Experimental and Applied Acarology最新文献

Tetranychus urticae Koch (Acari: Tetranychidae) is a widespread pest that causes significant crop losses. Although acaricides are commonly used for its control, the development of resistance often leads to control failures under field conditions. Therefore, there is a constant need for new compounds with novel modes of action. Novel neurotoxic insecticides targeting γ-aminobutyric acid (GABA) receptors, such as isoxazolines and meta-diamides, represent one of the most recent classes of insecticides. However, their toxicity to T. urticae, other tetranychid mites, and predatory mites remains poorly understood. The isoxazoline insecticides fluralaner and isocycloseram showed very high toxicity to all T. urticae populations, with LC₅₀ values ranging from 0.53 to 2.64 mg a.i./L and 0.04 to 0.26 mg a.i./L, respectively. Isocycloseram also caused 100% mortality in two other phytophagous mite species, Eutetranychus orientalis and Bryobia rubrioculus, at field application rates (30 mg a.i./L). In contrast, the meta-diamide broflanilide exhibited no toxicity against any of the tested phytophagous mites at the recommended field rate (20 mg a.i./L) and even at very high concentrations (5000 mg a.i./L), the mortality rate remained below 65% in all T. urticae populations except one. On the other hand, both isocycloseram and broflanilide, at their field rates, exhibited strong side effects ‒causing 100% mortality‒ on three predatory mite species: Phytoseiulus persimilis, Neoseiulus californicus, and Amblyseius swirskii. These findings highlight the potential of novel insecticides for mite control, while also emphasizing the importance of evaluating their non-target effects to support the development of sustainable pest management strategies.

European spruce bark beetle Ips typographus (Linnaeus 1758) (Scolytinae) is considered the most destructive and aggressive pest of Norway spruce in Europe. Recently, Ips duplicatus (Sahlberg 1836) (Scolytinae), another species of bark beetle, that also affects Picea trees, has expanded its range westwards in Europe. In spruce stands, bark beetle populations are closely associated with various organisms such as fungi, nematodes, and mites. While phoretic mites and their relationship with I. typographus have been extensively studied in Europe, only single study has focused on the populations of phoretic mites associated with I. duplicatus. The aim of this study is to analyze and document the communities of phoretic mites and their complex relationships with these two bark beetles species. The research was conducted in a stand located at the lower limit of spruce, where the two pest species have developed outbreaks together. Over 50,000 beetles were collected using wing-type pheromone traps, of which 4,348 were analyzed for the determination of phoretic mites (2,413 I. typographus; 1,935 I. duplicatus). In total, nine species of phoretic mites were identified, of which only six were found on Ips duplicatus. Among the nine species, Dendrolaelaps disetus Hirschmann, 1960 (Digamasellidae), Elattoma sp. (Pygmephoridae), and Paraleius leontonychus Berlese, 1910 (Oribatulidae) are reported for the first time in Romania. The results showed that although Ips typographus beetles carried significantly more phoretic mites than Ips duplicatus throughout the entire flight period, both species exhibited similar peaks in phoresy rate. ONE-WAY PERMANOVA test revealed significant differences between the two phoretic mite communities, differences also highlighted by diversity indices. These differences are most likely due to the presence of certain mite species only on I. typographus beetles, as well as differences between the populations of common species. The phoretic attachment location on host beetles varied across mite and host beetle species.

Evaluating the repellency of essential oils against Tetranychus urticae requires robust methodologies to detect time-dependent changes in their efficacy, due to differential efficacy, volatility, and sustained effectiveness. This study introduces the Pole-dance bioassay, a novel no-choice method optimized for high-throughput screening of time-dependent repellency, demonstrated through tests on twenty botanical volatiles against T. urticae. Four statistical models, probit, two-parameter Hill, four-parameter Hill, and Gaussian Process (GP) regression, were compared for analyzing time-response landing data, employing both experimental results and scenario-based synthetic datasets reflecting diverse curve shapes. GP regression often provided superior model fits, especially for biphasic or incomplete landing trajectories. While repellency rankings based on median effective time (ET₅₀) and area under the curve (AUC) were highly correlated within respective models, the choice of model significantly influenced parameter estimates. AUC proved essential for quantifying activity for highly potent compounds where ET₅₀ was inestimable (e.g., t-cinnamaldehyde, 1,8-cineole, (-)-terpinen-4-ol, thymol) and offered complementary insights into repellent effects. The Pole-dance bioassay combined with GP modeling establishes an optimized framework for statistically rigorous in vivo high-throughput screening against T. urticae.

Ecological interactions among organisms play a crucial role in shaping the dynamics of agricultural ecosystems, contributing to equilibrium and functional biodiversity within agroecosystems. In this study, we hypothesized that the presence of T. urticae detrimentally affect the population growth of T. ludeni on the host plant. The experimental design involved analyzing a multifaceted ecological dynamic related to four biological attributes: oviposition, olfactory cues, web effects, and mite interaction. Data were analyzed using Generalized Linear Mixed Model (GLMM). Our results showed that T. urticae does not significantly influence the oviposition rate of T. ludeni. However, T. ludeni prefers its conspecifics over heterospecifics, avoiding the presence of the web produced by T. urticae. Additionally, our findings indicate that T. ludeni has a low population growth in plants with T. urticae, whereas T. urticae is favored by the presence of T. ludeni. Since both spider mite species may damage crop production by piercing plant cells with their mouthparts, our results suggest that their interaction may have broader implications for herbivorous mite ecology in agroecosystems, particularly because the population of T. urticae seems to be favored by interacting with T. ludeni. Therefore, these findings are significant for pest control strategies, as the presence of both spider mite species in the same agricultural ecosystem may result in one outnumbering the other instead of self-regulating each other.

Equine piroplasmosis (EP) is a worldwide infection of Equides caused mainly by Theileria equi and Babesia caballi. Recently, these agents have been found in horses in the Republic of Altai. To identify probable vectors for EP agents in Western Siberia, 443 adult questing Dermacentor spp. (199 D. silvarum, 236 D. nuttalli, and 8 D. marginatus) were collected from vegetation in four districts of the Republic of Altai and examined for the presence of Piroplasmida DNA. Three Piroplasmida species were identified. Babesia caballi was found in ten (2.3%) Dermacentor spp., including eight D. silvarum and two D. nuttalli, indicating that these species are probable vectors of B. caballi in Siberia. The determined 18 S rRNA gene sequences of B. caballi from ticks were identical to those previously found in equine blood from the same region, which demonstrated their involvement in common transmission cycles. Another agent of EP, T. equi, was found in only one D. silvarum, indicating that in studied region Dermacentor spp. hardly can efficiently transmit T. equi transstadially. In addition to EP pathogents, the agent of bovine mild piroplasmosis, Babesia occultans, was identified in one D. marginatus; this is the first detection of this agent in Russia.

Terrestrial parasitengone mites (Prostigmata: Parasitengona) are known for their complex life cycles, with active forms confined to larvae, deutonymphs, and adults, and quiescent proto- and tritonymphal stages. Knowledge of the host range of parasitic larvae of most species is still limited, but it is likely that host choice and suitability may influence intraspecific variation of subsequent developmental instars. In this study we assessed the variation of morphometric traits in unfed deutonymphs of Allothrombium fuliginosum which developed from larvae that had parasitized four different aphid hosts: Acyrthosiphon pisum, Aphis sambuci, Macrosiphum rosae and Hyadaphis sp. Analysis of 48 morphometric traits in 80 deutonymphs revealed significant differences between host groups in 19 traits, with M. rosae contributing the most to observed variability. Principal component analysis showed some distinct clustering of deutonymphs according to the host species parasitized by larvae. The smaller, with respect to basic body measurements, deutonymphs developed from larvae that parasitized M. rosae, despite the overall larger body size of this host. Thus, factors other than host size influence the morphology of mites. The findings enhance our understanding of host-parasite interactions and highlight the need for further insight into sources of intraspecific variability within terrestrial Parasitengona.

Ticks transmit various diseases to humans and animals, posing a significant global threat to public health. The primary method currently employed to control tick infestations is the use of chemical acaricides. However, improper use leads to environmental contamination, residue in meat and milk, and the development of acaricide-resistant ticks. Therefore, alternative tick control methods that are safe for humans, animals, and the environment and that do not induce resistance are urgently needed. Diatomaceous earth (DE), a naturally occurring physical insecticide, has been proven to effectively kill various arthropods without producing resistance or toxic side effects. In the present study, the acaricidal effects of DE on larval, nymphal, and adult stages of Haemaphysalis longicornis ticks were evaluated using sprinkling and immersion methods. In larvae, mortality was first observed 20 min after sprinkling, with a 100% mortality rate by 200 min. Immersion treatment of nymphs with DE resulted in initial mortality observed after 120 min, and the mortality rate reached 100% after 12 h. The initial mortality rate for adult male ticks was 5% after 8 h of treatment, and 5% for adult female ticks after 6 h treatment. By 24 h, the mortality rates for both adult male and female ticks had reached 100%. These findings demonstrate that DE has acaricidal effects on the larval, nymphal, and adult stages of H. longicornis under laboratory conditions. Our study provides a foundation for future field trials to explore DE as a safe and effective alternative to chemical acaricides in tick control methods.

Phytotelmata provide favorable habitats for invertebrates, such as insects and mites. However, previous acarofauna studies on phytotelmata have primarily focused on tree holes, pitcher plants, and bromeliads, leaving other types, such as the leaf axils of aroids, underexplored. Therefore, the present study aimed to determine the composition of the acarofauna in the leaf axils of two Araceae species, Xanthosoma daguense Engl. and Xanthosoma sagittifolium (L.) Schott, as well as establish the aquatic and subaquatic aroid-mite network. For this, we collected mites from the phytotelmata of both species at two sites in the Colombian Central Mountain range. We found 16 morphospecies of mites belonging to the Gamasina, Uropodina, Sejida, Astigmatina, and other Oribatida groups associated with the phytotelmata of aroids. The most common genera identified were Histiostoma sp. and Hormosianoetus sp. (Histiostomatidae, Astigmatina). We reported for the first time the occurrence of Blattisocius dentriticus (Blattisociidae), Cheiroseius mesae (Blattisociidae), Galumna sp., Lucoppia sp., Malaconothrus sp., Oribotritia sp., and Uropodella sp. in phytotelmata, as well as B. dentriticus, Asca sp., Hormosianoetus sp., Lucoppia sp., Malaconothrus sp., and Phthicarus sp. in Colombia. The network exhibited high specialization and modularity; we identified three aroid-mite groups related to the Araceae species by sites. These results suggested that variations in the environmental conditions in the leaf axil and site scales affect the mite community. Thus, these results extend the understanding of phytotelma as habitats for mites, thereby contributing to the knowledge of their role in conserving these taxonomic groups.

Leaf structures influence the community structure of small arthropods on the leaf surface. For example, several taxa of mites, primarily fungivorous and carnivorous, use domatia as refuges, leading to direct and indirect interactions among predators, prey and plants. However, the impact of insect-induced leaf deformities (galls and leaf shelters) on the mite community remains poorly understood. In this study, we focused on a population of Eotetranychus asiaticus (Acari: Tetranychidae) colonising the galls formed by psyllid larvae (Trioza cinnamomi, Hemiptera: Triozidae) on the leaves of Cinnamomum yabunikkei (Lauraceae). We tested the hypothesis that inhabiting galls benefits E. asiaticus by reducing egg predation. In the field, almost all E. asiaticus individuals were found inside galls (96.7%). This spider mite inhabited 3.4% of the observed galls and reproduced within them, whereas leaves without galls hosted few mites. Predatory mites and Feltiella larvae used galls near those occupied by spider mites, indicating high predation pressure on the leaf surface. Laboratory experiments revealed that the proportion of eggs predated by Neoseiulus womersleyi (Phytoseiidae) females was lower on leaves with galls than on leaves without, suggesting that gall use provides an antipredatory advantage. In conclusion, psyllids indirectly assist the coexistence of E. asiaticus with predators by creating defensive microhabitats.

In practical agricultural systems, multiple pest species often coexist, posing a significant challenge for pest control. Polyphagous predatory mites, especially Phytoseiidae, play a dominant role in biological control, owing to their ability to suppress multiple pests. Currently, there is a lack of information on the effect of temperature shifts on prey preference of polyphagous predatory mites. In this study, we examined the prey consumption and prey preference of Amblyseius andersoni (Chant) on two important agricultural pests, the two-spotted spider mite (Tetranychus urticae Koch) and the western flower thrips (Frankliniella occidentalis Pergande), at five different temperatures (15, 20, 25, 30, and 35 °C). The preference for T. urticae larvae weakened with increasing temperature; the maximum at 15 °C (Manly's preference index β = 0.8952) and the minimum at 30 °C (β = 0.6584). The prey consumption of T. urticae was the lowest at 35 °C (5.93 per day) and the highest at 25 °C (9.23 per day); the highest and the lowest prey consumption of F. occidentalis were observed at 30 °C (1.73 per day) and 15 °C (0.33 per day), respectively. Moreover, we found that the prey preference of A. andersoni on the two prey may be related to the antipredator behavior of F. occidentalis, but not to the relative ratios of prey. Our study highlights the importance of temperature conditions when using generalist natural enemies to control multiple pests.