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1.
PLoS Negl Trop Dis ; 18(7): e0012172, 2024 Jul.
Article de Anglais | MEDLINE | ID: mdl-38985837

RÉSUMÉ

Usutu virus (USUV) is an emerging flavivirus that is maintained in an enzootic cycle with mosquitoes as vectors and birds as amplifying hosts. In Europe, the virus has caused mass mortality of wild birds, mainly among Common Blackbird (Turdus merula) populations. While mosquitoes are the primary vectors for USUV, Common Blackbirds and other avian species are exposed to other arthropod ectoparasites, such as ticks. It is unknown, however, if ticks can maintain and transmit USUV. We addressed this question using in vitro and in vivo experiments and field collected data. USUV replicated in IRE/CTVM19 Ixodes ricinus tick cells and in injected ticks. Moreover, I. ricinus nymphs acquired the virus via artificial membrane blood-feeding and maintained the virus for at least 70 days. Transstadial transmission of USUV from nymphs to adults was confirmed in 4.9% of the ticks. USUV disseminated from the midgut to the haemocoel, and was transmitted via the saliva of the tick during artificial membrane blood-feeding. We further explored the role of ticks by monitoring USUV in questing ticks and in ticks feeding on wild birds in the Netherlands between 2016 and 2019. In total, 622 wild birds and the Ixodes ticks they carried were tested for USUV RNA. Of these birds, 48 (7.7%) carried USUV-positive ticks. The presence of negative-sense USUV RNA in ticks, as confirmed via small RNA-sequencing, showed active virus replication. In contrast, we did not detect USUV in 15,381 questing ticks collected in 2017 and 2019. We conclude that I. ricinus can be infected with USUV and can transstadially and horizontally transmit USUV. However, in comparison to mosquito-borne transmission, the role of I. ricinus ticks in the epidemiology of USUV is expected to be minor.


Sujet(s)
Maladies des oiseaux , Infections à flavivirus , Flavivirus , Ixodes , Nymphe , Animaux , Ixodes/virologie , Ixodes/physiologie , Flavivirus/physiologie , Flavivirus/génétique , Infections à flavivirus/transmission , Infections à flavivirus/médecine vétérinaire , Infections à flavivirus/virologie , Nymphe/virologie , Maladies des oiseaux/virologie , Maladies des oiseaux/transmission , Oiseaux/virologie , Vecteurs arachnides/virologie , Vecteurs arachnides/physiologie , Pays-Bas , Femelle
2.
BMC Res Notes ; 17(1): 188, 2024 Jul 05.
Article de Anglais | MEDLINE | ID: mdl-38970085

RÉSUMÉ

Heavy metals are encountered in nature, and are used in several human endeavors, including in dental fillings. It is well known that the safety of metals depends on their chemical form, as well as the dose and route through which biological systems are exposed to them. Here, we used the Nauphoeta cinerea model to examine the mechanism by which salts of the heavy metals used in dental fillings - silver and mercury - exert their neurotoxicity. Nymphs exposed to heavy metals presented with reduced motor and exploratory abilities as they spent more time immobile, especially in the periphery of a novel object, and covered less distance compared with control nymphs. Exposure to AgNO3 and HgCl2 also exacerbated levels of oxidative stress markers (MDA & ROS) and the neurotransmitter regulators - AChE and MAO, while reducing antioxidant activity markers, both in biochemical (thiol & GST) and RT-qPCR (TRX, GST, SOD, Catalase) examinations, in neural tissues of the cockroach. The observed disruptions in neurolocomotor control, synaptic transmission and redox balance explain how heavy metal salts may predispose organisms to neurological disorders.


Sujet(s)
Oxydoréduction , Stress oxydatif , Animaux , Oxydoréduction/effets des médicaments et des substances chimiques , Stress oxydatif/effets des médicaments et des substances chimiques , Mercure/toxicité , Argent/pharmacologie , Argent/toxicité , Agents neuromédiateurs/métabolisme , Acetylcholinesterase/métabolisme , Nymphe/effets des médicaments et des substances chimiques , Nymphe/métabolisme , Monoamine oxidase/métabolisme , Comportement animal/effets des médicaments et des substances chimiques , Espèces réactives de l'oxygène/métabolisme , Nitrate d'argent/pharmacologie , Chlorure de mercure II/toxicité
3.
Insect Biochem Mol Biol ; 171: 104150, 2024 Aug.
Article de Anglais | MEDLINE | ID: mdl-38871132

RÉSUMÉ

Insect chitinases (Chts) play a crucial role in the molting process, enabling continuous growth through sequential developmental stages. Based on their high homology to insect Chts, TuCht1 (group II), TuCht4 (group I) and TuCht10 (group IV) were identified, and their roles during molting process were investigated. TuCht1 was mainly expressed in the deutonymphal stage, while TuCht4 was mainly expressed in the nymphal stage and the highest expression level of TuCht10 was observed in the larvae. Feeding RNAi assays have shown that group I TuCht4 and group Ⅳ TuCht10 are involved in mite molting. Suppression of TuCht4 or TuCht10 resulted in high mortality, molting abnormalities and the absence of distinct electron dense layers of chitinous horizontal laminae in the cuticle, as demonstrated by scanning electron microscopy and transmission electron microscopy. The nanocarrier mediated RNAi had significantly higher RNAi efficiency and caused higher mortality. The results of the present study suggest that chitinase genes TuCht4 and TuCht10 are potential targets for dietary RNAi, and demonstrates a nanocarrier-mediated delivery system to enhance the bioactivity of dsRNA, providing a potential technology for green pest management.


Sujet(s)
Chitinase , Mue , Tetranychidae , Animaux , Mue/génétique , Chitinase/génétique , Chitinase/métabolisme , Tetranychidae/génétique , Tetranychidae/croissance et développement , Nymphe/génétique , Nymphe/croissance et développement , Nymphe/métabolisme , Interférence par ARN , Protéines d'insecte/génétique , Protéines d'insecte/métabolisme , Larve/génétique , Larve/croissance et développement , Larve/métabolisme
4.
Parasites Hosts Dis ; 62(2): 217-225, 2024 May.
Article de Anglais | MEDLINE | ID: mdl-38835262

RÉSUMÉ

This study evaluated the potential repellent and acaricidal effects of 4 essential oils (clove, eucalyptus, lavender, and mint) against the Asian longhorned tick Haemaphysalis longicornis, a vector of various tick-borne diseases in medical and veterinary contexts. Selected for their potential repellent and acaricidal properties, the 4 essential oils were tested on adult and nymph H. longicornis ticks at different concentrations. The experiment assessed mortality rates and repellency, particularly during tick attachment to host skin. There was a significant increase (p<0.05) in tick mortality and repellency scores across all groups. At a 1% concentration, adult tick mortality ranged from 36% to 86%, while nymph mortality ranged from 6% to 97%. Clove oil exhibited notable efficacy, demonstrating high mortality rates of nymphs and adults. Clove oil also displayed strong repellency properties, with a repellency index of 0.05, surpassing those of mint, eucalyptus, and lavender oils. Clove oil showed the highest effectiveness in deterring nonattached adult ticks (90%) and nymphs (95%) when applied to skin. Clove oil was the most effective against adult and nymph ticks, achieving mortality rates of 86% and 97%, respectively, and led to the highest nonattachment rates when applied to skin. In conclusion, essential oils such as clove, eucalyptus, lavender, and mint oils present promising results for tick population control.


Sujet(s)
Acaricides , Ixodidae , Huile essentielle , Animaux , Huile essentielle/pharmacologie , Ixodidae/effets des médicaments et des substances chimiques , Acaricides/pharmacologie , Nymphe/effets des médicaments et des substances chimiques , Insectifuges/pharmacologie , Huiles végétales/pharmacologie , Femelle , Eucalyptus/composition chimique , Huile de clou de girofle/pharmacologie , Lavandula , Haemaphysalis longicornis
5.
Sci Rep ; 14(1): 13107, 2024 06 07.
Article de Anglais | MEDLINE | ID: mdl-38849451

RÉSUMÉ

The environmental risk of Lyme disease, defined by the density of Ixodes scapularis ticks and their prevalence of Borrelia burgdorferi infection, is increasing across the Ottawa, Ontario region, making this a unique location to explore the factors associated with environmental risk along a residential-woodland gradient. In this study, we collected I. scapularis ticks and trapped Peromyscus spp. mice, tested both for tick-borne pathogens, and monitored the intensity of foraging activity by deer in residential, woodland, and residential-woodland interface zones of four neighbourhoods. We constructed mixed-effect models to test for site-specific characteristics associated with densities of questing nymphal and adult ticks and the infection prevalence of nymphal and adult ticks. Compared to residential zones, we found a strong increasing gradient in tick density from interface to woodland zones, with 4 and 15 times as many nymphal ticks, respectively. Infection prevalence of nymphs and adults together was 15 to 24 times greater in non-residential zone habitats. Ecological site characteristics, including soil moisture, leaf litter depth, and understory density, were associated with variations in nymphal density and their infection prevalence. Our results suggest that high environmental risk bordering residential areas poses a concern for human-tick encounters, highlighting the need for targeted disease prevention.


Sujet(s)
Borrelia burgdorferi , Forêts , Ixodes , Maladie de Lyme , Animaux , Ixodes/microbiologie , Borrelia burgdorferi/isolement et purification , Borrelia burgdorferi/pathogénicité , Maladie de Lyme/épidémiologie , Maladie de Lyme/transmission , Maladie de Lyme/microbiologie , Prévalence , Ontario/épidémiologie , Peromyscus/microbiologie , Nymphe/microbiologie , Écosystème , Humains , Densité de population , Souris , Cervidae/microbiologie
6.
Front Cell Infect Microbiol ; 14: 1408362, 2024.
Article de Anglais | MEDLINE | ID: mdl-38938879

RÉSUMÉ

The Asian citrus psyllid (ACP) Diaphorina citri Kuwayama is the leading vector of Candidatus Liberibacter asiaticus (CLas), the causative agent of citrus Huanglongbing (HLB) disease. The distribution and dynamics of CLas within ACP are critical to understanding how the transmission, spread and infection of CLas occurs within its host vector in nature. In this study, the distribution and titer changes of CLas in various tissues of ACP 5th instar nymphs and adults were examined by fluorescence in situ hybridization (FISH) and real-time quantitative PCR (qPCR) techniques. Results demonstrated that 100% of ACP 5th instar nymphs and adults were infected with CLas following feeding on infected plants, and that CLas had widespread distribution in most of the tissues of ACP. The titers of CLas within the midgut, salivary glands and hemolymph tissues were the highest in both 5th instar nymphs and adults. When compared with adults, the titers of CLas in these three tissues of 5th instar nymphs were significantly higher, while in the mycetome, ovary and testes they were significantly lower than those of adults. FISH visualization further confirmed these findings. Dynamic analysis of CLas demonstrated that it was present across all the developmental ages of ACP adults. There was a discernible upward trend in the presence of CLas with advancing age in most tissues of ACP adults, including the midgut, hemolymph, salivary glands, foot, head, cuticula and muscle. Our findings have significant implications for the comprehensive understanding of the transmission, dissemination and infestation of CLas, which is of much importance for developing novel strategies to halt the spread of CLas, and therefore contribute to the efficient prevention and control of HLB.


Sujet(s)
Citrus , Hemiptera , Hybridation fluorescente in situ , Vecteurs insectes , Nymphe , Maladies des plantes , Animaux , Hemiptera/microbiologie , Vecteurs insectes/microbiologie , Maladies des plantes/microbiologie , Nymphe/microbiologie , Citrus/microbiologie , Rhizobiaceae/génétique , Rhizobiaceae/physiologie , Réaction de polymérisation en chaine en temps réel , Glandes salivaires/microbiologie , Hémolymphe/microbiologie
7.
Exp Appl Acarol ; 93(1): 49-69, 2024 Jun.
Article de Anglais | MEDLINE | ID: mdl-38869724

RÉSUMÉ

Ixodes ricinus is a vector of several pathogens of public health interest. While forests are the primary habitat for I. ricinus, its abundance and infection prevalence are expected to vary within forest stands. This study assesses the spatio-temporal variations in tick abundance and infection prevalence with three pathogens in and around a peri-urban forest where human exposure is high. Ticks were sampled multiple times in 2016 and 2018 in multiple locations with a diversity of undergrowth, using the consecutive drags method. Three zoonotic pathogens were screened for, Borrelia burgdorferi s.l., Coxiella burnetii, and Francisella tularensis. The influence of season, type of site and micro-environmental factors on tick abundance were assessed with negative binomial generalized linear mixed-effects models. We collected 1642 nymphs and 181 adult ticks. Ticks were most abundant in the spring, in warmer temperatures, and where undergrowth was higher. Sites with vegetation unaffected by human presence had higher abundance of ticks. Forest undergrowth type and height were significant predictors of the level of tick abundance in a forest. The consecutive drags method is expected to provide more precise estimates of tick abundance, presumably through more varied contacts with foliage. Borrelia burgdorferi s.l. prevalence was estimated from pooled ticks at 5.33%, C. burnetii was detected in six pools and F. tularensis was not detected. Borrelia afzelii was the dominant B. burgdorferi genospecies. Tick abundance and B. burgdorferi s.l. infection prevalence were lower than other estimates in Belgian forests.


Sujet(s)
Coxiella burnetii , Forêts , Francisella tularensis , Ixodes , Animaux , Belgique/épidémiologie , Ixodes/microbiologie , Ixodes/croissance et développement , Francisella tularensis/isolement et purification , Coxiella burnetii/isolement et purification , Coxiella burnetii/physiologie , Nymphe/microbiologie , Nymphe/croissance et développement , Borrelia burgdorferi/isolement et purification , Borrelia burgdorferi/physiologie , Saisons , Densité de population , Femelle
8.
Exp Appl Acarol ; 93(1): 197-210, 2024 Jun.
Article de Anglais | MEDLINE | ID: mdl-38869725

RÉSUMÉ

The goji berry psyllid, Bactericera gobica Logniova (Homoptera: Psyllidae), is one of the most important pests on goji berry plants (Lycium barbarum L.), whose fruits are widely used in traditional Chinese medicine and food. However, chemical control is still the predominant control strategy of this pest. Recently, two species of predatory mites, Neoseiulus setarius Ma, Meng & Fan and Neoseiulus barkeri Hughes were found to be associated with B. gobica in China. To assess their predation potential against B. gobica, the functional responses of these two phytoseiid species feeding on different densities (2, 4, 8, 12, 16, 24 and 32 individuals) of B. gobica eggs and 1st instar nymphs were compared at a temperature of 25ºC ± 1º C. Logistic regression analysis revealed that both predatory mite species exhibited type Holling-II functional responses on eggs and 1st instar nymphs of B. gobica, with the predation number increased for both predators as the density of prey increased. Overall, N. setarius consumed more prey compared to N. barkeri across all levels of prey densities. Meanwhile, the highest attack rate (α = 0.0283), the lowest handling time (Th = 1.1324 h prey- 1), and the highest estimated maximum predation rate (T/Th = 21.19 prey day- 1) were all observed for N. setarius fed with 1st instar nymphs of B. gobica. These findings suggest that it is worthy considering utilizing N. setarius and N. barkeri as candidate biocontrol agents of B. gobica, with N. setarius appearing to be a more effective predator than N. barkeri.


Sujet(s)
Hemiptera , Mites (acariens) , Nymphe , Ovule , Lutte biologique contre les nuisibles , Comportement prédateur , Animaux , Mites (acariens)/physiologie , Nymphe/croissance et développement , Nymphe/physiologie , Ovule/physiologie , Ovule/croissance et développement , Hemiptera/physiologie , Femelle , Densité de population
9.
Exp Appl Acarol ; 93(1): 81-95, 2024 Jun.
Article de Anglais | MEDLINE | ID: mdl-38869723

RÉSUMÉ

Ticks serve as vectors and reservoirs of various Borrelia species, potentially causing diseases in humans and animals. Mazandaran, a fertile green land in northern Iran, provides ample grazing grounds for livestock and harbors at least 26 hard tick species. This study investigated Borrelia infection in hard ticks from forest areas in this region and compared their genetic identity with the species data in the GenBank database. A total of 2,049 ticks were collected manually from mammalian hosts or using dragging and flagging methods. These ticks were then grouped into 190 pools and 41 individuals based on host, species, developmental stage, and gender. A real-time PCR (qPCR) detected Borrelia DNA in 26 pools from female, male, and nymph of Rhipicephalus annulatus (n = 17) and Ixodes ricinus (n = 9) ticks and one individual female Haemaphysalis punctata tick. The generated partial flaB and glpQ sequences from qPCR-positive Rh. annulatus ticks exhibited the highest identities of 98.1-100% and 98.2% with Borrelia theileri and closely related undefined isolates. Additionally, in phylogenetic analysis, these sequences clustered within well-supported clades with B. theileri and the closely related undefined isolates from various geographic regions, confirming the presence of B. theileri in the north of Iran. Divergence in B. theileri flaB and glpQ sequences across various geographical areas suggests potential subspeciation driven by adaptations to different tick species. This divergence in our flaB sequences implies the possible introduction of B. theileri-infected ticks from different geographical origins into Iran.


Sujet(s)
Borrelia , Rhipicephalus , Animaux , Iran , Femelle , Borrelia/isolement et purification , Borrelia/génétique , Mâle , Rhipicephalus/microbiologie , Nymphe/microbiologie , Nymphe/croissance et développement , Phylogenèse , Réaction de polymérisation en chaine en temps réel , Bovins
10.
PeerJ ; 12: e17483, 2024.
Article de Anglais | MEDLINE | ID: mdl-38881864

RÉSUMÉ

Background: South Downs National Park (SDNP) is UK's most visited National Park, and a focus of tick-borne Lyme disease. The first presumed UK autochthonous cases of tick-borne encephalitis and babesiosis were recorded in 2019-20. SDNP aims to conserve wildlife and encourage recreation, so interventions are needed that reduce hazard without negatively affecting ecosystem health. To be successful these require knowledge of site hazards. Methods: British Deer Society members submitted ticks removed from deer. Key potential intervention sites were selected and six 50 m2 transects drag-sampled per site (mostly twice yearly for 2 years). Ticks were identified in-lab (sex, life stage, species), hazard measured as tick presence, density of ticks (all life stages, DOT), and density of nymphs (DON). Sites and habitat types were analysed for association with hazard. Distribution was mapped by combining our results with records from five other sources. Results: A total of 87 Ixodes ricinus (all but one adults, 82% F) were removed from 14 deer (10 Dama dama; three Capreolus capreolus; one not recorded; tick burden, 1-35) at 12 locations (commonly woodland). Five key potential intervention sites were identified and drag-sampled 2015-16, collecting 623 ticks (238 on-transects): 53.8% nymphs, 42.5% larvae, 3.7% adults (13 M, 10 F). Ticks were present on-transects at all sites: I. ricinus at three (The Mens (TM); Queen Elizabeth Country Park (QECP); Cowdray Estate (CE)), Haemaphysalis punctata at two (Seven Sisters Country Park (SSCP); Ditchling Beacon Nature Reserve (DBNR)). TM had the highest DOT at 30/300 m2 (DON = 30/300 m2), followed by QECP 22/300 m2 (12/300 m2), CE 8/300 m2 (6/300 m2), and SSCP 1/300 m2 (1/300 m2). For I. ricinus, nymphs predominated in spring, larvae in the second half of summer and early autumn. The overall ranking of site hazard held for DON and DOT from both seasonal sampling periods. DBNR was sampled 2016 only (one adult H. punctata collected). Woodland had significantly greater hazard than downland, but ticks were present at all downland sites. I. ricinus has been identified in 33/37 of SDNPs 10 km2 grid squares, Ixodes hexagonus 10/37, H. punctata 7/37, Dermacentor reticulatus 1/37. Conclusions: Mapping shows tick hazard broadly distributed across SDNP. I. ricinus was most common, but H. punctata's seeming range expansion is concerning. Recommendations: management of small heavily visited high hazard plots (QECP); post-visit precaution signage (all sites); repellent impregnated clothing for deerstalkers; flock trials to control H. punctata (SSCP, DBNR). Further research at TM may contribute to knowledge on ecological dynamics underlying infection density and predator re-introduction/protection as public health interventions. Ecological research on H. punctata would aid control. SDNP Authority is ideally placed to link and champion policies to reduce hazard, whilst avoiding or reducing conflict between public health and ecosystem health.


Sujet(s)
Cervidae , Écosystème , Ixodes , Parcs de loisirs , Animaux , Cervidae/parasitologie , Ixodes/croissance et développement , Mâle , Infestations par les tiques/épidémiologie , Infestations par les tiques/médecine vétérinaire , Femelle , Royaume-Uni/épidémiologie , Nymphe/croissance et développement
11.
Pestic Biochem Physiol ; 202: 105939, 2024 Jun.
Article de Anglais | MEDLINE | ID: mdl-38879330

RÉSUMÉ

The brown planthopper (BPH), Nilaparvata lugens is a devastating agricultural pest of rice, and they have developed resistance to many pesticides. In this study, we assessed the response of BPH nymphs to nitenpyram, imidacloprid, and etofenprox using contact and dietary bioassays, and investigated the underlying functional diversities of BPH glutathione-S-transferase (GST), carboxylesterase (CarE) and cytochrome P450 monooxygenase (P450) against these insecticides. Both contact and ingestion toxicity of nitenpyram to BPH were significantly higher than either imidacloprid or etofenprox. Under the LC50 concentration of each insecticide, they triggered a distinct response for GST, CarE, and P450 activities, and each insecticide induced at least one detoxification enzyme activity. These insecticides almost inhibited the expression of all tested GST, CarE, and P450 genes in contact bioassays but induced the transcriptional levels of these genes in dietary bioassays. Silencing of NlGSTD2 expression had the greatest effect on BPH sensitivity to nitenpyram in contact test and imidacloprid in dietary test. The sensitivities of BPH to insecticide increased the most in the contact test was etofenprox after silencing of NlCE, while the dietary test was nitenpyram. Knockdown of NlCYP408A1 resulted in BPH sensitivities to insecticide increasing the most in the contact test was nitenpyram, while the dietary test was imidacloprid. Taken together, these findings reveal that NlGSTD2, NlCE, and NlCYP408A1 play an indispensable role in the detoxification of the contact and ingestion toxicities of different types of insecticides to BPH, which is of great significance for the development of new strategies for the sucking pest control.


Sujet(s)
Carboxylesterase , Cytochrome P-450 enzyme system , Glutathione transferase , Hemiptera , Insecticides , Néonicotinoïdes , Composés nitrés , Pyréthrines , Interférence par ARN , Animaux , Hemiptera/effets des médicaments et des substances chimiques , Hemiptera/génétique , Insecticides/toxicité , Insecticides/pharmacologie , Néonicotinoïdes/toxicité , Néonicotinoïdes/pharmacologie , Composés nitrés/toxicité , Glutathione transferase/métabolisme , Glutathione transferase/génétique , Carboxylesterase/génétique , Carboxylesterase/métabolisme , Cytochrome P-450 enzyme system/génétique , Cytochrome P-450 enzyme system/métabolisme , Pyréthrines/toxicité , Pyréthrines/pharmacologie , Inactivation métabolique , Nymphe/effets des médicaments et des substances chimiques , Nymphe/génétique , Protéines d'insecte/génétique , Protéines d'insecte/métabolisme , Résistance aux insecticides/génétique , Pyridines/toxicité , Pyridines/pharmacologie
12.
Vet Parasitol Reg Stud Reports ; 52: 101044, 2024 Jul.
Article de Anglais | MEDLINE | ID: mdl-38880575

RÉSUMÉ

Soft ticks pose significant health risks as vectors of various pathogens. This study explored the spatio-temporal distribution and genetic relationships of the soft tick species Argas persicus infesting domestic hens (Gallus gallus domesticus) across different districts in Pakistan. An examination of 778 hens revealed a notable tick infestation prevalence of 70.82%, with a total of 1299 ticks collected from 551 hens. The overall mean intensity was 2.19 soft ticks per infested chicken, and the overall mean abundance was 1.61 soft ticks per examined hen. Morphological identification confirmed all collected ticks (n = 1210) as A. persicus, comprising 719 males, 333 females, 121 nymphs, and 38 larvae. The Haveli, Muzaffarabad, and Kotli districts had the highest infestation rates, while Bagh had the lowest. Molecular analyses of tick DNA, focusing on 16S rDNA and 12S rDNA sequences, revealed genetic similarities among A. persicus soft ticks from Pakistan and other regions, providing insights into their evolutionary history. Importantly, no Babesia, Rickettsia, or Anaplasma infections were detected in the examined samples. These findings enhance the understanding of soft tick infestation patterns and the genetic diversity of A. persicus in the studied region.


Sujet(s)
Argas , Poulets , Phylogenèse , Maladies de la volaille , Infestations par les tiques , Animaux , Pakistan/épidémiologie , Poulets/parasitologie , Maladies de la volaille/parasitologie , Maladies de la volaille/épidémiologie , Infestations par les tiques/médecine vétérinaire , Infestations par les tiques/épidémiologie , Infestations par les tiques/parasitologie , Femelle , Prévalence , Mâle , Analyse spatio-temporelle , Babesia/isolement et purification , Babesia/génétique , Babesia/classification , Nymphe , Rickettsia/isolement et purification , Rickettsia/génétique , Rickettsia/classification , ARN ribosomique 16S/analyse , ARN ribosomique 16S/génétique , Larve/classification
13.
Appl Microbiol Biotechnol ; 108(1): 364, 2024 Jun 06.
Article de Anglais | MEDLINE | ID: mdl-38842723

RÉSUMÉ

Beauveria bassiana (Bal.-Criv.) is an important entomopathogenic fungus being used for the management of various agricultural pests worldwide. However, all strains of B. bassiana may not be effective against whitefly, Bemisia tabaci, or other pests, and strains show diversity in their growth, sporulation, virulence features, and overall bioefficacy. Thus, to select the most effective strain, a comprehensive way needs to be devised. We studied the diversity among the 102 strains of B. bassiana isolated from 19 insect species based on their physiological features, virulence, and molecular phylogeny, to identify promising ones for the management of B. tabaci. Strains showed diversity in mycelial growth, conidial production, and their virulence against B. tabaci nymphs. The highest nymphal mortality (2nd and 3rd instar) was recorded with MTCC-4511 (95.1%), MTCC-6289 (93.8%), and MTCC-4565 (89.9%) at a concentration of 1 × 106 conidia ml-1 under polyhouse conditions. The highest bioefficacy index (BI) was in MTCC-4511 (78.3%), MTCC-4565 (68.2%), and MTCC-4543 (62.1%). MTCC-4511, MTCC-4565, and MTCC-4543 clustered with positive loading of eigenvalues for the first two principal components and the cluster analysis also corresponded well with PCA (principal component analysis) (nymphal mortality and BI). The molecular phylogeny could not draw any distinct relationship between physiological features, the virulence of B. bassiana strains with the host and location. The BI, PCA, and square Euclidean distance cluster were found the most useful tools for selecting potential entomopathogenic strains. The selected strains could be utilized for the management of the B. tabaci nymphal population in the field through the development of effective formulations. KEY POINTS: • 102 B. bassiana strains showed diversity in growth and virulence against B. tabaci. • Bioefficacy index, PCA, and SED group are efficient tools for selecting potential strains. • MTCC-4511, 4565, and 4543 chosen as the most virulent strains to kill whitefly nymphs.


Sujet(s)
Beauveria , Gossypium , Hemiptera , Lutte biologique contre les nuisibles , Phylogenèse , Beauveria/génétique , Beauveria/pathogénicité , Beauveria/classification , Beauveria/isolement et purification , Animaux , Hemiptera/microbiologie , Virulence , Gossypium/microbiologie , Nymphe/microbiologie , Spores fongiques/croissance et développement , Variation génétique
14.
J Med Entomol ; 61(4): 911-918, 2024 Jul 12.
Article de Anglais | MEDLINE | ID: mdl-38742817

RÉSUMÉ

Hiking is a popular recreational activity in North Carolina that may expose people to ticks and tick-borne pathogens. However, there is a lack of knowledge on how ticks are distributed on and near trails. Our study tested the hypothesis that ticks are more likely to be encountered when moving further away from trails by measuring differences in relative abundance at various distances. We tested 4 distances (middle of trail, edge of trail, 5 m, 20 m), as well as an on-trail and off-trail grouping. We collected significantly more ticks and ticks were more likely to be collected at our 20 m and 5 m sampling distances rather than directly on or adjacent to trails, and significantly more were collected during off-trail collections than on-trails. When looking only at Amblyomma americanum, post hoc comparisons revealed that significantly more juvenile stages were collected at 5 m and 20 m distances, but not for adults. Our monthly sampling also allowed us to describe the phenology of A. americanum in North Carolina, which is consistent with the phenology of this species in the southeastern United States with adults peaking May-Jun, nymphs Jun-Jul, and larvae in Jul-Aug. These results generally demonstrate the importance of utilizing established trails when hiking to decrease tick-borne disease risk and should be communicated to the public as a recommendation for reducing tick-encounter risk.


Sujet(s)
Amblyomma , Animaux , Caroline du Nord , Amblyomma/croissance et développement , Amblyomma/physiologie , Nymphe/croissance et développement , Nymphe/physiologie , Répartition des animaux , Femelle , Larve/croissance et développement , Larve/physiologie , Marche à pied
15.
Insect Biochem Mol Biol ; 170: 104139, 2024 Jul.
Article de Anglais | MEDLINE | ID: mdl-38815735

RÉSUMÉ

Peroxisomes are ubiquitous cellular organelles participating in a variety of critical metabolic reactions. PEX14 is an essential peroxin responsible for peroxisome biogenesis. In this study, we identified the human PEX14 homolog in the brown planthopper, Nilaparvata lugens (Hemiptera: Delphacidae). N. lugens PEX14 (NlPEX14) showed significant topological similarity to its human counterpart. It is expressed throughout all developmental stages, with the highest expression observed in adult insects. Down-regulation of NlPEX14 through injection of NlPEX14-specific double-strand RNA impaired nymphal development. Moreover, females subjected to dsNlPEX14 treatment exhibited a significantly reduced lifespan. Additionally, we found abnormal ovarian development and a significant decrease in the number of eggs laid in NlPEX14-downregulated females. Further experiments support that the shortening of lifespan and the decrease in female fecundity can be attributed, at least partially, to the accumulation of fatty acids and reduced expression of vitellogenin. Together, our study reveals an indispensable function of NlPEX14 for insect reproduction and establishes a causal connection between the phenotypes and peroxisome biogenesis, shedding light on the importance of peroxisomes in female fecundity.


Sujet(s)
Fécondité , Hemiptera , Protéines d'insecte , Animaux , Hemiptera/génétique , Hemiptera/métabolisme , Hemiptera/physiologie , Hemiptera/croissance et développement , Femelle , Protéines d'insecte/métabolisme , Protéines d'insecte/génétique , Péroxysomes/métabolisme , Longévité , Nymphe/croissance et développement , Nymphe/métabolisme , Nymphe/génétique , Péroxines/métabolisme , Péroxines/génétique , Protéines membranaires/métabolisme , Protéines membranaires/génétique , Vitellogénines/métabolisme , Vitellogénines/génétique
16.
Parasit Vectors ; 17(1): 208, 2024 May 08.
Article de Anglais | MEDLINE | ID: mdl-38720313

RÉSUMÉ

BACKGROUND: Triatoma infestans, Triatoma brasiliensis, Triatoma pseudomaculata and Rhodnius prolixus are vectors of Trypanosoma cruzi, the etiological agent of Chagas disease. Chickens serve as an important blood food source for triatomines. This study aimed to assess the insecticidal activity of fluralaner (Exzolt®) administered to chickens against triatomines (R. prolixus, T. infestans, T. brasiliensis and T. pseudomaculata). METHODS: Twelve non-breed chickens (Gallus gallus domesticus) were randomized based on weight into three groups: negative control (n = 4); a single dose of 0.5 mg/kg fluralaner (Exzolt®) (n = 4); two doses of 0.5 mg/kg fluralaner (Exzolt®) (n = 4). Nymphs of 3rd, 4th and 5th instars of R. prolixus, T. infestans, T. brasiliensis and T. pseudomaculata (all n = 10) were allowed to feed on chickens before treatment, and at intervals of 1, 7, 14, 21, 28, 35 and 56 days after treatment, with insect mortality determined. RESULTS: Treatment with two doses of fluralaner showed higher insecticidal efficacy against R. prolixus, T. infestans and T. brasiliensis compared to the single-dose treatment. Similar insecticidal efficacy was observed for T. pseudomaculata for one and two doses of fluralaner. Insecticidal activity of fluralaner (Exzolt®) against triatomine bugs was noted up to 21 and 28 days after treatment with one and two doses of fluralaner, respectively. CONCLUSIONS: The results demonstrate that treatment of chickens with fluralaner (Exzolt®) induces insecticidal activity against triatomines for up to 28 days post-treatment, suggesting its potential use as a control strategy for Chagas disease in endemic areas.


Sujet(s)
Poulets , Insecticides , Isoxazoles , Animaux , Poulets/parasitologie , Isoxazoles/pharmacologie , Isoxazoles/administration et posologie , Insecticides/pharmacologie , Insecticides/administration et posologie , Vecteurs insectes/effets des médicaments et des substances chimiques , Maladie de Chagas/transmission , Maladie de Chagas/traitement médicamenteux , Maladie de Chagas/médecine vétérinaire , Triatominae , Nymphe/effets des médicaments et des substances chimiques , Maladies de la volaille/parasitologie , Maladies de la volaille/prévention et contrôle , Triatoma/effets des médicaments et des substances chimiques
17.
J Med Entomol ; 61(4): 1081-1085, 2024 Jul 12.
Article de Anglais | MEDLINE | ID: mdl-38712431

RÉSUMÉ

Amblyomma maculatum Koch, the Gulf Coast tick, is expanding northward from its original range in the southeastern United States. In 2013, its most northern collection was in Delaware. Amblyomma maculatum has since been found in Connecticut, Illinois, and New York. It is the vector of the human pathogen Rickettsia parkeri, the causative agent of R. parkeri rickettsiosis. We report the first finding of an established population of A. maculatum in Salem County, NJ, with a R. parkeri infection prevalence rate of 23.8%. Our finding of A. maculatum is consistent with other recent findings in the northeastern United States in that specimens were found in open areas devoid of tree canopy. This discovery demonstrates the importance of tick surveillance in order to identify expanding tick populations and the pathogens they may transmit.


Sujet(s)
Amblyomma , Rickettsia , Animaux , Amblyomma/physiologie , Amblyomma/croissance et développement , Amblyomma/microbiologie , New Jersey/épidémiologie , Rickettsia/isolement et purification , Femelle , Mâle , Répartition des animaux , Nymphe/croissance et développement , Nymphe/physiologie , Nymphe/microbiologie
18.
Ticks Tick Borne Dis ; 15(5): 102352, 2024 Sep.
Article de Anglais | MEDLINE | ID: mdl-38759344

RÉSUMÉ

In Egypt, tick-borne diseases pose a significant threat to human and animal health, and the threat to dromedaries (Camelus dromedarius), the country's dominant camelid species, is of particular concern. These animals are frequently infested with ticks, and may thus develop tick-borne diseases or become reservoirs of tick-borne pathogens. However, there is a paucity of data on tick infestation in Egyptian camels, especially in the south of the country. Accordingly, we aimed to determine the prevalence of tick infestation in southern Egyptian camel populations (in Luxor and Aswan governorates), and identify the hemoprotozoan parasites carried by camel-infesting ticks. Camels were checked for ticks during veterinary examination at quarantine and household checks, and ticks were collected from infested camels for species identification using morphological examination and PCR analyses. Tick and hemoprotozoan species were identified using Basic Local Alignment Search Tool analysis with subsequent confirmation in phylogenetic analyses. All camel-infesting ticks belonged to the species Hyalomma dromedarii, and were clustered with ticks of this species previously found in Egypt in a phylogenetic tree based on the 16S rRNA gene. Molecular analysis targeting the 18S rRNA gene revealed the presence of hitherto undetected hemoprotozoan parasites, Colpodella spp., in 30/297 (10.1 %) camel-infesting ticks. In phylogenetic analysis, these Colpodella spp. were highly homologous (94-98.6 %) with Colpodella spp. previously deposited in GenBank with accession numbers OQ540590Q, MH208621, and GQ411073, which relate to Colpodella spp. previously detected from Haemaphysalis longicornis, Rhipicephalus haemaphysaloides, and humans in China. PCR analyses with spherical body protein-4 (SBP-4) gene-specific primers revealed Babesia bovis in 16/297 (5 %) of camel-infesting ticks, however, Babesia bigemina and Theileria annulata were not detected. Here, we report the first detection of Colpodella spp. in H. dromedarii in Egypt. Further epidemiological studies are needed to assess the risk to camels and humans, and the transmission dynamics. Based on the high tick infestation rates in Egyptian camels and the identification of previously unreported protozoan hemoparasites in ticks, we consider that the dromedary should be subject to surveillance as a sentinel species for tick-borne diseases in Egypt. Our findings underline the need for surveillance and collecting data on lesser known pathogens circulating in camel-infesting ticks, as part of a public health strategy for dealing with tick-borne diseases in Egypt.


Sujet(s)
Chameaux , Ixodidae , Infestations par les tiques , Animaux , Chameaux/parasitologie , Égypte/épidémiologie , Ixodidae/parasitologie , Infestations par les tiques/médecine vétérinaire , Infestations par les tiques/épidémiologie , Infestations par les tiques/parasitologie , Femelle , Phylogenèse , Mâle , Prévalence , Nymphe/croissance et développement , Nymphe/parasitologie
19.
Ecotoxicol Environ Saf ; 279: 116491, 2024 Jul 01.
Article de Anglais | MEDLINE | ID: mdl-38805832

RÉSUMÉ

Transplant treatment with chlorantraniliprole (CAP) is a proactive approach to protect transplanted plants from pests during early establishment and has been comprehensively applied in tobacco fields in Guangdong Province, China. However, it is not known whether the high dose of CAP in transplant treatments has lethal or sublethal effects on the generalist predator Rhynocoris fuscipes Fabricius (Hemiptera: Reduviidae). To address this concern, the mortalities of R. fuscipes were assessed when 2nd instar larvae of R. fuscipes were in direct contact with or consuming CAP and when their eggs were exposed to CAP. Furthermore, 2nd instar nymphs R. fuscipes were long-term exposed to CAP until they reached adulthood, and their life table parameters were determined. After exposure to CAP, the activity of detoxification enzymes (P450, CaeE and GST) and the functional respond of R. fuscipes to their preys Agrotis ipsilon larvae were determined. In this study, CAP at all concentrations did not significantly increase the mortality of 2nd instar of R. fuscipes nymphs in comparison with the control. The detoxification enzyme (P450, CarE and GST) activities and the number of A. ipsilon larvae consumed by R. fuscipes in the transplant treatment were not affected by CAP after 3-d or long-term exposure. These results indicated that CAP was harmless to R. fuscipes according to IOBC protocols. However, during the treatment of 2nd instar nymphs with a label rate of 15 g AI/ha and a 5× label rate of 75 g AI/ha, CAP significantly prolonged the pre-adult and pre-oviposition periods, and treated adults had lower oviposition. Attention should be given to the time interval between transplant treatment and the release of this biocontrol agent into the field to minimize the impact of CAP on the predator R. fuscipes.


Sujet(s)
Fécondité , Insecticides , Larve , Nymphe , Comportement prédateur , ortho-Aminobenzoates , Animaux , ortho-Aminobenzoates/toxicité , Larve/effets des médicaments et des substances chimiques , Insecticides/toxicité , Nymphe/effets des médicaments et des substances chimiques , Nymphe/croissance et développement , Nymphe/physiologie , Fécondité/effets des médicaments et des substances chimiques , Comportement prédateur/effets des médicaments et des substances chimiques , Hemiptera/effets des médicaments et des substances chimiques , Hemiptera/physiologie , Chine , Femelle , Heteroptera/effets des médicaments et des substances chimiques , Heteroptera/physiologie , Chaine alimentaire
20.
Micron ; 183: 103656, 2024 08.
Article de Anglais | MEDLINE | ID: mdl-38759450

RÉSUMÉ

A trichobothrium is a complex sensory organ, which usually consists of a long, slender mechanoreceptive seta (trich), which is situated in a cuplike depression in the cuticle (bothrium). Nabidae (Hemiptera: Heteroptera: Cimicomorpha), also called damsel bugs, are a relatively small family within which two subfamilies, Nabinae and Prostemmatinae, are distinguished. Trichobothria are present in the number of one to seven pairs located laterally on the scutellum of adult representatives of Prostemmatinae. This feature is commonly used to distinguish this subfamily from Nabinae. Trichobothria are also found on the abdominal tergites of Prostemmatinae nymphs. Similar sensilla have been observed in adult representatives of Nabinae, but their homology has not yet been confirmed. During morphological studies on Nabidae, conducted using scanning electron microscopy, we noticed sensilla resembling trichobothria on the heads of these insects. This discovery prompted us to examine the presence of these structures in damsel bugs more carefully. Imagines of fifteen species of both subfamilies were analysed using a scanning electron microscope. The results present data on the distribution and micromorphology of the trichobothria in damsel bugs. A pair of dorsal and ventral cephalic trichobothria were observed in all of the examined species of subfamily Nabinae. These sensilla were not found on the heads of Prostemmatinae. The results of studies on scutellar trichobothria confirmed the previously known data regarding their occurrence in Prostemmatinae. Moreover, our research showed the presence of these sensory structures in all of the examined Nabinae species: one pair of trichobothria in Arachnocorini, Carthasini, Gorpini and Nabini, and two pairs in Stenonabini. The presence of abdominal trichobothria was shown in Nabini and Stenonabini. In the remaining studied tribes of Nabinae and in the subfamily Prostemmatinae, the presence of structures that could undoubtedly be considered abdominal trichobothria was not found.


Sujet(s)
Heteroptera , Microscopie électronique à balayage , Sensilles , Animaux , Heteroptera/anatomie et histologie , Heteroptera/ultrastructure , Sensilles/ultrastructure , Femelle , Mâle , Nymphe/ultrastructure , Nymphe/anatomie et histologie
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