Euseius Concordis Research Articles

Identity Matters: Multiple Herbivory Induces Less Attractive or Repellent Coffee Plant Volatile Emission to Different Natural Enemies.

Co-infestations by herbivores, a common situation found in natural settings, can distinctly affect induced plant defenses compared to single infestations. Related tritrophic interactions might be affected through the emission of changed blends of herbivore-induced plant volatiles (HIPVs). In a previous study, we observed that the infestation by red spider mite (Oligonychus ilicis) on coffee plants facilitated the infestation by white mealybug (Planococcus minor), whereas the reverse sequence of infestation did not occur. Here, we examined the involvement of the jasmonate and salicylate pathways in the plant-mediated asymmetrical facilitation between red spider mites and white mealybugs as well as the effect of multiple herbivory on attractiveness to the predatory mite Euseius concordis and the ladybug Cryptolaemus montrouzieri. Both mite and mealybug herbivory led to the accumulation of JA-Ile, JA, and cis-OPDA in plants, although the catabolic reactions of JA-Ile were specifically regulated by each herbivore. Infestation by mites or mealybugs induced the release of novel volatiles by coffee plants, which selectively attracted their respective predators. Even though the co-infestation by mites and mealybugs resulted in a stronger accumulation of JA-Ile, JA and SA than the single infestation treatments, the volatile emission was similar to that of mite-infested or mealybug-infested plants. However, multiple infestation had a negative impact on the attractiveness of HIPVs to the predators, making them less attractive to the predatory mite and a repellent to the ladybug. We discuss the potential underlying mechanisms of the susceptibility induced by mites, and the effect of multiple infestation on each predator.

Acaricide resistance in predatory mites of the genus Euseius (Acari: Phytoseiidae) and predation capacity on Brevipalpus yothersi (Acari: Tenuipalpidae)

One of the main citrus diseases in Brazil is citrus leprosis, transmitted by the mite Brevipalpus yothersi Baker (Acari: Tenuipalpidae). The predatory mites Euseius citrifolius Denmark & Muma and Euseius concordis (Chant) (Acari: Phytoseiidae) are important natural enemies for the pest mite. The objective of this work was to evaluate the susceptibility of different populations of E. concordis and E. citrifolius, from citrus groves in the state of São Paulo (SP), to the acaricides abamectin, fenpropathrin and chlorfenapyr; characterize the abamectin resistance in E. citrifolius, including studies on cross-resistance and biochemical mechanisms of resistance; and evaluate the predation capacity of an abamectin resistant population of E. citrifolius on B. yothersi. Significant differences in susceptibility to acaricides were observed among populations of E. citrifolius. Resistance ratios of 15.5 and 3.1 (times) were observed for abamectin and chlorfenapyr, respectively, comparing populations of E. citrifolius collected in the municipalities of Taquaral-SP and Bofete-SP. Studies with the synergist piperonyl butoxide indicated the involvement of cytochrome P450-dependent monooxygenases in the resistance of E. citrifolius to abamectin. Populations of E. concordis and E. citrifolius collected in Taquaral-SP showed low susceptibility to fenpropathrin, with LC50 values at least 95 times higher than the recommended concentration for the control of Brevipalpus mites in citrus in Brazil. The population of E. citrifolius from Taquaral showed a high capacity for predation of B. yothersi larvae, with consumption of up to 49.4 larvae per adult female per day.

Mite fauna on transgenic soybean in an experimental station in western Bahia, Brazil

The aim of this study was to identify mite fauna associated with soybean crops and to report new species of the Monsoy 8349 IPRO variety in the municipality of Luís Eduardo Magalhães, western region of Bahia. Samplings were performed in an area with transgenic soybeans, subdivided into three treatments: T01, with no use of agricultural pesticides; T02, complete package of pesticides, except for acaricides; and T03, complete package of pesticides including acaricides. Twenty plants were selected per treatment at each sampling; one apical, one median, and one basal leaf were collected from each plant, totaling 60 leaves per treatment. A total of 1,292 mites were found, belonging to three families, five genera, and six species. The major phytophagous mite species found were Mononychellus planki McGregor and Tetranychus urticae Koch, while the major predatory mites found were Neoseiulus transversus Denmark & Muma and Euseius concordis Chant.

Phytoseiidae (Acari: Parasitiformes: Mesostigmata) inhabiting native plants from three biomes in Mato Grosso State, Brazil, with description of a new species

Phytoseiidae (Acari: Mesostigmata) is one of the most studied mite families due to their use in biological control programs. The southwestern region of Mato Grosso State, Brazil remains poorly explored concerning its mite fauna. Therefore, the aim of this study was to conduct a survey of Phytoseiidae mites in the southwestern region of Mato Grosso State, Brazil. Samplings were carried out in three areas, representing the following: Amazon Forest (AF), Cerrado (CE) and Pantanal (PA) biomes. Five species of native plants commonly found throughout the areas were selected, as well as five others exclusive for each area. In total, five individuals from each plant species were collected. Thirty mite species belonging to 16 genera were recorded: AF (14 species), CE (15) and PA (23). The three most abundant species in this study belongs to the genus Amblyseius: A. acalyphus Denmark & Muma, A. aerialis (Muma) and A. chiapensis De Leon. In the AF the most abundant species were A. aerialis, A. chiapensis and Euseius concordis (Chant); in the CE were A. acalyphus, A. chiapensis and Typhlodromips furcus Lofego, Demite & Feres; lastly in the PA were A. acalyphus, A. aerialis and T. furcus. The plants which harbored the highest richness were common to the three biomes: Physocalymma scaberrimum Pohl (Lithraceae) (12), Cecropia pachystachya Trécul (Urticaceae) (11) and Siparuna guianensis Aubl. (Siparunaceae), (11). A new species, Amblyseius matogrossensis sp. nov., is described and illustrated.

Diverse non-crop vegetation assemblages as banker plants for predatory mites in strawberry crop

Non-crop plant diversity plays a fundamental role in the conservation of predatory mite (PM) and can be proposed as a banker plant system (BPS). BPSs provide plants that host natural enemies in greenhouses or field crops and may improve the efficiency of biological control. The aim of this study was to investigate if a diverse plant composition could be a suitable BPS for PMs in strawberry crops. A plant inventory characterized 22 species of non-crop plants harboring PMs. The most abundant PMs, in decreasing order, were Neoseiulus californicus, Neoseiulus anonymus, Euseius citrifolius, and Euseius concordis. PMs were randomly distributed among plants. We also found specific associations of Phytoseiidae species and phytophagous or generalist mites on plants. Due to this, four species were deemed suitable as banker plants: Capsicum sp., Leonurus sibiricus, Solanum americanum, and Urochloa mutica. Moreover, these plants combined a high PMs density and a low occurrence or absence of pest-mites. This study suggests shifting the traditional view that BPSs are composed of a limited number of species to use plant assemblages. This contributes to both conservation and augmentative biological control.

Euseius concordis (chant) (Acari: Phytoseiidae) as a potential agent for the control of yerba mate red mite Oligonychus yothersi (McGregor) (Acari: Tetranychidae)

Oligonychus yothersi (McGregor) (Acari: Tetranychidae), known as yerba mate red mite, is typically found on the abaxial face of leaves, feeding on mesophyll cell contents in yerba mate crops. Euseius concordis (Chant) is a generalist mite, feeding on other mites, pollen, and nectar, and can be a promising control agent of O. yothersi. This study aimed to evaluate development time, reproduction, survival, and sex ratio of this predatory mite when feeding on O. yothersi on yerba mate leaves. A life-cycle study was performed in a climate chamber at 22 ± 1 °C and 12 hours of photophase, 19 ± 1 °C during scotophase, and 70 ± 10% relative humidity. The study started with 36 experimental units, which were examined three times a day during immature development and once during the adult stage to evaluate reproductive parameters. Mean developmental times of egg, larva, protonymph, deutonymph, and egg-adult stages were the following: for females, 2.14 ± 0.15, 1.59 ± 0.12, 1.97 ± 0.11, 2.18 ± 0.13, and 7.88 ± 0.21, respectively; for males, 2.00 ± 0.67, 1.77 ± 0.52, 1.94 ± 0.52, 2.05 ± 0.69, and 7.75 ± 1.08. Mean pre-oviposition, oviposition, and post-oviposition periods were 3.31 ± 0.33, 10.4 ± 0.74, and 1.50 ± 0.28, respectively. Sex ratio was 0.67 and mean life expectancy was 15.22 days for females and 12.51 ± 1.91 days for males. Mean daily oviposition was 1.67 ± 0.08 eggs per female, with a mean value of 20.14 ± 1.42 eggs per female. T, Ro, rm, λ, and DT values were: 16.33, 10.03, 0.14, 1.15, and 4.91, respectively. This study demonstrated that E. concordis is a predator with potential to be used in biological control programs, successfully developing and reproducing when feeding on O. yothersi under laboratory conditions.

<p class="Body"><strong>Bioecological aspects of mites associated with </strong><strong><em>Vitis vinifera </em></strong><strong>varieties in the state of Rio Grande Do Sul, Brazil</strong></p>

Viticulture is an activity of economic importance in the state of Rio Grande do Sul, especially in Serra Gaúcha, which is the major grape-producing region. However, an increase in cultivated areas has been observed in other municipalities in the state. The aim of this study is to characterize mite diversity and community behavior on different varieties, recognizing which predatory species have potential to control phytophagous mites associated with Europan varieties in the Taquari Valley, Rio Grande do Sul state. The study was conducted in vineyards located in the municipalities of Marques de Souza: ‘BRS Vitória’ and cv ‘Itália’ “m”; Imigrante: cv ‘Itália’ “i”; Dois Lajeados: cv ‘Itália’ (c and f), ‘Tannat’ and ‘Chardonnay’; and Putinga: ‘Champanhe’ and ‘Moscato’. Samplings were carried out monthly in the period ranging from March 2017 to March 2018, during which twenty plants were randomly collected from each variety. Three leaves were clipped from each plant; one from the apical third, one from the median third, and one from the basal third, totaling 60 leaves per area. A total of 10,533 specimens were collected, belonging to 12 families, 38 genera, and 53 species, along with those belonging to the suborder Oribatida. The ‘Itália’ “c” variety had the highest abundance (2,012), followed by ‘Moscato’ (1,788) and ‘BRS Vitória’ (1,593). Phytoseiidae had the highest diversity among the mite families observed, with 20 species followed by Tetranychidae (8). The most abundant species were Polyphagotarsonemus latus (Banks) (3,420) and Euseius concordis (Chant) (565), present throughout the study period. ‘Chardonnay’ variety had the highest similarity (72.55%) among mite fauna compositions and the highest dissimilarity occurred between ‘BRS Vitória’ and ‘Champanhe’ varieties (95.48%). Environments evaluated in Dois Lajeados and Putinga were the most homogeneous concerning mite fauna diversity and abundance.

<p class="Body"><strong>Mites (Arachnida: Acari) associated with plants of family Myrtaceae from the Caatinga Domain, Brazil</strong></p>

The objective of the present study was to determine the mite fauna associated with Myrtaceae from Cariri, a microregion with peculiar climatic conditions in the center of the Caatinga Domain in northeastern Brazil. Samples were collected in eight municipalities in Cariri region. In each municipality, five collection sites equidistant at approximately 10 km were established. The sampling was carried out in two periods, rainy season (March to April 2013) and dry season (September to October 2013). A total of 3.831 mites distributed in 14 families, 39 genera and 46 species were recorded. The Phytoseiidae was the dominant predatory mite family with 11 species. The most common phytoseiid species was Euseius concordis (Chant), followed by Euseius citrifolius Demark & Muma and Euseius alatus De Leon. Among the phytophagous mites, two families were the most abundant: Tenuipalpidae and Tetranychidae. Our results indicated that Myrtaceae in Caatinga Domains hosts a considerable diversity of potentially important predatory mites for the control of phytophagous species.

Functional response of Euseius concordis feeding on Oligonychus ilicis (Acari: Phytoseiidae, Tetranychidae).

Oligonychus ilicis (McGregor) (Acari: Tetranychidae), commonly known as the southern red mite, or as the coffee red spider mite in Brazil, is one of the main species of herbivorous mites that causes serious damage to coffee plants (Coffea spp.) and thus negatively affects coffee production. Among the biocontrol agents, predatory mites of the family Phytoseiidae play an important role in many biological control programs worldwide due to their potential as suppressor of mite populations mainly from the family Tetranychidae. One of the phytoseiid mites usually associated with O. ilicis is Euseius concordis (Chant), which often occurs abundantly in the coffee crops of Minas Gerais State, Brazil. This study was conducted to assess the predation potential of E. concordis feeding on the larvae and nymph stages of O. ilicis on coffee plants (Coffea arabica L.). Logistic regression analysis revealed a Holling type II functional response, showing that the number of O. ilicis killed by E. concordis increased gradually as the density of O. ilicis increased. Average daily oviposition also increased with prey densities above 6.3 mites/cm2, indicating that maximum oviposition rate is about 1 egg/day. Results of this study suggest that E. concordis has the potential to reduce O. ilicis populations, and this predatory mite can therefore be considered an important natural enemy of the pest O. ilicis in coffee plantations.

Geographical Distribution of Schizotetranychus hindustanicus and Associated Mites in Roraima, Brazil

The Hindustan citrus mite, Schizotetranychus hindustanicus Hirst (Acari: Tetranychidae), is a quarantine pest present in the state of Roraima, Brazil. This mite, which was described in India in 1924, was reported in 2002 in Venezuela and spread to Roraima, where it was reported in 2008, and to Colombia, where it was reported in 2010. Its possible spread to other regions of Brazil is a threat to Brazilian citriculture. This study reports the current distribution of S. hindustanicus and potential predators of this pest and other mites associated with citrus in Roraima. A survey was conducted in August and September 2015 in the 15 municipalities of the state. In each municipality, orchards and citrus plants in backyards and public areas along highways and in urban areas were sampled. Samples of leaves and fruits were collected to identify the mite and its natural enemies. Schizotetranychus hindustanicus was found in all 15 municipalities in the state of Roraima. In total, 308 associated mites were found, with S. hindustanicus being the most abundant phytophagous mite, followed by Brevipalpus yothersi Baker. Amblyseius aerialis (Muma) was the most abundant predator, followed by Iphiseiodes zuluagai Denmark and Muma and Euseius concordis (Chant). The broad dispersal of S. hindustanicus in Roraima increases the risks of this pest reaching the main citrus-producing regions in Brazil.

<p class="Body">Phytoseiidae (Parasitiformes: Mesostigmata) from the Pantanal, Mato Grosso do Sul State, Brazil

Phytoseiidae is the most extensively studied family of predatory mites, some of which are effectively used as biological control agents. Nevertheless, studies of these mites in some Brazilian biomes such as the Pantanal are still scarce. The objective this publication was to assess the diversity of this family in Pantanal vegetation from Mato Grosso do Sul State, Brazil, verifying the importance of the native plants as reservoirs for these mites. Samplings were carried out in five phytophysiognomies of the Pantanal: Cambarazal, Capão (forest islet), Carandazal, Riparian Forest and Paratudal. Thirty-five phytoseiid species were recorded on 40 plant species of 28 families. The most common species were Amblyseius chiapensis De Leon and Euseius concordis De Leon, recorded on 21 and 18 plant species, respectively. Inga vera Willd. (Fabaceae) and Paullinia pinnata L. (Sapindaceae) were the host plants harboring the greatest richness of phytoseiids, 15 and 14 species, respectively. Our results suggest a high diversity of phytoseiid mites in the Pantanal biome. However, as only a small proportion of the total biome area was considered, only a fraction of the mite diversity was probably recovered. Thus, new studies on this biome are needed, especially in other well-preserved native vegetation remnants.

Biological performance of the predatory mites Amblyseius largoensis and Euseius concordis fed on eggs of Aleurodicus cocois

No abstract, but the first three sentences are shown below:Giant whiteflies, Aleurodicus cocois, commonly occur in some fruit trees, especially on cashew trees, and are actually recognized as a key pest in this crop. It is possible that some of the phytoseiid species that commonly occur on cashew trees have the potential to be used to control the giant whitefly. Amblyseius largoensis and Euseius concordis has been suggested as potential natural enemies of the giant whitefly. Thus, the present study evaluated the development and reproduction of A. largoensis and E. concordis when fed exclusively on giant whitefly eggs.

Effect of temperature and diet on the morphology of Euseius concordis (Acari: Phytoseiidae)

Mite identification is usually done by the examination of morphological characteristics, the variation of which is not always sufficiently known to allow reliable distinction between closely related species. Morphological variations can be associated with geographical distribution and/ or with host ranges. The objective of this study is to evaluate the morphological variations of a population of a predatory mite identified as Euseius concordis (Chant) (Phytoseiidae) collected in Piracicaba, southeastern Brazil, when reared at different combinations of temperatures (20°C or 28°C) and diets (pollen of Typha domingensis Pers or the eriophyid mite Aceria litchii (Keifer)). High variations were observed even among mites of each treatment. Temperature (especially) and diet caused significant changes in the dimensions of some structures. Extreme cases corresponded to the maximal lengths of the dorsal idiosomal setae z2 and z4, which were about twice their minimal lengths. It is argued that for practical taxonomic purposes, it is more relevant to determine the range of the variation of each structure than its mean or other statistical parameters describing populational variations.

Reciprocal intraguild predation and predator coexistence.

Intraguild predation is a mix of competition and predation and occurs when one species feeds on another species that uses similar resources. Theory predicts that intraguild predation hampers coexistence of species involved, but it is common in nature. It has been suggested that increasing habitat complexity and the presence of alternative food may promote coexistence. Reciprocal intraguild predation limits possibilities for coexistence even further. Habitat complexity and the presence of alternative food are believed to promote coexistence. We investigated this using two species of predatory mites, Iphiseiodes zuluagai and Euseius concordis, by assessing co‐occurrence in the field and on arenas differing in spatial structure in the laboratory. The predators co‐occured on the same plants in the field. In the laboratory, adults of the two mites fed on juveniles of the other species, both in the presence and the absence of a shared food source, showing that the two species are involved in reciprocal intraguild predation. Adults of I. zuluagai also attacked adults of E. concordis. This suggests limited possibilities for coexistence of the two species. Indeed, E. concordis invariably went extinct extremely rapidly on arenas without spatial structure with populations consisting of all stages of the two predators and with a shared resource. Coexistence was prolonged on host plant leaves with extra food sources, but E. concordis still went extinct. On small, intact plants, coexistence of the two species was much longer, and ended with the other species, I. zuluagai, often going extinct. These results suggest that spatial structure and the presence of alternative food increase the coexistence period of intraguild predators.

Rearing system for the predatory phytoseiid Euseius concordis (Acari: Phytoseiidae).

Several species of predatory mites, especially those of the family Phytoseiidae, are potentially useful for the control of pest mites and insects. Among the phytoseiids, Euseius concordis (Chant), a species commonly found in South America, has been studied for possible use as biological control agent of pest mites. Given that Euseius species are known to feed on plant leaves and on pollen, the objective of this study was to determine plant species and pollen sources suitable to establish a pilot method of production of that species, based on a set of comparisons in the laboratory. Out of four plant species evaluated in the study, higher survivorship of E. concordis females in the absence of supplementary food was observed on leaflets of Canavalia ensiformis L. Out of two pollen types, higher survivorship was obtained on pollen of Typha domingensis L. In a subsequent step, the population of E. concordis increased 19.3× within 21days when that pollen of T. domingensis was offered to the predator on plantlets of C. ensiformis, at 25.0±1°C, 70.0±10% RH and 12h photophase. Future studies may confirm the economic viability of this setup for the mass production of E. concordis.

Susceptibility of Euseius concordis (Mesostigmata: Phytoseiidae) to pesticides used in citrus production systems.

Euseius concordis (Chant) is an important predatory mite found in citrus orchards. The toxicity of 19 pesticides used in citrus orchards on biological and population parameters of this mite was assessed. Our results indicated that formetanate hydrochloride, dimethoate and phosmet were highly harmful (100% mortality) to E. concordis. Carbosulfan, diflubenzuron, fenpropathrin, gamma-cyhalothrin, imidacloprid, lambda-cyhalothrin, lambda-cyhalothrin+thiamethoxam, mineral and vegetable oils, spinosad and thiamethoxam reduced the female's survival and/or fecundity, and were moderately harmful to E. concordis. Besides the acute toxicity, carbosulfan and formetanate hydrochloride were highly persistent [>30days after spraying (DAS)]; dimethoate was moderately persistent (16-30 DAS); spinosad, gamma-cyhalothrin, lambda-cyhalothrin and lambda-cyhalothrin+thiamethoxam were slightly persistent (5-15 DAS); and the other pesticides were considered to be short-lived (<5 DAS). All compounds except lambda-cyhalothrin and thiamethoxam increased the pre-oviposition period in the female offspring. Carbosulfan, deltamethrin, diflubenzuron, etofenprox, fenpropathrin, gamma-cyhalothrin, mineral and vegetable oils, pyriproxyfen and tebufenozide reduced offspring fecundity, whereas thiamethoxam increased the fecundity. Mineral and vegetable oils reduced female longevity of the predator mite. Regarding population effects, imidacloprid, lambda-cyhalothrin, lambda-cyhalothrin+thiamethoxam and thiamethoxam led to an increase in net reproductive rate (R o ), intrinsic rate of increase (r), and finite rate of increase (λ) of E. concordis. Diflubenzuron, etofenprox, and mineral and vegetable oils reduced R o , r and λ. All pesticides except beta-cypermethrin, fenpropathrin and imidacloprid reduced the mean generation time (T) of the predator. Therefore, semi-field and field studies are needed to assess the compatibility of these compounds with E. concordis before adoption in IPM programs.

Moscas blancas y enemigos naturales asociados al cultivo de naranja bajo dos tipos de manejo sanitario en San Pedro, provincia de Buenos Aires

Whiteflies (Hemiptera: Aleyrodidae) are important pests that affect the genus Citrus. The objective of this study was to identify the species present in orange orchards in San Pedro (province of Buenos Aires) and to analyze their population evolution and that of their natural enemies under two sanitary management (conventional and organic). The density of adults, parasitized and non-parasitized nymphs, species and density of predators and parasitoids, presence of sooty mold on leaf/fruit, fruit yield and applied agrochemicals were recorded monthly. The prevalent species of whiteflies were Dialeurodes citri (Ashmead) and Singhiella citrifolii (Morgan), whose adult populations developed between October and May, without differences between types of management. The nymphs were present throughout the year, with higher density in organic crops. Sooty mold levels were similar for both managements. The predator Euseius concordis (Chant) (Acari: Phytoseiidae) was the most abundant natural enemy, with higher density in organic crops compared to conventional ones. There were low levels of parasitism by Encarsia protransvena Viggiani, Encarsia group strenua (Hymenoptera: Aphelinidae) and Neopomphale sp. (Hymenoptera: Eulophidae). The fruit field was higher in the conventional treatment. Results show the need of controlling the pest with less harmful products for the beneficial fauna.

Potential predation of the exotic Amblyseius swirskii on Euseius concordis (Acari: Phytoseiidae), a predatory mite commonly found in Brazil

ABSTRACTIntra/interspecific predation by A. swirskii.Both Benin and Netherlands populations of Amblyseius swirskii engaged in cannibalism, and in predation on Euseius concordis larvae. Provision of pollen decreased cannibalism considerably, but had a smaller effect on predation on E. concordis. Potential effect of the eventual introduction of A. swirskii for control of Bemisia tabaci in Brazil is discussed.

Factitious food for mass production of predaceous phytoseiid mites (Acari: Phytoseiidae) commonly found in Brazil.

Phytoseiid mites are commonly used as biological control agents of mite and small insect pests. To facilitate the production of phytoseiids, alternative food sources have been evaluated. The aim of this study was to evaluate the suitability of different food sources for the rearing of the phytoseiids Amblyseius tamatavensis Blommers, Euseius concordis (Chant) and Neoseiulus anonymus (Chant and Baker). This study evaluated the levels of oviposition of these predators when fed with 15 Astigmatina (Sarcoptiformes) mite species, one species of a bacteriophagous nematode, and pollen from five plant species. The highest oviposition rates of A. tamatavensis were obtained when fed on the mites Thyreophagus cracentiseta Barbosa, OConnor & Moraes and Aleuroglyphus ovatus (Troupeau) (2.6 and 2.1eggs/female/day, respectively). The five highest oviposition levels of E. concordis occurred when the food source was pollen, especially of Ricinus communis L. (1.7eggs/female/day). The evaluated oviposition levels of N. anonymus were at most 0.5eggs/female/day on all food sources. The construction of life tables of A. tamatavensis and E. concordis with the two most favorable food sources showed that in both cases the values of rm were higher when the predator was fed with T. cracentiseta and R. communis, respectively. The possible use of pollen of Elaeis guineensis L. should be further evaluated, given the acceptance of this type of pollen by E. concordis and the ease of obtaining large amounts of this pollen in areas where this crop is grown.

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.