Population survey of phytoseiid mites and spider mites on peach leaves and wild plants in Japanese peach orchard

A population survey of phytoseiid mites and spider mites was conducted on peach leaves and wild plants in Japanese peach orchards having different pesticide practices. The phytoseiid mite species composition on peach leaves and wild plants, as estimated using quantitative sequencing, changed during the survey period. Moreover, it varied among study sites. The phytoseiid mite species compositions were similar between peach leaves and some wild plants, such as Veronica persica, Paederia foetida, Persicaria longiseta, and Oxalis corniculata with larger quantities of phytoseiid mites, especially after mid-summer. A PCR-based method to detect the ribosomal ITS sequences of Tetranychus kanzawai and Panonychus mori from phytoseiid mites was developed. Results showed that Euseius sojaensis (specialized pollen feeder/generalist predator) uses both spider mites as prey in the field.     

Assessment of Amblyseius fallacis (Acari: Phytoseiidae) for biological control of tetranychid mites in an Ontario peach orchard

We introduced a mass-reared pyrethroid-resistant strain of the predatory phytoseiid mite Amblyseius fallacis (Garman) into an Ontario peach orchard in an attempt to control populations of the phytophagous mites Panonychus ulmi Koch and Tetranychus urticae Koch (Acari: Tetranychidae). Releases of 1,000 and 2,000 mites per tree were made, at three different times. The release of 2,000 mites per tree in June and in July resulted in significantly higher phytoseiid densities than was observed on control trees. However, densities of P. ulmi or T. urticae were not significantly affected by any release rate or by timing. The release of 1,000 A. fallacis per tree, or of any density in August, did not significantly increase phytoseiid abundance. In the following year, population dynamics of both phytoseiid and phytophagous mites were not significantly affected by the previous year's release. Amblyseius fallacis can be a useful predator in some fruit orchards. However, further research is necessary into the timing and rate of release, modified spray programmes, and with different crops, in order to clarify the role of this species for biological control in Ontario peach orchards.     

Overwintering Mite Diversity and Their Habitats in Apple and Pear Orchards of Korea with Emphasis on Phytoseiidae and Tetranychidae

Overwintering mite diversity and their habitats were studied in apple and pear orchards during 2002-2003 winter season. Twospotted spider mite was mostly found under the tree barks and fabric strips. European red mites were from crevices of twigs. Tydeid, tarsonemid and oribatid mites were mostly from soil and ground vegetation. Even in the protected overwintering habitat such as artificial fabric strip, twospotted spider mite suffered 81-91% mortality during winter. Predaceous phytoseiid mites found were Amblyseius womersleyi, A. makuwa, A. orientalis, A. rademacheri A. obtuserellus, and A. eharai. Amblyseius womersleyi was the most dominant species in both apple and pear orchards, followed by A. obtuserrellus in apple orchards and A. makuwa in pear orchards. Most phytoseiid mites were found on ground vegetation while their potential prey items were remained on the tree. Implication of the findings for conservation of beneficial mites and biological control of spider mite during season was further discussed.     

Effect of the width of the herbicide strip on mite dynamics in apple orchards

Herbicide strips are used in apple orchards to promote tree growth and survival, to increase yield and to reduce the risk of rodent damage to tree bark. However, herbicide strips, particularly wider ones, may cause problems including soil erosion, reduced organic matter, leaching of nitrates into ground water and increased incidence of plant diseases and pests, including two-spotted spider mites, Tetranychus urticae Koch. In this 2 year study we monitored mite dynamics in apple trees and used sticky bands on tree trunks to determine rates of T. urticae immigration into Nova Spy apple trees in plots with wide (2 m) or narrow (0.5 m) herbicide strips. Use of wider herbicide strips promoted two risk factors that could trigger outbreaks of tetranychid mites. First, concentrations of leaf N in apple trees were higher and those of P and K were lower with the wide strips. Such changes in nutritional quality of leaves would increase the potential for more rapid population growth of T. urticae, and to a lesser extent, the European red mite, Panonychus ulmi (Koch). Second, there were higher rates of T. urticae immigration from the ground cover vegetation into the trees. In 2006, and for most of 2007, densities of T. urticae were higher with wide herbicide strips, whereas densities of P. ulmi were not enhanced. However, by late August to early September in 2007, densities of both tetranychids were lower with wide herbicide strips. This is because both risk factors were counterbalanced, and eventually negated, by the enhanced action of phytoseiid predators, mostly Typhlodromus pyri Scheuten. From July through September 2006, ratios of phytoseiids to tetranychids were always several-fold lower with wide herbicide strips but in 2007, from mid-July onwards, predator–prey ratios were usually several-fold higher with wide strips. However, this numerical response of phytoseiids to prey density can only occur where the pesticide program in orchards is not too harsh on phytoseiids. Hence the impact of width of herbicide strip is contingent on the composition and size of the phytoseiid complex and the impact of pesticides on predation.     

纽氏钝绥螨、尼氏钝绥螨及其猎物—桔全爪螨生态学特性的比较研究

本文从天敌与猎物的种群内禀增长力,天敌对猎物不同密度的功能反应及数值反应三个方面来评价和比较纽氏钝绥螨、尼氏钝绥螨时其猎物——枯全爪螨的控制作用。在五种温度下,两种捕食螨的种群内禀增长力都大于桔全爪螨。它们对猎物的功能反应属HollingⅡ型。尼氏钝绥螨的捕食量大于纽氏钝绥螨,在25℃时两种捕食螨捕食量最大,应用Rogers的模型能较好地对试验结果进行模拟。尼氏钝绥螨对桔全爪不同虫态的取食不存在选择效应,纽氏钝绥螨则嗜食若螨和幼螨。两种捕食螨对桔全爪螨的数值反应表明,仅供给桔全爪螨雌成螨作为食物,对两种捕食螨都不利,尤其对尼氏钝绥螨更为明显。综上所述,两种捕食螨能比较有效地控制桔全爪螨种群,当猎物密度较高时,尼氏钝绥螨控制效果优于纽氏钝绥螨,但纽氏钝绥螨控制效果优于纽氏钝绥螨,但纽氏钝绥螨田间种群数量比尼氏钝绥螨稳定。柑桔园中存在其它补充食物时对这两种捕食敌有利。     

Pollen availability for predaceous mites on apple: spatial and temporal heterogeneity

It has been suggested that an abundance of alternate food early in the spring may be critical to the ability of generalist predaceous mites to suppress spider mite pests. One alternate food that is typically very abundant in spring is wind-dispersed pollen. Here we investigate, at several spatial scales, the heterogeneity in the availability of pollen to predaceous mites on apple. We found pollen to be abundant on apple leaves very soon after they opened (>100 grains/cm 2 ), and that the dominant pollen types at this time were wind-dispersed tree pollens (Betulaceae and Pinaceae). We found that most of the spatial variation in pollen abundance occurred at either small spatial scales (within trees) or very large spatial scales (among orchard blocks). Variability among orchards was clearly influenced by the surrounding vegetation, and probably also by the management regime (frequency of mowing). Spatial heterogeneity in pollen availability may affect the build-up of predatory mite populations in the spring, as we found early season abundances of Typhlodromus pyri (Phytoseiidae) and Zetzellia mali (Stigmaeidae) to be better correlated with early season pollen density than with abundance of mite prey (Aculus schlechtendali).     

Washing technique for monitoring mites in apple orchards

A shake-and-wash technique for monitoring the predatory phytoseiid mitesTyphlodromus pyri, Amblyseius finlandicus, and their prey,Panonychus ulmi, Tetranychus urticae andAculus schlechtendali in commercial apple orchards was developed. The removal and recovery of mites from leaves, shoots and spurs is based on agitating the plant material by hand in alcohol and subsequently removing the mites using a separating funnel. The mites are quickly killed and easily washed off the plant material, and are thus well preserved for further study. The technique is more efficient than directly counting the mites on plant material under a dissection microscope and can be easily employed both in the laboratory and in the field.     

Feeding preference of Zetzellia mali: does absolute or relative abundance of prey matter more?

The importance of the acarine predator, Zetzellia mali, in the control of phytophagous mites in apple orchards is not well understood. Zetzellia mali tends to prefer the eriophyid, Aculus schlechtendali, over the economically more significant tetranychid, Panonychus ulmi, but quite a wide range of preference values have been reported in the literature. In sets of laboratory choice trials, we determined that prey preference of this predator varies with the relative but not absolute density of its prey. We attempt to explain these results in terms of behavioural mechanisms and discuss the potential implications of our results for the effectiveness of Z. mali in the biological control of phytophagous mites in apple orchards.     

Different feeding behaviors in a single predatory mite species. 1. Comparative life histories of three populations of Phytoseiulus longipes (Acari: Phytoseiidae) depending on prey species and plant substrate

The spider mites Tetranychus evansi and T. urticae are key pests of tomato crops, for which no sustainable practical control strategy is available yet. A Brazilian (B) and an Argentinean (A) population of a phytoseiid predatory mite species, Phytoseiulus longipes, are able to develop and reproduce on T. evansi on tomato, whereas a Chilean (C) population is not. In order to better characterize the two distinct feeding behaviours of these three populations, life table data were assessed when the predator was offered T. evansi or T. urticae as prey on bean or tomato leaves. No effect of the prey offered nor the plant substrate was demonstrated on development durations of the three populations. However, immature mortality was low for the Argentinean and the Brazilian populations whatever the prey or plant substrate, whereas 89 % of P. longipes from Chile died before reaching adulthood when fed T. evansi on tomato. No difference in effect on female longevity was detected among the three populations. Finally, the demographic parameters of all populations were lower in presence of tomato compared to beans. Possible explanations for these results are discussed.     

Life-history trade-off in two predator species sharing the same prey: a study on cassava-inhabiting mites

In cassava fields, two species of predatory mites, Typhlodromalus aripo and T. manihoti, co-occur at the plant level and feed on Mononychellus tanajoa , a herbivorous mite. The two predator species are spatially segregated within the plant: T. manihoti dwells on the middle leaves, while T. aripo occurs in the apices of the plant during the day and moves to the first leaves below the apex at night.
To monitor the prey densities experienced by the two predator species in their micro-environment, we assessed prey and predator populations in apices and on the leaves of cassava plants in the field. Prey densities peaked from November to January and reached the lowest levels in July. They were higher on leaves than in the apices. To test whether the life histories of the two predator species are tuned to the prey density they experience, we measured age-specific fecundity and survival of the two predators under three prey density regimes (1 prey female/72 h, 1 prey female/24 h and above the predators level of satiation). T. manihoti had a higher growth rate than T. aripo at high prey densities, mainly due to its higher fecundity. T. aripo had a higher growth rate at low prey density regimes, due to its late fecundity and survival. Thus, each of the two species perform better under the prey density that characterizes their micro-habitat within the plant.     

Aerial dispersal of European red mites (Acari: Tetranychidae) in commercial apple orchards

Aerial dispersal of European red mite, Panonychus ulmi (Koch), in commercial apple orchards was estimated by trapping windborne mites. Studies were conducted at four orchards in eastern New York during 1989 and 1990 and at three orchards in western New York during 1989. In each orchard mites were trapped in three locations; the interior of the orchard, at the border of the orchard and in a field or woodlot beyond the orchard. Large numbers of mites were captured, even when the numbers of mites on apple foliage were well below levels where mite injury to leaves was visible (less than five per leaf). The log numbers of mites trapped were linearly related to the log density of mites on leaves and this relationship was consistent for each year and region the study was conducted. The trap captures among the three locations in and outside an orchard were highly correlated. The implications these findings may have on metapopulation dynamics and resistance to acaricide dynamics are discussed.     

Evidence of a high level of gene flow among apple trees in <Emphasis Type="Italic">Tetranychus urticae</Emphasis>

The dispersal mechanism of the two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) could affect predator–prey population dynamics and the spread of acaricide resistance. To investigate the propensity for spider mite migration in the field, the genetic structure of spider mite populations was studied in two apple orchards using five microsatellite markers. Adult female mites were collected from trees separated by approximately 10–24 m along a line covering a distance of about 100 m. The genetic data suggested that a high population density increased the migration rate among the breeding colonies within a single tree. Spatial autocorrelation analysis suggested a positive genetic structure in the first distance class within the two orchards, which might have been caused by crawling or short-distance aerial dispersal. Meanwhile, mites may also have a large-scale migration system that could cause a high level of gene flow and constrained isolation-by-distance or genetic clines within the approximately 100-m range of the study sites. Therefore, mites might aerially disperse over long distances on a scale of <100 m while also taking shorter trips among nearby trees within a distance of 10–24 m in the apple orchards.     

Irreversible prey diapause as an optimal strategy of a physiologically extended Lotka–Volterra model

We propose an optimal control framework to describe intra-seasonal predator–prey interactions, which are characterized by a continuous-time dynamical model comprising predator and prey density, as well as the energy budget of the prey over the length of a season. The model includes a time-dependent decision variable for the prey, representing the portion of the prey population in time that is active, as opposed to diapausing (a state of physiological rest). The predator follows autonomous dynamics and accordingly it remains active during the season. The proposed model is a generalization of the classical Lotka–Volterra predator–prey model towards non-autonomous dynamics that furthermore includes the effect of an energy variable. The model has been inspired by a specific biological system of predatory mites (Acari: Phytoseiidae) and prey mites (so-called fruit-tree red spider mites) (Acari: Tetranychidae) that feed on leaves of apple trees—its parameters have been instantiated based on laboratory and field studies. The goal of the work is to understand the decisions of the prey mites to enter diapause (a state of physiological rest) given the dynamics of the predatory mites: this is achieved by solving an optimization problem hinging on the maximization of the prey population contribution to the next season. The main features of the optimal strategy for the prey are shown to be that (1) once in diapause, the prey does not become active again within the same season and hence diapause is an irreversible process; (2) for the vast majority of parameter space, the portion of prey individuals entering diapause within the season does not decrease in time; (3) with an increased number of predators, the optimal population strategy for the prey is to start diapause earlier and to enter diapause more gradually. This optimal population strategy will be studied for its ESS properties in a sequel to the work presented in this article.     

Plantago asiatica groundcover supports Amblyseius tsugawai (Acari: Phytoseiidae) populations in apple orchards

Amblyseius tsugawai Ehara (Acari: Phytoseiidae) is a major predator of spider mites in orchards in Japan. To support populations in apple orchards in Akita Prefecture, northern Japan, we investigated whether it can use Plantago asiatica L. as a food resource. In laboratory tests, survival did not differ significantly between female adults given water only and those given a piece of P. asiatica leaf and water. However, A. tsugawai reproduces by feeding on P. asiatica pollen, and significantly more mites were reared on P. asiatica pollen than on tea pollen, which is commonly used for rearing phytoseiid mites. In orchards in 2013, female adults were observed on leaves of P. asiatica from late May; numbers peaked in mid-June and gradually decreased until late July. Most adults were found along veins on the hidden sides of the leaves. Female adults were also collected in Phyto traps attached to plants between late May and early August. Pollen production of P. asiatica peaked from mid-June to early July, when numbers of adults peaked on the plants. These results suggest that conservation of P. asiatica in apple orchards would sustain A. tsugawai populations.     

Pest management systems affect composition but not abundance of phytoseiid mites (Acari: Phytoseiidae) in apple orchards

We examined the faunal composition and abundance of phytoseiid mites (Acari: Phytoseiidae) in apple orchards under different pest management systems in Hungary. A total of 30 apple orchards were surveyed, including abandoned and organic orchards and orchards where integrated pest management (IPM) or broad spectrum insecticides (conventional pest management) were applied. A total of 18 phytoseiid species were found in the canopy of apple trees. Species richness was greatest in the organic orchards (mean: 3.3 species/400 leaves) and the least in the conventional orchards (1.4), with IPM (2.1) and abandoned (2.7) orchards showing intermediate values. The phytoseiid community’s Rényi diversity displayed a similar pattern. However, the total phytoseiid abundance in the orchards with different pest management systems did not differ, with abundance varying between 1.8 and 2.6 phytoseiids/10 leaves. Amblyseius andersoni, Euseius finlandicus, and Typhlodromus pyri were the three most common species. The relative abundance of A. andersoni increased with the pesticide load of the orchards whereas the relative abundance of E. finlandicus decreased. The abundance of T. pyri did not change in the apple orchards under different pest management strategies; regardless of the type of applied treatment, they only displayed greater abundance in five of the orchards. The remaining 15 phytoseiid species only occurred in small numbers, mostly from the abandoned and organic orchards. We identified a negative correlation between the abundance of T. pyri and the other phytoseiids in the abandoned and organic orchards. However, we did not find any similar link between the abundance of A. andersoni and E. finlandicus.     

Coincidental intraguild predation by caterpillars on spider mites

Intraguild predation (IGP) is defined as the killing and eating of prey species by a predator that also can utilize the resources of the prey. It is mainly reported among carnivores that share common herbivorous prey. However, a large chewing herbivore could prey upon sedentary and/or micro herbivores in addition to utilizing a host plant. To investigate such coincidental IGP, we observed the behavioral responses of the polyphagous mite Tetranychus kanzawai Kishida (Acari: Tetranychidae) when its host plant Cayratia japonica (Thunb.) Gagnep. (Vitaceae) was attacked by hornworms, Theretra japonica Boisduval (Sphingidae) and T. oldenlandiae Fabricius (Sphingidae). We also examined an interaction between the oligophagous mite Panonychus citri McGregor (Acari: Tetranychidae) and caterpillars of the swallowtail Papilio xuthus L. (Papilionidae) that share citrus plants as their main food source. Although all T. kanzawai and some active stage P. citri tried to escape from the coincidental IGP, some were consumed together with eggs, quiescent mites, and host plant leaves, suggesting that coincidental IGP occurs on spider mites in the wild. Moreover, neither hornworms nor swallowtail caterpillars distinguished between spider mite-infested and uninfested leaves, suggesting that the mite-infested leaves do not discourage caterpillar feeding. The reasons that the mites have no effective defense against coincidental IGP other than escaping are discussed.     

Eupalopsellidae and Stigmaeidae (Acari: Prostigmata) within citrus orchards in Florida: species distribution,relative and seasonal abundance within trees,associated vines,and ground cover plants

Seven citrus orchards on reduced- to no-pesticide spray programs were sampled for predacious mites in the families Eupalopsellidae and Stigmaeidae (Acari: Prostigmata) in central and south central Florida. Inner and outer canopy leaves, fruit, twigs, and trunk scrapings were sampled monthly between August 1994 and January 1996. Open flowers were sampled in March from five of the sites. Two species of eupalopsellid mites (Exothorhis caudata Summers and Saniosulus harteni (van-Dis and Ueckermann)) were identified from 252 specimens collected within citrus tree canopies within the seven citrus orchards of which 249 were E. caudata. Only two E. caudata were collected from ground cover plants within five of the seven orchards. Eight species of Stigmaeidae were identified from 5,637 specimens: Agistemus floridanus Gonzalez, A. terminalis Gonzalez, Eustigmaeus arcuata (Chandhri), E. sp. near arcuata, E. segnis (Koch), Mediostigmaeus citri (Rakha and McCoy), Stigmaeus seminudus Wood, and Zetzellia languida Gonzalez were collected from within citrus tree canopies from seven orchard sites. Agistemus floridanus was the only species in either family that was abundant with 5,483 collected from within citrus tree canopies compared with only 39 from vine or ground cover plants. A total of 431 samples from one or more of 82 vines and ground cover plants were sampled monthly between September 1994 and January 1996 in five of these orchards and one or more eupalopsellids or stigmaeids were collected from 19 of these plants. Richardia brasiliensis (Meg.) Gomez had nine A. floridanus from 5 of 25 samples collected from this plant. Solanum sp. had five A. floridanus from three samples taken. Both eupalopsellid and stigmaeid species numbers represented <1 % of the total numbers of phytoseiid species taken from the same plants. The two remaining orchards were on full herbicide programs and ground cover plants were absent. Agistemus floridanus was more abundant in the citrus orchards with on-going or recent herbicide programs compared with orchards having well-developed ground cover plants. Agistemus floridanus was most abundant on inner leaves between January and April and again during September through November. Additional collection records of E. caudata, S. harteni, A. terminalis, M. citri, Z. languida, and Zetzellia sp. near silvicola within Florida citrus orchards between 1989 and 2004 are included. Four species of Eupalopsellidae and ten species of Stigmaeidae occur within Florida citrus orchards.     

Functional and Numerical Responses of Three Species of Predatory Phytoseiid Mites (Acari: Phytoseiidae) to Thrips flavidulus (Thysanoptera: Thripidae)

Phytoseiid mites are considered the most effective natural enemies of pest mites. They also have been shown to attack pest thrips. It is unknown, however, whether phytoseiid mites can reduce high densities of Thrips flavidulus (Bagnall). We addressed this question by the study of functional and numerical responses. The aim of this research was to evaluate the potential predation success of the adults of three predatory mites, Neoseiulus cucumeris (Oudemans), Neoseiulus barkeri (Hughes), and Euseius nicholsi (Ehara & Lee), against the first-instar of T. flavidulus in a climatic chamber at five different temperatures. The results showed that the functional responses of those predators reflected the Holling type II functional response and were density dependent and positively related to temperature. For the three predatory mites, predation and successful attack rates increased with increasing temperature up to 26°C, reducing afterward. Handling time had the opposite trend. Reproductive ability also increased with an increase in temperature and prey consumption.     

Effect of a cotton intercrop on spider mite populations in jujube trees

In the arid and semi-arid parts of Xinjiang (China), jujube (Zizyphus jujube Mill) orchards are regularly intercropped with cotton. In 2016–2017, a field study was conducted to compare the species composition and infestation pressure of spider mites in local jujube trees under a cotton-jujube intercropping system and a jujube monocrop system. Our results showed that Tetranychus truncatus Ehara accounted for 94.2–98.5% of all spider mites in either cropping systems. Overall abundance of tree-inhabiting spider mites, including T. truncatus, in intercropped orchards was generally higher than in monocrop ones. Combining our work with earlier findings, we demonstrate how intercropping of cotton and jujube trees generally increases population levels of spider mites on either crop.     

Agistemus aimogastaensis sp. n. (Acari,Actinedida, Stigmaeidae), a recently discovered predator of eriophyid mites Aceria oleae and Oxycenus maxwelli,in?olive orchards in Argentina

A new species, Agistemus aimogastaensis, is described with the aid of optical and Scanning Electron Microscopy. This mite is an important predator of two eriophyid mites (Aceria oleae and Oxycenus maxwelli) in olive orchards (Olea europaea, variety Arauco) in La Rioja Province. The problems related to eriophyids in olive orchards in Argentina are highlighted and photos of the damage on leaves and fruit are included.