-
Scientific Reports Aug 2022Environmental RNAi has been developed as a tool for reverse genetics studies and is an emerging pest control strategy. The ability of environmental RNAi to efficiently...
Environmental RNAi has been developed as a tool for reverse genetics studies and is an emerging pest control strategy. The ability of environmental RNAi to efficiently down-regulate the expression of endogenous gene targets assumes efficient uptake of dsRNA and its processing. In addition, its efficiency can be augmented by the systemic spread of RNAi signals. Environmental RNAi is now a well-established tool for the manipulation of gene expression in the chelicerate acari, including the two-spotted spider mite, Tetranychus urticae. Here, we focused on eight single and ubiquitously-expressed genes encoding proteins with essential cellular functions. Application of dsRNAs that specifically target these genes led to whole mite body phenotypes-dark or spotless. These phenotypes were associated with a significant reduction of target gene expression, ranging from 20 to 50%, when assessed at the whole mite level. Histological analysis of mites treated with orally-delivered dsRNAs was used to investigate the spatial range of the effectiveness of environmental RNAi. Although macroscopic changes led to two groups of body phenotypes, silencing of target genes was associated with the distinct cellular phenotypes. We show that regardless of the target gene tested, cells that displayed histological changes were those that are in direct contact with the dsRNA-containing gut lumen, suggesting that the greatest efficiency of the orally-delivered dsRNAs is localized to gut tissues in T. urticae.
Topics: Animals; Pest Control; RNA Interference; RNA, Double-Stranded; Tetranychidae
PubMed: 36042376
DOI: 10.1038/s41598-022-19231-3 -
International Journal For Parasitology Sep 2023The ectoparasitic mite Varroa destructor is an invasive species of Western honey bees (Apis mellifera) and the largest pathogenic threat to their health world-wide. Its...
The ectoparasitic mite Varroa destructor is an invasive species of Western honey bees (Apis mellifera) and the largest pathogenic threat to their health world-wide. Its successful invasion and expansion is related to its ability to exploit the worker brood for reproduction, which results in an exponential population growth rate in the new host. With invasion of the mite, wild honeybee populations have been nearly eradicated from Europe and North America, and the survival of managed honeybee populations relies on mite population control treatments. However, there are a few documented honeybee populations surviving extended periods without control treatments due to adapted host traits that directly impact Varroa mite fitness. The aim of this study was to investigate if Varroa mite reproductive success was affected by traits of adult bee behaviours or by traits of the worker brood, in three mite-resistant honey bee populations from Sweden, France and Norway. The mite's reproductive success was measured and compared in broods that were either exposed to, or excluded from, adult bee access. Mite-resistant bee populations were also compared with a local mite-susceptible population, as a control group. Our results show that mite reproductive success rates and mite fecundity in the three mite-resistant populations were significantly different from the control population, with the French and Swedish populations having significantly lower reproductive rates than the Norwegian population. When comparing mite reproduction in exposed or excluded brood treatments, no differences were observed, regardless of population. This result clearly demonstrates that Varroa mite reproductive success can be suppressed by traits of the brood, independent of adult worker bees.
Topics: Bees; Animals; Varroidae; Reproduction; Fertility; Europe; France
PubMed: 37164049
DOI: 10.1016/j.ijpara.2023.04.001 -
Parasite (Paris, France) 2022The Chinese mole shrew, Anourosorex squamipes Milne-Edwards, 1872, is a common species of insectivorous mammal in Southwest China. Based on field investigations between...
The Chinese mole shrew, Anourosorex squamipes Milne-Edwards, 1872, is a common species of insectivorous mammal in Southwest China. Based on field investigations between 2001 and 2019, the present study reports the infestation of chiggers (larvae of chigger mites) on the shrew in Southwest China and certain ecology parameters for the first time. A total of 3169 chiggers were collected from 1694 A. squamipes and they were identified into 72 species and 10 genera in the family Trombiculidae. The overall infestation prevalence (P), mean abundance (MA) and mean intensity (MI) of A. squamipes with chiggers reached 11.1%, 1.87 and 16.86, respectively. The species diversity, species composition and infestation of chiggers on A. squamipes fluctuated in different environments (latitudes, altitudes, habitats and landscapes) and on different sexes and ages of the shrew hosts with high heterogeneity and low species similarity. In the established linear regression equation (M* = 0.173 + 1.054 M) for dominant mite Leptotrombidium densipunctatum, both the α and β values (α = 0.173, β = 1.054) exceeded the boundary values (F = 4.67, p < 0.05), and therefore the spatial distribution pattern of this mite was determined as an aggregated distribution among different individuals of shrew hosts. The species abundance distribution of the chigger community on A. squamipes conformed to the lognormal distribution, and its curve showed a gradually descending tendency from the rare mite species to the dominant mite species. The curve tendency of species-sample relationship implies that more species of chiggers would be found if the host samples infinitely keep increasing.
Topics: Altitude; Animals; China; Ecosystem; Humans; Mite Infestations; Mites; Shrews; Trombiculidae
PubMed: 35900094
DOI: 10.1051/parasite/2022038 -
PloS One 2023Host age at parasites' exposure is often neglected in studies on host-parasite interactions despite the important implications for epidemiology. Here we compared the...
Host age at parasites' exposure is often neglected in studies on host-parasite interactions despite the important implications for epidemiology. Here we compared the impact of the parasitic mite Varroa destructor, and the associated pathogenic virus DWV on different life stages of their host, the western honey bee Apis mellifera. The pre-imaginal stages of the honey bee proved to be more susceptible to mite parasitization and viral infection than adults. The higher viral load in mite-infested bees and DWV genotype do not appear to be the drivers of the observed difference which, instead, seems to be related to the immune-competence of the host. These results support the existence of a trade-off between immunity and growth, making the pupa, which is involved in the highly energy-demanding process of metamorphosis, more susceptible to parasites and pathogens. This may have important implications for the evolution of the parasite's virulence and in turn for honey bee health. Our results highlight the important role of host's age and life stage at exposure in epidemiological modelling. Furthermore, our study could unravel new aspects of the complex honey bee-Varroa relationship to be addressed for a sustainable management of this parasite.
Topics: Animals; Bees; Varroidae; Virus Diseases; Host-Parasite Interactions
PubMed: 37459342
DOI: 10.1371/journal.pone.0288821 -
Scientific Reports Jul 2023Varroa mites are serious pests of European honeybees (Apis mellifera). For detection of Varroa mite, a new molecular LAMP-based assay has been developed, which retains...
Varroa mites are serious pests of European honeybees (Apis mellifera). For detection of Varroa mite, a new molecular LAMP-based assay has been developed, which retains the body of the mite intact for morphological identification. Six novel Varroa LAMP primers were designed from existing DNA sequences of the COI locus to target V. destructor and V. jacobsoni, providing the ability to tell them apart from other non-target beehive associated mite and insect species. This LAMP assay is specific in detecting these Varroa species and has been tested on specimens originating from multiple countries. It produces amplification of V. destructor and V. jacobsoni in 16 ± 3.4 min with an anneal derivative of 78 ± 0.5 °C whilst another Varroa species,V. underwoodi, showed late amplification. A gBlock gene fragment, used here as a positive control has a different anneal derivative of 80 °C. Three non-destructive DNA extraction methods (HotShot, QuickExtract and Xtract) were tested and found to be suitable for use in the field. The LAMP assay was sensitive to very low levels of Varroa DNA, down to 0.24 picogram (~ 1 × 10 copies/µL of Varroa gBlock). This is a new molecular tool for rapid and accurate detection and identification of Varroa mites for pest management, in areas where these mites do not occur.
Topics: Animals; Bees; Varroidae; Biological Assay; DNA Primers
PubMed: 37488147
DOI: 10.1038/s41598-023-38860-w -
Scientific Reports May 2023Formic acid is the main component of the ant's major weapon against enemies. Being mainly used as a chemical defense, the acid is also exploited for recruitment and...
Formic acid is the main component of the ant's major weapon against enemies. Being mainly used as a chemical defense, the acid is also exploited for recruitment and trail marking. The repelling effect of the organic acid is used by some mammals and birds which rub themselves in the acid to eliminate ectoparasites. Beekeepers across the world rely on this effect to control the parasitic mite Varroa destructor. Varroa mites are considered the most destructive pest of honey bees worldwide and can lead to the loss of entire colonies. Formic acid is highly effective against Varroa mites but can also kill the honeybee queen and worker brood. Whether formic acid can also affect the behavior of honey bees is unknown. We here study the effect of formic acid on sucrose responsiveness and cognition of honey bees treated at different live stages in field-relevant doses. Both behaviors are essential for survival of the honey bee colony. Rather unexpectedly, formic acid clearly improved the learning performance of the bees in appetitive olfactory conditioning, while not affecting sucrose responsiveness. This exciting side effect of formic acid certainly deserves further detailed investigations.
Topics: Bees; Animals; Ants; Cognition; Drug-Related Side Effects and Adverse Reactions; Mitochondrial ADP, ATP Translocases; Sucrose; Varroidae; Mammals
PubMed: 37225773
DOI: 10.1038/s41598-023-35540-7 -
Turkiye Parazitolojii Dergisi Sep 2023This study was carried out to detect house dust mites in houses and to investigate group 1 antigens of Dermatophagoid species in Ordu, Giresun, Trabzon and Rize...
OBJECTIVE
This study was carried out to detect house dust mites in houses and to investigate group 1 antigens of Dermatophagoid species in Ordu, Giresun, Trabzon and Rize provinces of the Central and Eastern Black Sea Region.
METHODS
Dust samples obtained from the beds were subjected to both microscopic and antigenic examination. Samples prepared by the lactic acid method for microscopic examination were evaluated under a light microscope. Antigenic analysis was performed by investigating Der p 1 and Der f 1 belonging to and by ELISA test.
RESULTS
90.3% of the dust samples were evaluated positive by microscopic examination (10x, 40x) and 149 mites were detected. 74%, 13%, spp. growth forms 5%, spp. 1%, 1%, 1%, 1%, 1% and unidentified mites were detected at the rate of 3% respectively. Der p 1 antigen was detected in 93% and Der f 1 antigen in 84.7%. The highest amount of antigen detected in one gram of powder was 1,272 μg for Der p 1 and 0,482 μg for Der f 1.
CONCLUSION
No difference was observed between mite species and distribution in the provinces where the study was conducted (p<0.05). Dermatophagoides were found in 93% of the population. The low (4%) rate of storage/food mites is related to the fact that samples were not taken from the floors. Antigen accumulation may be important in the beds since the activity of the mites is observed throughout the year in temperate and humid regions. It is thought that this diagnosis method can be used and can be taken into account in terms of the environments in which sensitive people live.
Topics: Humans; Animals; Pyroglyphidae; Prevalence; Dermatophagoides pteronyssinus; Dust
PubMed: 37724368
DOI: 10.4274/tpd.galenos.2023.35744 -
PloS One 2021Varroa destructor Anderson and Trueman, is an ectoparasitic mite of honey bees, Apis mellifera L., that has been considered a major cause of colony losses. Synthetic...
Varroa destructor Anderson and Trueman, is an ectoparasitic mite of honey bees, Apis mellifera L., that has been considered a major cause of colony losses. Synthetic miticides have been developed and registered to manage this ectoparasite, however, resistance to registered pyrethroid and organophosphate Varroacides have already been reported in Canada. To test toxicity of miticides, current contact-based bioassay methods are designed to evaluate mites and bees separately, however, these methods are unlikely to give an accurate depiction of how miticides interact at the colony level. Therefore, the objective of this study was to develop a bioassay cage for testing the toxicity of miticides on honey bees and Varroa mites simultaneously using amitraz as a reference chemical. A 800 mL polypropylene plastic cage holding 100-150 bees was designed and officially named "Apiarium". A comparison of the effects of three subsequent dilutions of amitraz was conducted on: Varroa mites placed in glass vials, honey bees in glass Mason jars, and Varroa-infested bees in Apiariums. Our results indicated cumulative Varroa mortality was dose-dependent in the Apiarium after 4 h and 24 h assessments. Apiarium and glass vial treatments at 24 h also had high mite mortality and a positive polynomial regression between Varroa mortality and amitraz dose rates. Moreover, chemical application in the Apiarium was less toxic for bees compared to the Mason jar method. Considering these results, the Apiarium bioassay provides a simple, cheap and reliable method for simultaneous chemical screening on V. destructor and A. mellifera. Furthermore, as mites and bees are tested together, the Apiarium simulates a colony-like environment that provides a necessary bridge between laboratory bioassay testing and full field experimentation. The versatility of the Apiarium allows researchers to test a multitude of different honey bee bioassay experiments including miticide screening, delivery methods for chemical products, or development of new mite resistance-testing methodology.
Topics: Animals; Bees; Biological Assay; Survival Analysis; Toluidines; Varroidae
PubMed: 33901245
DOI: 10.1371/journal.pone.0250594 -
Biogerontology Feb 2023The early-life experience is important in modulating the late-life performance of individuals. It has been predicted that there were trade-offs between early-life...
The early-life experience is important in modulating the late-life performance of individuals. It has been predicted that there were trade-offs between early-life fitness and late-life success. Most of the studies on senescence have focused on the trade-offs between the reproduction and lifespan, and the influences of diet, mating, and other factors. Because the negative, non-consumptive effects of predators could also modulate the behaviour and underlying mechanisms of the prey, this study aimed to examine the different effects of predator-induced stress experienced in the early life compared with later life of the prey. The prey (Tyrophagus putrescentiae) was exposed to predation stress from the predator (Neoseiulus cucumeris) during different periods of its life (immature, oviposition period, and post-oviposition period). The results showed that the predation stress experienced during immature stages delayed development by 7.3% and prolonged lifespan by 9.7%, while predation stress experienced in the adult stage (both oviposition and post-oviposition periods) decreased lifespans of T. putrescentiae (by 24.8% and 28.7%, respectively). Predation stress experienced during immature stages also reduced female fecundity by 7.3%, whereas that experienced during the oviposition period reduced fecundity of the prey by 50.7%. This study demonstrated for the first time lifespan extension by exposure to predation stress when young and highlighted the importance of early-life experience to aging and lifespan.
Topics: Animals; Female; Longevity; Mites; Oviposition; Predatory Behavior
PubMed: 36085209
DOI: 10.1007/s10522-022-09990-x -
Communications Biology May 2023Dermanyssus gallinae is a blood-feeding mite that parasitises wild birds and farmed poultry. Its remarkably swift processing of blood, together with the capacity to...
Dermanyssus gallinae is a blood-feeding mite that parasitises wild birds and farmed poultry. Its remarkably swift processing of blood, together with the capacity to blood-feed during most developmental stages, makes this mite a highly debilitating pest. To identify specific adaptations to digestion of a haemoglobin-rich diet, we constructed and compared transcriptomes from starved and blood-fed stages of the parasite and identified midgut-enriched transcripts. We noted that midgut transcripts encoding cysteine proteases were upregulated with a blood meal. Mapping the full proteolytic apparatus, we noted a reduction in the suite of cysteine proteases, missing homologues for Cathepsin B and C. We have further identified and phylogenetically analysed three distinct transcripts encoding vitellogenins that facilitate the reproductive capacity of the mites. We also fully mapped transcripts for haem biosynthesis and the ferritin-based system of iron storage and inter-tissue trafficking. Additionally, we identified transcripts encoding proteins implicated in immune signalling (Toll and IMD pathways) and activity (defensins and thioester-containing proteins), RNAi, and ion channelling (with targets for commercial acaricides such as Fluralaner, Fipronil, and Ivermectin). Viral sequences were filtered from the Illumina reads and we described, in part, the RNA-virome of D. gallinae with identification of a novel virus, Red mite quaranjavirus 1.
Topics: Animals; Poultry; Mite Infestations; RNA-Seq; Virome; Chickens; Poultry Diseases; Mites
PubMed: 37179447
DOI: 10.1038/s42003-023-04907-x