The two-spotted spider mite, Tetranychus urticae, a polyphagous pest, can feed on many plants. Farmers generally prefer chemical control to mitigate T. urticae, the arthropod species in which pesticide resistance is most common. In this study, resistance development to spiromesifen + abamectin mixture formulation, mixture formulation with active ingredients spiromesifen and abamectin, and cross resistance rates to spirodiclofen, milbemectin and spirodiclofen + abamectin were determined in the T. urticae strain selected for resistance to the spiromesifen + abamectin mixture. Spiromesifen+abamectin with LC₅₀ and LC₉₀ values for the susceptible T. urticae (GSS) strain were 0.53 mg a.i./l and 2.66 mg a.i./l distilled water, respectively. In the strain selected and named IR, the LC₅₀ value increased to 640.50 mg a.i./l distilled water and the resistance ratio increased 1199-fold. The IR strain developed 1759 fold resistance to abamectin and 25 8874-fold resistance to spiromesifen, which is one of the active ingredients of the mixture. In cross-resistance studies, LC₅₀ resistance ratios for spirodiclofen, milbemectin and spirodiclofen + abamectin were increased by 224-, 40-, and 1069-fold, respectively. The use of pesticide mixtures used to delay or prevent the development of resistance of pest species should be reconsidered.

Amblyseius largoensis (Muma) is a predatory mite that occurs naturally in plants infested with the pest mite, Raoiella indica Hirst, and has been reported as a potential predator for the control of R. indica. Since A. largoensis is not available commercially, coconut producers have used products registered for another coconut pest mite (Aceria guerreronis Keifer) against R. indica with the aim of minimizing economic losses caused by this pest. However, it is possible to explore the natural contribution of this predator using control strategies that allow its conservation. Thus, in the present study, the effects of pesticides registered for the coconut crop (azadirachtin, abamectin, chlorfenapyr, and fenpyroximate) on the survival, consumption, oviposition, and feed conversion efficiency of A. largoensis were evaluated to determine the compatibility between acaricides and the predatory mite. The results showed that the acaricides abamectin, fenpyroximate, and chlorfenapyr reduced the survival of A. largoensis females. Abamectin was the only acaricide that reduced predation, oviposition, and the feed conversion efficiency of A. largoensis. Azadirachtin did not affect any of the assessed parameters. These results suggest a potential compatibility A. largoensis with the pesticides azadirachtin, fenpyroximate, and chlorfenapyr.

Predation stress can induce phenotypic plasticity in the life history traits of prey, especially early-life traits such as developmental time. Most previous transgenerational studies have focused on two generations and showed that the transgenerational effects induced by predation stress were negative on offspring fitness. Changes in sex ratio can also be an expression of transgenerational effects, influenced by many environmental and parental conditions. In this study, by using the prey–predator system of Tyrophagus putrescentiae and Neoseiulus cucumeris, we tested whether immature survival, developmental time, and sex ratio of offspring could be influenced by transgenerational exposure to predation stress. We tested the transgenerational effects of predation pressure on early life traits of the offspring over three generations. The results showed that parental effects interacting with grandparental effects increased the immature survival rates of F3 offspring, and that parental effects combined with offspring effects shortened the development duration of F2 offspring. However, neither grandparental exposure to predation stress nor parental experience had any influence on the sex ratio of offspring over three generations.

A new species of Xenotarsonemus Beer, 1954 (Acari: Heterostigmatina: Tarsonemidae), Xenotarsonemus krishnai sp. nov. Mondal & Ganguly is described based on the specimens collected from the fern species Arthromeris wallichiana naturally grown in the Himalayan forests of Darjeeling district in the state of West Bengal, India. This registers the first species of Xenotarsonemus from India and the eighth species from the Asian continent. A note on the ventral coxisternal fissures of Xenotarsonemus species and keys to differentiate the Asian species are provided.

During investigations of oribatid mites from Shiraz, Fars Province in southern Iran, a new species of Epilohmannia (Acari: Oribatida: Epilohmanniidae) was found from soils under oak and willow trees. Epilohmannia rotundistriata sp. nov. is distinguishable from other species by the broadly rounded rostrum with longitudinal striations; bothridial seta with long, finely barbed stalk and strongly swollen, fusiform head bearing many distinct barbs; anterior margin of notogaster concave; notogastral setae c₁ and c₂ situated transversely nearly at the same level; anal and adanal setae thickened, barbed, ad₃ distinctly shorter than the other two adanal setae; all apodemes well developed; tarsi of leg IV with three thick spine-like setae (a″, s and tc′). A key for identifying known species of Epilohmannia in Iran, is provided.

A new mite genus, Schwendingeriella gen. nov. (Mesostigmata: Uropodina: Urodinychidae), with Schwendingeriella tapanensis sp. nov. as type species, is described on the basis of 12 females and nine males collected in soil samples from Thailand. The new genus has a unique character combination which has not been previously observed within the family Urodinychidae: numerous needle-like prolongations on the anterior margin of the female genital shield; the presence of a pygidial shield; an unusual web-like structure on the dorsal shield; the wide and marginally pilose internal malae on the gnathosoma, and the palp apothele with four branches.

The genus Thyreophagus is distributed worldwide, containing species occurring in stored food, house dust, bark, subcortical habitats, scale insect associations, and nests of wasps and bees. As species of this genus prefer concealed habitats, the actual species diversity is currently underappreciated. In addition, some described taxa are poorly known and their species boundaries are not entirely clear. Only a few species are known from both adult and deutonymphal stages. Using high-resolution light microscope and scanning electron microscopy, we describe a new partenogenetic species, Thyreophagus calusorum sp. n. from Florida (USA) based on adult stage (female) and heteromorphic deutonymph. This species was reared in the lab and its morphological variation was also studied. We did not find any substantial variation in the shape of the female spermatheca, but in the heteromorphic deutonymph, we did find extensive variation in the shape of tibial setae hT I (a taxonomically important character). Furthermore, we summarized taxonomic data and compiled an annotated checklist of species of Thyreophagus, with 35 species-level taxa. We clarified the following nomenclatorial questions: type species designation in Monieziella Berlese, 1897 was done by A. Berlese in G. Leonardi 1900 (Tyroglyphus entomophagus Laboulbène) not by A. Jacot (1936) as it was though previously; Monieziella mali Berlese, 1897 is an unjustified emendation and junior objective synonym of the name Acarus malus Shimer, 1868, currently Hemisacoptes malus (Shimer, 1868). Three subspecies of Thyreophagus were elevated to the species status due to their distinct morphology: Thyreophagus italicus Vacante, 1989, stat. nov. (=Thyreophagus entomophagus italicus Vacante, 1989); Thyreophagus mauritianus (Fain, 1982), stat. nov. (=Michaelopus gallegoi mauritianus Fain, 1982), and Thyreophagus ponticus Kadzhaya, 1973, stat. nov. (=Thyreophagus entomophagus ponticus Kadzhaya, 1973).

Neoseiulus californicus (Acari: Phytoseiidae) is a commercialized predatory mite that is used as a biological control agent against Tetranychus urticae (Acari: Tetranychidae). Long-term feeding on alternative prey could impact the predatory capacity of N. californicus. Although most studies on the learning behavior of predatory mites have indicated that learning behavior could help them adapt from feeding on thrips (alternative prey) to spider mites (target prey), the role of learning behavior in adapting from feeding on astigmatid mites to spider mites has not been studied thus far. Therefore, this study explored the learning behavior of N. californicus in adapting from feeding on alternative prey (Oulenziella bakeri [Acari: Winterschmidtiidae]) to target mites (T. urticae). The attack latencies, prey preferences, and functional responses of female N. californicus were compared between two strains, N. californicus fed on T. urticae (TU) or O. bakeri (OB), and a learning behavior (LB) treatment. The results showed that the attack latency of OB strain was significantly longer than those of TU strain and LB treatment; OB strain did not show obvious prey preference between protonymphs of T. urticae and O. bakeri; and the functional response among TU, OB, and LB-treated strains were not significantly different. Our results demonstrated that long-term feeding on alternative prey had little effect on the predatory ability of N. californicus. To a certain extent, learning behavior can help N. californicus shift from feeding on alternative prey to target prey. Therefore, in the long run, it is reasonable to rear N. californicus on O. bakeri.

Larvae of the chigger mite Leptotrombidium album (Kamo, Kawashima & Nishimura, 1957) (Acariformes, Trombiculidae) are found in Kunashir island and recognized as parasites of bats Barbastella pacifica (Kruskop, Kawai & Tiunov, 2019) for the first time. Larvae were measured and photographed using SEM and DIC approaches. A stylostome is described in bats for the first time by histological with additional CLSM, DIC and polarized light methods. The stylostome belongs to the mesenchymal type and penetrates deep into the host dermis perpendicular to the skin surface. The stylostome is a straight relatively wide (80 µm) tube and may reach 250 µm long in the maximum development. The axial stylostome canal varies from 7.5 to 20 µm wide and distally is opened to the subjacent host tissue. A particular eosinophil cone of a gel consistency to which the larval cheliceral blades are tightly cemented represents the proximal stylostome portion. The main stylostome portion usually remains unstained and also shows a gel-like consistency. The distal stylostome portion—supposedly a fresh saliva portion—is typically stained by Azur in blue and seems to be a transitional condition between sol to gel. No birefringent components are found in the stylostome substance. The stylostome may immediately contact host tissues or may be surrounded by a mixed eosinophil substance composed of destroyed inflammatory cells. If present, this substance is tightly associated with the stylostome walls and may be considered as an analog of scab but distributed not on the surface but inside the skin. The stylostome formation is accompanied by a generalized inflammatory reaction with the predominance of neutrophil leukocytes. The activity of basophils, lymphocytes, macrophages and mast cells is relatively weak. A particular tissue sinus filled with inflammatory cells, an analog of the feeding cavity, situates underneath the stylostome. The disclosed stylostome organization confirms its species-specific character.

Allochaetophora urmiana sp. nov., a new species of the family Allochaetophoridae, is described and illustrated based on all instar stages (female, male, larva, protonymph and deutonymph). This is the second report of the family Allochaetophoridae for Iran and Asia, fourth for the world and first description of the protonymph stage. All specimens were collected from grassland in northwestern Iran. We also provide a key (based on the adult female and deutonymph) and a table of diagnostic characters for identification of all known species.

The Australian predatory mite, Transeius montdorensis, is an important natural enemy of Bemisia tabaci, thrips, spider mites, and many other pests, and thus might be important for their biological control. Therefore, we aimed to determine whether temperature influences the development of T. montdorensis when preying on B. tabaci. The survival rate and development time of T. montdorensis under different temperature conditions were compared when fed with 1 st to 3 rd instar nymphs of B. tabaci as its prey. We analyzed the association between temperature and the growth rate of T. montdorensis. The results show that the developmental period of T. montdorensis was significantly affected by temperature. The development period of T. montdorensis was the longest (23.23 days) at 15 °C and the shortest (4.62 days) at 35 °C. From 15–35 °C, the developmental period of T. montdorensis correlated negatively with temperature. In addition, increasing temperature (15–30 °C) promoted T. montdorensis survival. The survival rate was 64% at 15 °C and was highest (92%) at 30 °C; however, survival was reduced as the temperature increased from 30 to 35 °C; with only 66% survival at 35 °C. The logistic equation is better at correlating temperature and development than the linear one. The different developmental stages of T. Montdorensis varied in the temperature thresholds of development and effective thermal summation. The temperature threshold of development was 10.45 °C at the immature stage, which had an effective thermal summation of 99.87 d ·°C.

A new species of the genus Dolichotetranychus Sayed, 1938 (Acari: Trombidiformes: Tenuipalpidae), Dolichotetranychus babolicus sp. nov. is described from Dracaena trifasciata (Asparagaceae) grown in greenhouses in northern Iran (Mazandaran province). All active life stages are described and illustrated and anomalous features noted. Photographs of its colonies and damage symptoms are presented. This is the first report of the family Tenuipalpidae on this plant genus. Additionally, some data of D. iranicus Khadem & Asadi in Safdarkhani et al. 2016 is corrected.

Three spider mite species, Eotetranychus sexmaculatus, Eutetranychus orientalis and Oligonychus biharensis, are widely distributed in China, infesting rubber trees. They cause various damages in different areas with different landforms, climates and rubber-growing varieties. The difference in habitat of the spider mites may result in genetic differentiation. It supposed be one of the main reasons for their various damage levels in different geographic regions. To examine whether the population genetic differentiation exist between E. sexmaculatus, E. orientalis and O. biharensis, we collected samples of three mite species from ten locations in China and one in Vietnam. Mitochondrial COI sequences of collected samples were analyzed. The results showed that the value of genetic differentiation among populations of the three mites was: E. orientalis > O. biharensis > E. sexmaculatus. There were 16 haplotypes in eight populations of E. orientalis and relatively large genetic distances between haplotypes. E. orientalis had the maximum Fst and Gst values, 0.792 and 0.434, respectively. There was no significant differentiation of E. sexmaculatus among different geographic regions after excluding the Ruili population. Both O. biharensis and E. orientalis were clustered into three large branches in the phylogenetic tree. A single peak appeared in the total population mismatch distribution curve and a star-like haplotype network of E. sexmaculatus suggests a history of population expansion. Three rubber tree spider mites collected in Yunnan had the greatest genetic diversity with the maximum number of haplotypes. In contrast, the genetic diversity of these three spider mites collected in Hainan and Guangdong was relatively small, with few haplotypes. These results implied that genetic differentiation existed in these three spider mites. Specific property and geographic isolation might be the major factor triggering genetic differentiation of E. orientalis, E. sexmaculatus and O. biharensis.

A new species of phytoseiid mites, Neoseiulus neoagrestis sp. nov., was described based on all ontogenetic stages and extensive comparison with types/vouchers of closely related species and a thorough analysis of GenBank data. Mite specimens were collected in an area at the eastern coast of the Black Sea of Russia and cultured. Molecular barcoding revealed a close match (100–99.25%) with several unidentified COX1 sequences from Canada. Both Canadian and Russian mites reproduced sexually and had consistent morphology, including the presence of gd2 gland pores, indicating that they belong to a single species, N. neoagrestis sp. nov. The presence of gd2 gland pores distinguishes N. neoagrestis sp. nov. from a closely related, parthenogenetic species N. agrestis (Karg), which lacks gd2 gland pores. Despite having an arguably negligible morphological difference, these two species were clearly distinct by COX1 sequences (19.95–22.01% K2P distances). We studied the ontogeny of N. neoagrestis sp. nov. and provided comparison with related Neoseiulus species. Furthermore, our examination of types of N. agrestis, N. salish, and N. striatus indicated that the latter two species are potential junior synonyms of N. agrestis.

Adult female, male and all immature life stages of Cheylostigmaeus occultatus sp. nov. are described and illustrated from Sansa Gorge and Pülümür Valley in Turkey. The female of the family Stigmaeidae is ordinarily used for identification purposes, but, to the contrary, the identification of species in the genus Cheylostigmaeus is mainly and unusually dependent on the male's characters. However, the new species described in this paper has been identified from the female due to its distinctive characters: suranal shield is completely tucked under the body, suranal setae are slimmer and without hyaline sheath, subcapitulum is hyalinised distally, setae or₂ are thickened, curved and spinulate distally.

Two new species of the genus Flagellozetes (Oribatida, Galumnidae)—F. (Cosmogalumna) naredoi sp. nov. and F. (C.) sibuyanensis sp. nov.—are described from soil and leaf litter above decomposing log in Mount Guiting-guiting Natural Park on Sibuyan Island, Philippines. An identification key to the known species/subspecies of Flagellozetes is presented.

This article presents a species new to science called Phthiracarus paraferrugineus sp. nov., which was recorded in the nature reserve Cisy Staropolskie im. Leona Wyczółkowskiego in Wierzchlas. The authors also give information about new sites of occurrence and comments about the morphology of some species rarely found in Poland—Paratritia baloghi Moritz, 1966 (second record in Poland) and Euphthiracarus reticulatus (Berlese, 1913)—as well as several more common species (Phthiracarus bryobius Jacot, 1930, Phthiracarus clavatus Parry, 1979, Phthiracarus compressus Jacot, 1930, Phthiracarus longulus C.L. Koch, 1841, Phthiracarus nitens Nicolet, 1855). The article also contains a description of a previously unknown developmental stage—the tritonymph of Acrotritia duplicata (Grandjejan, 1953).

Phenotypic plasticity is a mechanism where different phenotypes are expressed from a genotype allowing individuals to survive variable environments. Diet-induced phenotypic plasticity was observed in the developmental time and size at maturity of the specialist predatory mite Phytoseiulus persimilis. As a preliminary study, we investigated variations in developmental time and size at maturity of P. persimilis under intermediate diet restriction of 10 and 20 spider mite (Tetranychus urticae) eggs using enclosed rearing cells. Analysis of covariance using consumption as a covariate showed no difference in the developmental time of P. persimilis between the different prey densities. Additionally, the size at maturity of P. persimilis given different prey densities was similar from the Wilcoxon rank sum test. However, when given 20 prey eggs, a relatively high variation was found in the consumption rate of both female and male P. persimilis. The findings of this study are essential for designing our later studies on the influence of diet restriction and lifespan of P. persimilis. This study also expands our understanding of the viability and adaptability of P. persimilis under food stress.

The development, survival, and reproduction of the predatory mite Euseius scutalis (Athias-Henriot) (Acari: Phytoseiidae) were studied under laboratory conditions (25 ±1 °C, 65 ± 5% RH, 16:8 (L: D) h) on strawberry spider mite, Tetranychus turkestani Ugarov and Nikolski (Acari: Tetranychidae), and four different pollen including date palm, cattail, golden shower tree and caper bush pollen. Our results showed that E. scutalis mites successfully developed into the adult stage and reproduced on natural prey and plant pollen tested. Diet type significantly affected the developmental time of immature stages of both females and males. Females reared on T. turkestani had a considerably shorter total developmental time than those raised on other diets. Date pollen and spider mites-fed females began laying eggs much earlier than other females. The lower number of laid eggs was recorded for the females raised on golden shower tree, followed by caper bush pollen. The net reproductive rate (R₀) of the predators fed golden shower tree was significantly lower than those provided cattail pollen and T. turkestani. Intrinsic and finite rates of increase (r and λ, respectively) were highest in the females fed T. turkestani (0.3300 ± 0.018 and 1.3910 ± 0.0247, respectively) followed by cattail pollen (0.2721 ± 0.0178 and 1.3126 ± 0.0233, respectively). Based on the current findings, it can be concluded that rearing of E. scutalis on the immatures of T. turkestani was considerably better than on other diets with higher values of egg production and population growth rate under laboratory conditions. Furthermore, cattail pollen followed by date palm pollen are suitable alternative diet sources for easy and cost-effective rearing of E. scutalis in the laboratory.