was carried out in four colonies: a control colony (C), one to which probiotics were not added, one to which probiotics were added to the larval medium (L+), one to which probiotics were added to the adult medium (A+), and one to which probiotics were added to both the larval and adult mediums (AL+). Emergence, flight ability, survival under stress conditions, and mating competitiveness, were all significantly improved by the LEK-PC treatment independently of the administration stage. The intestinal microbiota structure of various medfly V8-GSS colonies also underwent a significant shift, despite the fact that the core microbial community was unaffected by the LEK-PC administration stage, according to 16S metagenomics sequencing. Comparison of the metabolic function prediction and associated carbohydrate enzymes among colonies treated with “LEK-PC” showed an enrichment of metabolic functions related to carbohydrates, amino acids, cofactors, and vitamins metabolism, as well as, glycoside hydrolase enzymes in the AL+ colony compared to the control. This study enriches the knowledge regarding the benefits of probiotic treatment to modulate and restore the intestinal microbiota of C. capitata sterile males for a better effectiveness of the SIT.

Wolbachia effects on thermal preference of natural Drosophila melanogaster are influenced by host genetic background, Wolbachia type, and bacterial titer.

Temperature plays a fundamental role in the fitness of all organisms. In particular, it strongly affects metabolism and reproduction in ectotherms that have limited physiological capabilities to regulate their body temperature. The influence of temperature variation on the physiology and behaviour of ectotherms is well studied but we still know little about the influence of symbiotic interactions on thermal preference (Tp ) of the host. A growing number of studies focusing on the Wolbachia-Drosophila host-symbiont system found that Wolbachia can influence Tp in Drosophila laboratory strains. Here, we investigated the effect of Wolbachia on Tp in wild-type D. melanogaster flies recently collected from nature. Consistent with previous data, we found reduced Tp compared to an uninfected control in one of two fly strains infected with the wMelCS Wolbachia type. Additionally, we, for the first time, found that Wolbachia titer variation influences the thermal preference of the host fly. These data indicate that the interaction of Wolbachia and Drosophila resulting in behavioural variation is strongly influenced by the genetic background of the host and symbiont. More studies are needed to better understand the evolutionary significance of Tp variation influenced by Wolbachia in natural Drosophila populations.

The effect of microbiome on social spacing in Drosophila melanogaster depends on genetic background and sex.

The gut microbiome modulates many essential functions including metabolism, immunity, and behaviour. Specifically, within behaviour, social behaviours such as sociability, aggregation, mating preference, avoidance, oviposition, and aggression are known to be regulated in part by this host-microbiome relationship. Here, we show the microbiome's role in the determination of social spacing in a sex- and genotype-specific manner. Future work can be done on characterizing the microbiome in each of these fly strains to identify the species of microbes present as well as their abundance.

Genetics, genomics and mechanisms responsible for high levels of pyrethroid resistance in Musca domestica

Insecticide resistance is both economically important and evolutionarily interesting phenomenon. Identification of the mutations responsible for resistance allows for highly sensitive resistance monitoring and allows tools to study the forces (population genetics, fitness costs, etc.) that shape the evolution of resistance. Genes coding for insecticide targets have many well-characterized mutations, but the mutations responsible for enhanced detoxification have proven difficult to identify.We employed multiple strategies to identify the mutations responsible for the extraordinarily high permethrin resistance in the KS17-R strain of house fly (Musca domestica): insecticide synergist assays, linkage analysis, bulk segregant analyses (BSA), transcriptomics and long read DNA (Nanopore) sequencing. The >85,100-fold resistance in KS17-R was partially suppressed by the insecticide synergists piperonyl butoxide and S,S,S-tributylphosphorothionate, but not by diethyl maleate nor by injection. This suggests the involvement of target site insensitivity, CYP-mediated resistance, possibly hydrolase mediated resistance and potentially other unknown factors. Linkage analysis identified chromosomes 1, 2, 3 and 5 as having a role in resistance. BSA mapped resistance loci on chromosomes 3 and 5. The locus on chromosome 3 was centered on the voltage sensitive sodium channel. The locus on chromosome 5 was associated with a duplication of multiple detoxification genes. Transcriptomic analyses and long read DNA sequencing revealed overexpressed CYPs and esterases and identified a complex set of structural variants at the chromosome 5 locus.

Effect of X-ray Irradiation on Pupal Development of Bactrocera zonata and Bactrocera dorsalis under Laboratory Conditions

The studies were performed to check the effect of X-ray doses such as 20, 40, 60, 80 and 100 Gy on the Bactrocera zonata (Saunders) and Bactrocera dorsalis (Hendel) pupae reared on different diets. The laboratory strains of the Peach fruit fly and Oriental fruit fly reared on Guava, Mango and artificial diets. Results showed a significantly (P&lt;0.05) greater number of deformed adults (Males and Females) of B. zonata at 100 Gy dose of x-ray irradiation followed by B. dorsalis obtained from artificial diets. Less deformity in adults of both fruit fly species was found at the same dosage of irradiation when maggots tended on mango. Similarly, a reduced number of normal adults of both fruit flies were recorded at 100 Gy dose of X-rays reared on an artificial diet. Reduced pupal emergence was recorded on an artificial diet. From the above results, it is determined that B. zonata is more tolerant to different irradiation doses. Results of the present investigation would be useful to control or target fruit fly pupae in fruits of trade commodities as these pests are universally regulated as quarantine pests.

Evaluation of the stability of physiological and behavioral resistance to imidacloprid in the house fly (Musca domestica L.) (Diptera: Muscidae).

The house fly (Musca domestica L.) is a synanthropic fly species commonly associated with confined animal facilities. House fly control relies heavily on insecticide use. Neonicotinoids are currently the most widely used class of insecticide and have been formulated into granular fly baits since 2002. Physiological resistance to imidacloprid in house flies has been observed to be unstable and decline over time without continual selection pressure, indicating that resistance has a fitness cost to individuals in the absence of exposure to insecticides. The stability of behavioral resistance to imidacloprid in the house fly has not been evaluated. In the current study, we assess the stability of physiological and behavioral resistance in house flies to imidacloprid over time. Physiological susceptibility to imidacloprid varied significantly among three house fly strains examined, with WT-15 exhibiting the greatest susceptibility to imidacloprid with an LC50 and LC95 of 109.29 (95.96-124.49) μg g-1 and 1486.95 (1097.15-2015.23) μg g-1 , respectively. No significant differences in survival were observed across 30 generations of a house fly strain (BRS-1) previously selected for behavioral resistance to imidacloprid with percentage survival ranging from 93.20% at F0 in 2020 to 96.20% survival at F30 in 2022. These results have significant implications for the management of house flies exhibiting behavioral resistance in field settings. It appears that standard resistance management tactics deployed to reduce the prevalence of physiological resistance, such as rotating or temporarily discontinuing the use of specific insecticides, may not lead to reduced behavioral resistance to imidacloprid. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

DVT: a high-throughput analysis pipeline for locomotion and social behavior in adult Drosophila melanogaster

BackgroundDrosophila melanogaster is excellent animal model for understanding the molecular basis of human neurological and motor disorders. The experimental conditions and chamber design varied between studies. Moreover, most previously established paradigms focus on fly trace detection algorithm development. A comprehensive understanding on how fly behaves in the chamber is still lacking.ResultsIn this report, we established 74 unique behavior metrics quantifying spatiotemporal characteristics of adult fly locomotion and social behaviors, of which 49 were newly proposed. By the aiding of the developed analysis pipeline, Drosophila video tracking (DVT), we identified siginificantly different patterns of fly behavior confronted with different chamber height, fly density, illumination and experimental time. Meanwhile, three fly strains which are widely used as control lines, Canton-S(CS), w1118 and Oregon-R (OR), were found to exhibit distinct motion explosiveness and exercise endurance.ConclusionsWe believe the proposed behavior metrics set and pipeline should help identify subtle spatial and temporal differences of drosophila behavior confronted with different environmental factors or gene variants.

Cuticular competing endogenous RNAs regulate insecticide penetration and resistance in a major agricultural pest

BackgroundThe continuously developing pesticide resistance is a great threat to agriculture and human health. Understanding the mechanisms of insecticide resistance is a key step in dealing with the phenomenon. Insect cuticle is recently documented to delay xenobiotic penetration which breaks the previous stereotype that cuticle is useless in insecticide resistance, while the underlying mechanism remains scarce.ResultsHere, we find the integument contributes over 40.0% to insecticide resistance via different insecticide delivery strategies in oriental fruit fly. A negative relationship exists between cuticle thickening and insecticide penetration in resistant/susceptible, also in field strains of oriental fruit fly which is a reason for integument-mediated resistance. Our investigations uncover a regulator of insecticide penetration that miR-994 mimic treatment causes cuticle thinning and increases susceptibility to malathion, whereas miR-994 inhibitor results in opposite phenotypes. The target of miR-994 is a most abundant cuticle protein (CPCFC) in resistant/susceptible integument expression profile, which possesses capability of chitin-binding and influences the cuticle thickness-mediated insecticide penetration. Our analyses find an upstream transcriptional regulatory signal of miR-994 cascade, long noncoding RNA (lnc19419), that indirectly upregulates CPCFC in cuticle of the resistant strain by sponging miR-994. Thus, we elucidate the mechanism of cuticular competing endogenous RNAs for regulating insecticide penetration and demonstrate it also exists in field strain of oriental fruit fly.ConclusionsWe unveil a regulatory axis of lnc19419 ~ miR-994 ~ CPCFC on the cuticle thickness that leads to insecticide penetration resistance. These findings indicate that competing endogenous RNAs regulate insecticide resistance by modulating the cuticle thickness and provide insight into the resistance mechanism in insects.