Spider Mite Species Research Articles

Tenuipalpidae and Tetranychidae (Trombidiformes, Tetranychoidea) from Syria with a description of a new species of Bryobia

Surveys of Tenuipalpidae and Tetranychidae were conducted at three locations in Latakia governorate, Syria, in 2021. Eight species were collected; four flat mite species of which Aegyptobia beglarovi, Cenopalpus lineola, and Pentamerismus juniperi were new records for Syria; and four spider mite species among which Petrobia (Mesotetranychus) tunisiae represented a new record. A new tetranychid species, Bryobia (Lyobia) hadizeni sp. nov., collected from Calicotome villosa, is described and illustrated. The number of Tenuipalpidae species known from Syria increases to 16 and there are now 25 species of Tetranychidae.

ИНСТРУМЕНТАЛЬНЫЙ ЭКОНОМИЧЕСКИЙ УРОВЕНЬ ПОВРЕЖДЕННОСТИ И ЭКОНОМИЧЕСКИЙ ПОРОГ ВРЕДОНОСНОСТИ ПОПУЛЯЦИЙ ПАУТИННОГО КЛЕЩА НА ЗЕМЛЯНИКЕ

Spider mites of the genus Tetranychus are universally one of the significant pests that damage garden strawberries and many other crops. One of the important problems of the pest population management is to be able to identify the thresholds of this pest, which, when feeding, causes a change in the color of plant leaves. Since it is very difficult to determine visually the level of leaf damage by spider mites, the authors of the study turned to the previously substantiated instrumental method for assessing damage using the relative electron transport rate (rETR) based on chlorophyll fluorescence detection in the leaf. Instrumental thresholds of pest damage were calculated: the economic injury level (EIL) and the economic threshold (ET). Studies were carried out in the laboratory on the leaves of strawberry grown in conteiners at temperature of 22 ± 2°C, relative humidity of 75 ± 10%, photoperiod (L : D) 16:8 h, as well as on the experimental plot of the strawberry plantation of JSC “Lenin Sovkhoz” (Moscow region); registration of the population dynamics of spider mites on the leaves being made. At the same time, using the JUNIOR-PAM fluorimeter (Heinz Walz, Germany), the dynamics of chlorophyll fluorescence in the leaves of the control (without mites) and experimental (damaged by mites) variants were measured. As a result, two varieties of industrial strawberries obtained a range of variation of the numerical physiological index, expressed in terms of the ratio of rETRmax between the experimental and control variants, equal to 1.4–2.0 conventional units, which corresponded to the economic injury level (EIL) of strawberry leaves. The latter trait was comparable to the same parameter obtained in the laboratory – 1.6. The economic threshold (ET), which signals the beginning of pesticide treatments, if it is reasonably expected that the number of pests will reach or exceed the value of EIL, also expressed in terms of the ratio of rETRmax between the experimental and control variants, turned out to be equal to 1.1–1.2 conventional units. The authors recommend using the proposed instrumental criteria for the harmfulness of the Atlantic spider mite on strawberries. We believe that this approach can be applied to other species of spider mites, as well as sucking insects.

ECOLOGY Susceptibility of Apple Varieties to Tetranychus urticae Koch and Panonychus ulmi Koch and its Relation to the Nutrient Contents and Spider Mite Predators in Apple Trees

El-Abdallah, J., M. Muflih and L.H. Aslan. 2022. Susceptibility of Apple Varieties to Tetranychus urticae Koch and Panonychus ulmi Koch and its Relation to the Nutrient Contents and Spider Mite Predators in Apple Trees. Arab Journal of Plant Protection, 40(2): 119-126. https://doi.org/10.22268/AJPP-40.2.119126 The susceptibility to T. urticae and P. ulmi of eight apple varaietis were studied in southern Syria (Sweida) from 2018 to 2020. Significant differences of susceptibility to the two species between apple varieties, in addition to significant differences of apple-leaf nutrients content (NPK) were found. Results obtained showed that apple-leaf nutrients content affect the susceptibility to the two spider mite species differently. Principal component analysis (PCA) showed positive correlation to P. ulmi with apple-leaf contents of potassium and negative correlation with apple-leaf contents of nitrogen and showed positive correlation between T. urticae numbers and nitrogen and phosphorous content. T. urticae had a weak correlation with potassium apple-leaf content in 2019. Cluster analysis showed that apple varieties were distributed in three clusters based on the studied factors in 2020. The first cluster included the varieties Top Red, Starking Delicious and Starking Red Delicious which were the most sensitive to P. ulmi. The second cluster included Golden Delicious, Golden 972 and Granny Smith, and those were less sensitive to P. ulmi and the third cluster included Ozark Gold and Royal Red and these varieties were moderately sensitive to P. ulmi. The effects of studied factors were clearer on P. ulmi than on T. urticae. Keywords: Apple, T. urticae, P. ulmi, Phytoseiidae, Principal component analysis, PCA.

Natural Enemies Associated with Brevipalpus sp. (Acari: Tenuipalpidae), Vector of Citrus Leprosis

Natural Enemies Associated with <i>Brevipalpus</i> sp. (Acari: Tenuipalpidae), Vector of Citrus Leprosis

Genome-Wide Characterization and Identification of Long Non-Coding RNAs during the Molting Process of a Spider Mite, Panonychus citri.

Molting is essential for arthropods to grow. As one of the important arthropod pests in agriculture, key spider mite species (Tetranychus and Panonychus) can normally molt three times from the larva to adult stage within a week. This physiological strategy results in the short lifecycle of spider mites and difficulties in their control in the field. Long non-coding RNAs (lncRNAs) regulate transcriptional editing, cellular function, and biological processes. Thus, analysis of the lncRNAs in the spider mite molting process may provide new insights into their roles in the molting mechanism. For this purpose, we used high-throughput RNA-seq to examine the expression dynamics of lncRNAs and mRNAs in the molting process of different development stages in Panonychus citri. We identified 9199 lncRNAs from 18 transcriptomes. Analysis of the lncRNAs suggested that they were shorter and had fewer exons and transcripts than mRNAs. Among these, 356 lncRNAs were differentially expressed during three molting processes: late larva to early protonymph, late protonymph to early deutonymph, and late deutonymph to early adult. A time series profile analysis of differentially expressed lncRNAs showed that 77 lncRNAs were clustered into two dynamic expression profiles (Pattern a and Pattern c), implying that lncRNAs were involved in the molting process of spider mites. Furthermore, the lncRNA–mRNA co-expression networks showed that several differentially expressed hub lncRNAs were predicted to be functionally associated with typical molting-related proteins, such as cuticle protein and chitin biosynthesis. These data reveal the potential regulatory function of lncRNAs in the molting process and provide datasets for further analysis of lncRNAs and mRNAs in spider mites.

Sex dimorphism of life-history traits and their response to environmental factors in spider mites.

Sex dimorphism is ubiquitous in the animal kingdom and can be influenced by environmental factors. However, relatively little is known about how the degree and direction of sex difference vary with environmental factors, including food quality and temperature. With the spider mites from the family Tetranychidae as subjects, the sex difference of life-history traits in responses to host plant and temperature were determined in this meta-analytic review. Across the 42 studies on 26 spider mite species (N = 8057 and 3922 for female and male mites, respectively), female spider mites showed longer developmental duration than the males in all except two species. The direction of sex difference in development was consistent regardless of temperature and host plant. The 16 spider mite species in 33 studies generally showed female-biased longevity, with an overall effect size of 0.6043 [95%CI =0.4054-0.8031]. Host plant significantly influenced the sex difference in longevity, where the males lived longer than females below 22.5 ℃, but the reverse was true at higher and fluctuating temperature. Host plant also influenced the magnitude of sex difference in longevity, with females living longer than males when reared on herbs but not on trees. This study indicated that life-history traits are highly variable between sexes under temperature and host plant influence, highlighting that environmental conditions can significantly shape the direction and magnitude of sexual dimorphism of life-history traits.

Updated and annotated review of Tetranychidae occurring in mainland Portugal, the Azores, and Madeira Archipelagos

Data on the diversity, distribution, and main hosts of spider mites (Acari: Tetranychidae) are scarce in the Iberian Peninsula, particularly for Portugal, where only 21 species are recorded on the mainland and in the Azores and Madeira archipelagos. Moreover, the scientific information is mainly available in national publications, and difficult to access for international researchers. In this paper, we review the literature dealing with spider mites in mainland Portugal and the archipelagos of the Azores and Madeira, compiling and synthesizing the most relevant information on their distribution, hosts and pest potential. Further information was obtained by verifying slides in the acarological collection of the Instituto Nacional de Investigação Agrária e Veterinária (INIAV), the most important national collection, and by verifying mites collected on different plant hosts during the period 2018-2020. In total, we found records for 28 spider mite species in Portugal, comprising nine Bryobiinae and 19 Tetranychinae, and including new national records for Stigmaeopsis nanjingensis and Eotetranychus tiliarium. Additionally, we record a new exotic mite species for the mainland, Eotetranychus lewisi, which was found in two localities in the Algarve District on leaves of Euphorbia pulcherrima. This is the first record for continental Europe of an established population in outdoor conditions of this regulated quarantine pest. We also comment on the presence of seven species not reported by international taxonomic databases but already recorded from Portugal: Aplonobia histricina, Eotetranychus rubiphilus, Schizonobia sycophanta, Tetranychus kanzawai and Tetranycopsis horridus (at a national level), and Oligonychus perseae and Panonychus citri (for the mainland). New host records are given for Bryobia praetiosa, Petrobia (Tetranychina) harti, S. sycophanta, E. coryli, E. rubiphilus, Tetranychus kanzawai, Tetranychus lintearius, Tetranychus ludeni and Tetranychus turkestani.

&lt;p class="Body"&gt;&lt;strong&gt;Injurious status of &lt;em&gt;Schizotetranychus schizopus &lt;/em&gt;(Zacher, 1913) (Acari: Tetranychidae) on Indian Thorny Bamboo&lt;/strong&gt;&lt;/p&gt;

Spider mites, especially members of Schizotetranychus represent a common and dominant group of bamboo pests, enjoying worldwide distribution. The present paper highlights the feeding attributes of a notorious species of bamboo spider mite, viz. Schizotetranychus schizopus (Zacher, 1913) infesting the Indian Thorny Bamboo, Bambusa bambos (L.) Voss. Observations on feeding behavior of the mite were completed in the laboratory by collecting mite specimens from infested leaves of bamboo plants grown in Calicut University Botanical Garden. The species showed initial colonization on the abaxial surface of bamboo leaves, adjacent to the midrib and feeding activity of the members of the colony resulted in the development of damage symptoms like chlorotic spots, white patches, yellowing etc. Comparative analysis of the biochemical constituents of mite infested and uninfested leaves of B. bambos revealed significant alterations. Mite infested bamboo leaves presented significantly reduced values of chlorophyll fluorescence (30.10% loss in Fv/Fm ratio) thereby indicating a decline of photosynthetic efficiency. Significant reduction in total carbohydrate (58.87%) and total protein (21.02%) contents also could be accounted in mite infested leaves. Meanwhile, mite infestation was found to enhance the production of stress compounds such as Total Phenol (22.86%) and Proline (69.05%). An increase in the uptake of micro and macronutrients like Potassium (18.87%), Calcium (36.66%), Copper (48.76%) and Zinc (19.62%) was also observed in mite infested leaves. Despite this, the uptake of nutrients such as Phosphorus (8.22%), Magnesium (3.55%), Sulphur (1.54%), Iron (11.46%), Manganese (13.64%) and Boron (30.09%) significantly decreased owing to mite infestation. Significant decrease in moisture content also was evident in the mite infested bamboo leaves. The results of the study helped to evidence the biotic stress induced by the mite on its bamboo host, by promoting enhanced production of Total Phenol, Proline, Potassium, Calcium, Copper and Zinc which would play a substantial role in the defense mechanism of the plant.

&lt;strong&gt;Spider mites (Acari: Tetranychidae) from Serbia: new species for the country and the Balkan Peninsula, with a key to all known Serbian species &lt;/strong&gt;

Seven spider mite species were recorded for the first time in Serbia: Bryobia macedonica Hatzinikolis &amp; Panou, 1996 and Bryobia querci Hatzinikolis &amp; Panou, 1997 from Bryobiinae, and Eutetranychus orientalis Klein, 1936; Oligonychus bicolor Banks, 1894; Oligonychus platani McGregor, 1950 Tetranychus canadensis McGregor, 1950 and Tetranychus ludeni Zacher, 1913 from Tetranychinae. Together with previously reported data, these findings raise the number of known tetranychid species in Serbia to 44, the second highest number of spider mite species recorded in the Balkan countries. The records of O. bicolor and T. canadensis are also the first ones on the Balkan Peninsula. The most frequent species were T. ludeni and E. orientalis, found in 24 and 13 out of 57 sampling locations. Spider mites were recorded on host plants in four basic habitat types, but predominantly in cultivated habitats and woodlands. A total of 27 plant species from nine families were recorded as hosts for newly recorded spider mites, including 12 plant species as new hosts for four tetranychids, and three plant species as new hosts for the family Tetranychidae. Plant family Rosaceae had the highest number of new hosts (7) and harbored the highest number of spider mite species (5). Tetranychus ludeni had the highest number of host plants (11) with two plant species as its new hosts. Oligonychus bicolor was found on eight host plants including five new hosts for this species and one new host for the family Tetranychidae. The other two new hosts for the family Tetranychidae harbored O. platani and B. querci, respectively. Symptoms of heavy infestations by E. orientalis and T. ludeni were recorded on host plants in several locations.

Two new life types and assessment of web-associated behavioral characteristics of some Oligonychus species on various host plants.

The webbing life type of three spider mite species of the genus Oligonychus was studied based on web-associated behavioral characteristics. All tested Oligonychus species-viz., avocado brown mite, Oligonychus punicae (Hirst), date palm mite, Oligonychus afrasiaticus (McGregor), and banks grass mite, Oligonychus pratensis (Banks)-exhibited a complicated-web (CW) life type on various host plants. A new life type, 'CW-c,' was documented for O. punicae on the adaxial leaf side of Conocarpus erectus L. (Combretaceae). The weaving pattern with guy ropes is spun by the O. punicae female and is associated with stalked eggs; it appeared as a unique character in the CW-life type. Oligonychus afrasiaticus, also showed a new life type, 'CW-d,' when reared on the abaxial side of leaves of four host plants, viz., desert fan palm, maize, sorghum, and sugarcane. Oligonychus afrasiaticus showed a site for quiescence and a site for oviposition as variables, whereas the site for defecation (SD) was a persistent characteristic on all four tested host plants. Oligonychus pratensis showed the characteristics of the sub-type 'CW-u' on the abaxial leaf side of Washingtonia filifera (Lindl.) H. Wendl. (Arecaceae). The SD was a distinguishing behavioral characteristic used to separate O. afrasiaticus from O. pratensis when inhabiting the same host plant, W. filifera.

Carotenoid Metabolism in Terrestrial Animals.

Terrestrial animals, especially insects, contain various carotenoids that show structural diversity. These animals accumulated carotenoids derived from plants and other animals and modified them through metabolic reactions. Therefore, most of the carotenoids found in terrestrial animals originated from plants. Conversely, recent investigation revealed that some species of aphids and spider mites synthesized carotenoid themselves by carotenoid biosynthetic genes, which were horizontally transferred from fungi. In this chapter, carotenoids in terrestrial animals are described from the viewpoints of natural product chemistry, metabolism, food chain, and chemosystematics.

The species composition of the harmful entomofauna of soybean crops in the conditions of rice paddies

Goal. To determine the species composition of soybean phytophages under rice checks.&#x0D; Methods. The main field method with related phenological observations and analyzes. The study of the species composition of soybean pests was carried out in rice paddies of the Institute of Rice of the NAAS by collecting all objects with their subsequent identification. The survey was carried out once every 3—7 days: the first counts were in the third decade of May, when the plants were in the germination phase. Recorded plants were placed diagonally. On the experimental site, five plants were examined in 20 places.&#x0D; Results. Studies have been carried out to clarify the species composition of harmful entomofauna in soybean crops under the conditions of rice checks in the Southern Steppe of Ukraine. Found 20 species of phytophagus from 7 rows and 11 families and one species of spider mite: мeadow moth (Margaritia sticticalis L.); thistle, or vanessa thistle (Vanessa cardui L.); grass bug (Lygus rugulipennis Popp.); alfalfa bug (Carpocoris fuscispinus Boh.); alfalfa stink bug (Piezodorus lituratus F.); tobacco thrips (Thrips tabaci Lind.); scoop-gamma (Autographa gamma L.); alfalfa moth (Chloridea viriplaca Hfn.); green horse (Tettigonia viridissima L.); Italian Prussian (Calliptamus italicus L.); large cereal aphid (Sitobion avenae F.); Moroccan locust (Dociostaurus maroccanus Thunb.); six-point leafhopper (Macrosteles laevis Kib.); striped leafhopper (Psammotettix striatus L.); nosy tree (Aelia rostrata Bsh.); striped nodule weevil (Sitona lineatus L.); gray bristly weevil (Sitona crinitus Hfn.); cotton scoop (Helicoverpa armigera Hfn.); acacia moth (Etiella zinckenella Tr.), two-spotted spider mite (Tetranychus urticae Koch.).&#x0D; Conclusions. As a result of research in the conditions of the Southern Steppe of Ukraine, 20 species of phytophagous insects from 7 rows, 11 families and one species of tick were found in soybeans. The vast majority of pests in terms of numbers are among the Lepidoptera — 38%. These species damaged soybeans during the growing season and influenced the formation of the yield.

&lt;p class="Body"&gt;&lt;strong&gt;Description of a new species of &lt;em&gt;Aponychus&lt;/em&gt; and redescriprion of &lt;em&gt;Tetranychus armipenis&lt;/em&gt; (Tetranychidae)&lt;/strong&gt;&lt;/p&gt;

Spider mite surveys conducted in Rio Grande do Sul state, Brazil, allowed us to provide the redescription of Tetranychus armipenis Flechtmann &amp; Baker (Tetranychidae) from specimens collected on native plant species from Pampa biome, Rio Grande do Sul state. A new species of spider mite, Aponychus mauritianum sp. nov. is described and illustrated based on specimens collected from Solanum mauritianum Scop. (Solanaceae) in the municipality of Lajeado in the same state. New hosts for Atrichoproctus uncinatus Flechtmann and Schizotetranychus oryzae Rossi de Simons are also reported.

Varying responses to combined water-stress and herbivory in maize for spider mite species that differ in host specialization

Water-stress commonly affects crops grown in arid and semi-arid regions. Apart from the direct impact of this abiotic stress on yield, a diverse community of herbivores can outbreak under these conditions, and plant responses to abiotic stress may alter plant defense responses that deter herbivores. Outbreaks of both generalist and specialist spider mites are strongly associated with hot and dry conditions in the field settings. To understand how water-stress impacts maize responses to spider mites, we conducted parallel greenhouse and field experiments with maize plants (B73 inbred line) subjected to optimal irrigation and water-stress conditions (50-60% and 5-10% volumetric water content (VWC), and 25-32% and 10-15% VWC, in the greenhouse and field, respectively). In addition to recording B73 responses to water-stress alone, we measured the population growth of the generalist twospotted spider mite (Tetranychus urticae, TSM) and the specialist Banks grass mite (Oligonychus pratensis, BGM) on optimally watered and water-stressed plants. We also measured plant defense protein activities (peroxidase (POD), polyphenol oxidase (PPO), chitinase (CHI) and trypsin inhibitor (TI)) at 1, 3, and 7 days post mite introduction for each irrigation treatment. For B73 plants exposed to water-stress, we observed increases in leaf temperature, leaf water potential, POD activity, as well as decreases in stomatal conductance and stem height. Populations of both mite species increased more rapidly on water-stressed B73 plants. While optimally irrigated B73 plants responded with similar plant defense activity to both mite species, combinations of plant water-stress and TSM herbivory resulted in increases in CHI and TI activity that were not observed for the respective treatments with BGM. Collectively, our results highlight a role for species-specific factors, possibly associated with herbivore host plant breadth, in impacting plant responses to herbivory in combination with an abiotic stress.

Development and use of a single real‐time PCR assay to identify the three spider mite species Tetranychus urticae, Tetranychus lambi and Tetranychus ludeni (Acari: Tetranychidae)

AbstractTetranychid spider mites are a significant worldwide pest of agriculture with Tetranychus urticae being the most important. In Australian cotton, T. urticae is the most damaging, but Tetranychus ludeni and Tetranychus lambi are also present and can be difficult to distinguish morphologically. For this reason, a fast‐diagnostic assay was developed to identify T. urticae, T. lambi and T. ludeni in a single real‐time PCR reaction. The assay design was based on a universal primer pair to amplify the internal transcribed spacer of nuclear ribosomal DNA (ITS1) with three species‐specific TaqMan probes. The assay was validated by sequencing three known reference strains for T. urticae, T. lambi and T. ludeni and a blind test on 14 DNA samples that included species other than the three target species. The method correctly identified the target species and produced a negative result against other non‐target species. Furthermore, we examined 22 field‐collected spider mite populations from Australian cotton that had been laboratory maintained. Here, we found that 50% of the populations labelled as T. urticae were mixed with T. lambi and quarter of the populations labelled with T. lambi contained T. urticae. It demonstrates just how difficult it is to maintain strain integrity with multiple species in proximity. Finally, the assay was used by Biosecurity Australia to test 2125 mite quarantine intercept specimens. They found 1949 T. urticae, 1 T. lambi, 13 T. ludeni and 162 unknown specimens confirming assay accuracy and robustness. The diagnostic assay developed can provide quick spider mite species identification and can support multiple uses including species identification to support spray decisions or the precise identification of border quarantine intercepts where accuracy and turnaround time is critical.

Inter- and intraspecific variation of spider mite susceptibility to fungal infections: Implications for the long-term success of biological control.

Spider mites are severe pests of several annual and perennial crops worldwide, often causing important economic damages. As rapid evolution of pesticide resistance in this group hampers the efficiency of chemical control, alternative control strategies, such as the use of entomopathogenic fungi, are being developed. However, while several studies have focused on the evaluation of the control potential of different fungal species and/or isolates as well as their compatibility with other control methods (e.g., predators or chemical pesticides), knowledge on the extent of inter‐ and intraspecific variation in spider mite susceptibility to fungal infection is as yet incipient. Here, we measured the mortality induced by two generalist fungi, Beauveria bassiana and Metarhizium brunneum, in 12 spider mite populations belonging to different Tetranychus species: T. evansi, T. ludeni, and T. urticae (green and red form), within a full factorial experiment. We found that spider mite species differed in their susceptibility to infection by both fungal species. Moreover, we also found important intraspecific variation for this trait. These results draw caution on the development of single strains as biocontrol agents. Indeed, the high level of intraspecific variation suggests that (a) the one‐size‐fits‐all strategy may fail to control spider mite populations and (b) hosts resistance to infection may evolve at a rapid pace. Finally, we propose future directions to better understand this system and improve the long‐term success of spider mite control strategies based on entomopathogenic fungi.

Resistance risk assessment of the novel complex II inhibitor pyflubumide in the polyphagous pest Tetranychus urticae

Pyflubumide is a novel selective carboxanilide acaricide that inhibits mitochondrial complex II of spider mite species such as Tetranychus urticae. We explored the baseline toxicity and potential cross-resistance risk of pyflubumide in a reference panel of T. urticae strains resistant to various acaricides with different modes of action. A cyenopyrafen-resistant strain (JPR) was identified as the only strain with low-to-moderate level of cross-resistance to pyflubumide (LC50 = 49.07 mg/L). In a resistance risk assessment approach, JPR was subsequently selected which led to two highly resistant strains JPR-R1 (RR = 466.7) and JPR-R2 (RR = 614.8). Interestingly, compared to adult females, resistance was much less pronounced in adult males and eggs of the two JPR-R strains. In order to elucidate resistance mechanisms, we first sequenced the complex II subunits in susceptible and resistant strains, but target-site insensitivity could not be detected. In contrast, synergism/antagonism experiments strongly suggested that cytochrome P450 monooxygenases are involved in pyflubumide resistance. We therefore conducted genome-wide gene expression experiments to investigate constitutive and induced expression patterns and documented the overexpression of five cytochrome P450 and four carboxyl/choline esterase genes in the JPR-R strains after pyflubumide exposure. Together, we provide a first resistance risk assessment of a novel complex II inhibitor and provide first evidence for metabolic resistance mediated by cytochrome P450s in T. urticae.

Interspecific competition between invasive species of Frankliniella occidentalis and other insects

Frankliniella occidentalis is one of the most important invasive species.F.occidentalis inevitably competes with other insects in the process of its global invasion.In this paper,the interspecific competition between F.occidentalis and other species of thrips,whitefly and spider mites were reviewed.The roles of factors,such as temperature,CO 2,host plants,pesticide,natural enemy,in the competition displacement were analyzed.The research prospects and research methods of interspecific competition were discussed.The review will lay a foundation for revealing the population dynamics of F.occidentalis in China.

Analysis of the diversity of endosymbiotic microorganisms in two spider mite species

ABSTRACTThe symbiosis relationship between arthropods and microorganisms is common in nature and may aid herbivores to counteract plant defences and increase fitness. The spider mite Tetranychus evansi is a pest of tomato that manipulates important defence pathways, including those that lead to the production of protease inhibitors, causing great economic impacts. This ability may be related to the action of endosymbionts present in this specie. Thus, this study aimed to identify the microbiota present in the two species of spider mites, Tetranychus evansi and Tetranychus urticae. Microbial DNA was extracted from mite samples and subjected to polymerase chain reaction denaturing-gradient gel electrophoresis (PCR-DGGE), and then submitted to sequencing. Fungi were not identified in any of the mites. The diversity of bacteria was greater in T. evansi. In both spider mites, most of the bacteria species belong to the Proteobacteria phylum. The greater diversity of bacteria found in T. evansi may be related to the ability of this mite to manipulate plant defences, and novel studies could focus on the role of each bacterium in this mechanism. The study of the diversity of microorganisms will help to understand their efficiency as agricultural pests and provide alternatives to combat them.

A bittersweet meal: The impact of sugar solutions and honeydew on the fitness of two predatory gall midges

Adult survival and reproduction of many species of arthropod natural enemies depend exclusively on sugar-rich food such as honeydew. Here, we tested the impact of two types of honeydew as well as several sugars at different concentrations (10%, 25%, 50%) on the longevity and reproduction of two life-history omnivores. On the one hand, the aphid-feeding gall midge Aphidoletes aphidimyza (Rondani) and on the other hand the gall midge Feltiella acarisuga (Vallot) (Diptera: Cecidomiydae), a predator that can feed on many spider-mite species during the juvenile stage. Compared to a water control, females provided with the commercial sugar Biogluc® at a 10% concentration showed an increase in longevity by a factor of 3.6 for A. aphidimyza and 4.7 for F. acarisuga, respectively, whereas Biogluc® at a 50% concentration significantly reduced longevity in both species. Sucrose solutions had a positive, yet less pronounced effect. Feeding on Biogluc® or sucrose (all concentrations) raised the number of oocytes for A. aphidimyza and F. acarisuga by a factor 2.2–2.6 and 2.0–2.5, respectively. The highest realized fecundity during 72 h was recorded for A. aphidimiza females supplied with 50% Biogluc® (increase by 5.1) or in the case of F. acarisuga the strongest effect was observed with 10% Biogluc® (increase by 3.5). For the rest of the Biogluc® and sucrose solutions the effects were less pronounced. In contrast, aphid honeydew did not raise female longevity, nor the number of oocytes or eggs laid. Our results imply that sugar solutions at modest concentration (10%) are best suited for use to support these gall midges in the field as well as in mass rearing. Finally, given the positive association between the number of oocytes and the number of eggs laid for both species, we propose the use of the former as a proxy to assess the fertility for both species to simplify the procedures for quality assessments currently employed by the biocontrol industry.