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1.
J Insect Sci ; 21(2)2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33693804

RESUMO

Diurnal temperature amplitude is known to have a large influence on insect life history. Population density affects intraspecific competition and many other aspects of insect life history. However, there is limited information on the interactive effects of these factors on insects. Here, we tested the interactive effects of three diurnal temperature amplitudes (22 ± 0°C, 22 ± 6°C, and 22 ± 12°C) and three population densities on the development, survival, longevity, and fecundity of the English grain aphid Sitobion avenae (Fabricius) (Homoptera: Aphididae). At a constant temperature, increasing population density reduced the growth and survival of early-instar nymphs, increased longevity, and reduced fecundity. At a low population density, increasing temperature amplitude inhibited nymph development. However, even at a high temperature amplitude, nymph survival rate was higher than expected, and reproduction was possible because the recovery of the lower night-temperatures eliminated thermal stress. Increasing the population density reduced, and even reversed, the negative effects of the wide temperature amplitude. This may reflect synergistic interactions between population density and wide temperature amplitude as these stressors each incur energetic costs. These findings emphasize the importance of temperature amplitude and population density for improving prediction accuracy and damage assessment during pest control modeling.


Assuntos
Afídeos , Densidade Demográfica , Temperatura , Animais , Afídeos/crescimento & desenvolvimento , Afídeos/fisiologia , Fertilidade , Estágios do Ciclo de Vida , Ninfa/crescimento & desenvolvimento , Reprodução
2.
J Insect Sci ; 21(1)2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33560362

RESUMO

Laricobius nigrinus (Coleoptera: Derodontidae) Fender and Laricobius osakensis (Coleoptera: Derodontidae) Montgomery and Shiyake have been mass produced by Virginia Tech as biological control agents for the hemlock woolly adelgid (HWA), Adelges tsugae (Hemiptera: Adelgidae) Annand, for the past 15 and 9 yr, respectively. Herein, we describe modifications of our rearing procedures, trends and analyses in the overall production of these agents, and the redistribution of these agents for release to local and federal land managers. Based on these data, we have highlighted three major challenges to the rearing program: 1) high mortality during the subterranean portion of its life cycle (averaging 37% annually) reducing beetle production, 2) asynchrony in estivation emergence relative to the availability of their host HWA minimizing food availability, and 3) unintended field collections of Laricobius spp. larvae on HWA provided to lab-reared larvae complicating rearing procedures. We further highlight corresponding avenues of research aimed at addressing each of these challenges to further improve Laricobius spp. production.


Assuntos
Besouros/fisiologia , Hemípteros/fisiologia , Controle Biológico de Vetores/métodos , Animais , Agentes de Controle Biológico , Besouros/crescimento & desenvolvimento , Hemípteros/crescimento & desenvolvimento , Cicutas (Apiáceas)/crescimento & desenvolvimento , Larva/crescimento & desenvolvimento , Larva/fisiologia , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , Virginia
3.
Appl Environ Microbiol ; 87(7)2021 03 11.
Artigo em Inglês | MEDLINE | ID: mdl-33514519

RESUMO

The composition of tick microbiomes varies both within and among tick species. Whether this variation is intrinsic (related to tick characteristics) or extrinsic (related to vertebrate host and habitat) is poorly understood but important, as microbiota can influence the reproductive success and vector competence of ticks. We aimed to uncover what intrinsic and extrinsic factors best explain the microbial composition and taxon richness of 11 species of neotropical ticks collected from eight species of small mammals in 18 forest fragments across central Panama. Microbial richness varied among tick species, life stages, and collection sites but was not related to host blood source. Microbiome composition was best explained by tick life stage, with bacterial assemblages of larvae being a subset of those of nymphs. Collection site explained most of the bacterial taxa with differential abundance across intrinsic and extrinsic factors. Francisella and Rickettsia were highly prevalent, but their proportional abundance differed greatly among tick species, and we found both positive and negative cooccurrence between members of these two genera. Other tick endosymbionts (e.g., Coxiella and Rickettsiella) were associated with specific tick species. In addition, we detected Anaplasma and Bartonella in several tick species. Our results indicate that the microbial composition and richness of neotropical ticks are principally related to intrinsic factors (tick species and life stage) and collection site. Taken together, our analysis informs how tick microbiomes are structured and can help anchor our understanding of tick microbiomes from tropical environments more broadly.IMPORTANCE Blood-feeding arthropod microbiomes often play important roles in disease transmission, yet the factors that structure tick microbial communities in the Neotropics are unknown. Utilizing ticks collected from live animals in neotropical forest fragments, this study teases apart the contributions of intrinsic and extrinsic tick-associated factors on tick microbial composition as well as which specific microbes contribute to differences across tick species, tick life stages, the mammals they fed on, and the locations from where they were sampled. Furthermore, this study provides revelations of how notable tick-associated bacterial genera are interacting with other tick-associated microbes as well as the forest animals they encounter.


Assuntos
Bactérias/isolamento & purificação , Microbiota , Carrapatos/microbiologia , Animais , Florestas , Larva/crescimento & desenvolvimento , Larva/microbiologia , Mamíferos/parasitologia , Ninfa/crescimento & desenvolvimento , Ninfa/microbiologia , Panamá , Carrapatos/crescimento & desenvolvimento
4.
Parasitol Res ; 119(9): 2775-2781, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32737590

RESUMO

Triatoma platensis is occasionally found coexisting with Triatoma infestans in chicken coops in Argentina. Some authors have reported the presence of hybrid specimens of both species in chicken coops and other peridomestic habitats. Given the coexistence of T. infestans with T. platensis and the possibility of generating fertile hybrids, it is important to evaluate the vectorial competence of these hybrids. The objective of this study was to record the dynamics of feeding-defecation behavior in fifth-stage nymphs and adults of hybrids between both species and to compare it with T. platensis and T. infestans. Three experimental groups were formed separated by stage and sex: Hybrid group, T. infestans group, and T. platensis group. During feeding, the following variables were recorded for each group: (i) blood meal size, (ii) feeding time, (iii) number of defecations during feeding, and (iv) number of defecations at 10 and 30 min after feeding. The results indicate that adults and fifth-instar nymphs of hybrids have a feeding and defecation behavior similar to T. infestans: they achieve feeding in a short time and first defecation occurs during or just after feeding. Nevertheless, hybrid's ingestion of blood occurs at higher velocity and they require higher blood intake to provoke early defecations. Considering the blood ingestion velocity, the amount of blood ingested, and the short time required for the production of the first defecation, the results of this study suggest that hybrid can be a competent Trypanosoma cruzi vector.


Assuntos
Defecação/fisiologia , Comportamento Alimentar/fisiologia , Insetos Vetores/fisiologia , Triatoma/fisiologia , Animais , Argentina , Doença de Chagas/transmissão , Galinhas/parasitologia , Ecossistema , Fezes/parasitologia , Feminino , Masculino , Ninfa/crescimento & desenvolvimento , Trypanosoma cruzi/crescimento & desenvolvimento
5.
PLoS One ; 15(6): e0235506, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32603337

RESUMO

The brown planthopper (Nilapavata lugens: BPH) and whitebacked planthopper (Sogatella furcifera: WBPH) co-occur as the principal pests of rice in Asia. A review of previous studies suggests that the two species have similar temperature tolerances and similar temperature thresholds for development. However, the distribution and seasonality of WBPH suggest that its temperature optima for performance (survival, oviposition and growth) may be lower than for BPH. We compared adult longevity, oviposition, nymph survival and development success, as well as nymph biomass in both species across a gradient of constant temperatures from 15°C-40°C, at 5°C intervals. The most suitable temperatures for oviposition, nymph biomass and development success were 5-10°C lower for WBPH than for BPH. Furthermore, compared to BPH, WBPH demonstrated clear differences in oviposition on different rice subspecies and on rice at different growth stages at 25°C and 30°C, but not at other temperatures. The results suggest that aspects of herbivore performance within tolerable temperature ranges, which are not often included in temperature models, may be more useful than thermal tolerances or development thresholds in predicting the effects of global warming on pest damage to crops.


Assuntos
Hemípteros/fisiologia , Oviposição/fisiologia , Especificidade da Espécie , Temperatura , Animais , Ásia , Produtos Agrícolas , Ecossistema , Aquecimento Global , Herbivoria/fisiologia , Modelos Teóricos , Ninfa/crescimento & desenvolvimento , Oryza , Controle de Pragas
6.
Sci Rep ; 10(1): 10958, 2020 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-32616737

RESUMO

Road runoff carries a mixture of contaminants that threatens the quality of natural water bodies and the health of aquatic organisms. The use of sedimentation ponds is a nature-based solution for the treatment of road runoff. This study assessed the concentration of polycyclic aromatic hydrocarbons (PAHs) and their alkylated homologues in sediment from seven highway sedimentation ponds and three natural urban ponds. In addition, the study explored the bioaccumulation of PAHs in dragonfly nymphs (Anisoptera). Finally, biota-sediment accumulation factors (BSAFs) were estimated. The results revealed a significant difference in the concentrations of 16 priority PAHs in sediment, with overall higher levels in sedimentation ponds (2,911 µg/kg on average) compared to natural urban ponds (606 µg/kg on average). PAH levels increased substantially once alkylated homologues were considered, with alkylated comprising between 42 and 87% of the total PAH in sediment samples. These results demonstrate the importance of alkylated forms in the environmental assessment of PAHs. The bioaccumulation assessment indicates that dragonfly nymphs bioaccumulate PAHs to a certain degree. It is not clear, however, whether they metabolize PAHs. BSAF results ranged from approx. 0.006 to 10 and indicate that BSAFs can be a powerful tool to determine the functionality of sedimentation ponds.


Assuntos
Alquilantes/química , Monitoramento Ambiental/métodos , Sedimentos Geológicos/análise , Ninfa/metabolismo , Odonatos/metabolismo , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluentes Químicos da Água/análise , Alquilação , Animais , Bioacumulação , Sedimentos Geológicos/química , Ninfa/crescimento & desenvolvimento , Odonatos/crescimento & desenvolvimento , Hidrocarbonetos Policíclicos Aromáticos/química , Poluentes Químicos da Água/química
7.
J S Afr Vet Assoc ; 91(0): e1-e3, 2020 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-32501016

RESUMO

Sixty-four individuals of a macronyssid mite, Parasteatonyssus nyctinomi (Zumpt, Patterson 1951), were identified from Egyptian free-tailed bats Tadarida aegyptiaca (É. Geoffroy 1818) (Chiroptera: Molossidae) captured in the Kunene region of Namibia (southern Africa). This is the first report on P. nyctinomi in the country.


Assuntos
Distribuição Animal , Quirópteros/parasitologia , Ácaros/fisiologia , Animais , Feminino , Interações Hospedeiro-Parasita , Masculino , Ácaros/crescimento & desenvolvimento , Namíbia , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia
8.
J Insect Sci ; 20(3)2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32559297

RESUMO

Wolbachia is a maternally inherited bacterium ubiquitous in insects that has attracted interest as a prospective insect pest-control agent. Here, we detected and characterized Wolbachia in the leafhoppers Matsumuratettix hiroglyphicus (Matsumura) (Cicadellidae: Hemiptera) and Yamatotettix flavovittatus Matsumura (Cicadellidae: Hemiptera), insect vectors of the phytoplasma that cause white leaf disease in sugarcane. The 16S rRNA and wsp gene markers revealed that Wolbachia was not present in the M. hiroglyphicus but naturally occurs in Y. flavovittatus. Additionally, the infection rates in adult leafhoppers ranged from 0 to 100% depending on geographic location. Moreover, Wolbachia was detected in the eggs and first- to fifth-instar nymphs of Y. flavovittatus. A phylogenic tree of Wolbachia indicated that it resided in the monophyletic supergroup B clade and clustered in the Ori subgroup. Furthermore, fluorescence in situ hybridization revealed that Wolbachia localized to the egg apices, randomly distributed in the egg cytoplasm, and was concentrated in the nymph and adult bacteriomes, as well as occasional detection in the thorax and abdomen. To the best of our knowledge, the present study is the first to demonstrate the prevalence of Wolbachia in the leafhopper Y. flavovittatus. The obtained results would provide useful information for the future development of Wolbachia as a biological control agent for the leafhopper vectors.


Assuntos
Hemípteros/microbiologia , Simbiose , Wolbachia/fisiologia , Animais , Feminino , Hemípteros/crescimento & desenvolvimento , Insetos Vetores/crescimento & desenvolvimento , Insetos Vetores/microbiologia , Masculino , Ninfa/crescimento & desenvolvimento , Ninfa/microbiologia , Óvulo/crescimento & desenvolvimento , Óvulo/microbiologia , Doenças das Plantas/microbiologia , Saccharum/microbiologia
9.
J Insect Sci ; 20(3)2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32501501

RESUMO

Plant-derived compounds are sources of biopesticides for the control of insect pests. We compared the growth performance and enzymatic response of the grasshopper Calliptamus abbreviatus Ikonn to six plant-derived compounds (rutin, quercetin, nicotine, matrine, azadirachtin, and rotenone) in laboratory and field trials. When exposed to the six compounds, C. abbreviatus had significantly reduced growth and survival. All the compounds significantly induced an elevated level of reactive oxygen species, indicating oxidative damage. The activity of detoxifying enzymes, including cytochrome P450s, carboxylesterase, glutathione-S-transferase, and UDP-glucuronosyltransferase, and the antioxidant enzymes, including superoxide dismutase, catalase, and peroxidase, all significantly increased after exposure to the six compounds. These data suggest that the six plant-derived compounds had negative effects on C. abbreviatus. Of the six compounds, matrine, azadirachtin, and rotenone were more toxic to C. abbreviatus, followed by nicotine, quercetin, and rutin. These results show the potential of these compounds as botanical pesticides, which can be applied for the biological control of the grasshopper C. abbreviatus.


Assuntos
Dieta , Gafanhotos , Inseticidas , Animais , Feminino , Gafanhotos/enzimologia , Gafanhotos/crescimento & desenvolvimento , Inseticidas/classificação , Ninfa/enzimologia , Ninfa/crescimento & desenvolvimento , Distribuição Aleatória
10.
J Vet Sci ; 21(3): e41, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32476315

RESUMO

BACKGROUND: The poultry red mite, Dermanyssus gallinae, is a serious problem in the laying hen industry worldwide. Currently, the foremost control method for D. gallinae is the implementation of integrated pest management, the effective application of which necessitates a precise monitoring method. OBJECTIVES: The aim of the study was to propose an accurate monitoring method with a reliable protocol for caged-layer poultry farms, and to suggest an objective classification for assessing D. gallinae infestation on caged-layer poultry farms according to the number of mites collected using the developed monitoring method. METHODS: We compared the numbers of mites collected from corrugated cardboard traps, regarding with length of sampling periods, sampling sites on cage, and sampling positions in farm buildings. The study also compared the mean numbers of mites collected by the developed method with the infestation levels using by the conventional monitoring methods in 37 caged-layer farm buildings. RESULTS: The statistical validation provided the suitable monitoring method that the traps were installed for 2 days on feed boxes at 27 sampling points which included three vertical levels across nine equally divided zones of farms. Using this monitoring method, the D. gallinae infestation level can be assessed objectively on caged-layer poultry farms. Moreover, the method is more sensitive than the conventional method in detecting very small populations of mites. CONCLUSIONS: This method can be used to identify the initial stages of D. gallinae infestation in the caged-layer poultry farms, and therefore, will contribute to establishment of effective control strategies for this mite.


Assuntos
Criação de Animais Domésticos/métodos , Galinhas , Infestações por Ácaros/veterinária , Ácaros/fisiologia , Doenças das Aves Domésticas/epidemiologia , Animais , Larva/crescimento & desenvolvimento , Larva/fisiologia , Infestações por Ácaros/epidemiologia , Infestações por Ácaros/parasitologia , Ácaros/crescimento & desenvolvimento , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , Óvulo/fisiologia , Doenças das Aves Domésticas/parasitologia , República da Coreia/epidemiologia
11.
Folia Parasitol (Praha) ; 672020 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-32350156

RESUMO

Here we describe the new trypanosomatid, Phytomonas borealis sp. n., from the midgut of the spiked shieldbugs, Picromerus bidens (Linnaeus), collected in two locations, Novgorod and Pskov Oblasts of Russia. The phylogenetic analyses, based on the 18S rRNA gene, demonstrated that this flagellate is a sister species to the secondary monoxenous Phytomonas nordicus Frolov et Malysheva, 1993, which was concurrently documented in the same host species in Pskov Oblast. Unlike P. nordicus, which can complete its development (including exit to haemolymph and penetration into salivary glands) in Picromerus bidens, the new species did not form any extraintestinal stages in the host. It also did not produce endomastigotes, indispensable for transmission in other Phytomonas spp. These observations, along with the fact that P. bidens overwinters at the egg stage, led us to the conclusion that the examined infections with P. borealis were non-specific. Strikingly, the flagellates from the Novgorod population contained prokaryotic endosymbionts, whereas the parasites from the second locality were endosymbiont-free. This is a first case documenting presence of intracellular symbiotic bacteria in Phytomonas spp. We suggest that this novel endosymbiotic association arose very recently and did not become obligate yet. Further investigation of P. borealis and its intracellular bacteria may shed light on the origin and early evolution of endosymbiosis in trypanosomatids.


Assuntos
Fenômenos Fisiológicos Bacterianos , Heterópteros/parasitologia , Simbiose , Trypanosomatina/classificação , Animais , Heterópteros/crescimento & desenvolvimento , Ninfa/crescimento & desenvolvimento , Ninfa/parasitologia , Filogenia , RNA de Protozoário/análise , RNA Ribossômico 18S/análise , Federação Russa , Trypanosomatina/microbiologia
12.
Vet Parasitol ; 280: 109092, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32278223

RESUMO

The aim of this study was to determine imidacloprid's lethal activity against fifth-instar nymphs of Triatoma infestans. In the first stage of this work, it was assayed the topical application of this insecticide on non-fed and repletion-fed nymphs. Results showed a DL50 three times greater in non-fed bugs than in those fully engorged. The presence of food determined less time for the insecticide's maximum lethal effect: 24 h post topical application in fed nymphs and 72 h in non-fed nymphs. In the study's second stage, we assayed a xenointoxication assay on dogs. The commercial products, Advantage®, Bayer (imidacloprid 10 % p/v) and Power Ultra®, Brouwer (imidacloprid 5.15 %, permethrin 40 % and piperonyl butoxide [PBO] 3%) were evaluated. Following administration of the insecticide, nymphs were fed on dogs 24, 72, 168, 240 and 336 h. Blood intake was similar in nymphs exposed to treated dogs versus controls. Although both commercial products showed low triatomicidal activity, a higher efficacy of the product combining imidacloprid with the synergist piperonyl butoxide and permethrin versus the product with imidacloprid as the only active ingredient was observed, causing in nymphs a mortality rate of 36.3 % and 20.7 %, respectively. Our results suggest that imidacloprid, alone or in combination with permethrin and PBO, is not an alternative for control of T. infestans.


Assuntos
Insetos Vetores , Inseticidas , Neonicotinoides , Nitrocompostos , Triatoma , Animais , Controle de Insetos , Ninfa/crescimento & desenvolvimento , Triatoma/crescimento & desenvolvimento
13.
J Insect Sci ; 20(2)2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-32282036

RESUMO

We report a new positive-sense single-stranded RNA (ss RNA+) virus from the brown citrus aphid Aphis citricidus. The 20,300 nucleotide (nt)-long viral genome contains five open-reading frames and encodes six conserved domains (TM2, 3CLpro, TM3, RdRp, Zm, and HEL1). Phylogenetic analysis and amino acid sequence analysis revealed this virus might belong to an unassigned genus in the family Mesoniviridae. The presence of the virus was also confirmed in the field population. Importantly, analysis of the virus-derived small RNAs showed a 22-nt peak, implying that viral infection triggers the small interfering RNA pathway as antiviral immunity in aphids. This is the first report of a mesonivirus in invertebrates other than mosquitoes.


Assuntos
Afídeos/virologia , Especificidade de Hospedeiro , Nidovirales/fisiologia , RNA Viral/análise , Animais , Afídeos/crescimento & desenvolvimento , Ninfa/crescimento & desenvolvimento , Ninfa/virologia , Vírus de Plantas/fisiologia , Análise de Sequência de RNA
14.
Parasitol Res ; 119(5): 1553-1562, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32236709

RESUMO

We confirm the presence of nymphs of the introduced pentastomid, Linguatula serrata, in the introduced rabbit, Oryctolagus cuniculus, in Australia, based on morphological and molecular results. Two nymphs were collected from a single rabbit near the Kosciuszko National Park in New South Wales. Unlike reports of nymphs from domestic animals, these nymphs were not encapsulated, despite having the morphological features of infective nymphs. The possibility of different development pathways in lagomorphs is discussed. Examination of feral deer for L. serrata was unsuccessful and potential reasons for a lack of infection in these animals are postulated. Our results reiterate the need for a combined morphological and molecular approach to the identification of L. serrata. Further sampling of a range of feral and native animals is required to determine the true range of intermediate hosts and their relative importance in the transmission of L. serrata in Australia.


Assuntos
Especificidade de Hospedeiro/fisiologia , Lagomorpha/parasitologia , Doenças Parasitárias em Animais/parasitologia , Pentastomídeos/crescimento & desenvolvimento , Animais , Austrália/epidemiologia , Cervos/parasitologia , New South Wales/epidemiologia , Ninfa/crescimento & desenvolvimento , Doenças Parasitárias em Animais/epidemiologia , Prevalência , Coelhos
15.
Vet Parasitol ; 280: 109095, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32251919

RESUMO

The aim of the present study was to test the in vitro acaricidal activity of saturated fatty acids (hexanoic, octanoic, decanoic, lauric, myristic, palmitic, octadecanoic, eicosanoic, docosanoic and tetracosanoic) against Rhipicephalus microplus and select a candidate compound for the subsequent determination of its clinical safety for mice and bovines as well as its in vivo efficacy (ethical clearance number 507/2013). None of the compounds exhibited in vitro larvicidal effectiveness, but acaricidal effectiveness was greater than 95 % in the adult immersion test at 40 mg/ml (hexanoic, octanoic, decanoic, lauric, myristic, palmitic and eicosanoic acids). After a second AIT evaluation of serial concentrations of the fatty acids, lauric and myristic acids were selected for the safety and in vivo efficacy assays. No adverse effect was found in the local lymph node assay in mice treated with lauric or myristic acid. Moreover, no clinical signs of systemic poisoning or dermatological, hematological or biochemical abnormalities were found in cattle after the topical application of 1 % lauric acid. In the dose determination test, the 1% solution of this compound exhibited 86% efficacy in cattle naturally infested by a field population of Rhipicephalus microplus susceptible to all chemical groups, except synthetic pyrethroids. The efficacy of 1 % lauric acid was 53.4 % in the dose confirmation test performed on another herd with a field R. microplus population resistant to all chemical groups of acaricides. In conclusion, fatty acids are potential bioactive compounds for the control of R. microplus. Topically applied lauric acid (C12) exhibits in vivo acaricide activity against adults, nymphs and larvae of R. (B) microplus and is safe for cattle.


Assuntos
Acaricidas , Doenças dos Bovinos/prevenção & controle , Ácidos Láuricos , Rhipicephalus , Infestações por Carrapato/veterinária , Acaricidas/efeitos adversos , Animais , Bovinos , Feminino , Larva/crescimento & desenvolvimento , Ácidos Láuricos/efeitos adversos , Ninfa/crescimento & desenvolvimento , Rhipicephalus/crescimento & desenvolvimento , Infestações por Carrapato/prevenção & controle
16.
Vet Parasitol ; 279: 109064, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32143012

RESUMO

Tick serpins are involved in enzyme activity, food digestion, blood-feeding, immune response and anticoagulation. Little is known about the potential roles of serpins in tick reproduction. RHS8, a serpin from the tick Rhipicephalus haemaphysaloides, has an open reading frame 1212 bp long and encodes a protein that has 404 amino acids and a predicted molecular weight of 45 kDa. RHS8 exhibits 89.58 % amino acid identity with RmS15 in Rhipicephalus microplus. RHS8 was expressed primarily in larvae and nymphs. RHS8 mRNA expression in the ovaries, fat bodies and salivary glands were up-regulated from feeding to ovipositing ticks. RNAi results showed that RHS8 dsRNA-injected ticks had a lower body weight, longer feeding time, fewer eggs laid and lower egg hatchability. Tick reproduction, such as egg laying and hatching, was disrupted by RNAi. Compared with the control group, ovaries of the RHS8 interference group were light brown color, indicating a reduction in yolk granule accumulation. Western blot results showed that the expression of RHVg3 and RHVg4 proteins in ovaries was reduced in the RHS8 dsRNA-injected group. These results indicate that RHS8 is related to tick reproduction and its interference affects vitellogenesis.


Assuntos
Proteínas de Artrópodes/genética , Rhipicephalus/fisiologia , Serpinas/genética , Vitelogênese/genética , Sequência de Aminoácidos , Animais , Proteínas de Artrópodes/química , Proteínas de Artrópodes/metabolismo , Feminino , Larva/crescimento & desenvolvimento , Larva/fisiologia , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , Filogenia , Interferência de RNA , Rhipicephalus/genética , Rhipicephalus/crescimento & desenvolvimento , Alinhamento de Sequência , Serpinas/química , Serpinas/metabolismo
17.
Proc Natl Acad Sci U S A ; 117(10): 5525-5531, 2020 03 10.
Artigo em Inglês | MEDLINE | ID: mdl-32098850

RESUMO

Insects living in the temperate zone enter a physiological state of arrested or slowed development to overcome an adverse season, such as winter. Developmental arrest, called diapause, occurs at a species-specific developmental stage, and embryonic and pupal diapauses have been extensively studied in mostly holometabolous insects. Some other insects overwinter in the nymphal stage with slow growth for which the mechanism is poorly understood. Here, we show that this nymphal period of slow growth is regulated by temperature and photoperiod through separate pathways in the cricket Modicogryllus siamensis The former regulates the growth rate, at least in part, through the insulin / target of rapamycin (TOR) signaling pathway. Lower temperature down-regulates the expression of insulin -like peptide (Ms'Ilp) and Target of rapamycin (Ms'Tor) genes to slow down the growth rate without affecting the number of molts. The latter regulates the number of molts independent of temperature. Short days increase the number of molts through activation of the juvenile hormone (JH) pathway and down-regulation of myoglianin (Ms'myo), a member of the TGFß family, which induces adult metamorphosis. In contrast, long days regulate Ms'myo expression to increase during the fifth to sixth instar to initiate adult metamorphosis. When Ms'myo expression is suppressed, juvenile hormone O-methyl transferase (Ms'jhamt) was up-regulated and increased molts to prolong the nymphal period even under long-day conditions. The present findings suggested that the photoperiod regulated Ms'myo, and the JH signaling pathway and the temperature-controlled insulin/TOR pathway cooperated to regulate nymphal development for overwintering to achieve seasonal adaptation of the life cycle in M. siamensis.


Assuntos
Adaptação Fisiológica , Gryllidae/crescimento & desenvolvimento , Insulina/metabolismo , Hormônios Juvenis/metabolismo , Ninfa/crescimento & desenvolvimento , Fotoperíodo , Serina-Treonina Quinases TOR/metabolismo , Animais , Gryllidae/metabolismo , Ninfa/metabolismo , Estações do Ano , Transdução de Sinais , Temperatura , Fator de Crescimento Transformador beta/metabolismo
18.
Prev Vet Med ; 174: 104837, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31756672

RESUMO

The objectives of this study were to evaluate the resistance of Amblyomma mixtum and Rhipicephalus microplus ticks from co-infested bovines from the Veracruz region in Mexico to different acaricide families and to demonstrate the viability of the packet test on different A. mixtum instars. The following acaricide families were used: a combination (cypermethrin 15 g + chlorpyrifos 25 g + citronella 1 g + butoxide piperonyl 15 g), amidine (formamidine 12.5 g), pyrethroid (cypermethrin 15 g), and organophosphate (dichlorvos 60 g + chlorpyrifos 20 g). Regarding the packet test in both species, resistance was found for the pyrethroid and amidine families in A. mixtum and R. microplus, as efficacy did not surpass 40 %, including in immature instars; regarding the adult immersion test in R. microplus, the efficacy was 93.3 % for the amidine family and 26.2 % for the pyrethroid family. The proposed methodology is an alternative technique to optimize resistance detection in immature ticks with a heteroxenous life cycle.


Assuntos
Acaricidas/farmacologia , Resistência a Medicamentos , Ixodidae/efeitos dos fármacos , Animais , Feminino , Ixodidae/crescimento & desenvolvimento , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , México , Ninfa/efeitos dos fármacos , Ninfa/crescimento & desenvolvimento , Rhipicephalus/efeitos dos fármacos , Rhipicephalus/fisiologia
19.
Med Vet Entomol ; 34(2): 184-191, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-31876331

RESUMO

Rhipicephalus sanguineus is a canine tick that infests dogs throughout the world and is frequently found in homes and dog kennels. Management of this tick species is complicated by the presence of resistance to commonly utilized acaricides. Fungal formulations could provide a valuable alternative tool for management and are especially relevant indoors where detrimental environmental effects on fungal spores are of less concern. Two commercially available fungal formulations, one containing Metarhizium anisopliae and the other containing Beauveria bassiana, were compared for time to death and sporulation in nymphal ticks exposed for 60 min in treated filter paper packets. Beauveria bassiana exposure killed ticks faster than M. anisopliae exposure and B. bassiana was more likely to sporulate on tick cadavers than M. anisopliae. To determine whether infected ticks could disseminate fungus to their conspecifics, ticks were marked and treated with fungus before being placed with untreated ticks. Fungus was successfully transmitted from treated to untreated ticks. Mortality of ticks exposed to B. bassiana-exposed conspecifics occurred sooner than for those exposed to M. anisopliae-exposed conspecifics, indicating faster dissemination in the former. Therefore, although both formulations resulted in decreased longevity of ticks compared with the controls, the B. bassiana formulation holds the most promise for direct or indirect application with respect to brown dog tick management.


Assuntos
Beauveria/fisiologia , Metarhizium/fisiologia , Controle Biológico de Vetores , Rhipicephalus sanguineus/microbiologia , Controle de Ácaros e Carrapatos , Animais , Ninfa/crescimento & desenvolvimento , Ninfa/microbiologia , Rhipicephalus sanguineus/crescimento & desenvolvimento
20.
Insect Biochem Mol Biol ; 116: 103281, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31740347

RESUMO

Arthropod EFLamide genes in chelicerates, myriapods, decapods and non pterygote hexapods encode various EFLamide paracopies on a single precursor. However, in more advanced insect species such multiple EFLamide paracopies encoding genes are absent. In some Hemiptera putative exons of an EFLamide gene coding for a single EFLamide have been identified, while in the migratory locust a similar exon could potentially code for two EFLamide peptides. The recent identification of an EFLGamide from Platynereis dumerilii as the ligand for an ortholog of the TRH GPCR, suggested that the arthropod EFLamides might similarly activate TRH GPCR orthologs. We here identify the TRH GPCR ortholog from Locusta migratoria and show that it is activated in nanomolar concentrations by the two EFLamides previously predicted from this species. We also show that in the central nervous system there seems to be only a single bilateral neuron in the protocerebrum expressing this peptide. Given this very limited expression of EFLamide in locusts, it is perhaps not surprising that this gene and its receptor have been lost in many other insect species. This shows again that although neuropeptides and their receptors may persist in different evoltionary lineages, their functions can change dramatically.


Assuntos
Proteínas de Insetos/genética , Locusta migratoria/genética , Neuropeptídeos/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Feminino , Proteínas de Insetos/química , Proteínas de Insetos/metabolismo , Locusta migratoria/crescimento & desenvolvimento , Neuropeptídeos/química , Neuropeptídeos/metabolismo , Ninfa/genética , Ninfa/crescimento & desenvolvimento , Filogenia
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