Densities Of Predatory Mites Research Articles

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

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

Practical use of inoculative release of the predatory mite, <i>Amblyseius swirskii</i> Athias-Henriot, against thrips on broad bean in open fields

The practical effect of the inoculative release of the predatory mite Amblyseius swirskii Athias-Henriot against thrips on broad bean was evaluated in commercial farmer fields. Experiments were conducted at six different fields from October to December in 2019 in Ibusuki City, Kagoshima, Japan. The dominant species of thrips was Thrips hawaiiensis（Morgan）. The population densities of thrips when A. swirskii was released were significantly lower throughout experiment and decreased by approximately 35% on average compared to the control （non-treatment） trials in the five fields. However, the predatory mites were not effective in one field. Differences in the densities of predatory mites on broad bean might affect the efficacy. Further research is required to improve the efficacy and success of biological control for broad bean.

Fungicide reduction favors the control of phytophagous mites under both organic and conventional viticulture

Pesticides can have detrimental effects on non-target biodiversity, especially in intensively managed agroecosystems such as vineyards. However, new fungus-resistant grape varieties can greatly reduce the need and use of fungicides. Fungicides can have direct and indirect effects on economically important predatory mites (mainly Phytoseiidae) and on phytophagous mites (Tetranychidae, Eriophyidae) on which they prey. We investigated the impact of fungicide treatments on beneficial and phytophagous mite densities in 32 vineyards of organic and conventional wineries planted with susceptible and fungus-resistant grape varieties in the Palatinate region, Germany. Organic vineyards were sprayed with different formulations of sulfur, copper and potassium bicarbonate, while conventional vineyards received mostly synthetic fungicides. Fungicide applications were reduced by 47-80 % in fungus-resistant varieties, with stronger reductions under organic than under conventional management. Regardless of organic or conventional management, predatory mites (Phytoseiidae and Tydeidae) were significantly enhanced in vineyards planted with fungus-resistant varieties. Contrastingly, phytophagous mites (Eriophyidae) were enhanced in vineyards with fungus-susceptible varieties and in those under organic management. Densities of further predatory mite families increased under organic farming (Anystidae) or showed an interactive response to farming system and grape variety (Trombidiidae). Reduced fungicide applications through cultivation of fungus-resistant varieties enhance predatory mite densities and thus contribute to higher natural pest control potential. Thus, the cultivation of fungus-resistant grape varieties is an effective approach towards more environmentally friendly viticulture.

Predatory Mites (Acari: Phytoseiidae) in Agro-Ecosystems and Conservation Biological Control: A Review and Explorative Approach for Forecasting Plant-Predatory Mite Interactions and Mite Dispersal

Phytoseiidae mites are efficient predators able to control pest mites and small arthropods in crops all over the world, using the three biological control strategies : (i) augmentation, (ii) classical and (iii) conservation. This paper focuses on this latter strategy. Most of those predatory mite species are generalist predators; they are naturally present in agro-ecosystems both on crops and adjacent natural vegetation. Because of such characteristics, their occurrence is usually associated to a lesser use of pesticides providing so ecosystem services. As a first baseline for managing their occurrence in agro-ecosystems, a review of the present knowledge of plants and predatory mite interactions and predator dispersal ability is proposed. In addition, based on the author own occurrence database, the study aims at analysing (i) plant traits and the potential co-evolutionary relationships between plants and predatory mite species and (ii) how this can be used for forecasting the plants favourable to key predatory mites. For this, some examples were taken, i.e. vine and citrus crops, and three species, Kampimodromus aberrans, Euseius stipulatus and Typhlodromus (Typhlodromus) pyri. The main conclusion is that the occurrence database can help in determining the probability to find some predatory mite species on crops and non crop plants. However, because some elements are lacking, especially predatory mite density, plant traits and real overall distribution, it is at that time and using the analyses presently carried out, difficult to associate plant traits and plant phylogeny to Phytoseiidae diversity. Additional meta-analyses in collaboration with plant specialists would be required. Finally, the paper presents some examples of agroecosystem management at different scales (intercropping, agroforestry, borders management, landscape).

Minimal Pruning and Reduced Plant Protection Promote Predatory Mites in Grapevine.

Improving natural pest control by promoting high densities of predatory mites (Acari: Phytoseiidae) is an effective way to prevent damage by pest mites (e.g., Eriophyidae, Tetranychidae) and other arthropod taxa that can cause serious damage to vineyards. Here, we investigate the influence of innovative management on predatory mite densities. We compare (i) full versus reduced fungicide applications and (ii) minimal pruning versus a traditional trellis pruning system in four fungus-resistant grapevine varieties. As predatory mites also feed on fungus mycelium, we assessed fungal infection of grapevine leaves in the experimental vineyard. Predatory mites were significantly more abundant in both minimal pruning and under reduced plant protection. Increases in predatory mites appeared to be independent of fungal infection, suggesting mostly direct effects of reduced fungicides and minimal pruning. In contrast to predatory mites, pest mites did not increase under innovative management. Thus, conditions for natural pest control are improved in fungus-resistant grapevines and under minimal pruning, which adds to other advantages such as environmental safety and reduced production cost.

<p class="HeadingRunIn"><strong>The biodiversity, density and population trend of mites (Acari) on <em>Capsicum annuum</em> L. in temperate and semi-arid zones of Turkey</strong></p>

This study investigated mite biodiversity and density on Capsicum annuum in temperate (Bursa and Yalova provinces) and semi-arid (Ankara province) zones of Turkey from 2009 to 2010. A total of twenty-six phytophagous, predatory and generalist mite species were established on pepper leaves. Tetranychus urticae (Tetranychidae) was the single predominant species on the plants in all zones, while Phytoseius plumifer, Neoseiulus californicus (Phytoseiidae) and Tarsonemus bifurcatus (Tarsonemidae) were found to be other common species. Mite diversity and density were higher in temperate zone provinces than in Ankara, which has semi-arid conditions. This variation was significantly correlated with high humidity in the temperate zone, but only for phytophagous mites. The highest number of predatory species was found in the temperate zone, a finding also correlated with humidity, but not significantly. Although phytophagous mite diversity was lower than that of predatory mites in both zones, phytophagous mites were more than abundant than both predatory and generalist mites. The current study observed a significantly high population density of T. urticae from late July to mid August of 2010 and 2011. The sharp decline in T. urticae density on pepper was found to be associated with the onset of rainfall in June and September. Consequently, similar population growth patterns in phytoseiids [Neoseiulus bicaudus, N. californicus and Typhlodromus (Anthoseius) recki in Bursa and Yalova; Phytoseius plumifer in Ankara] were found in all zones and in both years. Generally, predatory mite density showed a gradually increasing population growth pattern from late July to early October.

Role of supplemental foods and habitat structural complexity in persistence and coexistence of generalist predatory mites.

Plant traits can influence the interactions between herbivore arthropods and their natural enemies. In these interactions generalist predators are often present, preying on herbivores and also on other arthropods in the same trophic guild. Variation in the strength of intraguild predation (IGP) may be related to habitat structural complexity and to additional resources outside the narrow predator-prey relationship. In this paper we study the food web interactions on grape, which involves two generalist predatory mites. We evaluated the effects of grape powdery mildew (GPM) as supplemental food, and habitat structural complexity provided by domatia. The inoculation of GPM resulted in higher predatory mite densities and reduced the negative impact of unfavorable leaf structure for one species. Access to domatia was the main factor in promoting population abundance and persistence of predatory mites. Access to domatia and GPM availability favored the coexistence of predatory mites at a low density of the intraguild prey. Our findings suggest that structural and nutritional diversity/complexity promote predatory mite abundance and can help to maintain the beneficial mites - plants association. The effect of these factors on coexistence between predators is influenced by the supplemental food quality and relative differences in body size of interacting species.

Supplemental food that supports both predator and pest: a risk for biological control?

Supplemental food sources to support natural enemies in crops are increasingly being tested and used. This is particularly interesting for generalist predators that can reproduce on these food sources. However, a potential risk for pest control could occur when herbivores also benefit from supplemental food sources. In order to optimize biological control, it may be important to select food sources that support predator populations more than herbivore populations. In this study we evaluated the nutritional quality of four types of supplemental food for the generalist predatory mites Amblyseius swirskii Athias-Henriot and Amblydromalus (Typhlodromalus) limonicus (Garman and McGregor), both important thrips predators, and for the herbivore western flower thrips Frankliniella occidentalis Pergande, by assessing oviposition rates. These tests showed that application of corn pollen, cattail pollen or sterilized eggs of Ephestia kuehniella Zeller to chrysanthemum leaves resulted in three times higher oviposition rates of thrips compared to leaves without additional food. None of the tested food sources promoted predatory mites or western flower thrips exclusively. Decapsulated cysts of Artemia franciscana Kellogg were not suitable, whereas cattail pollen was very suitable for both predatory mites and western flower thrips. In addition, we found that the rate of thrips predation by A. swirskii can be reduced by 50 %, when pollen is present. Nevertheless, application of pollen or Ephestia eggs to a chrysanthemum crop still strongly enhanced the biological control of thrips with A. swirskii, both at low and high release densities of predatory mites through the strong numerical response of the predators. Despite these positive results, application in a crop should be approached with caution, as the results may strongly depend on the initial predator-prey ratio, the nutritional quality of the supplemental food source, the species of predatory mites, the distribution of the food in the crop and the type of crop.

Effect of different ground cover management on spider mites (Acari: Tetranychidae) and their phytoseiid (Acari: Phytoseiidae) enemies in citrus orchards

We determined the effect of ground cover on phytoseiid predatory mite populations and the potential biological control of Panonychus citri (McGregor). Results showed that citrus trees with ground cover contained higher population densities of predatory mites and provided better regulation of P. citri than trees in bare soil. The ground cover Ageratum conyzoides L. performed better than Palspalum notatum Flugge in sheltering phytoseiid mites.

夏秋ピーマンにおけるスワルスキーカブリダニの主要微小害虫に対する防除効果と硫黄粉剤畝上散布が密度に及ぼす影響

夏秋ピーマンにおけるスワルスキーカブリダニの主要微小害虫に対する防除効果と硫黄粉剤畝上散布が密度に及ぼす影響

Influence of leaf trichomes on predatory mite density and distribution in plant assemblages and implications for biological control

Non-glandular trichomes on leaves or stems are strongly positively correlated with the abundance of many predatory phytoseiid mite species. Some perennial fruit crops have few or no trichomes and overcoming this limitation of leaf habitat for natural enemy mites could improve biological control of pest mites in agricultural crops. This study evaluated whether juxtaposing plants with and without trichomes will promote more abundant natural enemies throughout an ensemble of plants. We first asked whether the pattern of increased phytoseiid retention with higher trichome densities on a single leaf “scales up” to larger plantings. For three patch sizes (1, 4 or 16 plants) of two grape varieties inoculated with phytoseiids, no strong effect of patch size on Typhlodromus pyri Scheuten abundance was observed in the trichome-rich Baco plantings or in the trichome-free Dechaunac plantings. No predator populations established in Dechaunac plantings of any size. Second, we asked whether the addition of a plant with leaf trichomes within a row (“array”) of plants lacking leaf trichomes can increase phytoseiid density throughout arrays. In both a greenhouse and a field experiment, predatory mites moved onto and established on a neighboring plant only if that plant had trichomes; phytoseiids rapidly dispersed from trichome-free plants even when the plant was the one inoculated with predators. The overall number of phytoseiids decreased over time in ensembles that included both trichome-rich and trichome-free plants in the greenhouse and the field experiments, clearly indicating that for biological control programs to be successful, all plants must express trichomes.

Leaf trichomes influence predatory mite densities through dispersal behavior

AbstractHabitat complexity can mediate interactions among predators and herbivores and influences arthropod population density and community structure. The abundance of many predatory mites (Acari: Phytoseiidae) is positively associated with abundance of non‐glandular trichomes. We hypothesized that (1) increasing the complexity (trichome density mimicked with cotton fiber patches) of the habitat that predatory mites encounter on leaves would reduce adult dispersal from plants, and (2) increasing habitat complexity would reduce the time that mites spend walking. Typhlodromus pyri Scheuten retention on plants increased linearly in the presence of trichome mimics; mites placed on plants lacking leaf trichomes showed a behavioral response that led to active dispersal. Phytoseiid retention increased with both fiber patch size and fiber density within patches. Moving fiber patches from the underside of the leaf to the upper leaf surface did not change phytoseiid retention but did alter egg distribution, suggesting trichomes do not exclusively influence phytoseiid behavior. Phytoseiid activity level as measured by the amount of time spent walking did not decrease with the addition of fibers. Overall, increasing habitat complexity in the form of non‐glandular trichomes strongly reduced T. pyri dispersal behavior; the predatory mites showed a consistent preference for complex trichome‐rich habitat that was manifest both rapidly and in absence of predators. Hence, the frequently observed pattern of population‐level accumulation of phytoseiids on trichome‐rich plants appears to be driven by a behavioral response to the presence and abundance of non‐glandular trichomes on the leaf surface manifested in the level of dispersal and/or retention. The primary implication of phytoseiid–habitat interactions for biocontrol programs is that where plants have no trichomes, T. pyri will not establish. Whether this behavioral response pattern is a general response of phytoseiids to leaf trichomes or varies with species is a question that remains unanswered.

Effects of Generalist Phytoseiid Mites and Grapevine Canopy Structure on Spider Mite (Acari: Tetranychidae) Biocontrol

Specialist-feeding phytoseiid mites have a well-documented role in biological control of phytophagous spider mites. However, although there is evidence for the importance of generalist-feeding phytoseiid mites in spider mite suppression, their role is less clear than that of specialists. The effectiveness of generalists as biocontrol agents and their interactions with specialists might be directly influenced by canopy structure or indirectly affected by altering plant microclimate. We manipulated densities of generalist phytoseiid mites and canopy size (large and small) in open-field experiments in an abandoned vineyard. In the first experiment, we increased generalist densities by transferring grapevine foliage housing robust generalist populations, whereas in the second experiment, we lowered generalist densities using the broad-spectrum insecticide chlorpyrifos. In both experiments, we also altered canopy size by tying grapevine shoots. Increasing densities of generalists resulted in lower spider mite densities. Generalists initially decreased densities of specialist phytoseiid mites as well, although specialist densities rebounded as spider mite densities increased later in the experiment. Lowering generalist densities appeared to slightly increase densities of both spider and specialist mites, consistent with the first experiment. However, these effects were not statistically significant, possibly because the reduction in generalist densities through chlorpyrifos application was not as dramatic as our generalist augmentation in the first experiment. Canopy size did not significantly affect pest or predatory mite densities in either experiment. These field experiments demonstrate that generalists can slow spider mite population growth in grapes. In contrast, canopy architecture appeared to have little impact on spider mite biocontrol.

Role of neonicotinyl insecticides in Washington apple integrated pest management. Part II. Nontarget effects on integrated mite control

The effect of neonicotinyl insecticides on integrated mite control in Washington apple was examined from 0 In a series of 20 field trials (54 treatments) designed primarily to look at efficacy against the codling moth, Cydia pomonella, nearly half of the treatments using four or more applications of acetamiprid had peak mite densities exceeding the economic threshold of 5 mites per leaf. Overall, acetamiprid treatments had 4.6-fold higher mite densities than the standard organophosphate insecticide treatment. Of the treatments with high mite populations, Panonychus ulmi, the European red mite, and Tetranychus urticae, the twospotted spider mite, were the dominant species in roughly equal numbers of cases. Only 11.1% of the thiacloprid treatments exceeded 5 mites per leaf; these experimental treatments included eight applications, whereas the current label restricts the number of applications at the rate for C. pomonella to two applications. One out of six clothianidin treatments caused a significantly higher mite density than the standard treatment; however, this material appeared to suppress predatory mites. Neonicotinyl insecticides did not eliminate predatory mites, but they inhibited their ability to respond normally to increasing prey populations. In field trials designed specifically to examine mite population densities where neonicotinyl insecticides were used, significantly higher levels of tetranychid mites occurred in one or more acetamiprid treatments (one, two or four applications) in five out of six trials. In the sixth trial (in a commercial orchard), only two acetamiprid applications were made, and mite populations were low in all treatments. While elevated mite densities were more likely to occur with four applications, in one case it occurred following a single application. The predominant tetranychid mite species (either P. ulmi or T. urticae) varied from trial to trial; however, there was no apparent bias regarding stimulation of the two species. Horticultural mineral oil was used with acetamiprid in some trials in an attempt to mitigate mite outbreaks. However, the addition of oil did not counteract the tendency of acetamiprid to increase tetranychid mite populations, and in one trial, had a negative effect on predatory mite densities. Seasonal tetranychid mite density was positively related to the total grams AI (or number of applications) of acetamiprid, thus reducing the number of applications per season should lower the probability of mite outbreaks.AI active ingredient CMD cumulative mite days

Role of neonicotinyl insecticides in Washington apple integrated pest management. Part II. Nontarget effects on integrated mite control

The effect of neonicotinyl insecticides on integrated mite control in Washington apple was examined from 0 In a series of 20 field trials (54 treatments) designed primarily to look at efficacy against the codling moth, Cydia pomonella, nearly half of the treatments using four or more applications of acetamiprid had peak mite densities exceeding the economic threshold of 5 mites per leaf. Overall, acetamiprid treatments had 4.6-fold higher mite densities than the standard organophosphate insecticide treatment. Of the treatments with high mite populations, Panonychus ulmi, the European red mite, and Tetranychus urticae, the twospotted spider mite, were the dominant species in roughly equal numbers of cases. Only 11.1% of the thiacloprid treatments exceeded 5 mites per leaf; these experimental treatments included eight applications, whereas the current label restricts the number of applications at the rate for C. pomonella to two applications. One out of six clothianidin treatments caused a significantly higher mite density than the standard treatment; however, this material appeared to suppress predatory mites. Neonicotinyl insecticides did not eliminate predatory mites, but they inhibited their ability to respond normally to increasing prey populations. In field trials designed specifically to examine mite population densities where neonicotinyl insecticides were used, significantly higher levels of tetranychid mites occurred in one or more acetamiprid treatments (one, two or four applications) in five out of six trials. In the sixth trial (in a commercial orchard), only two acetamiprid applications were made, and mite populations were low in all treatments. While elevated mite densities were more likely to occur with four applications, in one case it occurred following a single application. The predominant tetranychid mite species (either P. ulmi or T. urticae) varied from trial to trial; however, there was no apparent bias regarding stimulation of the two species. Horticultural mineral oil was used with acetamiprid in some trials in an attempt to mitigate mite outbreaks. However, the addition of oil did not counteract the tendency of acetamiprid to increase tetranychid mite populations, and in one trial, had a negative effect on predatory mite densities. Seasonal tetranychid mite density was positively related to the total grams AI (or number of applications) of acetamiprid, thus reducing the number of applications per season should lower the probability of mite outbreaks.

Distribution patterns of coconut mite, Aceria guerreronis, and its predator Neoseiulus aff. paspalivorus in coconut palms.

Distribution patterns and numerical variability of the coconut mite Aceria guerreronis Keifer (Acari: Eriophyidae) and its predator Neoseiulus aff. paspalivorus DeLeon (Phytoseiidae) on the nuts of 3- to 7-month-old bunches of coconut palms were studied at two sites in Sri Lanka. At the two sites, coconut mites were present on 88 and 75% of the nuts but no more than three-quarters of those nuts showed damage symptoms. N. aff. paspalivorus was found more on mature nuts than on immature nuts. Spatial and temporal distribution of coconut mites and predatory mites differed significantly. The mean number of coconut mites per nut increased until 5-month-old bunches and declined thereafter. The densities of predatory mites followed a similar trend but peaked 1 month later. Variability in the numbers of mites among palms and bunches of the same age was great, but was relatively low on 6-month-old bunches. The results indicate that assessment of infestation levels by damage symptoms alone is not reliable. Sampling of coconut and/or predatory mite numbers could be improved by using several nuts of 6-month-old bunches. The effect of predatory mites on coconut mites over time suggests that N. aff. paspalivorus could be a prospective biological control agent of A. guerreronis.

Soil microarthropod community structure and dynamics in organic and conventionally managed apple orchards in Western Colorado, USA

We studied the influences of organic and conventional management practices on microarthropod diversity, densities, and dynamics in apple orchards on the Western Slope of Colorado. The ‘organic’ orchards differed from the ‘conventional’ orchards in that they used natural fertilizers (versus synthetic) and did not use insecticides and/or herbicides. Based on findings from annual agroecosystems, we hypothesized that the conventionally managed (CM) apple orchards would support a lower diversity and density of soil microarthropods than the organically managed (OM) apple orchards. We located nine sites, three OM orchards, three CM orchards, and three native sites. From each site, microarthropods were extracted from soil samples taken from June to September of 1997 and April to September of 1998. The richness and diversity of functional groups and families did not differ among the OM orchards, CM orchards and/or native sites. We did find significantly greater ( P≤0.05) densities of soil microarthropods early in growing season, June 1997 and April 1998, in the OM orchards in comparison to the CM orchards and native sites. Furthermore, the densities of predatory mites were significantly greater in the OM orchards in comparison to both the CM orchards and native sites on selective dates throughout the period of study. Organic management practices have increased the densities of microarthropods above those found in CM orchards and native sites. These results may be due to the interaction between a greater accumulation of plant litter and organic matter in the OM orchards and the heavy pesticide use in the CM orchards.

Diflubenzuron-Based Management of the Pear Pest Complex in Commercial Orchards of the Hood River Valley in Oregon

In the Hood River Valley of Oregon, a pear pest management program based on the insect growth regulator, diflubenzuron, was compared with conventional programs based on broad-spectrum pesticides during 1987-1989. Diflubenzuron-based programs allowed for the immigration and development of natural enemies of the pear psylla, Cacopsylla pyricola Forster. In 13 of 14 comparisons, natural enemies were more abundant in diflubenzuron-based plots than in conventional plots, but additional psyllacides were almost always required to prevent unacceptable fruit damage. Psylla densities were determined by both pesticide applications and seasonal predator-prey interactions. Psylla densities were lower in plots where a light oil was added to the first 2 diflubenzuron applications. Codling moth, Cydia pomonella (L.), were suppressed effectively in both diflubenzuron-based and conventional plots. Miticides were frequently required in all plots, conventional or otherwise, but mites were suppressed best in plots where diflubenzuron with oil was applied. Densities of predatory mites were low at all sites during all years.

Interplanting alfalfa as a source of Metaseiulus occidentalis (Acari: Phytoseiidae) for managing spider mites in cotton

Abstract Cotton, Gossypium hirsutum L. (Malvaceae), plots were established in 1988 and 1989 with an alfalfa, Medicago sativa L. (Fabaceae), strip at one edge to determine whether alfalfa could serve as a source of the western predatory mite, Metaseiulus (= Typhlodromus = Galandromus) occidentalis Nesbitt (Acari: Phytoseiidae). Western predatory mites were released into the alfalfa early in the season. Spider mite (Acari: Tetranychidae) and western predatory mite density was monitored in alfalfa and in cotton at varying distances from alfalfa. Western predatory mite successfully established populations in alfalfa in both 1988 and 1989. Western predatory mite density was significantly higher close to alfalfa early in the season, indicating that alfalfa was the source. Average seasonal spider mite density was significantly lower close to the alfalfa. Spider mites were effectively controlled and cotton yield was higher adjacent to alfalfa in 1989 but not in 1988. Our results indicate that there is potential in the use of alfalfa as a nursery crop for enhancing western predatory mites in agricultural systems.