Aculops Lycopersici Research Articles

Tiny tomato suppressor

Symbiosis Acarid arthropods are common and economically important pests of crop plants. The tomato russet mite Aculops lycopersici is only 175 micrometers long but can potently suppress the host plant's natural resistance. It has a highly streamlined genome of 32.5 megabases, more closely resembling that of a protist than a metazoan. Greenhalgh et al. discovered that this mite leaves no room in its genome for hangers-on. It contains few transposons, has slimmed intergenic spaces to almost none, has almost done away with chemosensory apparatus and detox pathways, and has even reduced its number of legs from eight to four in the interests of economy. However, it has retained the capacity to suppress the tomato's jasmonic acid signaling pathway, which blocks the ability of the tomato host plant to produce defensive metabolites and proteins. However, the selective forces resulting in this genome diminution remain a puzzle—perhaps one is the poor nutritional value of tomato plants. eLife 9 , e56689 (2020).

Genome streamlining in a minute herbivore that manipulates its host plant.

The tomato russet mite, Aculops lycopersici, is among the smallest animals on earth. It is a worldwide pest on tomato and can potently suppress the host's natural resistance. We sequenced its genome, the first of an eriophyoid, and explored whether there are genomic features associated with the mite's minute size and lifestyle. At only 32.5 Mb, the genome is the smallest yet reported for any arthropod and, reminiscent of microbial eukaryotes, exceptionally streamlined. It has few transposable elements, tiny intergenic regions, and is remarkably intron-poor, as more than 80% of coding genes are intronless. Furthermore, in accordance with ecological specialization theory, this defense-suppressing herbivore has extremely reduced environmental response gene families such as those involved in chemoreception and detoxification. Other losses associate with this species' highly derived body plan. Our findings accelerate the understanding of evolutionary forces underpinning metazoan life at the limits of small physical and genome size.

Distribution and biological features of Typhlodromus (Anthoseius) recki (Acari: Phytoseiidae) on Tetranychus urticae, T. evansi (Acari: Tetranychidae) and Aculops lycopersici (Acari: Eriophyidae)

The mite family Phytoseiidae contains predatory species used in biological control. However, among the 2,521 valid species, only a few are presently considered for pest management. The study focuses on a species, frequently observed in agrosystems, but whose biology is almost totally unknown: Typhlodromus (Anthoseius) recki. The objectives were to assess its distribution and to determine under laboratory conditions: (i) the development of three populations fed on three tomato pests (Tetranychus urticae, T. evansi, Aculops lycopersici), (ii) the dispersion along the tomato stem, and (iii) the dispersion from mint to infested tomato leaf discs. Based on its distribution, this species seems to be adapted to Mediterranean climate, and is preferentially found on Boraginaceae, Solanaceae, Asteraceae and Lamiaceae. Results show that T. (A.) recki is a generalist predator, with good performance regarding the number of prey consumed. Differences were observed between the populations considered; one population out of the three tested shows even a higher mean consumption of T. urticae than that recorded for Neoseiulus californicus and N. cucumeris. It is attracted by food source and is able to walk along the tomato stem. These results are encouraging enough to consider T. (A.) recki as a good natural enemy candidate for biological control (especially based on biodiversity conservation). Further experiments should be developed to test the predatory ability of this species at larger scale (entire tomato plants and tomato fields or greenhouses).

<p class="Body"><strong>Eriophyoid mites (Acariformes) from wild and cultivated Solanaceae plants from Brazil⁠—new taxa, supplementary descriptions, a first report and new host plants of the tomato russet mite</strong></p>

The results of a survey of Eriophyoidea mites on wild and cultivated Solanaceae plants in Central Brazil are presented. Five new taxa associated with plants in the genus Solanum are described and illustrated. They include one new genus with type species belonging to Phyllocoptinae, Calacarini - Viginticus lupusmalum gen. nov. & sp. nov.; two new species in the Eriophyinae, Aceriini - Aceria solani sp. nov. and Paraphytoptus tuberacutus sp. nov., all of them associated with Solanum lycocarpum St. Hil.; and one new species in the Phyllocoptinae, Athocoptini - Aculus michereffi sp. nov., associated with Solanum acanthodes Hook.. New host plants for the tomato russet mite, Aculops lycopersici (Tryon 1917), are reported. In addition, the first record of Calacarus speciosissimum Flechtmann, 1999 for Brazil and from Capsicum as host plants, and the first record of Rhynacus lippius Duarte, Chetverikov & Navia, 2016, on solanaceous plants are presented; supplementary descriptions of these species were elaborated. Diagnostic traits for Calacarus mites collected on Solanaceae plants around the world are summarized.

<p class="Body"><strong>Mites associated to chile piquín (<em>Capsicum annuum</em> L. var. <em>glabriusculum</em>) in two Protect Natural Areas in Northeastern México</strong></p>

The conservation status of an ecosystem is checked by studying the composition and diversity of the organisms that interact in trophic chains. The aim of this study was to evaluate the biodiversity of mites associated to Capsicum annuum L. var glabriusculum (Solanaceae) at three sampling sites corresponding to two Protected Natural Areas (PNA) in Tamaulipas state, Mexico. Samplings were carried out in “Cañón de la Peregrina” and “Altas Cumbres” situated in the PNA "Altas Cumbres" and “Ojo de Agua”, located in the "El Cielo" Biosphere Reserve. Mite diversity was H = 1.09 ± 0.14 in Ojo de Agua, and it was H = 1.08 ± 0.08 and H = 1.11 ± 0.06 in Altas Cumbres and Cañón de la Peregrina, respectively. A total of 47 species were identified belonging to 35 genera of 18 families associated to C. annuum L. var glabriusculum in Mexico. Predatory mite richness was higher than that of generalist and phytophagous mites (31, 11 and 5 species, respectively) for the two ANP. The similarity index of Jaccard between OA–AC (IJ = 0.257; P < 0.05), CP–AC (IJ = 0.293; P < 0.05) and AC–CP (IJ = 0.324; P < 0.05) was low. Pseudopronematalus sp. 4 (Iolinidae) was predatory mite most abundant in both ANP (Pi = 9.311); followed by Metaseiulus (Metaseiulus) negundinis (Denmark) (Phytoseiidae) only for ANP “Altas Cumbres” (Pi = 1.004). While for phytophagus mite, Aculops lycopersici (Tryon) (Eriophyidae) and Tetranychus merganser Boudreaux (Tetranychidae) presented the highest abundances in all sites (Pi = 79.919 and 5.142, respectively). The high number of mites species associated to chile piquín suggests stability in the PNA despite anthropogenic activities, and that the PNA works as a mite reservoir.

Mitespotting: approaches for Aculops lycopersici monitoring in tomato cultivation.

Aculops lycopersici is a major pest in tomato cultivation worldwide, and lately its relevance in German tomato cultivation has increased markedly. Aculops lycopersici causes damage to tomato plants by feeding on the surface of leaves, stem and fruits and can lead to the loss of whole plants. Given the small size of the pest, A. lycopersici infestation may go unnoticed for quite a length of time. When discovered symptoms can be easily confused with those of diseases. In addition to these issues A. lycopersici has a very high reproduction rate. In this study, fluorescence measurements were performed on the stem of A. lycopersici-inoculated potted tomato plants and these were compared with a visual bare eye assessment and a sticky tape imprint method for classification of these plants as either infested or healthy. The best correct classification rate was achieved with sticky tape, but this method is time intensive, which makes it unsuitable for large-scale monitoring in practice. Classification based on a ridge regression performed on stem fluorescence measurements was at least as good as the classification based on the visual assessment, and detection was robust against symptoms of drought stress. In a second trial the specificity of stem fluorescence measurements for A. lycopersici against Trialeurodes vaporariorum was tested successfully. The fluorescence method is promising as this method allows for high automation and thereby has the potential to increase monitoring efficacy in practice considerably. The relevance of the tested monitoring methods for practical tomato cultivation and the next steps to be taken are discussed.

Distinct Signatures of Host Defense Suppression by Plant-Feeding Mites.

Tomato plants are attacked by diverse herbivorous arthropods, including by cell-content-feeding mites, such as the extreme generalist Tetranychus urticae and specialists like Tetranychus evansi and Aculops lycopersici. Mite feeding induces plant defense responses that reduce mite performance. However, T. evansi and A. lycopersici suppress plant defenses via poorly understood mechanisms and, consequently, maintain a high performance on tomato. On a shared host, T. urticae can be facilitated by either of the specialist mites, likely due to the suppression of plant defenses. To better understand defense suppression and indirect plant-mediated interactions between herbivorous mites, we used gene-expression microarrays to analyze the transcriptomic changes in tomato after attack by either a single mite species (T. urticae, T. evansi, A. lycopersici) or two species simultaneously (T. urticae plus T. evansi or T. urticae plus A. lycopersici). Additionally, we assessed mite-induced changes in defense-associated phytohormones using LC-MS/MS. Compared to non-infested controls, jasmonates (JAs) and salicylate (SA) accumulated to higher amounts upon all mite-infestation treatments, but the response was attenuated after single infestations with defense-suppressors. Strikingly, whereas 8 to 10% of tomato genes were differentially expressed upon single infestations with T. urticae or A. lycopersici, respectively, only 0.1% was altered in T. evansi-infested plants. Transcriptome analysis of dual-infested leaves revealed that A. lycopersici primarily suppressed T. urticae-induced JA defenses, while T. evansi dampened T. urticae-triggered host responses on a transcriptome-wide scale. The latter suggests that T. evansi not solely down-regulates plant gene expression, but rather directs it back towards housekeeping levels. Our results provide valuable new insights into the mechanisms underlying host defense suppression and the plant-mediated facilitation of competing herbivores.

Tritrophic relationships among tomato cultivars, the rust mite, Aculops lycopersici (Massee) (Eriophyidae), and its predators

Trichome-mediated defence in wild and cultivated tomato cultivars has been extensively studied against some mite species for several decades. Previous studies have shown that this mechanism negatively affects phytophagous mites and their predators. To better explain the tritrophic relationship of tomatoes, the interactions between population densities of the tomato rust mite, Aculops lycopersici (Massee) (Acari: Eriophyidae), and its predators on the tomato cultivars, namely, Dora, Etna, Grande, H2274, Jana and M1103, and the trichome densities of these cultivars were investigated in both a climatic room and an organic tomato field from 2014-2015. Under both controlled and field conditions, the A. lycopersici population density was significantly higher in the stake tomato cultivars, Jana and Etna, than in other tomato cultivars. When the tomato rust mite’s population density was the highest during mid-August and mid-September in the tomato field, the population density of the predator species, Tydeus kochi Oudemans (Tydeidae), showed a similar population pattern and significant positive correlation with the A. lycopersici density. However, density of this predator mite was significantly lower than that of A. lycopersici over the entire season. Remarkably, the glandular trichome type VI density was significantly higher in the stake cultivars than other cultivars. In contrast, significantly fewer glandular trichomes were found in the indeterminate tomato cultivars, Grande and H2274, which had fewer tomato rust mites and larger tydeid mite predator densities. These results support the hypothesis that trichomes provide excellent shelter for tomato rust mites and are obstacles for its predator mites. However, the population density of the insect predator, Macrolophus sp., was not affected by the trichome density or tomato cultivar, but its population density was not significantly correlated with that of the A. lycopersici population.

Life tables of the predatory mite Neoseiulus cucumeris (Acari: Phytoseiidae) on two pest mites as prey, Aculops lycopersici and Tetranychus urticae

Studies on the life history and life table parameters of Neoseiulus cucumeris Oudemans (Acari: Phytoseiidae) were carried out under laboratory conditions of 25 ± 1 °C and 65 ± 5% RH; 30 ± 1 °C and 60 ± 5% RH; 35 ± 1 °C and 55 ± 5% RH. As prey, immature stages of tetranychid spider mite T. urticae Koch (Acari: Tetranychidae) and the moving stages of the Tomato Russet Mite A. lycopersici (Massee) (Acari: Eriophyideae) were selected. The predatory phytoseiid mite, Neoseiulus cucumeris (Oudemans) was able to develop successfully from egg to adult stage through the entire life history on both preys. The higher of different temperatures and relative humidities shortened the development and increased reproduction and prey consumption and vice versa. The maximum reproduction (3.91, and 3.09 eggs/♀/day) was recorded at 35 °C and 65% RH, while the minimum (2.12, and 1.90 eggs/♀/day) was at 25 ± 1 °C and 55 ± 5% RH. when N. cucumeris fed on A. lycopersici and T. urticae, respectively. The reproductive rate on eriophyid was significantly higher than previously recorded on tetranychid. Life table parameters indicated that feeding of phytoseiid mite N. cucumeris on tomato russet mite A. lycopersici led to the highest reproduction rate (rm = 0.268, 0.232 and 0.211 females/female/day), while feeding on T.urticae gave the lowest reproduction rate (rm = 0.159, 0.143 and 0.131) at 35 °C and 55% RH, 30 °C and 60% RH and 25 °C and 65% RH, respectively. The population of N. cucumeris multiplied (36.81, 28.71 and 20.47) and (24.60, 19.58 and 14.62 times) in a generation time of (20.10, 23.20 and 25.14) and (22.35, 25.36 and 27.79 days) when a predator fed on A. lycopersici and T. urticae at the same temperature above mentioned, respectively. These results suggest that the two mites, particularly A. lycopersici, proved to be suitable prey for N.cucumeris, as a facultative predator.

Binomial sampling plan for tomato russet mite (Aculopslycopersici (Tryon) (Acari: Eriophyidae) in protected tomato crops

AbstractThe tomato russet mite (TRM), Aculops lycopersici, is a worldwide pest of cultivated tomatoes. Currently, no effective biological control agents are available on the market. Therefore, chemical spray applications are required. Fast and reliable detection, monitoring and evaluation of interventions are a challenge, slowing down the development of an appropriate integrated pest management (IPM) strategy. This study describes a binomial sampling plan with the aim to reduce the efforts and costs for an accurate monitoring of A. lycopersici. Sampling was performed by taking pictures of the upper leaf surface with a smartphone through an attached magnification lens. A binomial sampling plan was developed based on the linear relationship between ln(mean TRM densities) and ln(−ln(1‐PT), where PT is the proportion of samples with more than T (tally threshold) mites. The minimum precision threshold of 0.30 was determined for the different models. A resampling for validation of sample plans (RVSP) programme with a fixed sample number was used for validation of the model on an independent data set. The binomial sampling plans were validated at tally thresholds of T = 9 and T = 15 with fixed sample sizes of 15, 20, 25 and 30. Precision levels were satisfying within a range of PT‐values from 0.29 to 0.97 for T = 15 at a fixed sample size of 20. This range was much smaller for T = 9, where the PT‐values range between 0.40 and 0.92 at the same sample size. A binomial sampling model with T = 9 with a fixed sample size of 15, which has the lowest time investment, is feasible for glasshouse tomato growers in practice. However, for the development of pest management programmes, a more intensive and more accurate binomial sampling plan with T = 15 and a sample size of minimum 20 is suggested.

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Experiments were conducted at Faculty of Agriculture farm Shebin Elkom and laboratory of Economic Entomology and Agricultural Zoology Department to study the eriophyid mites associated with three vegetable plants, five fruit trees, and two ornamental plants during the period from 2013/2015. Incidence studies indicated that 11 species of eriophyid mites belonging to 7 Genera was collected. Five plant extracts were chosen to determine their effect on Aculops lycopersici mite, after one week the redaction percentages were the highest when cayenne pepper and garlic used 98, 91 % while this percentage approximately ranged between 85, 88 % for other plant extracts, three weeks after application the reduction percentages were 100% in all plant extracts treatment except thyme record 98%. Ten chemical compounds as pesticides were experimented to show their effect on Aculops lycopersici. One day after application Sino S recorded the highest reeducation percentage 97% followed by Citrogard and Dumber 90%, while the lowest reduction percentages ware recorded by Vermex and Arrow 43, 46 %. Also, studied effect of some control methods against eriophyid mites on some morphological characters of tomato plants. It was observed that plant length increase in all treatments than untreated plants, increase percentage were 88.6, 89.7 % for Acari stop and high point treatment, while it was 88.4 , 90.9% in Cayenne pepper and Garlic three weeks after application. Biology of eriophyid mite Aceria dioscoridis reared in laboratory under 28± 2 C and 75± 5% R. H. the mean of incubation period was 1.75± 0.32 days, 72% from eggs was hatched to active larvae. Some biological aspects of predatory mite were studies when used Aceria dioscoridis ,Cisabroptus Kenyaeas prey, the incubation period of predator egg was 2.44± 0.61days for female, while it was 2.42± 0.51days for male. The life cycle of the predatory mite ranged from 8:12 days for female and 7: 12 for male.

Drought stress promotes the colonization success of a herbivorous mite that manipulates plant defenses

Climate change is expected to bring longer periods of drought and this may affect the plant’s ability to resist pests. We assessed if water deficit affects the tomato russet mite (TRM; Aculops lycopersici), a key tomato-pest. TRM thrives on tomato by suppressing the plant’s jamonate defenses while these defenses typically are modulated by drought stress. We observed that the TRM population grows faster and causes more damage on drought-stressed plants. To explain this observation we measured several nutrients, phytohormones, defense-gene expression and the activity of defensive proteins in plants with or without drought stress or TRM. TRM increased the levels of total protein and several free amino acids. It also promoted the SA-response and upregulated the accumulation of jasmonates but down-regulated the downstream marker genes while promoting the activity of cysteine—but not serine—protease inhibitors, polyphenol oxidase and of peroxidase (POD). Drought stress, in turn, retained the down regulation of JA-marker genes and reduced the activity of serine protease inhibitors and POD, and altered the levels of some free-amino acids. When combined, drought stress antagonized the accumulation of POD and JA by TRM and synergized accumulation of free sugars and SA. Our data show that drought stress interacts with pest-induced primary and secondary metabolic changes and promotes pest performance.

The tomato russet mite, Aculops lycopersici (Tryon 1917) (Acari: Trombidiformes: Eriophyidae), is recorded for the first time in Yemen

ABSTRACTThe tomato russet mite, Aculops lycopersici (Tryon) (Trombidiformes: Eriophyidae), is reported for the first time in Yemen from tomatoes, Solanum lycopersicum L. (Solanaceae). This is the second record of A. lycopersici from the Arabian Peninsula after Saudi Arabia.

Occurrence of Tomato Russet Mites, Aculops lycopersici Massee (Acari: Eriophyidae) in a Greenhouse and Selection of an Eco-friendly Organic Insecticide

Occurrence of Tomato Russet Mites, Aculops lycopersici Massee (Acari: Eriophyidae) in a Greenhouse and Selection of an Eco-friendly Organic Insecticide

Detección de la presencia del ácaro (Aculops lycopersici) causante del bronceamiento del tomate (Lycoprsicon esculentum) en El Salvador, América Central

In October 1989, microscopic specimens of (acaros) with symptoms of browning and plant mortality in young and older tomato plants from various locations in El Salvador were sent tó the entomologist Ing. Ronald Ochoa from Costa Rica. lng. Ronald Ochoa is associated with the Diagnostics Network of the Centro Agronomico Tropical de Investigation y Enseñanza (CATlE) based in Turrialba, Costa Rica. Microscopic examination of this material confirmed the taxonomic identification as Aculops lycopersici (Acariformes: Eriophyidae), suspected since May 1988 with the first observation and collection of samples. Abrief review of literature and a phone conversation with the specialist who identified the material, permits reporting for the first time of the presence of this species in El Salvador. This finding is a warning about this pest which could be apotential problem in the tropics of Central America. This paper discusses personal observations of some of the characteristics, habits and appearances of this species, small experiments, and it includes a review of literature pertinent to this subject

<p class="Body"><strong>Suitability of the litchi erineum mite, <em>Aceria</em> <em>litchii</em> (Keifer), as prey for the mite <em>Phytoseius</em> <em>intermedius</em> Evans & MacFarlane (Acari: Eriophyidae, Phytoseiidae)</strong></p>

Litchi (Litchi chinensis Sonn.; Sapindaceae) is a plant native to Southeast Asia, where it is mostly cultivated. This crop has been severely damaged in Australia, Brazil, China, Hawaii, India and Pakistan by the litchi erineum mite, Aceria litchii (Keifer) (Eriophyidae), which attacks mainly leaves but also flowers and fruits. Phytoseius intermedius Evans & McFarlane is one of the phytoseiid mites most commonly found in association with this pest in Brazil. The objectives of this study were to: a) to compare the predation and oviposition rates of P. intermedius when fed A. litchii with the same rates when the predator was fed other food sources [the eriophyid Aculops lycopersici Tryon, the spider mite Tetranychus urticae Koch and pollen of Typha domingensis (Pers.)]; b) to evaluate the life history parameters of P. intermedius fed A. litchii. The results indicated that A. litchii is a suitable food source for nymphs and adults P. intermedius. The combined immature stages (egg-adult) lasted 6.0 ± 0.1 days, with fecundity recorded at 25.4 ± 1.5 eggs, and a corresponding average oviposition rate of 1.2 ± 0.1 eggs per day. The intrinsic rate of increase (rm) was 0.229 female/female/day. All field collected specimens and laboratory reared progeny of P. intermedius consisted of females, indicating that it most likely reproduces by thelytokous parthenogenesis.

Definition of the concordis species group of the genus Euseius (Acari:Phytoseiidae), with a morphological reassessment of the species included.

Phytoseiidae (Acari) is the best known family of predatory mites. Within this family, Euseius Wainstein is one of the largest genera. The species of this genus have generalist feeding behavior, including in their diet mites and pollen. Some studies have demonstrated the potential of certain Euseius species to control pest mites. Euseius concordis (Chant) has been mentioned in the literature as potentially useful for the control of the tomato russet mite, Aculops lycopersici (Tryon) (Eriophyidae). Several other American species are morphologically similar to E. concordis; the morphological variation of these species is poorly understood. The objective of this study was a taxonomic re-evaluation of E. concordis and of the world species most similar to it. Measurements of species collected in this study and a taxonomic key to separate the species of this group are provided. Morphological evaluations confirmed that Euseius flechtmanni Denmark & Muma is a junior synonym of E. concordis, and determined that Euseius caseariae De Leon is also a junior synonym of E. concordis, that Euseius ho (De Leon) and Euseius brazilli (El-Banhawy) are junior synonyms of Euseius mesembrinus (Dean) and that Euseius vivax (Chant & Baker) is not a junior synonym of Euseius fructicolus (Gonzalez & Schuster), as previously thought.

Defense suppression benefits herbivores that have a monopoly on their feeding site but can backfire within natural communities.

BackgroundPlants have inducible defenses to combat attacking organisms. Hence, some herbivores have adapted to suppress these defenses. Suppression of plant defenses has been shown to benefit herbivores by boosting their growth and reproductive performance.ResultsWe observed in field-grown tomatoes that spider mites (Tetranychus urticae) establish larger colonies on plants already infested with the tomato russet mite (Aculops lycopersici). Using laboratory assays, we observed that spider mites have a much higher reproductive performance on russet mite-infested plants, similar to their performance on the jasmonic acid (JA)-biosynthesis mutant def-1. Hence, we tested if russet mites suppress JA-responses thereby facilitating spider mites. We found that russet mites manipulate defenses: they induce those mediated by salicylic acid (SA) but suppress those mediated by JA which would otherwise hinder growth. This suppression of JA-defenses occurs downstream of JA-accumulation and is independent from its natural antagonist SA. In contrast, spider mites induced both JA- and SA-responses while plants infested with the two mite species together display strongly reduced JA-responses, yet a doubled SA-response. The spider mite-induced JA-response in the presence of russet mites was restored on transgenic tomatoes unable to accumulate SA (nahG), but russet mites alone still did not induce JA-responses on nahG plants. Thus, indirect facilitation of spider mites by russet mites depends on the antagonistic action of SA on JA while suppression of JA-defenses by russet mites does not. Furthermore, russet mite-induced SA-responses inhibited secondary infection by Pseudomonas syringae (Pst) while not affecting the mite itself. Finally, while facilitating spider mites, russet mites experience reduced population growth.ConclusionsOur results show that the benefits of suppressing plant defenses may diminish within communities with natural competitors. We show that suppression of defenses via the JA-SA antagonism can be a consequence, rather than the cause, of a primary suppression event and that its overall effect is determined by the presence of competing herbivores and the distinct palette of defenses these induce. Thus, whether or not host-defense manipulation improves an herbivore’s fitness depends on interactions with other herbivores via induced-host defenses, implicating bidirectional causation of community structure of herbivores sharing a plant.Electronic supplementary materialThe online version of this article (doi:10.1186/s12915-014-0098-9) contains supplementary material, which is available to authorized users.

Biological aspects of the predaceous mite, agistemus vulgaris soliman and gomaa and life table parameters on three host phytophagous mite species, (Acari: stigmaeidae)

Mites of family Stigmaeidae are potential predators of various species of phytophagous mites through the world.The present study was conducted in Acarology Research Laboratory Plant Protection Research Institute, Dokki, Egypt. The aim of this work was to study the effect of different prey species on the biology of stigmaeid mite, Agistemus vulgaris Soliman and Gomaa. The results showed that A.vulgaris completed its life cycle in 12.56 days when fed on Tetranychus urticae Koch as compared to 12.09 and 10.75 days when fed on Oligonychus sayedi Zaher, Gomaa & El-Enany and Aculops lycopersici Massee, respectively. The maximum average fecundity (53.75 eggs/female) was recorded after feeding on O. sayedi where as after feeding on T. urticae and A. lycopersici , it was 28.43 and 21.93, respectively. Predatory mite has better life table parameters in comparison with the other prey mites. The biological aspects of the predator was as follow, Mean generation time (T) averaged 18.63, 19.18 and 15.34 days, respectively; Net reproductive rate (Ro) averaged 12.82, 24.38 and 9.81; intrinsic rate of natural increase (rm) was 0.13, 0.16 and 0.14; finite rate of increase (λ) averaged 1.14, 1.18 and 1.16 when the mite fed on immature stages of T. urticae, O. sayedi and A. lycopersici, respectively. A. vulgaris is considered a promising biological control agent against phytophagous mites.

Defense suppression benefits herbivores that have a monopoly on their feeding site but can backfire within natural communities

BackgroundPlants have inducible defenses to combat attacking organisms. Hence, some herbivores have adapted to suppress these defenses. Suppression of plant defenses has been shown to benefit herbivores by boosting their growth and reproductive performance.ResultsWe observed in field-grown tomatoes that spider mites (Tetranychus urticae) establish larger colonies on plants already infested with the tomato russet mite (Aculops lycopersici). Using laboratory assays, we observed that spider mites have a much higher reproductive performance on russet mite-infested plants, similar to their performance on the jasmonic acid (JA)-biosynthesis mutant def-1. Hence, we tested if russet mites suppress JA-responses thereby facilitating spider mites. We found that russet mites manipulate defenses: they induce those mediated by salicylic acid (SA) but suppress those mediated by JA which would otherwise hinder growth. This suppression of JA-defenses occurs downstream of JA-accumulation and is independent from its natural antagonist SA. In contrast, spider mites induced both JA- and SA-responses while plants infested with the two mite species together display strongly reduced JA-responses, yet a doubled SA-response. The spider mite-induced JA-response in the presence of russet mites was restored on transgenic tomatoes unable to accumulate SA (nahG), but russet mites alone still did not induce JA-responses on nahG plants. Thus, indirect facilitation of spider mites by russet mites depends on the antagonistic action of SA on JA while suppression of JA-defenses by russet mites does not. Furthermore, russet mite-induced SA-responses inhibited secondary infection by Pseudomonas syringae (Pst) while not affecting the mite itself. Finally, while facilitating spider mites, russet mites experience reduced population growth.ConclusionsOur results show that the benefits of suppressing plant defenses may diminish within communities with natural competitors. We show that suppression of defenses via the JA-SA antagonism can be a consequence, rather than the cause, of a primary suppression event and that its overall effect is determined by the presence of competing herbivores and the distinct palette of defenses these induce. Thus, whether or not host-defense manipulation improves an herbivore’s fitness depends on interactions with other herbivores via induced-host defenses, implicating bidirectional causation of community structure of herbivores sharing a plant.