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Insects May 2024The mechanisms of action behind decreased mite reproduction (DMR) are still unknown, but current hypotheses state that DMR is the result of brood-intrinsic and/or...
The mechanisms of action behind decreased mite reproduction (DMR) are still unknown, but current hypotheses state that DMR is the result of brood-intrinsic and/or external disturbances in the -honey bee pupa signal interactions. For accurate and precise DMR phenotyping, sufficient single infested honey bee brood cells are required (e.g., 35), which requires extensive labor and time and may exclude many samples not reaching the threshold. We defined a new comprehensive trait called the 'mean reproduction rate' (mVR), which describes the mean number of offspring mites per infested cell in the sample while compensating for the reduced number of offspring with increasing multiple infested cells. We found a significant correlation between mVR and DMR, allowing for an estimation of DMR based on the mVR only. When the mVR was calculated with 10 infested cells, we found an average variation in mVR of 16.8%. For the same variation in DMR determination, 40 single infested cells are required. This broader look at resistance phenotyping can improve the applicability and effectiveness of traits related to reproduction in honey bee breeding programs.
PubMed: 38921112
DOI: 10.3390/insects15060397 -
Insects May 2024Resistance against amitraz in mite populations has become a subject of interest in recent years due to the increasing reports of the reduced field efficacy of amitraz...
Resistance against amitraz in mite populations has become a subject of interest in recent years due to the increasing reports of the reduced field efficacy of amitraz treatments, especially from some beekeepers in France and the United States. The loss of amitraz as a reliable tool to effectively reduce mite infestation in the field could severely worsen the position of beekeepers in the fight to keep infestation rates in their colonies at low levels. In this publication, we present data from French apiaries, collected in the years 2020 and 2021. These data include the field efficacy of an authorized amitraz-based treatment (Apivar ,Véto-pharma, France) and the results of laboratory sensitivity assays of mites exposed to the reference LC concentration of amitraz. In addition, a total of 240 mites from Eastern, Central, and Southern regions in France that were previously classified as either "sensitive" or "resistant" to amitraz in a laboratory sensitivity assay were genotyped. The genetic analyses of mite samples are focused on the β-adrenergic-like octopamine receptor, which is considered as the main target site for amitraz in mites. Special attention was paid to a single-nucleotide polymorphism (SNP) at position 260 of the gene that was previously associated to amitraz resistance in French mites, . Our findings confirm that amitraz resistance occurs in patches or "islands of resistance", with a less severe reduction in treatment efficacy compared to pyrethroid resistance or coumaphos resistance in mites. The results of our genetic analyses of mites call into question the hypothesis of the SNP at position 260 of the gene being directly responsible for amitraz resistance development.
PubMed: 38921105
DOI: 10.3390/insects15060390 -
Insects May 2024The dispersal strategies of a species can affect its invasion success. Investigations into the dispersal strategies of invasive species in relation to different factors...
The dispersal strategies of a species can affect its invasion success. Investigations into the dispersal strategies of invasive species in relation to different factors help improve our understanding of invasion mechanisms and provide knowledge for population management and invasion evaluation. Zacher (Acari: Tetranychidae) is an invasive species which is native to Europe but is now cosmopolitan. Here, we examined the effects of age and density on dispersal in mated females. Our results show that older females that are capable of producing more eggs within 24 h were more likely to disperse and moved longer distances than younger ones with fewer eggs. Older females spread most of their eggs out of their natal habitats and over longer distances, which reduced competition and increased offspring fitness. Females exhibited significantly increased dispersal probability and distances with an increase in population density to avoid crowding. The synchronization of dispersal and reproduction, along with the positive density-dependent dispersal strategy, may facilitate the habitat colonization and invasion speed of .
PubMed: 38921102
DOI: 10.3390/insects15060387 -
Insects May 2024(Acari: Tetranychidae) has caused serious economic losses on some crops (soybean, corn, and cotton) in China, and has developed resistance to most acaricides. Our...
Differential Antioxidant Enzyme Gene Expression and Functional Analysis of Pyridaben-Susceptible and -Resistant Strains of (Acari: Tetranychidae) under High Temperature Stress.
(Acari: Tetranychidae) has caused serious economic losses on some crops (soybean, corn, and cotton) in China, and has developed resistance to most acaricides. Our laboratory study found that was resistant to pyridaben and also adapted to high temperature (34-40 °C). High temperature stress may cause arthropods to produce a large amount of reactive oxygen species (ROS), causing oxidative damage. Antioxidant enzymes, as the main antioxidants, can reduce the damage caused by excessive ROS in arthropods. In order to study the adaptation mechanism of the pyridaben-resistant strain of to high temperature and the role of antioxidant enzyme genes under high temperature stress, four antioxidant enzyme genes, , , , and , were screened according to the transcriptome sequencing data of pyridaben-susceptible and -resistant strains in . Firstly, the phylogeny and structure analyses of these four genes were carried out. Then, real-time quantitative PCR (RT-qPCR) technology was used to analyze the gene expression patterns of antioxidant enzymes in two strains of at three different high temperature ranges (34 °C, 38 °C, and 42 °C). The results showed that the expression levels of four antioxidant enzyme genes of two strains of were induced by high temperature stress, and the expression levels of antioxidant enzyme genes were significantly different in each development state. The gene expression of antioxidant enzyme genes in resistant strains at the adult stage was significantly higher than that in susceptible strains. After the and genes of adult mites of the resistant strain were silenced by RNA interference (RNAi) technology, the mortality rate of mites with gene silencing reached 41.11% after 96 h at 34 °C, which was significantly higher than that of the control and gene silencing. It has been confirmed that the gene plays a key role in the adaptation of pyridaben-resistant strain of to high temperature. It lays a theoretical foundation for revealing the thermal adaptation mechanism of .
PubMed: 38921096
DOI: 10.3390/insects15060381 -
Ecology and Evolution Jun 2024A sustainable solution to the global threat of the mite is the selection of varroa-resistant honey bee () colonies. Both "mite non-reproduction" (MNR) and "varroa...
A sustainable solution to the global threat of the mite is the selection of varroa-resistant honey bee () colonies. Both "mite non-reproduction" (MNR) and "varroa sensitive hygiene" (VSH) appear to be promising selection traits for achieving the goal of a resistant honey bee. MNR describes colonies that have a high number of non-reproductive mites (no offspring, no males, or delayed development of mite offspring). High numbers of non-reproductive mites have been observed in selected colonies, but the mechanism behind this trait has not yet been identified. The specialized hygienic behavior of selected honey bees, called VSH, is the removal of varroa-infested brood. These traits were thought to be linked by VSH bees preferentially removing reproductive varroa females leaving only non-reproductive mites behind in cells and thus creating colonies with high levels of MNR. To further investigate this link, we used an experimental setup and data sets from a four-year selection project designed to breed for MNR and VSH colonies. In addition, we sought to answer the question of whether non-reproductive mites are a direct consequence of worker removal behavior. To test this, we artificially induced removal behavior, and after providing the mite with enough time to re-enter another cell, we opened all capped cells, relocated the mites, and evaluated their reproduction. As shown in previous studies and in this study, VSH had no effect on MNR levels. Also, the induced removal behavior did not lead to non-reproduction in the subsequent reproductive cycle post interruption. We thus concluded that breeding for non-reproductive mites does not automatically breed for VSH behavior and worker removal behavior does not cause subsequent reproductive failure of the mites forced to flee and find a new cell for reproduction.
PubMed: 38919649
DOI: 10.1002/ece3.11595 -
BioRxiv : the Preprint Server For... Jun 2024Vagal sensory neurons convey sensations from internal organs along the vagus nerve to the brainstem. Pruriceptors are a subtype of neurons that transmit itch and induce...
Vagal sensory neurons convey sensations from internal organs along the vagus nerve to the brainstem. Pruriceptors are a subtype of neurons that transmit itch and induce pruritus. Despite extensive research on the molecular mechanisms of itch, studies focusing on pruriceptors in the vagal ganglia still need to be explored. In this study, we characterized vagal pruriceptor neurons by their responsiveness to pruritogens such as lysophosphatidic acid, -alanine, chloroquine, and the cytokine oncostatin M. We discovered that lung-resident basophils produce oncostatin M and that its release can be induced by engagement of FcRI. Oncostatin M then sensitizes multiple populations of vagal sensory neurons, including Tac1 and MrgprA3 neurons in the jugular ganglia. Finally, we observed an increase in oncostatin M release in mice sensitized to the house dust mite or to the fungal allergen , highlighting a novel mechanism through which basophils and vagal sensory neurons may communicate during type I hypersensitivity diseases such as allergic asthma.
PubMed: 38915548
DOI: 10.1101/2024.06.11.598517 -
American Journal of Physiology. Lung... Jun 2024Chitin, a polysaccharide found in the fungal cell wall and the exoskeletons of house dust mites and cockroaches, has garnered attention as a potential immunoreactive...
Chitin, a polysaccharide found in the fungal cell wall and the exoskeletons of house dust mites and cockroaches, has garnered attention as a potential immunoreactive allergen. Mammals have evolved to express chitin-degrading chitinases (acidic mammalian chitinase/AMCase and chitotriosidase) that may modulate immune responses to chitin. We have previously reported that mice deficient in AMCase (-/-) demonstrated better lung function during allergic fungal asthma. As expected, we show that mice overexpressing AMCase (SPAM mice) had worse airway hyperreactivity (AHR) during allergic fungal asthma. We further demonstrate that chitin-positive conidia are detectable in the allergic lung during chronic exposure. Lung function in -/- and SPAM mice directly correlated with the level of chitinase activity during chronic fungal exposure (-/- mice, negligible chitinase activity, lower AHR; SPAM mice, heightened chitinase activity, higher AHR), suggesting that the breakdown of chitin promoted AHR. However, chronic exposure of normal mice to purified chitin resulted in only moderate inflammatory changes in the lung which were not sufficient to induce AHR. Moreover, despite having dramatic differences in chitinase activity, chronic exposure of -/- and SPAM mice to purified chitin likewise did not modulate AHR. Collectively, these results indicate that chronic exposure to fungal chitin alone is incapable of driving AHR. Furthermore, our data suggests that the chitinase-mediated degradation of chitin associated with conidia may facilitate unmasking and/or liberation of other fungal cell wall components that drive inflammatory responses which contribute to AHR.
PubMed: 38915287
DOI: 10.1152/ajplung.00041.2024 -
Philosophical Transactions of the Royal... Jul 2024One of the fundamental aims of ecological, epidemiological and evolutionary studies of host-parasite interactions is to unravel which factors affect parasite virulence....
One of the fundamental aims of ecological, epidemiological and evolutionary studies of host-parasite interactions is to unravel which factors affect parasite virulence. Theory predicts that virulence and transmission are correlated by a trade-off, as too much virulence is expected to hamper transmission owing to excessive host damage. Coinfections may affect each of these traits and/or their correlation. Here, we used inbred lines of the spider mite to test how coinfection with impacted virulence-transmission relationships at different conspecific densities. The presence of on a shared host did not change the relationship between virulence (leaf damage) and the number of transmitting stages (i.e. adult daughters). The relationship between these traits was hump-shaped across densities, both in single and coinfections, which corresponds to a trade-off. Moreover, transmission to adjacent hosts increased in coinfection, but only at low densities. Finally, we tested whether virulence and the number of daughters were correlated with measures of transmission to adjacent hosts, in single and coinfections at different conspecific densities. Traits were mostly independent, meaning that interspecific competitors may increase transmission without affecting virulence. Thus, coinfections may impact epidemiology and parasite trait evolution, but not necessarily the virulence-transmission trade-off.This article is part of the theme issue 'Diversity-dependence of dispersal: interspecific interactions determine spatial dynamics'.
Topics: Animals; Virulence; Tetranychidae; Host-Parasite Interactions; Coinfection; Female
PubMed: 38913066
DOI: 10.1098/rstb.2023.0139 -
Philosophical Transactions of the Royal... Jul 2024Parasites are known to have direct effects on host dispersal ability and motivation. Yet, parasites have a variety of impacts on host populations, including shaping...
Parasites are known to have direct effects on host dispersal ability and motivation. Yet, parasites have a variety of impacts on host populations, including shaping predation and cannibalism rates, and therefore may also have indirect effects on host dispersal; these indirect pathways have not been studied. We tested the hypothesis that parasites influence host dispersal through effects on cannibalism using backswimmers () and Hydrachnidia freshwater mites. Mite parasitism impedes swimming in backswimmers, which we found increased their vulnerability to cannibalism. We imposed a manipulation that varied cannibalism rates across experimental populations consisting of a mix of backswimmers with and without simulated parasites. Using simulated parasites allowed us to examine the effects of cannibalism without introducing infection risk. We found that the odds of dispersal for infected backswimmers increased by 2.25× with every 10% increase in the risk of being cannibalized, and the odds of dispersal for healthy backswimmers increased by 2.34× for every additional infected backswimmer they consumed. Our results suggest that cannibalism was used as an energy source for dispersal for healthy individuals, while the risk of being eaten motivated dispersal in infected individuals. These results elucidate the complex ways that parasites impact host populations and strengthen our understanding of host-parasite interactions, including host and parasite population stability and spread. This article is part of the theme issue 'Diversity-dependence of dispersal: interspecific interactions determine spatial dynamics'.
Topics: Animals; Cannibalism; Host-Parasite Interactions; Mites; Animal Distribution; Heteroptera
PubMed: 38913057
DOI: 10.1098/rstb.2023.0134 -
Journal of Immunology (Baltimore, Md. :... Jun 2024Neutrophils play important roles in inflammatory airway diseases. In this study, we assessed whether apolipoprotein A-I modifies neutrophil heterogeneity as part of the...
Neutrophils play important roles in inflammatory airway diseases. In this study, we assessed whether apolipoprotein A-I modifies neutrophil heterogeneity as part of the mechanism by which it attenuates acute airway inflammation. Neutrophilic airway inflammation was induced by daily intranasal administration of LPS plus house dust mite (LPS+HDM) to Apoa1-/- and Apoa1+/+ mice for 3 d. Single-cell RNA sequencing was performed on cells recovered from bronchoalveolar lavage fluid on day 4. Unsupervised profiling identified 10 clusters of neutrophils in bronchoalveolar lavage fluid from Apoa1-/- and Apoa1+/+ mice. LPS+HDM-challenged Apoa1-/- mice had an increased proportion of the Neu4 neutrophil cluster that expressed S100a8, S100a9, and Mmp8 and had high maturation, aggregation, and TLR4 binding scores. There was also an increase in the Neu6 cluster of immature neutrophils, whereas neutrophil clusters expressing IFN-stimulated genes were decreased. An unsupervised trajectory analysis showed that Neu4 represented a distinct lineage in Apoa1-/- mice. LPS+HDM-challenged Apoa1-/- mice also had an increased proportion of recruited airspace macrophages, which was associated with a reciprocal reduction in resident airspace macrophages. Increased expression of a common set of proinflammatory genes, S100a8, S100a9, and Lcn2, was present in all neutrophils and airspace macrophages from LPS+HDM-challenged Apoa1-/- mice. These findings show that Apoa1-/- mice have increases in specific neutrophil and macrophage clusters in the lung during acute inflammation mediated by LPS+HDM, as well as enhanced expression of a common set of proinflammatory genes. This suggests that modifications in neutrophil and macrophage heterogeneity contribute to the mechanism by which apolipoprotein A-I attenuates acute airway inflammation.
PubMed: 38912868
DOI: 10.4049/jimmunol.2300459