Experimental and Applied Acarology最新文献

Entomopathogenic fungi (EPF) is one of the most promising alternatives to regulate tick populations. However, these fungi may lose acaricidal effectiveness over time, due to the storage period and/or successive cultivation on artificial media. It is known that using arthropod pests as a substrate for EPF could potentially alter their acaricidal behavior over time, however, studies using ticks for this purpose are scarce. Hence, the aims of this research were: (1) to isolate strains of Metarhizium anisopliae from paddocks of cattle farms, (2) to evaluate the effect of engorged adult ticks of Rhipicephalus microplus as a substrate on the tickicide behavior of Metarhizium anisopliae strains, and (3) to determine the lethal time of each M. anisopliae strain to kill 50% (LT50) and 99% (LT99) of engorged ticks. First, the natural acaricidal effect of 10 strains of M. anisopliae sensu lato isolated from soils of cattle farms on R. microplus was evaluated. Second, the influence of substrate (R. microplus, Galleria mellonella and Sabouraud dextrose agar [SDA]) on the acaricidal activity and virulence index (lethal time) of each strain during four generations was evaluated. Strains MaV69, MaV60 and MaV67 showed more than 90% mortality at day 20 post-treatment. The use of engorged adult ticks as substrate increased the virulence of five M. anisopliae s.l. strains. Larvae of G. mellonella and SDA as substrate did not modify the acaricidal behavior of the 10 strains evaluated. Seven of ten EPF decreased their LT50 and three decreased their LT99 as an index of their virulence enhancement.

The Varroa destructor (hereafter referred to as Varroa) is a major pest of honeybees that is generally controlled using pyrethroid-based acaricides. However, resistance to these insecticides has become a growing problem, driven by the acquisition of knockdown resistance (kdr) mutations in the mite's voltage-gated sodium channel (vgsc) gene. Resistance mutations in the vgsc gene, such as the L925V mutation, can confer resistance to pyrethroids like flumethrin and tau-fluvalinate. Monitoring genotypic resistance through molecular mutation screening is crucial for tracking and mitigating resistance spread. In this study, the frequency of resistance mutations in the vgsc was examined using a Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) approach in Varroa populations sampled throughout the Mediterranean, Aegean, and Black Sea regions of Türkiye. Considering all the samples analyzed, the results demonstrated a mean resistance allele frequency of 83.29%, indicating a relatively high frequency of resistant alleles. We observed 94.58%, 85.71%, and 69.58% resistant allele frequencies in populations sampled from the Mediterranean, Aegean, and Black Sea regions, respectively, in our study. The results of our investigation demonstrated substantial regional variations in the frequencies of resistant alleles among Varroa populations throughout Türkiye, with notably elevated resistance levels observed in the Mediterranean and Aegean regions. Due to the significant resistance mutation frequency differences between both provinces and regions, long-term monitoring of resistance alleles and the planning of regional control strategies are required for effective control of this pest.

Tick salivary proteins are crucial for efficient and successful tick feeding. Most of them are still uncharacterized, especially those involved in the formation of tick cement. Tick salivary protein PA107 is a putative cement protein, which is transcribed in salivary glands during the initial phase of tick feeding. It is a tick-unique protein, with homologs described in several tick genera. In this study, a detailed in silico analysis of its primary and tertiary structure was performed, along with the immunogenicity assessment for the PA107 protein from Ixodes ricinus species. The screening of the primary structure placed it to the glycine-rich protein family, revealing in parallel an overlapping 15mer at the C-terminus and borderline homology to non-tick proteins with antimicrobial activity. The analysis of tertiary structure revealed a high degree of intrinsic disorder for monomeric PA107, in contrast to highly ordered structures for different oligomeric states that might correlate with the putative role in the tick cement formation process. Regarding in silico PA107 immunogenicity inference, obtained results were inconclusive, which aligns with the in vitro findings showing definitely the lack of humoral response induction in experimentally infested rats and persons bitten by the I. ricinus ticks. The results represent new pieces of a huge puzzle depicting a complex tick-host relationship, but also identify PA107 as a possible compound of novel formulations to be used in biomedicine as bioadhesives, and as a target for new anti-tick strategies, by interfering with the cement cone formation and stability, i.e. tick attachment and feeding.

The balance between mating benefits and costs shapes reproductive strategies and life history traits across animal species. For biological control programs, understanding how mating rates influence life history traits is essential for optimising population management and enhancing predator efficacy. This study investigates the impact of mating opportunity availability, delayed mating, and male mating history (copulation frequency) on the lifespan (both sexes), female reproductive traits (duration of oviposition and of pre- and post-oviposition periods, and lifetime oviposition), and offspring quality (egg size and offspring survival) of the predatory mite Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae), an important biological control agent against spider mites. We examined three mating treatments-no mating, limited mating opportunity (24-h access), and continuous lifetime access-to assess their effects on lifespan (both sexes), female reproductive traits, and offspring quality. Further analyses examined the impact of delayed mating and male copulation history on female reproductive success and offspring traits. Our results showed a sexually differentiated response to repeated mating: females with continuous access to mates had similar lifespans in comparison with those mated for only 24 h, while males with continuous mating access exhibited significantly shorter lifespans. Both unlimited mating and delayed mating prolonged the female pre-oviposition period. However, neither varied mating opportunities, delayed mating, nor male copulation had any significant effect on other female reproductive traits or offspring quality. This suggests that repeated mating provides no reproductive advantage and imposes no observable costs on P. persimilis females.

Babesia species (Piroplasmida) are hemoparasites that infect erythrocytes of mammals and birds and are mainly transmitted by hard ticks (Acari: Ixodidae). These hemoparasites are known to be the second most common parasites infecting mammals, after trypanosomes, and some species may cause malaria-like disease in humans. Diagnosis and understanding of Babesia diversity increasingly rely on genetic data obtained through molecular techniques. Among hard ticks, several Ixodes species are known vectors of Babesia microti-like species in the Northern Hemisphere. Recently, Ixodes and Amblyomma ticks have been recorded parasitizing the Andean bear (Tremarctos ornatus) in Ecuador. Previous reports have suggested babesiosis in a fatal case of this threatened bear species in that country. This study aimed to detect Piroplasmida DNA in hard ticks collected from Andean bears at two sites in Ecuador. This species plays a critical role as an ecological engineer and a seed disperses, contributing significantly to the maintenance and health of Andean ecosystems. Twelve ticks screened with conventional PCR and Piroplasmida DNA was amplified from one Ixodes montoyanus tick collected from a free-living female Andean bear at Llanganates National Park. Two Babesia sequences were characterized: one for the 18 S ribosomal rRNA gene and another for the cytochrome c oxidase 1 gene. Phylogenetic analyses for both loci placed these sequences within the B. microti-like clade. This study reports a novel B. microti-like genotype identified in an I. montoyanus parasitizing a female Andean bear, contributing to the knowledge of the diversity of this group in South America. Given their conservation status, future epidemiological surveillance of Babesia and other tick-borne infectious agents in Andean bears is needed.

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is a major pest of various plants with a worldwide distribution. Extensive use of chemical pesticides has led to the development of resistance in this pest, making biological control agents a viable alternative for its management. The predatory mites, Neoseiulus californicus (McGregor) and Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) are the most important predators of the two-spotted spider mites. In this study, the toxicity of two acaricides chlorfenapyr and acequinocyl, on these predators was evaluated, and the walking behavior of predatory mites after exposure to residues of the pesticides was assessed using a video tracking system. Based on the results, the LC₅₀ values of both acaricides was estimated to be higher than their field concentration, and chlorfenapyr was found to be five-fold more toxic than acequinocyl. In the behavioral assay, both acaricides significantly affected the distance and speed of walking, resting time, and frequency of stops of both predatory mites. In the escape assay, both compounds had an irritable effect on both predatory mites, as the mites avoided areas contaminated with pesticide residues and their presence in the untreated area was significantly longer than in the treated area (P < 0.05). However, the study found no correlation between toxicity and irritability. According to the results of this study, N. californicus and P. persimilis possess the ability to detect the presence of pesticide residues in their environment and try to avoid them. Moreover, both compounds are at low risk to these mites, but acequinocyl is much safer and is a suitable option for use in integrated pest management.

Cyclamen mite (Phytonemus pallidus) causes injury to new growth of strawberry plants and is difficult to control because it is protected by folded leaves and plant crowns. Since cyclamen mite is easily transferred from strawberry nurseries to fruiting fields, dipping transplants in biopesticides may reduce initial populations. However, cyclamen mite numbers at 1 and 3 months-after-planting, and yield and cyclamen mite injury to fruit in the following season did not differ among transplants immersed for 30 s in Captiva® Prime, EcoTrol® EC, Landscape Oil, SuffOil-X® or Kopa Insecticidal Soap or the untreated control. Cyclamen mite is primarily controlled with foliar applications of acaricides, but there are few registered products. In greenhouse experiments, fenazaquin and pyridaben reduced cyclamen mite numbers by more than 90% in new leaves compared to the control, similar to that of the standard abamectin. New leaf injury ratings were reduced from 1 on average (scale of 0-3; 0 = no injury) pre-application to 0.25-0.5 for fenazaquin, pyridaben, and abamectin-treated plants compared to increasing to 2 for control plants 2 weeks after application. Spiromesifen and chlorfenapyr reduced cyclamen mite numbers in folded leaves in one greenhouse experiment. In the field, all acaricides reduced cyclamen mite numbers by 90-99% at 2- and 6-weeks post-application and by 75-90% at 10 months post-application. Abamectin and pyridaben resulted in 0.5-1.0% of strawberries with cyclamen mite damage compared to 3.0% for the control. All acaricides except chlorfenapyr improved strawberry yield and size. Overall, fenazaquin, pyridaben and spiromesifen should help diversify the chemical toolbox for cyclamen mite in field strawberry.

Agricultural management increases the seasonal dynamics of soil-dwelling organisms compared to natural habitats. Our knowledge is very poor about the relationship between seasonal changes of soil microorganisms and the microbivorous soil arthropods. To reveal these connections, we have to know more about the seasonal changes of soil-dwelling microarthropods in croplands. Actinedid mites are rarely the subject of synecological studies, however, this group regularly reaches the dominant part of mite assemblages in agro-ecosystems. In this study, we investigated the seasonal density changes of actinedid mites from two independent studies of agricultural fields. Soil samples were taken from maize and wheat fields for two years, and from newly established meadows for one year in summer and autumn in Hungary. Soil-dwelling mites were enumerated and identified at the suborder level and soil parameters were measured. Actinedid mites dominated most of our soil samples. The density of Endeostigmata was the highest in the summer and the density of Heterostigmata was the highest in the autumn within one year among different crop species, soil types, and years. Endeostigmatid mites had negative relationships with soil nitrogen parameters and positive with soil moisture. Heterostigmatid mites had various relationships with soil moisture. The ecology of actinedid mites is under-examined but their high number in agricultural fields may justify the fact that they should receive more attention. We assume that Actinedida, mainly Endeostigmata and Heterostigmata are worth to investigate in croplands as a starting point to reveal the connection between the seasonality of soil mites and soil microbiota.

Typhlodromus (Anthoseius) recki feeds on pest mites on tomato plants and its introduction into crops via companion plants, Mentha suaveolens and Phlomis fruticosa, has been recently investigated. This study aims at assessing the predator arrestment behavior, through lab choice tests to determine the effects of (i) prey (Aculops lycopersici and Tetranychus urticae) vs Typha angustifolia pollen deposited on companion plant or Solanum nigrum, (ii) T. urticae vs A. lycopersici on S. nigrum and (ii) M. suaveolens vs P. fruticosa using pollen as food source. The predator position, the number of eggs laid and the number of T. urticae eggs consumed were assessed during 4 days. The predator was more observed on leaf discs with A. lycopersici vs pollen when the pollen was deposited on S. nigrum and M. suaveolens, but was more found on leaf discs with pollen on P. fruticosa. It was equally found on leaf discs with T. urticae vs pollen for all the plants tested. No difference in predator arrestment behavior was noted between A. lycopersici and T. urticae, but a higher proportion was observed on leaf discs with A. lycopersici at the beginning of the experiment than at the end. Finally, the predator was more observed on leaf discs of P. fruticosa than of M. suaveolens. The highest fecundity was observed in systems with pollen and A. lycopersci + pollen, and the lowest with T. urticae + pollen; T. urticae consumption was not different with pollen or A. lycopersici. The predator less arrested on pollen vs A. lycopersici that provides a high fecundity; however, surprisingly it was more attracted to pollen vs a prey T. urticae, questioning the cues perceived by T. (A.) recki. The strong preference for P. fruticosa without prey vs S. nigrum with prey or M. suaveolens with pollen, suggests for the second time for Phytoseiidae, direct effects of plant (may be via odors) and questions the ecological advantages of such a behavior. For practical issues, M. suaveolens would be a better bank plant than P. fruticosa; an arrestment on patches of A. lycopersici within tomato plant is expected even if pollen is present and in case of T. urticae infestation a low dispersal to this prey will probably occur, questioning the interest to use T. (A.) recki in combination with other Phytoseiidae species, specialized in T. urticae predation, as Phytoseiulus persimilis.