Experimental and Applied Acarology最新文献

The two-spotted spider mite, Tetranychus urticae Koch, is a significant pest in strawberry cultivation worldwide, causing substantial crop damage and economic losses. Biological control using predatory mites such as Amblyseius swirskii Athias-Henriot and Neoseiulus californicus (McGregor) is an essential component of integrated pest management (IPM) strategies. However, the efficacy of these natural enemies can be negatively affected by acaricide applications. This study assessed the sublethal effects of two acaricides; bromopropylate, a synthetic agent, and GC-Mite, a botanical formulation, on the life history and population growth parameters of A. swirskii and N. californicus feeding on T. urticae in strawberry crops. Acute toxicity assays demonstrated that both predatory mites exhibited significantly lower susceptibility to these acaricides than T. urticae, with A. swirskii showing the greatest resistance. Perinatal exposure to LC₂₅ residue of bromopropylate and GC-Mite prolonged immature development, reduced adult longevity, and decreased fecundity in both predatory mite species. N. californicus experienced more pronounced negative effects, including marked declines in survival rates and reproductive output, whereas A. swirskii displayed greater resilience and more stable reproductive potential. Population growth parameters, such as the intrinsic rate of increase (r) and net reproductive rate (R₀), declined significantly under acaricide treatments, with bromopropylate producing stronger adverse effects than GC-Mite. These results emphasize the relative compatibility of GC-Mite within IPM programs due to its lower toxicity to beneficial predatory mites. Careful selection and application of acaricides that minimize harm to natural enemies are crucial for sustainable management of T. urticae in strawberry cultivation.

Understanding how long-term climatic changes shape the distribution of disease vectors is essential to anticipate future health and ecological risks. Using long term climatic data (1960-2019) across Europe, we analysed temporal trends, abrupt shifts, and the velocity of climate change in maximum and minimum temperature and vapor pressure deficit (VPD) and evaluated their influence on the climatic niche of the tick Ixodes ricinus. Our results reveal a widespread warming and drying trend, with strong regional heterogeneity. A major regime shift occurred during the 1980s, leading to an abrupt increase of the slope of growth of minimum temperature in northern Europe, or VPD, particularly in the Mediterranean Basin. The length of growing season and accumulated degree days increased markedly after this decade, consistent with a climate tipping point. Despite these shifts, climate velocity remained relatively low (< 5 km year⁻¹), indicating that local adaptation of tick populations may buffer spatial displacement. Habitat suitability models show that I. ricinus expanded eastwards and northwards after 1990, with maximum increases of ~ 48% in climatic suitability, yet overall climate niche stability remained high (90-93%) supporting a high niche conservatism. Generalized linear models identified minimum temperature and VPD trends as the main drivers of these changes. Collectively, these findings suggest that recent climate dynamics, particularly after the 1980s, have subtly enhanced the potential range of I. ricinus without major shifts in its core environmental niche. The methods applied in this study could be of particular interest for human health authorities mapping long term resilience of tick populations under the current climate trends.

Ticks play an important role in the ecology of zoonotic diseases, however their diversity and host associations in insular ecosystems remain insufficiently documented in Türkiye. We investigated tick occurrence on yellow-legged Gulls (Larus michahellis) and within their nesting environment on Gull Island (Sinop, Türkiye) between March and June 2025. A total of 574 gull chicks and 833 nests were examined, yielding eight tick specimens. Morphological examination and molecular analyses revealed three noteworthy observations: (i) the detection of an adult Ixodes ricinus female attached to a yellow-legged gull chick, representing a rare avian host record, (ii) the presence of a questing male Hyalomma marginatum on the island floor, and (iii) the first record of Ornithodoros maritimus in Türkiye, confirmed by mitochondrial 16 S rRNA sequencing and phylogenetic analysis. The findings suggest that small insular habitats can be intermittently colonized by tick species of medical relevance, likely through host-mediated dispersal, while also highlighting ecological constraints that may limit long-term population establishment. These observations contribute to the faunistic knowledge of ticks in Türkiye and underscore the need for targeted surveillance of seabird-associated soft ticks along coastal ecosystems.

Sphingomyelin synthase (SMS) is a key enzyme in sphingolipid metabolism that catalyzes the synthesis of sphingomyelin (SM). The potential roles of SMS involved in the egg development and female fecundity on the tremendous pest mite Panonychus citri, however, remain unknown. In this study, we determined the function of sphingomyelin synthase gene in P. citri across different developmental stages. We silenced the PcSMS in adult females of P. citri via feeding on detached citrus leaves that absorbed dsRNAs. The survival rates and lifespan, along with the expressions of ROS and apoptosis genes were significantly changed. Additionally, fecundity and oviposition periods of P. citri were shortened. The expression levels of vitellogenin and its receptor genes were downregulated. Knockdown of PcSMS also affected egg hatching, resulting in developmental delays and egg lethal phenotypes. Our findings shed light on the metabolism underlying the biological functions of egg development and adult females fecundity of P. citri and render lipid metabolism the attractive target for biopesticide to control citrus spider mite.

Repellent activities of essential oils extracted from sweet fern were evaluated against nymph and adult Ixodes scapularis and Dermacentor variabilis ticks. Essential oils were extracted by hydrodistillation and analyzed by gas chromatography-mass spectrometry for qualitative chemical characterization. Eucalyptol (17.9%) and β-caryophyllene (35.3%) were identified as the main components, followed by terpinene-4-ol (5.1%) and γ-terpinene (4.0%). Sweet fern essential oils exerted significant repellent activity towards I. scapularis nymphs, and the response was dose- and time-dependent. In a four-way olfactometer, I. scapularis and D. variabilis adult ticks were offered to choose between a novel tick-attractant mixture and an attractant mixed with the sweet fern essential oil at 1.25% v/v to test the ability of the oil to reduce tick attraction. Approximately 60% (p < 0.01) of ticks selected the attractant mixture; however, when the attractant mixture was offered with the essential oils, the selection of the attractant mixture significantly decreased (2.2-16/7%), indicating that ticks were repelled. Sweet fern essential oils exhibit promising repellent properties against Ixodes ticks and the potential for reducing disease transmission.

Tetranychus merganser and Oligonychus punicae are two pest mites that cause severe damage and economic losses in various crops in Mexico. Currently, the control of each pest primarily depends on the use of agrochemicals. However, these compounds harm the environment and the health of humans and mammals. Therefore, using biological predators to control populations of these mite species is an alternative to minimize the impact of these chemicals. Phytoseiulus persimilis is a specialist phytoseiid mite that feeds exclusively on Tetranychus species. Neoseiulus californicus is a generalist phytoseiid mite that feeds on different species of arthropods and pollen. However, P. persimilis and N. californicus have not been evaluated on T. merganser. The aim of this study was to evaluate the preference, predatory capacity and functional response of a single adult female and a 1:1 combination of both predators on the eggs and adult females of T. merganser and O. punicae. The results revealed that adult females of P. persimilis and N. californicus fed on the eggs and females of both T. merganser and O. punicae. P. persimilis exhibited higher levels of predation on T. merganser eggs and adult females, while N. californicus consumed more O. punicae eggs and adult females. Some differences in handling time (Th) and attack rate (a) were observed between and within phytoseiid species, but the functional response was consistently Type II. The differences in predatory capacity, Th, a, and preference were likely due to the varying lifestyles of the predators, predator size, the size of the prey offered (egg or adult female), and the species of prey provided.

The predatory mites, Neoseiulus longispinosus (Evans), remain one of the most frequently recorded indigenous biological control agent of Tetranychus urticae in India. Understanding the influence of acaricides on predatory mites is essential for the success of a pest management. In this study, we evaluated the effects of sublethal concentrations (LC₁₀ and LC₃₀) of cyenopyrafen on Neoseiulus longispinosus in F₁ generation by leaf dip bioassay method under laboratory conditions using age-stage, two-sex life table analysis. The egg, larval, protonymph, and deutonymph stages were notably prolonged for both sexes with increasing cyenopyrafen concentrations. However, the overall lifespan was significantly reduced at LC₁₀ and LC₃₀ compared to control. The shortest oviposition period was recorded at LC₃₀ (7.53 ± 0.12 days), with the lowest fecundity as females produced only 25.34 ± 0.23 eggs per female, along with the lowest egg hatchability. The marked reduction in male survival and female proportion suggests a potential disruption of reproductive dynamics in the population. The intrinsic rate of increase (r) and finite rate of increase (λ) were significantly lower at LC₃₀ and also mean generation time was significantly shorter at LC₃₀. Survival analysis showed that female survival rates were 77% at LC₁₀ and 62% at LC₃₀, whereas male survival rates were lower, at 25% and 17%, respectively. These findings indicate that sublethal exposure to cyenopyrafen may compromise the population growth potential of N. longispinosus, potentially limiting its role in suppressing T. urticae populations under field conditions.

The clinical significance of house dust mites (HDMs) as sources of allergens for medical diagnostics, allergen-specific immunotherapy, and allergology research is dependent on accurate morphological and molecular data analysis for species identification and characterization. Here, we report the species identification and allergenicity of a tropical HDM, Suidasia pontifica (Sp), via morphological-molecular characterization tandem and IgE ELISA, respectively. Electron microscopy of monocultures of HDM samples collected from Laguna, Philippines, revealed different traits related to chaetotaxy, cuticle pattern, and body anatomy. Genus-specific characters such as the length of the scapular setae, cuticle patterns, vertical setae, ω1 setae, along with species-specific traits such as short dorsal setae, long h3 setae, average c1 to c1 verrucae count, presence of sclerotized bursa copulatrix (female), and c3 setae size, suggest that the sample identity is Sp. In addition, PCR amplification from the HDM monoculture genomic DNA and bidirectional sequencing of the 18S and COI gene markers were performed. Sequences were subjected to sequence assembly, consensus acquisition, sequence alignment, and phylogenetic inference. The COI gene showed an exact match and phylogenetic attachment of the sample assembly to Sp, confirming the species-level identification, corroborated with morphological data. Furthermore, 18S gene character analysis was able to prove phylogenetic demarcation of the Sp 18S gene from the sister species S. nesbitti and other allergenic sarcoptiform species. Our molecular phylogenetic analysis, which is strongly supported by electron microscopy data, indicates the identity of our monocultures as Sp. Interestingly, the Sp allergenicity profile of allergic patients and controls (n = 200) suggests 47% IgE-binding reactivity, confirming its allergenicity and clinical importance among atopic patients. This study emphasizes the resolving power of the morphological-molecular phylogenetic approach and IgE-reactivity to objectively verify Sp species identity and allergenicity for downstream immunological studies.

Hyperparasitism in ticks, particularly in nymphs of the order Ixodidae, is a rare phenomenon. In our laboratory tick colony, female rabbits are used as a blood source for the ticks, housing them under controlled conditions. Feeding Dermacentor marginatus nymphs monitoring was performed daily, and engorged and detached ticks were collected and stored in desiccators at constantly 24 ± 2 °C and 85-90% relative humidity (16 h light/8 hours dark). Nymphs suspected of conspecific hyperparasitism were preserved in ethanol for analysis and imaging. This study presents the first documented case of hyperparasitism in D. marginatus and contributes to the limited literature on hyperparasitism in Ixodidae nymphs. While such cases are observed in controlled tick colonies, their occurrence in the wild, especially in Ixodidae, is extremely rare compared to Argasidae ticks. Furthermore, the frequency of this phenomenon in the wild and its possible eco-epidemiological significance remain poorly understood.

Understanding the interactions among hosts, vectors, and pathogens is essential for elucidating the ecology of tick-borne diseases. However, studies on tick fauna and pathogenic infections in large mammals in Hokkaido, Japan remain limited. We examined the spatial and temporal (region and season) and host factors (sex and age) affecting pathogen prevalence and tick infestation in sika deer (Cervus nippon yesoensis) and brown bears (Ursus arctos yesoensis) in Hokkaido. We selected Anaplasma and Hepatozoon, two prevalent pathogens in sika deer and brown bears, respectively, to analyze host-vector-pathogen relationships. Between 2021 and 2024, we tested samples from 223 deer and 437 bears for these pathogens and examined tick infestation patterns in 157 deer and 255 bears across four regions. Anaplasma infection prevalence was high in deer from South and East Hokkaido but low in those from North Hokkaido. Hepatozoon infection in bears was high in South and Central Hokkaido, and low in the East and North. Generalized linear mixed models (GLMMs) indicated that Anaplasma prevalence was determined by regional factors, whereas Hepatozoon infection was influenced by region and host age, with adults showing lower infection rates. Six tick species were identified: Ixodes ovatus, Ixodes persulcatus, Haemaphysalis japonica, Haemaphysalis megaspinosa, Haemaphysalis flava, and Haemaphysalis longicornis. The GLMMs revealed that I. ovatus was more prevalent on male deer than females. Conversely, I. persulcatus nymphs were less prevalent male bears than females. Older hosts showed higher levels of infestation across multiple tick species. These findings reveal the complex interplay shaping tick-borne disease ecology in wildlife.