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The abundance and diversity of eriophyid and phytoseiid mites in south and central Florida were assessed in six citrus orchards under three different pest management systems, conventional, organic, and untreated. Tree canopy, ground cover, and leaf litter were sampled every two months in two groves for each of the three pest management systems from April 2019 to February 2021. The citrus rust mite, Phyllocoptruta oleivora (Ashmead) represented 95 to 99% of the rust mites sampled in each grove except in one untreated orchard where it accounted for 45% of the samples (n = 938 total P. oleivora mounted specimens). The pink citrus rust mite, Aculops pelekassi (Keifer) was present in organic and untreated orchards at 5% and 28%, respectively, but absent from conventional orchards (n = 134 total A. pelekassi mounted specimens). Twenty-nine species of phytoseiid mites were identified from 1778 specimens. Thirteen species were present in the canopy, fifteen in the ground cover, and eighteen in the leaf litter with some common species among these habitats. In the tree canopy, Typhlodromalus peregrinus (39%), Euseius spp. (25%), and Iphiseiodes quadripilis (19%) were the dominant species. Typhlodromalus peregrinus (43%), Typhlodromips dentilis (25%), and Proprioseiopsis mexicanus (13%) were the major species in the ground cover. Species richness was lower in organic orchards (3.0) compared to conventional and untreated orchards (5.0 and 4.7, respectively). In the leaf litter, Amblyseius curiosus (26%), Proprioseiopsis carolinianus (15%), Chelaseius floridanus (14%), and Amblyseius tamatavensis (12%) were the most common species. Shannon index was significantly higher in conventional orchards (1.45) compared to organic and untreated orchards (1.02 and 1.05, respectively). Evenness was also higher in conventional orchards (0.86) compared to organic and untreated (0.72 and 0.68, respectively). Finding of several phytoseiids in abundance across pest management programs suggest the need for identifying their role in pest suppression particularly mites.

The predatory mite Amblyseius swirskii quickly became one of the most successful biocontrol agents in protected cultivation after its introduction into the market in 2005 and is now released in more than 50 countries. There are several key factors contributing to this success: (1) it can control several major pests including the western flower thrips, Frankliniella occidentalis, the whiteflies Bemisia tabaci and Trialeurodes vaporariorum and the broad mite, Polyphagotarsonemus latus, simultaneously in vegetables and ornamental crops; (2) it can develop and reproduce feeding on non-prey food sources such as pollen, which allows populations of the predator to build up on plants before the pests are present and to persist in the crop during periods when prey is scarce or absent; and (3) it can be easily reared on factitious prey, which allows economic mass production. However, despite the fact that A. swirskii provides growers with a robust control method, external demands were initially a key factor in promoting the use of this predator, particularly in Spain. In 2006, when exports of fresh vegetables from Spain were stopped due to the presence of pesticide residues, growers were forced to look for alternatives to chemical control. This resulted in the massive adoption of biological control-based integrated pest management programmes based on the use of A. swirskii in sweet pepper. Biological control increased from 5 % in 2005, 1 year before A. swirskii was commercially released, to almost 100 % of a total 6,000 ha of protected sweet pepper in Spain within 3 years. Later, it was demonstrated that A. swirskii was equally effective in other crops and countries, resulting in extensive worldwide use of A. swirskii in greenhouses.

In this study, we investigated the effects of different diets on the development and reproduction of the predatory mite Amblyseius eharai. The results show that feeding on citrus red mite (Panonychus citri) led to the fastest life cycle completion (6.9 ± 0.22 days), the longest oviposition period (26.19 ± 0.46 days), the greatest female longevity (42.03 ± 0.43 days), and the highest total number of eggs per female (45.63 ± 0.94 eggs). Feeding on Artemia fanciscana cysts resulted in the highest oviposition rate (1.98 ± 0.04 eggs), a high total number of eggs per female (33.93 ± 0.36 eggs), and the highest intrinsic rate of increase (rm = 0.242). The hatching rate did not differ significantly among the five types of food, and the proportion of females ranged from 60% to 65% across all diets.

Introduced herbivores often alter predator–prey dynamics between native organisms. We investigated whether the exotic mite Raoiella indica can interfere in the predation relationships between the predator Amblyseius largoensis and the native herbivorous mite Oligonychus pratensis and be favored as a result. Populations of A. largoensis were established in laboratory, one reared with exotic prey and another with native prey. For each population, of A. largoensis were evaluated for: egg-to-adult developmental time, oviposition rate, and feed conversion efficiency (FCE) of females. Also, to observe the interaction with prey, behavioral tests were conducted, evaluating the time to the first attack, oviposition site preference, and prey preference consumption. Regardless of prey offered, there was no prey effect on immature developmental time or female oviposition rate. However, A. largoensis showed superior FCE feed on exotic (11.4%) over native prey (3.9%). Both A. largoensis populations preferred to prey on eggs of native species and also tended to choose oviposition sites containing native prey eggs. Those reared on exotic prey attacked their first prey in less time than those reared on native prey. Therefore, the presence of R. indica affects both predator population growth and the feeding preference for native prey, which causes a risk of displacement of O. pratensis .

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.

Cannibalism is commonly found among phytoseiids at almost all mobile life stages. The avoidance of kin cannibalism in the presence of non-kin has been observed in a limited number of phytoseiid species. However, studies examining kin recognition by individuals at different life stages are limited. Early experience with conspecifics can alter individuals’ social behaviour at later stages. In this study, we examined the influence of ontogenetic isolation on cannibalism and kin recognition by the predatory mite Amblyseius herbicolus (Chant) (Acari: Phytoseiidae) at different life stages. In a choice test, A. herbicolus protonymphs, deutonymphs, pre-ovipositional adults, and ovipositional adults were used as predators, and larvae (siblings vs. non-siblings) were given as prey. Two rearing treatments were applied to the predators to generate different social experience during ontogeny: reared in isolation or in pairs with ad libitum mixed stages of Carpoglyphus lactis (Acari: Carpoglyphidae). Social experience with siblings during ontogeny significantly reduced the cannibalism rate. Despite the social experience during ontogeny, protonymphs, deutonymphs, and pre-ovipositional adults did not discriminate siblings from non-siblings during cannibalism. The discrimination behaviour between siblings and non-siblings of A. herbicolus occurred after adults became ovipositional. We hypothesize that A. herbicolus adults could learn the characteristics of their larvae through the contact with and assessment of their eggs during oviposition. The result of this study shows that kin discrimination could be phase-specific. Future studies can investigate if contact with non-kin (or non-sibling) eggs and subsequently hatching larvae can influence the discrimination ability of ovipositional adults.

Diaphorina citri Kuwayama (Hemiptera: Liviidae) is a vector of the bacteria that cause Huanglongbing, the fatal disease threatening citriculture worldwide. One of the most important management methods is the control of D. citri with pesticides, but their intensive use causes development of resistance and pollution. An alternative method is therefore necessary to manage this vector-pathogen system. The generalist predatory mite Amblyseius herbicolus Chant (Acari: Phytoseiidae) can be found on citrus and orange jasmine plants, important hosts of D. citri in Brazil. Here we show that this phytoseiid can reproduce and develop on D. citri eggs. The predation rate was higher on D. citri eggs collected from plants in the field than on eggs from small plants from a laboratory rearing. Yet the predator preferred eggs from the laboratory. This may indicate that the higher predation rate of eggs from the field served to compensate for these eggs being of lower nutritional quality. This was confirmed with a series of experiments with limited numbers of eggs. We conclude that Amblyseius herbicolus is a potential biological control agent of D. citri , and its performance and control may be affected by the quality of the host plant.

Plant diversity can enhance natural pest control in agriculture by providing resources and conditions that are not regularly available in conventional crops to natural enemies of crop pests. Extrafloral nectar-producing plants, for example, might cause reduction of pest densities on neighboring plants because the nectar can increase the performance of natural enemies. Coffee agroforestry systems often contain extrafloral-nectar-producing Inga spp. trees that serve several purposes. Recent studies suggest that they attract and arrest a diversity of natural enemies that contribute to the control of coffee pests. Mites from the Phytoseiid family are key natural enemies of coffee pest mites, but no study has investigated whether Inga extrafloral nectar increases the performance of predatory mites in coffee ecosystems. Thus, here, we assessed whether the extrafloral nectar of Inga edulis Mart. (Fabaceae) can be considered a suitable nutritional resource for the predatory mite Amblyseius herbicolus (Chant), one of the most abundant phytoseiids in coffee crops. We found that feeding on extrafloral nectar allows for development and survival, but not reproduction, of A. herbicolus . Whereas individuals that fed on a diet of nectar during their immature development could subsequently only oviposit after having fed on a pollen diet, individuals that had developed on pollen stopped ovipositing when fed nectar. Our findings suggest that interplanted Inga trees can help to conserve populations of predatory mites in crop ecosystems through the provision of nectar and may boost biological control services. Future research should investigate the effects of extrafloral nectar-producing trees on coffee pest control by these predatory mites.

Our search for a suitable biological agent to control the tomato russet mite (TRM), Aculops lycopersici, was initiated in 2013. Neoseiulus californicus, Amblyseius andersoni, and Neoseiulus fallacis showed a promising pest reduction potential in a curative control strategy. Although these beneficials had a low survival on tomato and were not able to eradicate the pest, plants did not present typical TRM damage. However, their inability to establish in the tomato crop means that their commercial use would require repeated introductions, making their use too expensive for growers. Other predatory mites in the survey, such as the iolinids Homeopronematus anconai and Pronematus ubiquitus, showed the potential for a preventative strategy as they can establish and reach high densities on tomato with weekly or biweekly provision of Typha angustifolia pollen as a food source. When the tomato crop was adequately colonized by either iolinid, the development of TRM and any damage symptoms could be successfully prevented. The potential of iolinid predatory mites for biological control of eriophyids is discussed.

Intraguild predation (IGP) and cannibalism influence the effectiveness of biological control with generalist predators. In Japanese citrus orchards, two generalist phytoseiid species, Euseius sojaensis (Ehara) and Amblyseius eharai Amitai et Swirski, occur simultaneously, but only the former can control Aculops pelekassi (Keifer). First, we investigated the intensity of IGP and cannibalism in E. sojaensis and A. eharai in the presence and absence of pine pollen, which is a high-quality alternative food for these predatory mites. Amblyseius eharai was a stronger intraguild predator and cannibalistic predator than E. sojaensis with or without pollen. In the presence of pollen, although IGP and cannibalism were relaxed in both species, they were not dramatically reduced in A. eharai . Next, we investigated the effects of IGP and cannibalism on A. pelekassi control by changing the release ratio of E. sojaensis and A. eharai in the presence of pollen. With release of E. sojaensis alone, the E. sojaensis population increased and thus A. pelekassi was controlled. With release of A. eharai alone, however, the A. eharai population did not increase and thus A. pelekassi was not controlled. Simultaneous release of E. sojaensis and A. eharai reduced the rate of E. sojaensis population increase. Moreover, A. pelekassi densities were higher with a higher release ratio of A. eharai . These results suggest that A. eharai diminishes the biological control efficiency of the phytoseiid complex owing to IGP and cannibalism, even in the presence of high-quality food, and thus could indirectly increase pest populations.