Mite Density Research Articles

Quantitative identification and sensor sensitivity analysis in detection of odor volatile compounds emitted by scaly grain mites, Suidasia pontifica Oudemans.

In Thailand, the scaly grain mite, Suidasia pontifica Oudemans, impacts the feed industry by emitting a lemongrass-like odor in contaminated feed, reducing its palatability. This study focused on identifying volatile organic compounds (VOCs) associated with this odor in contaminated chicken feeds and ground maize, as well as individual mites using gas chromatography-mass spectrometry (GC-MS). We explored the relationship between VOC concentration and mite population size in chicken feed cultures, aiming to detect minimal mite presence through regression models. Additionally, we tested the sensitivity of nine electronic odor sensors in detecting these VOCs. Our results showed Z-citral and E-citral present in mite-contaminated ground maize, chicken feeds, but absent in uncontaminated samples. Mite populations in chicken feed followed a normal distribution, increasing rapidly, peaking, and then declining, a pattern mirrored in the concentrations of Z-citral and E-citral. Simple linear regression models confirmed a positive correlation between mite density and citral concentrations. Polynomial regression models indicated Z-citral is detectable at mite densities over 67 individuals per gram and E-citral over 3.89 individuals per gram. Odor sensors showed varying readings across different citral concentrations, uncontaminated, and mite-infested chicken feeds. Our study confirms that S. pontifica are responsible for the lemongrass-like odor in infested samples, due to Z-citral and E-citral. The citral concentrations increase with mite population growth and are detectable at low mite densities, suggesting their effectiveness as biomarkers for early mite infestation detection. Additionally, MQ series odor sensors detected these VOCs, indicating their potential for monitoring mite infestations in storage environments. This article is protected by copyright. All rights reserved.

Effect of Tetranychus urticae and Polyphagotarsonemus latus (Acari: Tetranychidae, Tarsonemidae) at different infestation levels and feeding durations on chlorophyll content of bean plants

The study investigated the effects of different initial infestation levels and feeding durations of Tetranychus urticae and Polyphagotarsonemus latus (Acari: Tetranychidae, Tarsonemidae) on the chlorophyll content of the pinto bean plants [Phaseolus vulgaris L. (Fabaceae)]. The experiment was carried out on 3 cm diameter leaf discs and potted plants. To determine the effects of mite feeding on the chlorophyll content of leaf disc, 0 (control), 5, 10, 15, 20, and 25 mated adult females (24-48 hours old) were separately placed on each disc. Chlorophyll measurements were made 5 and 10 days after the initial infestation. For the potted plant bioassay, young plants were infested separately with different densities of P. latus or T. urticae (5, 10, 15, 20, and 25 females per plant) while noninfested plants acted as the control. Data were obtained at intervals of 5 days for a total of 5 times. The chlorophyll contents at infestation levels of 15, 20, and 25 T. urticae per disc were statistically lower than the control discs after exposure for 5 days. The heavily infested discs with 10 or more T. urticae were destroyed until the second measurement. On the other hand, there was no significant difference between the chlorophyll contents of P. latus-infested and noninfested discs 5 days after infestation. However, the content was significantly lower in infested discs at all infestation levels than in noninfested discs 10 days after infestation. According to the potted plant experiment, the chlorophyll contents of T. urticae and P. latus-infested plants were significantly lower than the noninfested plants at all infestation levels from the 10th and 20th days of the infestation, respectively. A highly significant negative correlation was recorded between chlorophyll content and mite density, as well as exposure time indicating that the leaf chlorophyll content of infested bean plants decreased with increasing mite density and time. It was also determined that P. latus required a longer feeding time than T. urticae to affect the chlorophyll content of the bean plants.

Study on the Population Density of Insect Pests of Broccoli, Brassica Oleracea, in the Jadiriyah Area of Baghdad, Iraq

A field study was conducted in the fields of the College of Agricultural Engineering Sciences at the University of Baghdad in Al-Jadriya during the 2018 agricultural season. The objective was to survey the population densities of pests affecting broccoli (Brassica oleracea). The results revealed that the broccoli plants in the open field were affected by various pests. On September 24, the highest density of two-spotted red mite (Tetranychus urticae) eggs reached 35 eggs per leaf. On November 12, the highest density of mite nymphs was recorded at 28 nymphs per leaf. The leaf miner, Liriomyza sativae, exhibited the highest density of 23 tunnels per leaf on September 17. Additionally, the highest density of whitefly nymphs (Bemisia tabaci) was observed on October 1 and November 17, reaching 29 nymphs per leaf. The results also indicated the presence of the aphid lion, Chrysoperla carnea, as a natural enemy. Furthermore, the parasitoid Diglyphus isaea was found on the leaf miner, while the parasitoid Eretmocerus mundus was identified on the whitefly. Therefore, understanding the species of pests and their density attacking agricultural crops is crucial. This knowledge allows for the release of natural enemies in the field to mitigate pest infestations.

Biomechanical adaptations enable phoretic mite species to occupy distinct spatial niches on host burying beetles.

Niche theory predicts that ecologically similar species coexist by minimizing interspecific competition through niche partitioning. Therefore, understanding the mechanisms of niche partitioning is essential for predicting interactions and coexistence between competing organisms. Here, we study two phoretic mite species, Poecilochirus carabi and Macrocheles nataliae that coexist on the same host burying beetle Nicrophorus vespilloides and use it to 'hitchhike' between reproductive sites. Field observations revealed clear spatial partitioning between species in distinct host body parts. Poecilochirus carabi preferred the ventral side of the thorax, whereas M. nataliae were exclusively found ventrally at the hairy base of the abdomen. Experimental manipulations of mite density showed that each species preferred these body parts, largely regardless of the density of the other mite species on the host beetle. Force measurements indicated that this spatial distribution is mediated by biomechanical adaptations, because each mite species required more force to be removed from their preferred location on the beetle. While P. carabi attached with large adhesive pads to the smooth thorax cuticle, M. nataliae gripped abdominal setae with their chelicerae. Our results show that specialist biomechanical adaptations for attachment can mediate spatial niche partitioning among species sharing the same host.

Evaluation of the impact of two citrus plants on the variation of Panonychus citri (Acari: Tetranychidae) and beneficial phytoseiid mites.

The abundance of Panonychus citri McGregor 1916 (Acari: Tetranychidae) and its associated enemies (Euseius stipulatus Athias-Henriot, 1960; Typhlodromus sp.; Phytoseiulus persimilis Athias-Henriot, 1957) was studied on two 12-year-old citrus cultivars, specifically Clementine "Nules" (Citrus Clementina) and Valencia (Citrus sinensis), in the Gharb region of Morocco. Throughout the entire monitoring period in the Valencia late cultivar, the density of the spider mite P. citri on leaves was notably higher at 38.0% (n = 1,212 mobile forms). Predator P. persimilis exhibited a leaf occupancy of 25.0% (n = 812), followed by Typhlodromus sp. at 20.0% (n = 643). Conversely, the abundance of E. stipulatus was lower at 17.0% (n = 538). In the Nules variety, P. citri abundance recorded a higher percentage at 48.0% (n = 1,922). E. stipulatus emerged as the most abundant predator at 23.0% (n = 898), followed by P. persimilis with 16.0% (n = 639). Meanwhile, the population of Typlodromus sp. remained notably low at 13.0% (n = 498). Regarding the fluctuation of the different mites studied on the two cultivars across monitoring dates, the period from May 4 to June 1 was characterized by low temperatures and a diminished presence of mite populations (P. citri, E. stipulatus, Typhlodromus sp., and P. persimilis). However, from June 7 to June 19, characterized by high temperatures, a notable increase in the presence of mite populations was observed. As regards the effect of the variety on the different mites studied, the varietal impact was significant.

Impact of land use history and soil properties on soil mite communities (Acari, Mesostigmata) inhabiting stands growing on post‐agricultural land

AbstractDecades of agriculture in a former—type of ecosystem, for example, deciduous forests—result in severe habitat degradation. The planted tree species encounter harsh conditions due to physically and chemically transformed soil environments. In addition, afforestation itself significantly modifies the upper soil horizons. It may impact the soil fauna communities, including mites from the Mesostigmata order (Mesostigmata = Gamasida). Due to their sensitivity, mesostigmatid mites are good bioindicators of changes in the soil. A decrease in the density, species richness, and diversity of mites indicates disturbances in the soil environment and may confirm the impact of agricultural practice on the soil environment. Our research aim was to examine the impact of soil properties and land use history on the mesostigmatid mite communities in stands growing on forest and post‐agricultural lands. These sites were afforested with different tree species (Betula pendula Roth., Fagus sylvatica L., Pinus sylvestris L., and Quercus robur L.). Thus, 21 research plots were established on forest and post‐agricultural land, each on rusty soils considered to be one of the most common in Central European forests. We collected a total of 567 soil samples during three sampling sessions in spring and autumn for soil Mesostigmata investigation. We also described the soil profile on each plot and collected soil and litter samples to measure pH, litter thickness, soil organic matter, bulk density, soil moisture, soil organic carbon, and elements content. Our study revealed that 16 out of 30 environmental parameters differed between habitat types. A total of 1355 mites were classified into 58 taxa (50 species and 8 genera). The most numerous species were Veigaia nemorensis (165 ind.; 12.2% of all mesostigmatid mites), Zercon peltatus (156; 11.5%), and Paragamasus conus (141; 10.4%). The highest abundance was recorded in birch stands on forest land, whereas the lowest abundance for oak stands growing on post‐agricultural land. Interestingly, in oak stands we recorded both the highest diversity of mite communities (forest land) and the lowest on post‐agricultural land. Furthermore, our study showed that post‐agricultural land and Na content in forest litter affected the abundance, species richness, and diversity of mesostigmatid mite communities. Species richness was additionally affected by tree species, that is, pine and oak. Our research indicated that long‐term agricultural practice negatively affected the density, species richness, and diversity of Mesostigmata communities 20 years after afforestation.

Biotic potential of Transeius montdorensis (Acari: Phytoseiidae) under technocenosis conditions

The subtropical mite species Transeius montdorensis is widely used to control thrips and other sucking pests in European countries. To develop a domestic technology for the mass rearing of T. montdorensis, its biotic potential has been evaluated under large scale production. The growth rate of T. montdorensis is 0.19±0.017, the doubling time is 4.7±0.29 days at 26–27 °C. In the tested range of mite densities (5–80 ind./ml), the growth rate tends to decrease as the density increases. This trend can be approximated by a logarithmic curve. The density 60–80 ind./ml causes not only a significant drop in the population growth rate but also the decrease in range of its fluctuations. Higher fluctuations of growth rate at lower predator densities (5–15 ind./ml) are probably due to the fact that, in some containers, the predator is unable to hold back outbreaks of its prey (the flour mite Tyrophagus entomophagus). As a result, the prey overpopulates the substrate, which causes its contamination by waste products stimulating microflora development. The growth rate in the density range of 5–15 ind./ml is lower than expected and does not differ significantly from that in the range of 20–30 ind./ml. This indicates that the prey uncontrolled growth inhibit the reproduction of T. montdorensis. The population doubling time is a reliable indicator for screening the best stock culture of T. montdorensis for its successful rearing up to density 60 ind./ml within 6–8 days, i.e., before mass growth of fungi in the substrate. The range of 20–30 ind./ml is the optimal starting density for mass rearing, and when the predator reaches a density of more than 60 ind./ml, it should be resettled or offered for sale.

[Responses of taxonomic and functional diversity of soil mites to altitudinal changes in forest ecosystems of Lyuliang Mountains, Shanxi, China].

The altitudinal gradient pattern of mountain biodiversity and its formation mechanism are hot topics in ecological research. The altitudinal variations of belowground invertebrates are less understood than aboveground plants and animals. With soil mites as the model soil animals, we investigated their distribution patterns from 1318 m to 2500 m above sea level in three mountains of Lyuliang Mountains based on species diversity and functional diversity. We used soil pH, total N, total P, total K, and organic matter content to identify potential drivers of soil mite communities and diversity along the altitudinal gradient. A total of 715 soil mites were collected, belonging to 3 orders, 27 families, 28 genera, and 29 species. Phthiracarus clemens, Geolaelaps praesternalis and Diapterobates humeralis were dominant mites. Non-metric multidimensional scaling showed that soil mites community composition varied significantly among different altitudes due to Epilohmannia ovata predominated in high altitude and P. clemens predominated in middle altitude. There were significant differences in individual density of soil mites among different altitudes. The Margalef, Shannon, and Simpson indices followed a unimodal distribution pattern along the altitudinal gradient. Functional richness and functional evenness showed a unimodal distribution pattern along the altitudinal gradient, while other functional diversity indices changed little with altitude. The RDA results indicated that total K and soil pH were the major drivers for the variations in soil mite communities. The Pielou index of soil mites was significantly positively correlated with soil pH, while functional evenness was negatively correlated with altitude. Individual density, species number, Margalef, Simpson and Shannon indices were significantly positively correlated with functional richness index. Species diversity and functional diversity of soil mites varied differently with altitude. In the future, we should strengthen long-term monitoring and dynamic functional properties of soil mites and the community assembly to deeply understand the relationship between biodiversity and ecosystem functions.

THE CORRELATION BETWEEN KNOWLEDGE AND BEHAVIOR WITH THE PRESENCE OF HOUSE DUST MITES IN STUDENT BOARDING ROOMS IN EAST CEMPAKA PUTIH AND THE REVIEW OF ISLAMIC PERSPECTIVE

Introduction: House dust mites (HDM) are the most common allergen found in homes and spread worldwide. The factors that cause TDR life are behaviour and habits that rarely clean the bedroom. Currently, many students still need knowledge and behaviour regarding clean living. This study aims to determine the presence of house dust mites in student boarding rooms and their relationship with students' knowledge and behaviour towards house dust mites. Methods: This research method is quantitative with a cross-sectional approach. This type of research is descriptive correlation research. The population and sample of this study were 50 students in boarding settlements in Cempaka Putih Timur Village, Cempaka Putih District, Central Jakarta. The sample used the Quota Sampling technique. The data collection instrument used a questionnaire. The testing method used is the validity and reliability test using the SPSS application. Data analysis techniques using univariate and bivariate analysis. Results: The results showed that the number of rooms with positive house dust mite presence was less than those with negative house dust mite presence. Than, mattress dust has a higher density of house dust mites. Most students had a good level of knowledge and positive behaviour. Conclusion: There is no significant corelation between knowledge and behaviour with the presence of house dust mites in boarding rooms students. In Islam, a Muslim must have extensive knowledge and good behaviour. Good Muslims will keep themselves and their environment clean so that they are away from sources of disease, including house dust mites.

Soil mite (Acari: Oribatida) communities in the limestone quarry of Saskhori (Gerogia)

Abstract The present publication provides a review of the soil mite (Acari; Oribatida) community’s structure and the connection between changes in environmental factors and oribatid mite diversity in the limestone quarry of Saskhori and its adjacent areas. Overall, 52 species were recorded during the study. The most abundant oribatid mite species were Steganacarus carinatus, Aleurodamaeus setosus, Xenillus tegeocranus, Ceratoppia bipilis, Oribatula tibialis, and Punctoribates punctum. Interestingly, 23 species of oribatid mites were recorded for the first time from the limestone quarry of Saskhori, and one species (Liacarus oribatelloides) was a new record for the Caucasus fauna. The following indices were analyzed: abundance (N), species diversity (S), Shannon’s diversity index (H), and Pielou’s evenness index (J’). Regarding the obtained results, the highest density of oribatid mites was recorded in the habitat with Shibliak shrubbery (332 inds/m2), while the forest habitat was characterized with the highest value for Shannon’s diversity index (2,64). In the publication, we also provide a detailed morphological description of the newly recorded species L. oribatelloides, with the respective illustration, as no figures are given in its original description.

Taxonomic and ecological structure of oribatid mites (Acari: Oribatida) of mesophilic grasslands on the Transcarpathian lowland

The article analyzes the taxonomic diversity, dominance structure, spectra of morpho-ecological types, biotope complexes and groups of oribatid mites of mesophilic grasslands on Transcarpathian lowland. Prior to our works, there were almost no studies of the oribatid communities of the studied area. The research plots located on the sorrounding areas of the city of Mukachevo and the village of Kalnyk of the Mukachevo district. Soil samples selected for 2013-2014. The geographical coordinates of the first meadow are: 48º22.79' N, 22º40.14' E, and the second one is 48º30.86' N, 22º34.65' E. The total area of the first biotope is 0.45, and the second is 37.5 hectares. In relation to the humidity of the substrate, this type of biotope is characterized by mesophilic conditions. Extraction of mites from soil was carried out using Tullgren funnel method. Permanent preparations were prepared. Identification of the specimens was carried out using a microscope (Olympus BX 51). Oribatid mites of the investigated mesophilic grasslands are represented by 26 species from 22 genera and 16 families. The families Oppiidae and Scheloribatidae are the most represented. The average density of oribatid mites of the mesophilic grasslands on Transcarpathian lowland has relatively small values (3.7 thousand specimens per m2). The dominant species include Punctoribates punctum (C. L. Koch, 1839) and Ceratozetes mediocris Berlese, 1908. They together make up 44% of the total density of oribatids. Margalef, Menkhinik, Simpson, Shannon and Berger-Parker indices were calculated. 10 morpho-ecological types of oribatid mites were found on mesophilic grasslands. Oribatids - inhabitants of small soil crevices – predominate. Representatives of five biotope complexes (euryoecic, hygrophilous, hygro-mesophilous, mesophilous and xerophilous) and four biotope groups (eurytopic, forest, forest-meadow, meadow) were identified in the structure of ecological groups of Oribatids. Mesophilous and meadow species of oribatid mites have the largest share.

Bermudagrass mite (Acari: Eriophyidae) infestation worsens in response to increasing nitrogen fertility and decreasing irrigation volume but not mowing height.

Severe bermudagrass mite (Aceria cynodoniensis Sayed) infestation stunts turfgrass growth and reduces the aesthetic and recreational value of managed bermudagrass. Management practices, such as fertilization, mowing, and irrigation, may impact bermudagrass mite infestation and damage, but empirical evidence is lacking. Two 20 wk experiments were conducted with potted bermudagrass in a greenhouse or nursery to evaluate the effect of varying nitrogen rates (0, 24.5, or 49 kg N/ha), mowing heights (1.3, 2.5, 3.8, or 5 cm), and irrigation rates (60%, 100%, or 140% evapotranspiration [ET] rate) on the densities of witch's brooms (i.e., stunted and deformed terminals symptomatic of infestation) and bermudagrass mites. Increasing nitrogen fertility from 0 to 49 kg N/ha increased witch's broom and bermudagrass mite densities by 292% and 339%, respectively. Bermudagrass fertilized with nitrogen maintained higher turf quality than unfertilized grass despite greater mite damage. Decreasing irrigation from 140% to 60% of the ET rate also increased witch's broom densities by 124%. Mowing height did not consistently affect witch's broom or mite densities. Witch's broom and mite densities were positively correlated and followed a general trend with greater densities in April-August and a decline in densities in August-October. These findings suggest that nitrogen fertilization and water stress influence bermudagrass mite damage. Thus, limiting nitrogen fertilization to a level necessary to maintain turfgrass health and quality (0.5 kg N/ha) and minimizing turfgrass water stress can complement current chemical control strategies as part of an integrated pest management program.

Effect of Leaf Removal and Insecticide Applications on Population Densities of Leafhoppers and Mites Associated with Grapevines.

In this study, we tested the effects of mechanical leaf removal, insecticide application, and their interaction on leafhoppers and phytophagous and predatory mites occurring in two vineyards over three growing seasons. Leaf removal was performed in the fruit zone using a two-head pulsed air leaf remover, while insecticides were applied with a tunnel air-assisted sprayer at the maximum dose/ha recommended on the product label. Results demonstrated the efficacy of insecticide application in reducing the population densities of leafhoppers but also their detrimental effects on predatory mites. In a number of case studies, leaf removal reduced leafhopper and predatory mite densities. In one vineyard, phytophagous mite populations increased some weeks after leaf removal and insecticide application, highlighting the need to carefully consider the potential impact of vineyard management practices on non-target arthropods in the IPM framework.

Entomopathogenic fungi and their biological control of Tetranychus urticae: Two-spotted spider mites

The two-spotted spider mite (TSSM) Tetranychus urticae, is regarded as one of the most dangerous pests responsible for great losses in most of agricultural crops. It is a persistent pest in Saudi Arabia, especially in greenhouses where T. urticae is primarily controlled by chemical pesticides. The main problem for the two-spotted spider mites is its high resistance to pesticides and high fertility rate. In the long term, chemical pesticides cause health problems and economic losses, so it was necessary to search for a safe alternative method for human health and the environment. One of these alternative methods was the selection of plant varieties resistant to the TSSM, in addition to biological control that includes mites or predatory insects and entomopathogenic fungi. The growth, reproduction, and life-table parameters of T. urticae were examined in a laboratory setting with a 16L:8D photoperiod at 28 ± 1 °C and 65 ± 5% RH, in the presence of three major members of Family: Solanaceae tomato, eggplant, and pepper. Pepper was shown to be less conducive to T. urticae growth and reproduction compared to eggplant and tomato. Tetranychus urticae proceeded through all five stages of its life cycle (egg, larva, protonymph, deutonymph, and adult) on tested solanaceous plants, and these plants significantly influenced its growth, reproduction, and Life-table parameters. Additionally, entomopathogenic fungi have been used against insects that have proven highly effective in controlling and reducing the density of two-spotted spider mites. Eight fungi were isolated from 80 insect and mite samples collected from several Saudi Arabia regions. Analysis of the 18S rRNA sequences revealed that the fungal strains identified as Beauveria bassiana, Fusarium sp. F. equiseti, F. oxysporium, Scopulariopsis brevicaulis1, S. brevicaulis2, Aspergillus sclerotiorum, and Penicillium citrinum. The ability of isolated fungi to secrete enzymes degrading the two-spotted spider mite cuticle, namely lipase, protease, and chitinase, were studied.

Pest management of postharvest potatoes: lethal, sublethal and transgenerational effects of the ectoparasitic mite Pyemotes zhonghuajia on the potato worm Phthorimaea operculella.

Potato, Solanum tuberosum, is one of the most important food crops in the world, playing a significant role in global food security. However, many potato industries and farms may suffer losses of tuber yield and quality in storage due to lepidopteran pests. Here, we evaluated the effectiveness of an ectoparasitic idiobiont mite Pyemotes zhonghuajia in the biological control of the potato tuber moth (PTM) Phthorimaea operculella by determining the lethal, sublethal (nonconsumptive) and transgenerational effects of P. zhonghuajia of various population densities and exposure durations on PTM survival, development and reproduction. Pyemotes zhonghuajia females were capable of killing all instar stages of PTM, while resistance to mite parasitism increased with the development of PTM life stage. The mortality of mature larvae (i.e., fourth instar) and pupae increased with increasing mite density and exposure duration. P. zhonghuajia imposed significant negative sublethal impacts on PTM pupation rate, female fecundity and adult longevity but not on immature development. The sublethal stress was transgenerational, resulting in lower reproduction in the offspring generation. P. zhonghuajia induces lethal, sublethal and transgenerational effects and significantly decreases PTM survival and reproductive out, demonstrating its high efficiency in the biological control of PTM. Our study provides insight into the mechanisms underlying the nonconsumptive effects of parasitism in an ectoparasite-host system and delivers critical information for the design and implementation of augmentative releases of P. zhonghuajia in the biological control of PTM in potato storage. © 2023 Society of Chemical Industry.

Suppression of hemp russet mite, Aculops cannabicola (Acari: Eriophyidae), in industrial hemp in greenhouse and field.

Hemp russet mite, Aculops cannibicola Farkas (Acari: Eriophyidae), is one of the key pests of hemp, Cannabis sativa L. (Rosales: Cannabaceae). Hemp russet mite feeds primarily on new growth and can reach high densities, frequently exceeding a thousand mites per leaf, and leading to a decrease in yield and quality of cannabinoids. The objective of this experiment was to determine the efficacy of reduced-risk pesticides used in organic crop protection as well as conventional insecticides in managing hemp russet mites in a greenhouse and field. Hemp (var. Unicorn) was exposed to leaves heavily infested with hemp russet mites, and once mite densities reached an average of 50 mites per leaf, the following insecticides were applied to the plants: abamectin, etoxazole, fenpyroximate, rosemary oil, and 2 concentrations of a mineral oil. An application of sulfur was also included in the field experiment. Treatments were replicated 9 times in the greenhouse and 6 times in the field. Each of the pesticides significantly reduced hemp russet mite densities in the greenhouse, with all treatments resulting in significant decrease in mite populations 10 days after the initial treatment that persisted until the end of the experiment. On the other hand, only fenpyroximate, sulfur, and rosemary oil provided strong and effective suppression of the mites in the field. This is the first study to test these products against hemp russet mites in hemp, and our outcomes indicate that several pesticides available for organic crop production can provide effective control of the pest.

Eggplant-garlic intercrops reduce the density of Tetranychus urticae on eggplant and improve crop yield.

Diversification of cultivation systems plays a critical role in ecosystem functions such as pest control, diversity of beneficial arthropods, and soil fertility. Repellent plants (releasing volatile organic compounds as arthropod repellents and providing alternative prey for natural enemies) may be used in an intercropping system for pest control; however, little is known concerning their relative priority. In this study, the impact of intercropping eggplant (E) (Solanum melongena L.) and garlic (G) (Allium sativum L.) in three designs -with row ratios of 4E:4G, 4E:8G, or 4E:12G -was assessed on the density of the two-spotted spider mite (TSSM) (Tetranychus urticae Koch), the abundance and diversity of predators, and crop yields, compared with the sole crops over two growing seasons of 2019 and 2020. In three intercrops, a significant decrease in the density of TSSM egg and mobile stages was observed compared with the sole eggplant at each growth stage of eggplant. The damage index by TSSM on eggplants was lower in intercrops (8.1-11.5%) compared with sole crop (37.0-40.3%) in the two seasons. The abundance of Stethorus gilvifrons was lower in the three intercrops than in the sole crop on the blooming-initial fruit set and the fruit development stages of eggplant. The density of Orius niger was higher in the three intercrops compared with the sole crop on vegetative growth and flowering to initial fruit set stages of eggplants. The abundance of Chrysoperla carnea was not significant among treatments. Greater values of the Shannon diversity index and the Pielou's evenness index for the construction of TSSM predators were recorded in the three intercrops compared with the sole eggplant over both growing seasons. In addition, a significant improvement in the yield per unit area of eggplant and garlic was obtained in intercrops compared with sole crops. These results indicate intercropping eggplant and garlic was a practical solution for reducing TSSM on eggplant, promoting the abundance of predators, and improving the crop yields of eggplant and garlic compared with the sole crops.

Field and Laboratory Observations on the Biology of Aceria angustifoliae with Emphasis on Emergence of Overwintering Mites.

Data on the life strategy of A. angustifoliae (population fluctuation in buds and on leaves, emergence and migration to the overwintering sites), as well as its temperature-dependent emergence from overwintering sites at constant temperatures, were determined. The eriophyid mite overwintered into buds and the density of active mites inside them from winter 2017 to spring 2018 was higher than that in winter 2018-spring 2019. In the second half of March 2018 and in winter 2018-spring 2019, the mite density inside the buds decreased gradually with a peak of emergence occurring at the beginning of plant blossoming. Population density on leaves increased in summer, reaching a higher and later peak in 2018, and gradually decreased in autumn with mites migrating to overwintering sites. A lower developmental threshold of 4.5 °C was calculated. About half of the mite population was estimated to emerge from the overwintering sites at an accumulation of degree days ranging, on average, between 85.5 (at 20 °C) and 104.4 (at 10 °C) degree days above the assessed threshold.

Growth, allergen profile and microbiome studies in Dermatophagoides pteronyssinus cultures

Mites are mass-cultured to manufacture allergen extracts for allergy diagnostics and therapeutic treatment. This study focused on characterizing the growth, the allergen profile, and the microbiome of Dermatophagoides pteronyssinus cultures. Mite population, protein profile, total protein content and major allergen levels (Der p 1, Der p 2, Der p 23) were monitored at different times of three independent cultures. The allergenicity was studied by immunoblot using a pool of sera from allergic patients. Mite microbiome was characterized by sequencing the 16S rRNA gene from 600 adult mites from the last day of the culture. Endotoxin content was also analyzed. The cultures had a fast and unrelenting evolution. Mite density, total protein content, major allergen levels and the allergenicity were increased progressively during the cultures. Regarding the microbiome studies, the results confirm the presence of non-pathogenic bacteria, being firmicutes and actinobacteria the most common bacterial taxa, with a very low content of Gram-negative bacteria and endotoxin content. The allergenicity and levels of the main allergens in the mite cultures are objective methods useful to monitor the mite culture that help to produce standardized allergen extracts. The high presence of Gram-positive bacteria found limits the possibility for vaccine contamination by bacterial endotoxins.

Study of the influence of the contribution of fragmented rameal wood and manure on the density of microscopic fungi and the density of mites and collemboles of a sandy loam soil in Constantine (Algeria)

The objective of our work is to study the influence of the contribution of Fragmented Rameal Wood (BRF) and cattle manure on the density of microscopic fungi and the density of mites and springtails of a limono-sandy soil in Constantine (Algeria). A 100 m² parcel is subdivided into 15 plots of 2 m² each with 5 different plots where we determined the species of microscopic fungi and their density during March, April, May, June and November 2014. Thus, the density of springtails and mites was monitored monthly from March 2014 to January 2015. The results obtained show that the contribution of BRF or BRF mixture to cattle manure have a beneficial effect on the evolution of the density of microscopic fungi and the density of springtails and mites in the amended plots compared to the unamended plots.