Displaying publications 101 - 120 of 661 in total

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  1. Takaoka H, Low VL, Huang YT, Fukuda M, Ya'cob Z
    Acta Trop, 2021 Oct;222:106023.
    PMID: 34161814 DOI: 10.1016/j.actatropica.2021.106023
    Two new black fly species, Simulium (Gomphostilbia) kaohsiungense and S. (G.) shoufengense, are described from females, males and pupae in Taiwan. These new species are placed in the S. asakoae species-group. Simulium (G.) kaohsiungense sp. nov. is characterized by a combination of the elongate female sensory vesicle, male upper-eye (large) facets in 15 vertical columns and 15 or 16 horizontal rows, male hind basitarsus 1.02-1.15 times the width of the hind femur, and widened pupal terminal hooks. These characteristics distinguish this new species from most species of the S. asakoae species-group. Simulium (G.) shoufengense sp. nov. is similar in the female and male to S. (G.) asakoae Takaoka & Davies originally described from Peninsular Malaysia but is distinguished from the latter species in the pupa by the combined length of the primary and secondary stalks of the dorsal triplet of gill filaments as long as or longer than the common basal stalk of the gill, and dorsum of abdominal segments 1 and 2 not darkened. The species previously regarded in Taiwan as S. (G.) metatarsale Brunetti, originally described from India, is morphologically and molecularly identified as S. (G.) asakoae.
    Matched MeSH terms: Larva
  2. Ivorra T, Martínez-Sánchez A, Rojo S
    Acta Trop, 2022 Feb;226:106233.
    PMID: 34808117 DOI: 10.1016/j.actatropica.2021.106233
    The larval development of Chrysomya albiceps and Lucilia sericata is a well-known and valuable tool for estimating the postmortem interval (PMI). The third instar larvae of Ch. albiceps are facultative predators of the larvae of other necrophagous dipterans, and this behaviour is undoubtedly an important factor to consider. Both species are found together during human autopsies in Spain and other parts of Europe, where they cohabit, so a precise knowledge of their larval coexistence data is essential. The aim of this study is to investigate their coexistence and the intraguild predation of Ch. albiceps on L. sericata under experimental conditions and in real case reports. To analyse intra- and interspecific competition, four densities were used under controlled abiotic conditions [25ºC, 60-70% RH and 12:12 (D:N)]. The experimental data were compared with data corresponding to their coexistence in natural conditions, so annual activity and forensic case reports for both species were studied. The results indicate that the mortality of immature specimens in both species, the preimaginal developmental time, and adult size were affected by competition. In natural conditions, adult coexistence during the spring-summer period was confirmed. The simultaneity of the two species colonising human corpses is frequent in the studied area, with Ch. albiceps being the dominant species, and L. sericata the relevant species for estimating the minimum postmortem interval.
    Matched MeSH terms: Larva
  3. Kropachev II, Vassilieva AB, Orlov NL, Rybaltovsky EM, Nguyen TT
    Zootaxa, 2021 Sep 14;5039(1):144-148.
    PMID: 34811091 DOI: 10.11646/zootaxa.5039.1.9
    To date, 20 species of Kurixalus Ye, Fei, and Dubois have been described, and all of these species are distributed throughout South and Southeast Asia, from eastern India, throughout Myanmar and the mountainous regions of southern China, to Indochina, western and northern peninsular Thailand, Malaysia, Sumatra, Borneo, and the Philippines (Frost 2021). Descriptions of the tadpoles of only 6 species have been published: K. berylliniris and K. wangi Wu, Huang, Tsai, Li, Jhang, Wu (Wu et al. 2016); K. eiffingeri (Boettger) (Kuramoto Wang 1987); K. idiootocus (Kuramoto Wang) (Kuramoto Wang 1987); K. cf. verrucosus (Boulenger) (Ziegler Vences 2002), and Kurixalus yangi Yu, Hui, Rao, Yang (Humtsoe et al. 2020). A description of the tadpoles of K. baliogaster (Inger, Orlov, Darevsky) is also given in the species description (Inger et al. 1999), but described larvae are assigned tentatively to this species in the published text. Additional studies on the identification of the conspecificity of the described tadpoles with K. baliogaster have not been conducted. Based on the much larger size of the tadpole body (TL up to 40.3 mm), as well as the labial tooth row formula 6(26)/5(1) given by Inger et al. (1999), we concluded that these described tadpoles cannot be larval K. baliogaster and most likely belong to some other species of rhacophorid frogs.
    Matched MeSH terms: Larva
  4. Takaoka H, Fukuda M, Otsuka Y, Low VL, Ya'cob Z
    Acta Trop, 2022 Jan;225:106207.
    PMID: 34687650 DOI: 10.1016/j.actatropica.2021.106207
    Simulium (Gomphostilbia) omutaense Ogata & Sasa, 1954 is the only named species in the Simulium batoense species-group of the subgenus Gomphostilbia Enderlein recorded from Honshu and Kyushu, Japan. It represents the northernmost distribution of this species-group, of which most members are distributed in the Oriental region. This species, the only member of the Simulium omutaense subgroup, is unique among the seven subgroups of the S. batoense species-group by having the pupal gill with one long filament and seven short filaments, similar to the arrangement of the pupal gill filaments in the S. zonatum subgroup of the S. epistum species-group in the same subgenus. This species is fully redescribed based on adults, pupal exuviae and mature larvae, and is most similar to species of the S. decuplum subgroup, based on adult morphological characteristics, although the pupal gill of the latter subgroup is markedly different by having 10 or 12 short filaments. Its close relationship to the S. decuplum subgroup is supported by a DNA analysis using COI gene sequences, with genetic distances of 9.30-11.02%. On the other hand, genetic distances between S. (G.) omutaense and species of the S. zonatum subgroup were 16.32-16.93%. Our study shows that a similar arrangement of the pupal gills in two different species-groups, which is rarely seen, has evolved independently and its occurrence does not necessarily reflect phylogenetic relationships.
    Matched MeSH terms: Larva
  5. Avicor SW, Wajidi MFF, Achoribo ES, Ong MT, Hamzah SN
    Trop Biomed, 2021 Jun 01;38(2):186-191.
    PMID: 34172709 DOI: 10.47665/tb.38.2.056
    Plants contain bioactive compounds and are constantly explored as safer alternatives to conventional insecticides. Despite numerous studies on many plants, information on the insecticidal potential of underutilised plants like tiger nut, Cyperus esculentus L., are scant, although their pharmacological potentials are well known. Hence, this study investigated the larvicidal potential of crude aqueous extracts of two C. esculentus varieties (black and yellow) on the mosquitoes Aedes aegypti (L.) and Culex quinquefasciatus (Say). Mosquito larvae were exposed to C. esculentus crude extracts using the larval bioassay technique of the World Health Organization. Differential larvicidal responses were observed in the test mosquitoes and extracts of Black Dried Tiger nuts (BDT) were more larvicidal than Yellow Dried Tiger nuts (YDT). Acute larval toxicity of the extracts was more pronounced on Cx. quinquefasciatus than Ae. aegypti. The results indicate the potential of C. esculentus (particularly BDT) as a source of mosquito bioinsecticide and merits further studies as a safer alternative to conventional insecticide-based vector control.
    Matched MeSH terms: Larva
  6. Haq IU, Khurshid A, Inayat R, Kexin Z, Changzhong L, Ali S, et al.
    PLoS One, 2021;16(11):e0259749.
    PMID: 34752476 DOI: 10.1371/journal.pone.0259749
    The fall armyworm (Spodoptera frugiperda) is a major economic pest in the United States and has recently become a significant concern in African and Asian countries. Due to its increased resistance to current management strategies, including pesticides and transgenic corn, alternative management techniques have become more necessary. Currently, silicon (Si) is being used in many pest control systems due to its ability to increase plant resistance to biotic and abiotic factors and promote plant growth. The current experiments were carried out at the College of Plant Protection, Gansu Agricultural University, Lanzhou, China, to test the effect of Si on lifetable parameters and lipase activity of fall armyworm and vegetative and physiological parameters of maize plants. Two sources of Si (silicon dioxide: SiO2 and potassium silicate: K2SiO3) were applied on maize plants with two application methods (foliar application and soil drenching). The experiment results revealed that foliar applications of SiO2 and K2SiO3 significantly (P≤0.05) increased mortality percentage and developmental period and decreased larval and pupal biomass of fall armyworm. Similarly, both Si sources significantly (P≤0.05) reduced lipase activity of larvae, and fecundity of adults, whereas prolonged longevity of adults. Among plant parameters, a significant increase in fresh and dry weight of shoot, stem length, chlorophyll content, and antioxidant activity was observed with foliar applications of Si. Root fresh and dry weight was significantly (P ≤ 0.05) higher in plants treated with soil drenching of SiO2 and K2SiO3. Moreover, SiO2 performed better for all parameters as compared to K2SiO3 and control treatment. The study conclusively demonstrated a significant negative effect on various biological parameters of fall armyworm when plants were treated with Si, so it can be a promising strategy to control this pest.
    Matched MeSH terms: Larva
  7. Alih RA, Solomon SG, Olufeagba SO, Cheikyula JO, Abol-Munafi AB, Okomoda VT
    Zygote, 2022 Feb;30(1):125-131.
    PMID: 34176523 DOI: 10.1017/S0967199421000411
    The study sought to investigate the chronology of events and timing of embryogenesis, as well as breeding performances of three strains of Heterobranchus longifilis from Nigeria. Fish samples were collected from Benue River in Makurdi, Niger River in Onitsha, and Rima River in Sokoto for this study. Induced spawning of the strains was carried out so that egg development could be tracked from fertilization to hatching using a simple microscope. The microphotographs obtained showed that the embryogenesis of the strains followed a similar pattern to those of other members of the family Clariidae, however with changes occurring in the specific timing of the sequences of events (i.e. interstrain and interspecies differences). When the different strains were compared, the study noted similarities (P > 0.05) in the overall breeding performance (except for fertilization rate), survival at different stages of development, timing of embryogenesis, and larvae characteristics. The outcomes of this study, therefore, provide baseline information on what genetic improvement of the species through strain crossing can be attempted in future studies.
    Matched MeSH terms: Larva
  8. Takaoka H, Srisuka W, Saeung A
    J Med Entomol, 2017 Jan;54(1):91-99.
    PMID: 28082635 DOI: 10.1093/jme/tjw153
    Simulium (Gomphostilbia) maleewongae sp. nov. is described based on the adult males and females, their pupal exuviae, and larvae from Thailand. This new species is placed in the Simulium gombakense species-group of Simulium (Gomphostilbia). It is characterized by the female cibarium with a cup-like appendage, male ventral plate deeply depressed ventromedially, pupal gill composed of an inflated structure and eight slender filaments, cone-shaped pupal terminal hooks, and cocoon with an anterodorsal projection. Taxonomic notes are given to separate this new species from 10 other species of the same species-group known from China, India, Malaysia, Thailand, Nepal, and Vietnam. Keys to identify all 11 species of the S. gombakense species-group are provided for females, males, pupae, and larvae.
    Matched MeSH terms: Larva/anatomy & histology; Larva/classification; Larva/growth & development
  9. Takaoka H, Sofian-Azirun M, Chen CD, Lau KW, Halim MRA, Low VL, et al.
    J Med Entomol, 2017 May 01;54(3):576-586.
    PMID: 27974360 DOI: 10.1093/jme/tjw208
    Two new species, Simulium (Gomphostilbia) sunapii and S. (G.) rangatense, are described based on adults, pupae, and mature larvae from Flores, in the eastern part of the Sunda Archipelago, Indonesia. Simulium (G.) sunapii sp. nov. is placed in the S. asakoae species-group, representing the easternmost geographical record for the group in this archipelago. It is characterized by a small number of male upper-eye large facets in eight or nine vertical columns and 12 horizontal rows. Simulium (G.) rangatense sp. nov. is placed in the S. ceylonicum species-group and is characterized by the pupal gill with six filaments. This new species, together with two related species of the S. ceylonicum species-group in Flores, suggests the species radiation of this species-group might have been accompanied by a reduction of the number of pupal gill filaments from eight to four through six. Taxonomic notes are provided to distinguish these two new species from related species.
    Matched MeSH terms: Larva/anatomy & histology; Larva/classification; Larva/growth & development
  10. Takaoka H, Srisuka W, Saeung A
    J Med Entomol, 2018 05 04;55(3):569-574.
    PMID: 29361148 DOI: 10.1093/jme/tjx242
    Simulium (Asiosimulium) saeungae sp. nov. (Diptera: Simuliidae) is described based on females, males, pupae, and mature larvae collected from Nan Province, Northern Thailand. It is characterized by the medium-long cerci in the female, enlarged hind basitarsus, and broad ventral plate with its posterior margin not deeply concave in the male, arborescent pupal gill with 42-56 filaments in the pupa and smaller number of primary rays of the labral fan (30-33) in the larva. This is the fifth species of the subgenus Asiosimulium, the second smallest among 10 subgenera in the Oriental Region. Taxonomic notes are given to distinguish this new species from the three known species from Thailand and one from Nepal.
    Matched MeSH terms: Larva/anatomy & histology; Larva/classification; Larva/growth & development
  11. Takaoka H, Sofian-Azirun M, Chen CD, Lau KW, Halim MR, Low VL, et al.
    Zootaxa, 2017 Feb 21;4236(1):zootaxa.4236.1.8.
    PMID: 28264343 DOI: 10.11646/zootaxa.4236.1.8
    Simulium (Gomphostilbia) lemborense sp. nov. is described based on adults, pupae and mature larvae from Flores, in the eastern part of the Sunda Archipelago, Indonesia. This new species is placed in the Simulium batoense species-group of the subgenus Gomphostilbia Enderlein, representing the most eastern distribution record for the group. This new species is characterized by a narrow female frons and pupal gill with eight filaments, of which two filaments of the ventral pair are three to four times as long as the six other filaments. Taxonomic notes are provided to distinguish this new species from related species.
    Matched MeSH terms: Larva
  12. Takaoka H
    Zootaxa, 2017 Nov 24;4353(3):425-446.
    PMID: 29245496 DOI: 10.11646/zootaxa.4353.3.2
    Species of eight species-groups (seven named and one unnamed) of Simulium (Simulium) Latreille are revised chiefly based on the adult female and male genitalia. Four species-groups are each divided into more than two groups. Thus, the S. christophersi species-group is divided into two (S. christophersi and S. nebulicola species-groups), the S. griseifrons species-group into six (S. griseifrons, S. grossifilum, S. chungi, S. crocinum, S. indicum and S. yadongense species-groups), the S. malyschevi species-group into two (S. malyschevi and S. pavlovskii species-groups), and the S. melanopus species-group into three (S. melanopus, S. dumogaense and S. iridescens species-groups). The S. crassifilum species-group is merged with the S. variegatum species-group. Simulium fulvipes (Ono) of the former S. malyschevi species-group and S. dentastylum Yang, Chen & Luo of Simulium s. str. species unplaced to species-group are removed from the subgenus Simulium because their male styles are subequal in length to the coxites. A revised classification of species of the 15 species-groups including eight new species-groups of Simulium (Simulium) is presented. Keys to 20 species-groups of Simulium (Simulium) in the Oriental Region are provided for adult females and males.
    Matched MeSH terms: Larva
  13. Dieng H, Ellias SB, Satho T, Ahmad AH, Abang F, Ghani IA, et al.
    Environ Sci Pollut Res Int, 2017 Jun;24(17):14782-14794.
    PMID: 28470499 DOI: 10.1007/s11356-017-8711-4
    In dengue mosquitoes, successful embryonic development and long lifespan are key determinants for the persistence of both virus and vector. Therefore, targeting the egg stage and vector lifespan would be expected to have greater impacts than larvicides or adulticides, both strategies that have lost effectiveness due to the development of resistance. Therefore, there is now a pressing need to find novel chemical means of vector control. Coffee contains many chemicals, and its waste, which has become a growing environmental concern, is as rich in toxicants as the green coffee beans; these chemicals do not have a history of resistance in insects, but some are lost in the roasting process. We examined whether exposure to coffee during embryonic development could alter larval eclosion and lifespan of dengue vectors. A series of bioassays with different coffee forms and their residues indicated that larval eclosion responses of Aedes albopictus and Ae. aegypti were appreciably lower when embryonic maturation occurred in environments containing coffee, especially roasted coffee crude extract (RCC). In addition, the lifespan of adults derived from eggs that hatched successfully in a coffee milieu was reduced, but this effect was less pronounced with roasted and green coffee extracts (RCU and GCU, respectively). Taken together, these findings suggested that coffee and its residues have embryocidal activities with impacts that are carried over onto the adult lifespan of dengue vectors. These effects may significantly reduce the vectorial capacity of these insects. Reutilizing coffee waste in vector control may also represent a realistic solution to the issues associated with its pollution.
    Matched MeSH terms: Larva
  14. Hasnol S, Lim JW, Wong CY, Lam MK, Ntwampe SKO
    Environ Sci Pollut Res Int, 2020 Jul;27(19):24574-24581.
    PMID: 32350833 DOI: 10.1007/s11356-020-09034-2
    The anaerobic decomposition of coconut endosperm waste (CEW), residue derived from cooking, has been insidiously spewing greenhouse gasses. Thus, the bioconversion of CEW via in situ fermentation by exo-microbes from commercial Rid-X and subsequent valorization by black soldier fly larvae (BSFL) was the primary objective of the current study to gain sustainable larval lipid and protein. Accordingly, various concentrations of exo-microbes were separately homogenized with CEW to perform fermentation amidst feeding to BSFL. It was found that 2.50% of exo-microbes was the threshold amount entailed to assuage competition between exo-microbes and BSFL for common nutrients. The presence of remnant nutrients exuded from the fermentation using 2.50% of exo-microbes was confirmed to promote BSFL growth measured as maximum larval weight gained and growth rate. Although the BSFL could accumulate the highest protein (16 mg/larva) upon feeding with CEW containing 2.50% of exo-microbes, more lipid (13 mg/larva) was stored in employing 0.10% of exo-microbes because of minimum loss to metabolic processes while prolonging the BSFL in its 5th instar stage.
    Matched MeSH terms: Larva
  15. El Mahmoudi A, Fegrouche R, Tachallait H, Lumaret JP, Arshad S, Karrouchi K, et al.
    Pest Manag Sci, 2023 Dec;79(12):4847-4857.
    PMID: 37500586 DOI: 10.1002/ps.7686
    BACKGROUND: Sphodroxia maroccana Ley is a pest of cork oak crops that damages the roots of seedlings and can severely impair cork oak regeneration. Since the banning of carbosulfan and chlorpyriphos, which were widely used against the larvae of Sphodroxia maroccana because of their harmful impact on the environment, until now there has been no pesticide against these pests. Therefore, it is particularly urgent to develop highly effective insecticidal molecules with novel scaffolds. Isoxazolines are a class of insecticides that act on γ-aminobutyric acid (GABA)-gated chloride channel allosteric modulators. In this work, a green synthesis of novel 3,5-disubstituted isoxazoline-sulfonamide derivatives was achieved in water via ultrasound-assisted four-component reactions, and their insecticidal activities against fourth-instar larvae of S. maroccana were evaluated.

    RESULTS: Most of the tested compounds showed insecticidal activity compared to fluralaner as positive control and commercially available insecticide. Especially, the isoxazoline-secondary sulfonamides containing halogens (Br and Cl) on the phenyl group attached to the isoxazoline, 6g (LC50  = 0.31 mg/mL), 6j (LC50  = 0.38 mg/mL), 6k (LC50  = 0.18 mg/mL), 6L (LC50  = 0.49 mg/mL), 6m (LC50  = 0.24 mg/mL), 6q (LC50  = 0.46 mg/mL), exhibited much higher larvicidal activity than fluralaner (LC50  = 0.99 mg/mL).

    CONCLUSION: Novel isoxazolines containing sulfonamide moieties were designed, synthesized and confirmed by two single-crystal structures of 4e and 6q. Their bioassay results showed significant larvicidal activity with significant morphological changes in vivo. These results will lay the foundation for the further discovery and development of isoxazoline-sulfonamide derivatives as novel crop protection larvicides of cork oak. © 2023 Society of Chemical Industry.

    Matched MeSH terms: Larva
  16. Yap FC, Chen HN, Chan BKK
    Sci Rep, 2023 Jun 14;13(1):9668.
    PMID: 37316644 DOI: 10.1038/s41598-023-33738-3
    Coral-associated organisms often exhibit a continuum of host specificities. We do not know whether the variation in host specificity is related to the settlement organs or preferential settlement behaviours of the larvae. We examined the morphology of attachment discs, the settlement and metamorphosis of coral barnacles-Pyrgoma cancellatum (lives in a single coral species), Nobia grandis (two families of corals), and Armatobalanus allium (six families of corals). Our results revealed that the attachment organ of all three species are spear-shaped with sparse villi, indicating that the morphology of the attachment organs does not vary among species with different host specificities. Larvae of P. cancellatum and N. grandis only settle on their specific hosts, suggesting that chemical cues are involved in the settlement. Cyprids of N. grandis display close searching behaviour before settlement. Cyprids of P. cancellatum settle immediately on their specific host corals, without any exploratory behaviour. The host specificity and exploratory behaviours of coral barnacle cyprids are results of adaptive evolution. We argue that there is a trade-off between exploration and energy conservation for metamorphosis processes. Coral barnacle metamorphosis is longer when compared to free-living species, likely because it involves the development of a tube-shaped base on the coral surface.
    Matched MeSH terms: Larva
  17. Trop Biomed, 2023 Jun 01;40(2):241-249.
    PMID: 37650412 DOI: 10.47665/tb.40.2.016
    The development of new alternatives strategies to synthetic insecticides aimed at reducing pest populations by developing pesticides based on plant extracts without negative effects in non target organisms and environment. The present study was undertaken in order to assess the insecticidal activity of the crude methanolic extract of the Algerian Asteraceae Cotula cinerea, against the larval and the pupal stage of Culex pipiens (Diptera: Culicidae). It is also to determine the chemical composition of the used extract, and to understand the mechanism of toxic action of the tested extract. Based on the preliminary tests, five concentrations of the crude methanolic extract of C. cinerea (0.62, 1.25, 2.50, 3.75, and 5 mg/mL) were tested for their insecticidal activity according to the protocol recommended by the World Health Organization. The chemical profile of the extract was also obtained by high performance liquid chromatography (HPLC). Histopathological effects and inhibition of acetylcholinesterase activity in treated mosquitoes with LC90 were examined to elucidate the mechanism of the toxic effect of the tested extract (48 h post treatment). Eight compounds have been identified by HPLC. That includes four flavonoids (rutin, quercetin, myrcetin and cathechin), three phenolic acids (benzoic acid, vanillic acid, p-coumaric acid) and one alkaloid (berberine). C. cinerea methanolic extract showed good larvicidal and pupicidal activities with LC50 and LC90 values of 1.10 and 4.37 mg/mL respectively against pupae, 24h post treatment and 1.26, 2.35 mg/mL respectively against the fourth instar larvae. Data of enzymatic assay performed on LC50 and LC90 pupae and larvae revealed prominent neurotoxic effects. C. cinerea extract reduced the activity of acetylcholinesterase (AChE) enzyme in a concentration dependent manner. Obtained inhibition percentages, 48 h after treatment, were 35.11 ± 7.44 and 51.83 ± 4.04% for pupal stage and 30.98 ± 2.97 % and 48.77 ± 4.72% for the fourth instar larvae for LC50 and LC90 values respectively. Treated larvae and pupae showed also histopathological damages in the pupal cuticle and larval midgut. The results of this study showed that C. cinerea crude methanolic extract could be considered as an eco-friendly alternative for mosquito control.
    Matched MeSH terms: Larva
  18. Agus Nurjana M, Srikandi Y, Wijatmiko TJ, Hidayah N, Isnawati R, Octaviani O, et al.
    J Water Health, 2023 Nov;21(11):1741-1746.
    PMID: 38017604 DOI: 10.2166/wh.2023.270
    One of the factors that influence the development of mosquitoes is the water container. This study was performed to determine the relationship between the characteristics of water containers and the preferable conditions for laying eggs by Aedes sp. A single larva method was conducted during March 2019 in 300 houses in two villages (Turikale and Adatongeng) at Maros Regency, Indonesia. In total, 1,269 water containers were considered, and among them buckets were found to be the most common container. Logistic regression analysis showed that the type, container location, and weekly drainage were related to the presence of larvae/pupae in the Maros Regency (p-value < 0.05). Non-water containers, which are kept indoors and are not drained at least once a week, have a greater chance of breeding Aedes sp. More attention is given to non-water containers that are located inside the house. Prevention activities, especially draining water containers properly at least once a week ensures that they do not become breeding sites for Aedes sp. mosquitoes and helps to prevent the transmission of dengue viral fever.
    Matched MeSH terms: Larva
  19. Zhang Y, Liu S, De Meyer M, Liao Z, Zhao Y, Virgilio M, et al.
    J Adv Res, 2023 Nov;53:61-74.
    PMID: 36574947 DOI: 10.1016/j.jare.2022.12.012
    INTRODUCTION: The oriental fruit fly Bactrocera dorsalis is one of the most destructive agricultural pests worldwide, with highly debated species delimitation, origin, and global spread routes.

    OBJECTIVES: Our study intended to (i) resolve the taxonomic uncertainties between B. dorsalis and B. carambolae, (ii) reveal the population structure and global invasion routes of B. dorsalis across Asia, Africa, and Oceania, and (iii) identify genomic regions that are responsible for the thermal adaptation of B. dorsalis.

    METHODS: Based on a high-quality chromosome-level reference genome assembly, we explored the population relationship using a genome-scale single nucleotide polymorphism dataset generated from the resequencing data of 487 B. dorsalis genomes and 25 B. carambolae genomes. Genome-wide association studies and silencing using RNA interference were used to identify and verify the candidate genes associated with extreme thermal stress.

    RESULTS: We showed that B. dorsalis originates from the Southern India region with three independent invasion and spread routes worldwide: (i) from Northern India to Northern Southeast Asia, then to Southern Southeast Asia; (ii) from Northern India to Northern Southeast Asian, then to China and Hawaii; and (iii) from Southern India toward the African mainland, then to Madagascar, which is mainly facilitated by human activities including trade and immigration. Twenty-seven genes were identified by a genome-wide association study to be associated with 11 temperature bioclimatic variables. The Cyp6a9 gene may enhance the thermal adaptation of B. dorsalis and thus boost its invasion, which tended to be upregulated at a hardening temperature of 38 °C. Functional verification using RNA interference silencing against Cyp6a9, led to the specific decrease in Cyp6a9 expression, reducing the survival rate of dsRNA-feeding larvae exposed to extreme thermal stress of 45 °C after heat hardening treatments in B. dorsalis.

    CONCLUSION: This study provides insights into the evolutionary history and genetic basis of temperature adaptation in B. dorsalis.

    Matched MeSH terms: Larva
  20. Ya'cob Z, Takaoka H, Pramual P, Low VL, Sofian-Azirun M
    Parasit Vectors, 2016 Apr 19;9:219.
    PMID: 27094088 DOI: 10.1186/s13071-016-1492-7
    BACKGROUND: Preimaginal black flies (Diptera: Simuliidae) are important components of the stream ecosystem. However, there has been limited research undertaken on the vertical distribution of preimaginal black flies and their associated ecological factors. Stream conditions are generally variable along the altitudinal gradient. Therefore, we conducted an in-depth entomological survey to investigate the simuliid distribution pattern along an altitudinal gradient in Peninsular Malaysia.

    METHODS: A total of 432 collections were performed in this study (24 samplings at each of 18 fixed-streams at monthly intervals) from February 2012 to January 2014. Larvae and pupae attached on aquatic substrates such as grasses, leaves and stems, twigs, plant roots and rocks were collected by hand using fine forceps. Stream depth (m), width (m), velocity (m/s), water temperature (°C), acidity (pH), conductivity (mS/cm) and dissolved oxygen (mg/L) were measured at the time of each collection.

    RESULTS: A total of 35 black fly species were recorded in the present study. The most frequently collected species were Simulium tani (31.7%) and S. whartoni (21.5%), while the relatively common species were Simulium sp. (nr. feuerborni) (16.2%), S. decuplum (15.5%), S. angulistylum (14.8%), S. bishopi (13.2%) and S. izuae (11.8%). Total estimated species richness ranged between 39.8 and 41.3, which yielded more than 80% of sampling efficiency. Six simuliid species were distributed below 500 m, whereas eight species were distributed above 1400 m. Simulium sp. (nr. feuerborni) and S. asakoae were found from middle to high altitudes (711-1813 m). Simulium whartoni, S. brevipar and S. bishopi were distributed widely from low to high altitudes (159-1813 m). Regression analysis between species richness and PCs revealed that the species richness was significantly associated with wider, deeper and faster streams at low altitude, normal water temperature (23-25 °C), low conductivity, higher discharge, more canopy cover and riparian vegetation and with larger streambed particles (F = 20.8, df = 1, 422, P 

    Matched MeSH terms: Larva/classification; Larva/growth & development; Larva/physiology
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