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1.
PLoS One ; 16(10): e0255321, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34634069

RESUMO

BACKGROUND: An. funestus is a major Afrotropical vector of human malaria. This study sought to investigate the larval ecology, sporozoite infection rates and blood meal sources of An. funestus in western Kenya. METHODS: Larval surveys were carried out in Bungoma (Highland) and Kombewa (lowland) of western Kenya. Aquatic habitats were identified, characterized, georeferenced and carefully examined for mosquito larvae and predators. Indoor resting mosquitoes were sampled using pyrethrum spray catches. Adults and larvae were morphologically and molecularly identified to species. Sporozoite infections and blood meal sources were detected using real-time PCR and ELISA respectively. RESULTS: Of the 151 aquatic habitats assessed, 62/80 (78%) in Bungoma and 58/71(82%) in Kombewa were positive for mosquito larvae. Of the 3,193 larvae sampled, An. funestus larvae constitute 38% (1224/3193). Bungoma recorded a higher number of An. funestus larvae (85%, 95%, CI, 8.722-17.15) than Kombewa (15%, 95%, CI, 1.33-3.91). Molecular identification of larvae showed that 89% (n = 80) were An. funestus. Approximately 59%, 35% and 5% of An. funestus larvae co-existed with An. gambiae s.l, Culex spp and An. coustani in the same habitats respectively. Of 1,221 An. funestus s.l adults sampled, molecular identifications revealed that An. funestus constituted 87% (n = 201) and 88% (n = 179) in Bungoma and Kombewa, respectively. The Plasmodium falciparum sporozoite rate of An. funestus in Bungoma and Kombewa was 2% (3/174) and 1% (2/157), respectively, and the human blood index of An. funestus was 84% (48/57) and 89% (39/44) and for Bungoma and Kombewa, respectively. CONCLUSION: Man-made ponds had the highest abundance of An. funestus larvae. Multiple regression and principal component analyses identified the distance to the nearest house as the key environmental factor associated with the abundance of An. funestus larvae in aquatic habitats. This study serves as a guide for the control of An. funestus and other mosquito species to complement existing vector control strategies.


Assuntos
Anopheles/embriologia , Larva/crescimento & desenvolvimento , Malária Falciparum/transmissão , Controle de Mosquitos/métodos , Mosquitos Vetores/crescimento & desenvolvimento , Mosquitos Vetores/parasitologia , Animais , Anopheles/parasitologia , Ecologia , Humanos , Mosquiteiros Tratados com Inseticida , Inseticidas/farmacologia , Quênia , Larva/parasitologia , Plasmodium falciparum/isolamento & purificação
2.
Nat Commun ; 12(1): 5489, 2021 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-34531391

RESUMO

Intraspecific competition is a major force in mediating population dynamics, fuelling adaptation, and potentially leading to evolutionary diversification. Among the evolutionary arms races between parasites, one of the most fundamental and intriguing behavioural adaptations and counter-adaptations are superparasitism and superparasitism avoidance. However, the underlying mechanisms and ecological contexts of these phenomena remain underexplored. Here, we apply the Drosophila parasite Leptopilina boulardi as a study system and find that this solitary endoparasitic wasp provokes a host escape response for superparasitism avoidance. We combine multi-omics and in vivo functional studies to characterize a small set of RhoGAP domain-containing genes that mediate the parasite's manipulation of host escape behaviour by inducing reactive oxygen species in the host central nervous system. We further uncover an evolutionary scenario in which neofunctionalization and specialization gave rise to the novel role of RhoGAP domain in avoiding superparasitism, with an ancestral origin prior to the divergence between Leptopilina specialist and generalist species. Our study suggests that superparasitism avoidance is adaptive for a parasite and adds to our understanding of how the molecular manipulation of host behaviour has evolved in this system.


Assuntos
Drosophila melanogaster/parasitologia , Proteínas Ativadoras de GTPase/genética , Interações Hospedeiro-Parasita/genética , Proteínas de Insetos/genética , Vespas/genética , Vespas/patogenicidade , Animais , Aprendizagem da Esquiva , Comportamento Animal , Coevolução Biológica , Sistema Nervoso Central/parasitologia , Ingestão de Alimentos , Feminino , Proteínas Ativadoras de GTPase/classificação , Proteínas Ativadoras de GTPase/metabolismo , Expressão Gênica , Proteínas de Insetos/classificação , Proteínas de Insetos/metabolismo , Larva/parasitologia , Masculino , Família Multigênica , Espécies Reativas de Oxigênio/metabolismo , Vespas/metabolismo
3.
Sci Rep ; 11(1): 16029, 2021 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-34362964

RESUMO

Anopheline larvicidal property of T. asperellum has been found recently in medical science. The mechanism of actions exhibited by T. asperellum to infect mosquito larvae is the pivotal context of our present study. To infect an insect, entomopathogens must undergo some events of pathogenesis. We performed some experiments to find out the mechanisms of action of T. asperellum against anopheline larvae and compared its actions with other two well recognized entomopathogens like Metarhizium anisopliae and Beauveria bassiana. The methodology adopted for this includes Compound light and SE Microscopic study of host-pathogen interaction, detection of fungal spore adhesion on larval surface (Mucilage assay), detection of cuticle degrading enzymes (Spore bound pr1, chitinase and protease) by spectro-photometric method, Quantitative estimation of chitinase and protease enzymes, and determination of nuclear degeneration of hemocyte cells of ME (methanolic extract) treated larvae by T. asperellum under fluorescence microscope. Compound light microscopic studies showed spore attachment, appressorium and germ tube formation, invasion and proliferated hyphal growth of T. asperellum on epicuticle and inside of dead larvae. SEM study also supported them. After 3 h of interaction, spores were found to be attached on larval surface exhibiting pink colored outer layer at the site of attachment indicating the presence of mucilage surrounding the attached spores. The enzymatic cleavage of the 4-nitroanilide substrate yields 4-nitroaniline which indicates the presence of spore-bound PR1 protein (Pathogenecity Related 1 Protein) and it was highest (absorbance 1.298 ± 0.002) for T. asperellum in comparison with control and other two entomopathogens. T. asperellum exhibited highest enzymatic index values for both chitinase (5.20) and protease (2.77) among three entomopathogens. Quantitative experiment showed that chitinase enzyme concentration of T. asperellum (245 µg mL-1) was better than other two M. anisopliae (134.59 µg mL-1) and B. bassiana (128.65 µg mL-1). Similarly protease enzyme concentration of this fungus was best (298.652 µg mL-1) among three entomopathogens. Here we have detected and estimated fragmentized nuclei of hemocyte cells by fluorescence microscopy in treated larvae with different ME doses of T. asperellum, and also observed that mosquito larvae exposed to 0.1 mg mL-1 dose of ME showed maximum (100%) nuclear fragmentations of hemocytes and while 20, 45, 70 and 85% of nuclear deformities were recorded at 0.02, 0.04, 0.06 and 0.08 mg mL-1 concentrations of ME. The knowledge of this work certainly will help in understanding of mechanism of action of T. asperellum for anopheline larval killing and consequently in eradication of malaria vector.


Assuntos
Anopheles/parasitologia , Interações Hospedeiro-Patógeno , Hypocreales/fisiologia , Larva/parasitologia , Mosquitos Vetores/parasitologia , Esporos Fúngicos/fisiologia , Animais , Hemócitos/parasitologia , Hypocreales/isolamento & purificação
4.
PLoS One ; 16(8): e0242645, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34398898

RESUMO

Entomopathogenic nematodes (EPNs) have been successfully applied as biological control agents against above ground and soil stages of insect pests. However, for commercial application, it is crucial to mass culture these nematodes using in vitro liquid culture technology, as it is not attainable when using susceptible insects as hosts. Lobesia vanillana (Lepidoptera: Tortricidae) is regarded a sporadic pest of wine grapes in South Africa. The in vivo- and in vitro-cultured South African EPNs, Steinernema yirgalemense and Steinernema jeffreyense (Rhabditida: Steinernematidae), were evaluated against larvae and pupae of L. vanillana in laboratory bioassays. For larvae, high mortality was observed for all treatments: In vitro-cultured S. yirgalemense (98%) performed better than S. jeffreyense (73%), while within in vivo cultures, there was no difference between nematode species (both 83%). No significant difference was detected between in vivo- and in vitro cultures of the same nematode species. The LD50 of the in vitro-cultured S. yirgalemense, was 7.33 nematodes per larva. Mortality by infection was established by dissecting L. vanillana cadavers and confirming the presence of nematodes, which was > 90% for all treatments. Within in vitro cultures, both S. yirgalemense and S. jeffreyense were able to produce a new cohort of infective juveniles from L. vanillana larvae. Pupae, however, were found to be considerably less susceptible to EPN infection. This is the first study on the use of EPNs to control L. vanillana. The relative success of in vitro-cultured EPN species in laboratory assays, without any loss in pathogenicity, is encouraging for further research and development of this technology.


Assuntos
Insetos/parasitologia , Mariposas/parasitologia , Rabditídios/patogenicidade , Animais , Agentes de Controle Biológico/administração & dosagem , Laboratórios , Larva/parasitologia , Controle Biológico de Vetores/métodos , Pupa/parasitologia , Solo/parasitologia , África do Sul
5.
PLoS One ; 16(7): e0253122, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34270565

RESUMO

The invasion and wide spread of Spodoptera frugiperda represent real impediments to food security and the livelihood of the millions of maize and sorghum farming communities in the sub-Saharan and Sahel regions of Africa. Current management efforts for the pest are focused on the use of synthetic pesticides, which are often economically unviable and are extremely hazardous to the environment. The use of biological control offers a more economically and environmentally safer alternative. In this study, the performance of the recently described parasitoid, Cotesia icipe, against the pest was elucidated. We assessed the host stage acceptability by and suitability for C. icipe, as well as its ovigenic status. Furthermore, the habitat suitability for the parasitoid in the present and future climatic conditions was established using Maximum Entropy (MaxEnt) algorithm and the Genetic Algorithm for Rule-set Prediction (GARP). Cotesia icipe differentially accepted the immature stages of the pest. The female acceptance of 1st and 2nd instar larvae for oviposition was significantly higher with more than 60% parasitism. No oviposition on the egg, 5th and 6th larval instars, and pupal stages was observed. Percentage of cocoons formed, and the number of emerged wasps also varied among the larval stages. At initial parasitism, parasitoid progenies, time to cocoon formation and overall developmental time were significantly affected by the larval stage. Egg-load varied significantly with wasp age, with six-day-old wasps having the highest number of mature eggs. Ovigeny index of C. icipe was 0.53. Based on the models, there is collinearity in the ecological niche of the parasitoid and the pest under current and future climate scenarios. Eastern, Central and parts of coastal areas of western Africa are highly suitable for the establishment of the parasitoid. The geographic distribution of the parasitoid would remain similar under future climatic conditions. In light of the findings of this study, we discuss the prospects for augmentative and classical biological control of S. frugiperda with C. icipe in Africa.


Assuntos
Spodoptera/parasitologia , Vespas , Animais , Ecossistema , Etiópia , Feminino , Interações Hospedeiro-Parasita , Espécies Introduzidas , Quênia , Larva/parasitologia , Masculino , Oviposição , Controle Biológico de Vetores/métodos , Spodoptera/crescimento & desenvolvimento
6.
Ticks Tick Borne Dis ; 12(5): 101773, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34229999

RESUMO

Understanding the abiotic and biotic variables affecting tick populations is essential for studying the biology and health risks associated with vector species. We conducted a study on the phenology of exotic Haemaphysalis longicornis (Asian longhorned tick) at a site in Albemarle County, Virginia, United States. We also assessed the importance of wildlife hosts, habitats, and microclimate variables such as temperature, relative humidity, and wind speed on this exotic tick's presence and abundance. In addition, we determined the prevalence of infection with selected tick-borne pathogens in host-seeking H. longicornis. We determined that the seasonal activity of H. longicornis in Virginia was slightly different from previous studies in the northeastern United States. We observed nymphal ticks persist year-round but were most active in the spring, followed by a peak in adult activity in the summer and larval activity in the fall. We also observed a lower probability of collecting host-seeking H. longicornis in field habitats and the summer months. In addition, we detected H. longicornis on several wildlife hosts, including coyote (Canis latrans), eastern cottontail (Sylvilagus floridanus), raccoon (Procyon lotor), Virginia opossum (Didelphis virginiana), white-tailed deer (Odocoileus virginianus), woodchuck (Marmota monax), and a Peromyscus sp. mouse. This latter record is the first detection of a larval H. longicornis on a North American rodent host important to the enzootic maintenance of tick-borne pathogens of humans and animals. Finally, we continued to detect the exotic piroplasm parasite, Theileria orientalis Ikeda, in H. longicornis as well as other pathogens, including Rickettsia felis, Anaplasma phagocytophilum (AP-1), and a Hepatozoon sp. previously characterized in Amblyomma americanum. These represent some of the first detections of arthropod-borne pathogens native to the United States in host-seeking H. longicornis. These data increase our understanding of H. longicornis biology in the United States and provide valuable information into the future health risks associated with this tick and pathogens.


Assuntos
Ecossistema , Interações Hospedeiro-Parasita , Interações Hospedeiro-Patógeno , Ixodidae , Animais , Feminino , Ixodidae/crescimento & desenvolvimento , Ixodidae/microbiologia , Ixodidae/parasitologia , Ixodidae/fisiologia , Larva/crescimento & desenvolvimento , Larva/microbiologia , Larva/parasitologia , Larva/fisiologia , Masculino , Ninfa/crescimento & desenvolvimento , Ninfa/microbiologia , Ninfa/parasitologia , Ninfa/fisiologia , Estações do Ano , Virginia
7.
PLoS One ; 16(7): e0254193, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34288953

RESUMO

In recent years, the Asian gall wasp Dryocosmus kuriphilus has invaded chestnut trees and significantly affected the Portuguese chestnut production. Studies in other countries, such as Japan or Italy, have shown that the parasitoid Torymus sinensis can successfully achieve biological control of D. kuriphilus. Mathematical models help us to understand the dynamics of the interaction between the pest D. kuriphilus and its parasitoid T. sinensis and, consequently, they can help to implement measures that enhance crop pest management. In this work, the evolution of the density of D. kuriphilus and T. sinensis across time and space is studied through the numerical solution of models that include parameters based on observations made in Portugal. Simultaneous releases of the parasitoid are simulated at various locations and at different times. The results indicate that, in the case of a small and homogeneous orchard, biological control can be effective, but, in the case of extensive domains, the pest control is much more difficult to achieve. In order for biological control to be efficient, it is necessary to implement, in each chestnut-producing region, a collective strategy based on the annual monitoring of infestation levels.


Assuntos
Fagaceae/parasitologia , Modelos Teóricos , Controle Biológico de Vetores/métodos , Tumores de Planta/parasitologia , Vespas/parasitologia , Animais , Simulação por Computador , Larva/parasitologia , Estágios do Ciclo de Vida , Controle Biológico de Vetores/estatística & dados numéricos , Densidade Demográfica , Portugal , Pupa , Estações do Ano , Vespas/crescimento & desenvolvimento
8.
Science ; 373(6554): 535-541, 2021 07 30.
Artigo em Inglês | MEDLINE | ID: mdl-34326235

RESUMO

Interkingdom competition occurs between hymenopteran parasitoids and insect viruses sharing the same insect hosts. It has been assumed that parasitoid larvae die with the death of the infected host or as result of competition for host resources. Here we describe a gene family, parasitoid killing factor (pkf), that encodes proteins toxic to parasitoids of the Microgastrinae group and determines parasitism success. Pkfs are found in several entomopathogenic DNA virus families and in some lepidopteran genomes. We provide evidence of equivalent and specific toxicity against endoparasites for PKFs found in entomopoxvirus, ascovirus, baculovirus, and Lepidoptera through a mechanism that elicits apoptosis in the cells of susceptible parasitoids. This highlights the evolutionary arms race between parasitoids, viruses, and their insect hosts.


Assuntos
Entomopoxvirinae/fisiologia , Proteínas de Insetos/toxicidade , Lepidópteros/parasitologia , Lepidópteros/virologia , Proteínas Virais/toxicidade , Vespas/fisiologia , Animais , Apoptose , Evolução Biológica , Transferência Genética Horizontal , Genoma de Inseto , Interações Hospedeiro-Parasita , Proteínas de Insetos/química , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Vírus de Insetos/fisiologia , Larva/genética , Larva/parasitologia , Larva/virologia , Lepidópteros/genética , Lepidópteros/metabolismo , Nucleopoliedrovírus/fisiologia , Spodoptera/genética , Spodoptera/metabolismo , Spodoptera/parasitologia , Spodoptera/virologia , Proteínas Virais/química , Proteínas Virais/genética , Proteínas Virais/metabolismo , Vespas/crescimento & desenvolvimento
9.
PLoS One ; 16(6): e0251884, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34077444

RESUMO

Varroa mites (Varroa destructor) are parasitic mites that, combined with other factors, are contributing to high levels of honey bee (Apis mellifera) colony losses. A Varroa-active dsRNA was recently developed to control Varroa mites within honey bee brood cells. This dsRNA has 372 base pairs that are homologous to a sequence region within the Varroa mite calmodulin gene (cam). The Varroa-active dsRNA also shares a 21-base pair match with monarch butterfly (Danaus plexippus) calmodulin mRNA, raising the possibility of non-target effects if there is environmental exposure. We chronically exposed the entire monarch larval stage to common (Asclepias syriaca) and tropical (Asclepias curassavica) milkweed leaves treated with concentrations of Varroa-active dsRNA that are one- and ten-fold higher than those used to treat honey bee hives. This corresponded to concentrations of 0.025-0.041 and 0.211-0.282 mg/g leaf, respectively. Potassium arsenate and a previously designed monarch-active dsRNA with a 100% base pair match to the monarch v-ATPase A mRNA (leaf concentration was 0.020-0.034 mg/g) were used as positive controls. The Varroa mite and monarch-active dsRNA's did not cause significant differences in larval mortality, larval or pupal development, pupal weights, or adult eclosion rates when compared to negative controls. Irrespective of control or dsRNA treatment, larvae that consumed approximately 7500 to 10,500-mg milkweed leaf within 10 to 12 days had the highest pupal weights. The lack of mortality and sublethal effects following dietary exposure to dsRNA with 21-base pair and 100% base pair match to mRNAs that correspond to regulatory genes suggest monarch mRNA may be refractory to silencing by dsRNA or monarch dsRNase may degrade dsRNA to a concentration that is insufficient to silence mRNA signaling.


Assuntos
Borboletas/crescimento & desenvolvimento , Interações Hospedeiro-Parasita , Larva/crescimento & desenvolvimento , RNA de Cadeia Dupla/toxicidade , Varroidae/fisiologia , Animais , Borboletas/efeitos dos fármacos , Borboletas/genética , Borboletas/parasitologia , Larva/efeitos dos fármacos , Larva/genética , Larva/parasitologia
10.
PLoS One ; 16(6): e0241023, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34166376

RESUMO

BACKGROUND: The scale-up of indoor residual spraying and long-lasting insecticidal nets, together with other interventions have considerably reduced the malaria burden in The Gambia. This study examined the biting and resting preferences of the local insecticide-resistant vector populations few years following scale-up of anti-vector interventions. METHOD: Indoor and outdoor-resting Anopheles gambiae mosquitoes were collected between July and October 2019 from ten villages in five regions in The Gambia using pyrethrum spray collection (indoor) and prokopack aspirator from pit traps (outdoor). Polymerase chain reaction assays were performed to identify molecular species, insecticide resistance mutations, Plasmodium infection rate and host blood meal. RESULTS: A total of 844 mosquitoes were collected both indoors (421, 49.9%) and outdoors (423, 50.1%). Four main vector species were identified, including An. arabiensis (indoor: 15%, outdoor: 26%); An. coluzzii (indoor: 19%, outdoor: 6%), An. gambiae s.s. (indoor: 11%, outdoor: 16%), An. melas (indoor: 2%, outdoor: 0.1%) and hybrids of An. coluzzii-An. gambiae s.s (indoors: 3%, outdoors: 2%). A significant preference for outdoor resting was observed in An. arabiensis (Pearson X2 = 22.7, df = 4, P<0.001) and for indoor resting in An. coluzzii (Pearson X2 = 55.0, df = 4, P<0.001). Prevalence of the voltage-gated sodium channel (Vgsc)-1014S was significantly higher in the indoor-resting (allele freq. = 0.96, 95%CI: 0.78-1, P = 0.03) than outdoor-resting (allele freq. = 0.82, 95%CI: 0.76-0.87) An. arabiensis population. For An. coluzzii, the prevalence of most mutation markers was higher in the outdoor (allele freq. = 0.92, 95%CI: 0.81-0.98) than indoor-resting (allele freq. = 0.78, 95%CI: 0.56-0.86) mosquitoes. However, in An. gambiae s.s., the prevalence of Vgsc-1014F, Vgsc-1575Y and GSTe2-114T was high (allele freq. = 0.96-1), but did not vary by resting location. The overall sporozoite positivity rate was 1.3% (95% CI: 0.5-2%) in mosquito populations. Indoor-resting An. coluzzii had mainly fed on human blood while indoor-resting An. arabiensis fed on animal blood. CONCLUSION: In this study, high levels of resistance mutations were observed that could be influencing the mosquito populations to rest indoors or outdoors. The prevalent animal-biting behaviour demonstrated in the mosquito populations suggest that larval source management could be an intervention to complement vector control in this setting.


Assuntos
Anopheles/fisiologia , Comportamento Alimentar , Resistência a Inseticidas , Inseticidas/farmacologia , Malária/transmissão , Mosquitos Vetores/fisiologia , Descanso/fisiologia , Animais , Anopheles/efeitos dos fármacos , Meio Ambiente , Gâmbia/epidemiologia , Humanos , Larva/efeitos dos fármacos , Larva/parasitologia , Malária/tratamento farmacológico , Malária/epidemiologia , Malária/parasitologia , Controle de Mosquitos , Mosquitos Vetores/efeitos dos fármacos , Esporozoítos/efeitos dos fármacos , Esporozoítos/fisiologia , Canais de Sódio Disparados por Voltagem/metabolismo
11.
Zootaxa ; 4990(3): 583-586, 2021 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-34186741

RESUMO

Bee flies of the genus Heterostylum Macquart are medium-sized species (1015 mm) characterized primarily by a robust body covered with long pile and by an indented hind margin of the eye (Cunha et al. 2007). There are several studies on the immatures of some species of Heterostylum (Bohart et al. 1960; Yeates Greathead 1997), which are considered ectoparasites of fossorial solitary bee larvae and pupae (Yeates Greathead 1997).


Assuntos
Abelhas/parasitologia , Dípteros/classificação , Animais , Argentina , Larva/parasitologia , Pupa/parasitologia
12.
Parasitol Res ; 120(6): 2135-2148, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33991246

RESUMO

Habitat loss, climate change, environmental contaminants, and parasites and pathogens are among the main factors thought to act singly or together in causing amphibian declines. We tested for combined effects of neonicotinoid pesticides and parasites (versus parasites-only) on mortality, growth, and white blood cell profiles of a model amphibian: the northern leopard frog (Rana pipiens). We first exposed infectious stages of frog trematodes (cercariae of Echinostoma spp.) to low and high concentrations of thiamethoxam or clothianidin versus water-only controls. There were no differences in survival of trematode cercariae between treatments. For the main experiment, we exposed tadpoles to clean water versus high concentrations of clothianidin or thiamethoxam for 2 weeks and added trematode cercariae to all tanks after 1 week. Exposure of tadpoles and parasites to high concentrations of thiamethoxam or clothianidin did not affect parasite infection success. Tadpole survival was not different between treatments before or after parasite addition and there were no significant differences in tadpole snout-to-vent lengths or developmental stages between treatments. Tadpoles exposed to thiamethoxam + parasites had smaller widths than parasite-only tadpoles, whereas tadpoles exposed to clothianidin + parasites had higher eosinophil to leukocyte ratios compared to parasite-only tadpoles. Tadpoles of both neonicotinoid + parasite treatments had significantly lower monocyte to leukocyte ratios relative to parasite-only tadpoles. High concentrations of neonicotinoid combined with parasites appear to influence tadpole immune function important for further defense against parasites and pathogens. This work highlights the need for more holistic approaches to ecotoxicity studies, using multiple stressors.


Assuntos
Células Sanguíneas/efeitos dos fármacos , Neonicotinoides/toxicidade , Praguicidas/toxicidade , Trematódeos/patogenicidade , Animais , Contagem de Células Sanguíneas , Células Sanguíneas/patologia , Cercárias/efeitos dos fármacos , Cercárias/patogenicidade , Echinostoma/patogenicidade , Ecotoxicologia , Larva/efeitos dos fármacos , Larva/imunologia , Larva/parasitologia , Rana pipiens , Trematódeos/efeitos dos fármacos
13.
Insect Biochem Mol Biol ; 134: 103584, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34033897

RESUMO

In healthy Drosophila melanogaster larvae, plasmatocytes and crystal cells account for 95% and 5% of the hemocytes, respectively. A third type of hemocytes, lamellocytes, are rare, but their number increases after oviposition by parasitoid wasps. The lamellocytes form successive layers around the parasitoid egg, leading to its encapsulation and melanization, and finally the death of this intruder. However, the total number of lamellocytes per larva remains quite low even after parasitoid infestation, making direct biochemical studies difficult. Here, we used the HopTum-l mutant strain that constitutively produces large numbers of lamellocytes to set up a purification method and analyzed their major proteins by 2D gel electrophoresis and their plasma membrane surface proteins by 1D SDS-PAGE after affinity purification. Mass spectrometry identified 430 proteins from 2D spots and 344 affinity-purified proteins from 1D bands, for a total of 639 unique proteins. Known lamellocyte markers such as PPO3 and the myospheroid integrin were among the components identified with specific chaperone proteins. Affinity purification detected other integrins, as well as a wide range of integrin-associated proteins involved in the formation and function of cell-cell junctions. Overall, the newly identified proteins indicate that these cells are highly adapted to the encapsulation process (recognition, motility, adhesion, signaling), but may also have several other physiological functions (such as secretion and internalization of vesicles) under different signaling pathways. These results provide the basis for further in vivo and in vitro studies of lamellocytes, including the development of new markers to identify coexisting populations and their respective origins and functions in Drosophila immunity.


Assuntos
Drosophila melanogaster , Hemócitos/imunologia , Proteínas de Membrana/isolamento & purificação , Animais , Animais Geneticamente Modificados , Moléculas de Adesão Celular/isolamento & purificação , Encapsulamento de Células , Proteínas de Drosophila/isolamento & purificação , Drosophila melanogaster/imunologia , Drosophila melanogaster/metabolismo , Drosophila melanogaster/parasitologia , Eletroforese em Gel Bidimensional , Feminino , Hemócitos/metabolismo , Interações Hospedeiro-Parasita/imunologia , Proteínas de Insetos/isolamento & purificação , Integrinas/isolamento & purificação , Larva/imunologia , Larva/metabolismo , Larva/parasitologia , Espectrometria de Massas , Proteômica , Transdução de Sinais
14.
Sci Rep ; 11(1): 8990, 2021 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-33903703

RESUMO

Therophilus javanus (Bhat & Gupta) is an exotic larval endoparasitoid newly imported from Asia into Africa as a classical biological control agent against the pod borer Maruca vitrata (Fabricius). The parasitoid preference for the five larval instars of M. vitrata and their influence on progeny sex ratio were assessed together with the impact of larval host age at the time of oviposition on development time, mother longevity and offspring production. In a choice situation, female parasitoids preferred to oviposit in the first three larval instars. The development of immature stages of the parasitoid was observed inside three-day-old hosts, whereby the first two larval instars of T. javanus completed their development as endoparasites and the third larval instar as ectoparasite. The development time was faster when first larval instars (two- and three-day-old) of the host caterpillars were parasitized compared to second larval instar (four-day-old). The highest proportion of daughters (0.51) was observed when females were provided with four-day-old hosts. The lowest intrinsic rate of increase (r) (0.21 ± 0.01), the lowest rate of increase (λ) (1.23 ± 0.01), and the lowest net reproductive rate (Ro) (35.93 ± 6.51) were recorded on four-day-old hosts. These results are discussed in the light of optimizing mass rearing and release strategies.


Assuntos
Mariposas/parasitologia , Controle Biológico de Vetores , Vespas/fisiologia , Animais , Feminino , Larva/parasitologia , Masculino , Reprodução
15.
Parasit Vectors ; 14(1): 183, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33794970

RESUMO

BACKGROUND: Migratory birds can cross geographical and environmental barriers and are thereby able to facilitate transmission of tick-borne pathogens both as carriers of infected ticks and as reservoirs of pathogenic microorganisms. Ixodes ricinus is one of the most abundant tick species in the Northern Hemisphere and a main vector of several Babesia species, some which pose a potential threat to human and animal health. At present only two cases of overt babesiosis in humans have so far been reported in Sweden. To better understand the potential role of birds as disseminators of zoonotic Babesia protozoan parasites, we investigated the presence of Babesia species in ticks removed from migratory birds. METHODS: Ticks were collected from birds captured at Ottenby Bird Observatory, south-eastern Sweden, from March to November 2009. Ticks were molecularly identified to species, and morphologically to developmental stage, and the presence of Babesia protozoan parasites was determined by real-time PCR. RESULTS: In total, 4601 migratory birds of 65 species were examined for tick infestation. Ticks removed from these birds have previously been investigated for the presence of Borrelia bacteria and the tick-borne encephalitis virus. In the present study, a total of 1102 ticks were available for molecular analysis of Babesia protozoan parasites. We found that 2.4% of the ticks examined, all I. ricinus, were positive for mammal-associated Babesia species. Out of all Babesia-positive samples, Babesia venatorum was the most prevalent (58%) species, followed by Babesia microti (38%) and Babesia capreoli (4.0%). B. venatorum and B. capreoli were detected in I. ricinus larvae, whereas B. microti was only present in I. ricinus nymphs. This supports the view that the two first-mentioned species are vertically (transovarially) transmitted in the tick population, in contrast to B. microti. The largest number of Babesia-infected ticks was removed from the common redstart (Phoenicurus phoenicurus) and European robin (Erithacus rubecula). CONCLUSIONS: This study reveals that Babesia protozoan parasites are present in ticks infesting migratory birds in south-eastern Sweden, which could potentially lead to the dissemination of these tick-borne microorganisms into new areas, thus posing a threat to humans and other mammals.


Assuntos
Babesia/classificação , Babesia/genética , Babesiose/transmissão , Ixodes/parasitologia , Passeriformes/parasitologia , Infestações por Carrapato/veterinária , Migração Animal , Animais , Babesia/isolamento & purificação , Babesia/patogenicidade , Babesiose/parasitologia , Feminino , Ixodes/genética , Larva/parasitologia , Ninfa/parasitologia , Passeriformes/classificação , Suécia , Zoonoses/parasitologia , Zoonoses/transmissão
16.
Sci Rep ; 11(1): 9041, 2021 04 27.
Artigo em Inglês | MEDLINE | ID: mdl-33907243

RESUMO

Insecticides, especially pyrethroids, are the most important in the insect pest control and preventing insect vector-borne human diseases. However, insect pests, including mosquitoes, have developed resistance in the insecticides that used against them. Cytochrome P450s are associated with insecticide resistance through overexpression and detoxification mechanisms in insect species. In this study, we utilized a powerful tool, the RNAi technique, to determine the roles of key P450 genes overexpressed in permethrin resistant mosquitoes that confer insecticide resistance to unravel the molecular basis of resistance mechanisms in the mosquito Culex quinquefasciatus. The results showed that knockdown of 8 key P450 genes using RNAi techniques significantly decreased resistance to permethrin in resistant mosquitoes. In silico modeling and docking analysis further revealed the potential metabolic function of overexpressed P450 genes in the development of insecticide resistance in mosquitoes. These findings not only highlighted the functional importance of these P450 genes in insecticide resistance, but also revealed that overexpression of multiple P450 genes was responsible for the high levels of insecticide resistance in a mosquito population of Culex quinquefasciatus.


Assuntos
Culex/genética , Sistema Enzimático do Citocromo P-450/genética , Inativação Metabólica/genética , Proteínas de Insetos/genética , Resistência a Inseticidas/genética , Permetrina/farmacologia , Animais , Culex/efeitos dos fármacos , Culex/crescimento & desenvolvimento , Culex/parasitologia , Feminino , Perfilação da Expressão Gênica , Inativação Metabólica/efeitos dos fármacos , Inseticidas/farmacologia , Larva/genética , Larva/crescimento & desenvolvimento , Larva/parasitologia
17.
Arch Insect Biochem Physiol ; 107(2): e21786, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33818830

RESUMO

Cotesia kariyai (Ck) larvae implanted into the body cavity of the Mythimna separata (armyworm) larvae get melanized and encapsulated after adhesion by hemocytes called hyperspread cells (HSCs). The present study showed that HSCs could not adhere to the implanted Ck larvae in armyworm larvae after injection of Ck polydnavirus (CkPDV) + venom (V), thus melanization and encapsulation could not occur. A C-type lectin called Mys-IML of the host armyworm larvae was considered to be involved in the recognition of foreign substances which always expressed in hemocytes. The CkPDV DNA encodes a C-type lectin called Cky811 that has high amino acid homology to Mys-IML. HSCs did not adhere when CkPDV + V was mixed with the hemolymph of armyworm larvae on glass slides and incubated in vitro, but the addition of anti-Cky811 antibody enabled HSCs to adhere. The messenger RNA (mRNA) expression of Mys-IML in armyworm larvae injected with CkPDV + V became undetectable by 6 h. On the contrary, Cky811 mRNA was well expressed in the hemocytes of armyworm larvae injected with CkPDV + V from 0.5 to 6 h. Cky811 protein was also detected in the crude extracts from Ck venom gland + Ck venom reservoir, suggesting that these proteins regulate foreign substance recognition by the armyworm within 0.5 h. These results suggest that CkPDV + V suppresses mRNA expression of Mys-IML, and that Cky811 protein expressed in hemocytes regulates foreign substance recognition of Mys-IML, resulting in inhibition of the downstream reaction steps: HSCs adhesion, melanization, and encapsulation.


Assuntos
Lectinas Tipo C/imunologia , Mariposas/parasitologia , Polydnaviridae , Vespas , Animais , Anticorpos Antivirais/metabolismo , Hemócitos/imunologia , Hemócitos/metabolismo , Interações Hospedeiro-Parasita/imunologia , Imunidade , Larva/imunologia , Larva/metabolismo , Larva/parasitologia , Lectinas Tipo C/metabolismo , Mariposas/imunologia , Polydnaviridae/metabolismo , Proteínas Virais/imunologia , Proteínas Virais/metabolismo , Vespas/patogenicidade , Vespas/virologia
18.
Parasitol Res ; 120(5): 1909-1914, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33686501

RESUMO

Temporary ponds are ecologically valuable habitats and useful sites for studies of diversity, ecology, evolution, and climate change. Organisms inhabiting these environments have developed strategies to ensure their survival. However, little is known about the temporal dynamics and strategies of parasites in these habitats. A 4-year study was carried out in a temporary pond to analyze the larval digenean assemblage in Biomphalaria peregrina, a potential vector of Schistosoma mansoni, a zoonosis of global importance. This environment had intermittent and irregular hydroperiods, and the overall prevalence showed differences throughout the years. After drought seasons, eight out of a total of nine species of digeneans were observed, and almost half of the snails were parasitized. In addition, six of the nine species of digeneans showed some type of abbreviation of their life cycles. These results suggest that digeneans have certain degree of plasticity in their life cycles in response to environmental changes in this pond, and the abbreviation of the digenean life cycle could be regarded as a parasite strategy to resist prolonged periods of desiccation.


Assuntos
Biomphalaria/parasitologia , Secas , Lagoas , Schistosoma mansoni/isolamento & purificação , Animais , Argentina , Vetores de Doenças , Ecossistema , Larva/parasitologia , Estágios do Ciclo de Vida , Estações do Ano
19.
Ticks Tick Borne Dis ; 12(4): 101711, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33774480

RESUMO

Ticks (Ixodidae, also known as hard ticks) as principal vectors of zoonotic diseases such as severe fever with thrombocytopenia syndrome (SFTS), Lyme borreliosis, relapsing fever, anaplasmosis, ehrlichiosis, babesiosis, coxiellosis (Q fever), and tularemia pose a major public health threat. This study was conducted to identify the distribution profile of ticks and tick-borne pathogens in Daejeon and the adjacent areas in South Korea, where no such epidemiological study has been conducted. From April to October 2019, 16,765 ticks were collected from three genera and four species: Haemaphysalis longicornis (n = 14,949; 89.2 %), Haemaphysalis flava (n = 987; 5.9 %), Ixodes nipponensis (n = 828; 5.0 %), and Amblyomma testudinarium (n = 1; 0.01 %). Homogenized samples of ticks were screened by real-time reverse transcription polymerase chain reaction (PCR), real-time PCR, and PCR for the presence of the following tick-borne pathogens: SFTS virus (SFTSV), Borrelia spp., Babesia microti, Coxiella burnetii, Francisella tularensis, Anaplasma phagocytophilum, and Ehrlichia spp. As a result, SFTSV (2 cases), Borrelia spp. (32 cases), and Babesia microti (7 cases) were detected. The findings of this study will contribute to the prevention and management of tick-borne zoonoses.


Assuntos
Distribuição Animal , Ixodidae , Animais , Feminino , Ixodidae/crescimento & desenvolvimento , Ixodidae/microbiologia , Ixodidae/parasitologia , Ixodidae/fisiologia , Larva/crescimento & desenvolvimento , Larva/microbiologia , Larva/parasitologia , Larva/fisiologia , Masculino , Ninfa/crescimento & desenvolvimento , Ninfa/microbiologia , Ninfa/parasitologia , Ninfa/fisiologia , República da Coreia , Doenças Transmitidas por Carrapatos
20.
J Med Entomol ; 58(3): 1188-1196, 2021 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-33570154

RESUMO

Although parasites are by definition costly to their host, demonstrating that a parasite is regulating its host abundance in the field can be difficult. Here we present an example of a gregarine parasite, Ascogregarina taiwanensis Lien and Levine (Apicomplexa: Lecudinidae), regulating its mosquito host, Aedes albopictus Skuse (Diptera: Culicidae), in Bermuda. We sampled larvae from container habitats over 2 yr, assessed parasite prevalence, and estimated host abundance from egg counts obtained in neighboring ovitraps. We regressed change in average egg count from 1 yr to the next on parasite prevalence and found a significant negative effect of parasite prevalence. We found no evidence of host density affecting parasite prevalence. Our results demonstrate that even for a parasite with moderate virulence, host regulation can occur in the field.


Assuntos
Aedes/fisiologia , Apicomplexa/fisiologia , Interações Hospedeiro-Parasita , Mosquitos Vetores/fisiologia , Aedes/crescimento & desenvolvimento , Aedes/parasitologia , Animais , Bermudas , Larva/crescimento & desenvolvimento , Larva/parasitologia , Larva/fisiologia , Mosquitos Vetores/crescimento & desenvolvimento , Mosquitos Vetores/parasitologia , Dinâmica Populacional
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