Agroforestry management and phytoseiid communities in vineyards in the South of France

This study deals with the long-term effect of agroforestry management (trees within vine crops) on communities of phytoseiid mites. Several plots were considered: vineyards co-planted with Sorbus domestica or Pinus pinea, monocultures of vines and monocultures of S. domestica or P. pinea. All vine plots included two vine cultivars, Syrah and Grenache. Phytoseiid mites have been surveyed in these plots during several years within the previous 10 years. In 2010, samplings were again carried out in these same plots, from May to September, twice a month. Significantly higher densities of Phytoseiidae were observed on the cultivar Syrah (0.85 phytoseiids per leaf) than on Grenache (0.26 phytoseiids per leaf). Furthermore, significantly higher phytoseiid mite densities were observed in the monocultural grapevine plot than in the two co-planted ones. The main species found was Typhlodromus (Typhlodromus) exhilaratus in all vine plots considered. However, Kampimodromus aberrans was observed in the grapevine plots co-planted with the two trees, but never in the monocultural vine plot. Surprisingly, this phytoseiid species was not found on the co-planted trees, nor in the neighbouring uncultivated vegetation. Several hypotheses are discussed to explain such an unexpected distribution. Furthermore, contrary to what has been observed previously, agroforestry management did not seem to favour phytoseiid mite development, especially on the Grenache cultivar. Again, some hypotheses are developed to explain such observations and density modifications.     

Immigration of Phytoseiid Mites from Surrounding Uncultivated Areas into a Newly Planted Vineyard

This study reports (1) a faunistic survey of phytoseiid mites observed inside a vine plot and in neighbouring vegetation (other vine plots and uncultivated areas) and (2) dispersal of phytoseiid mites into the plot studied. These data aim to raise some hypotheses concerning natural colonisation of a vineyard by predatory mites. The study was carried out over 3 years (1999, 2000 and 2001) in an experimental plot planted with two cultivars (Grenache and Syrah) and with Sorbus domestica in a framework of agroforestry investigations. Phytoseiid mites were collected in both cultivated and uncultivated areas surrounding the experimental plot, and their dispersal into the plot studied using “aerial” traps. Densities remained quite low compared to previous studies. The main species encountered in the uncultivated areas and in the traps was Typhlodromus phialatus. Despite the low numbers of phytoseiid mites trapped, densities of phytoseiid mites into the vine field increased during 3 years. Typhlodromus phialatus, the species mainly found in the neighbouring uncultivated areas, was rarely found in vineyards. Another morphologically close species was predominant on vines: Typhlodromus exhilaratus. However, Kampimodromus aberrans the main phytoseiid mite species in vineyards of Southern France was not found in the present survey. Hypotheses for this colonisation process are discussed.     

Assessment of pesticide susceptibility for <Emphasis Type="Italic">Typhlodromus exhilaratus</Emphasis> and <Emphasis Type="Italic">Typhlodromus phialatus</Emphasis> strains (Acari: Phytoseiidae) from vineyards in the south of France

Two species of Phytoseiidae predominated in and around vineyards in an experimental site in the south of France: Typhlodromus exhilaratus is the dominant species on grapes, whereas T. phialatus occurs in the uncultivated areas surrounding these crops. To help understand their distribution, this study aims to determine their susceptibility to a fungicide (dimethomorph + mancozeb) and an insecticide (chlorpyriphos-ethyl), which have been widely used at the experimental site for at least four years. The hypothesis tested is that the effects of these two pesticides differ between T. exhilaratus and T. phialatus. Two populations of T. exhilaratus, one collected on a vine crop where the two pesticides were applied and the other in an unsprayed orchard of Sorbus domestica, and one population of T. phialatus collected on Viburnum tinus from uncultivated areas adjacent to the vine crop, were tested under laboratory conditions. The fungicide seems to affect the females of T. phialatus more than those of T. exhilaratus from vine. However, at the recommended field concentration the female mortality rates of the three strains were low and female fecundities were not significantly different. Conversely, mortality rates were very high for the three strains at the recommended field concentration of chlorpyrifos-ethyl. The strain of T. exhilaratus from vine seems to be more tolerant and 20% of females survived the recommended field rate. This suggests better survival after insecticide application than females of T. phialatus (100% mortality at a lower concentration than the recommended rate). As extrapolation of laboratory results to the field is often irrelevant, these differences could be just one of several factors affecting the spatial segregation of the two species in the agrosystem considered. Possible explanations other than pesticides for the poor settlement of T. phialatus in vine plots are discussed.     

Cannibalism and intraguild predation in Typhlodromus exhilaratus and T. phialatus (Acari: Phytoseiidae) under laboratory conditions

Two species of Phytoseiidae are found in the same agroecosystem: Typhlodromus exhilaratus prevails in vine plots, while T. phialatus prevails in uncultivated surrounding areas. The objective of the present paper was to investigate whether the poor settlement of T. phialatus in vine plots can be explained by intraguild predation of these two species and/or cannibalism. Predatory abilities of the females on larvae and protonymphs were studied under laboratory conditions. A first experiment was conducted with only conspecific or heterospecific phytoseiid prey, in a second experiment Tetranychus urticae eggs were added to the phytoseiid prey. Oviposition, prey consumption, and escape rates of females were recorded. Oviposition and intraguild predation rates were higher for T. exhilaratus than for T. phialatus. Typhlodromus exhilaratus consumed fewer conspecifics than heterospecific phytoseiids, and oviposited when feeding on both diets. Typhlodromus phialatus consumed equal amounts of con- and heterospecifics. Although these two generalist predators belong to the type III defined by McMurtry and Croft (Annual Review of Entomology 42:291–321, 1997), our results suggest that they have different predation behaviour. However, because these results were obtained in experiments where no choice was given between the two phytoseiid species, they are difficult to link to previous studies conducted on the intraguild predation of the Phytoseiidae. The greater voracity and prolificacy of T. exhilaratus could partially explain the poor settlement of T. phialatus in vineyards and the predominance of T. exhilaratus. However, a full understanding of this phenomenon will require the study of other factors, such as susceptibility to pesticides and micro-climatic conditions, as well as the ability to cope with different food sources and host plants.     

The presence of <Emphasis Type="Italic">Tetranychus urticae</Emphasis> (Acari: Tetranychidae) and its predators on plants in the ground cover in commercially treated vineyards

The presence of Tetranychus urticae and its predators on plants in the ground cover in commercially treated vineyards in the Hex River Valley, Western Cape Province, South Africa was investigated. Six Barlinka and six Dauphine vineyards were surveyed. Leaf samples from the plants on the vineyard floor were taken at monthly intervals and microscopically examined for spider mites and their predators. The coverage of the plants was determined using a co-ordinate sampling system. A wide variety of plant species was found on the vineyard floor. Most of the spider mites found on these plants were T. urticae. The phytoseiid mites on the plants were Euseius rubicolus, Neoseiulus californicus and an undescribed Typhlodromus species. The presence of these plants made it possible for T. urticae and phytoseiid mites to occur throughout the year, with a similar pattern in their seasonal activity on the vineyard floor and the vine leaves.     

Overwintering phenology of a predacious mite, Typhlodromus vulgaris (Acari: Phytoseiidae), on Japanese pear trees, observed with Phyto traps

Phyto traps were attached to twigs, main branches and trunks of Japanese pear trees in central Japan in autumn of 2004, to evaluate the effectiveness of the trap as a tool to study overwintering phenology of arboreal phytoseiid mites. A subset of the traps was inspected and replaced at two-weeks intervals (“short-term Phyto trap”), in order to evaluate movement of phytoseiid mites on the trees in a short-term. The remaining traps were left undisturbed and collected monthly from January to May 2005 (“long-term Phyto trap”), to know what species overwinter in the traps and when they leave them. Most phytoseiid mites were collected in the traps on twigs. The most abundant phytoseiid species was Typhlodromus vulgaris Ehara. In the short-term traps on twigs, adult females and males of T. vulgaris were collected until mid-November 2004, when the pear trees became completely defoliated, but few mites were collected from December to April. On the other hand, adult females of T. vulgaris were abundant in the long-term traps on twigs sampled from January to April, but other stages of mites were never collected. These results indicate that T. vulgaris had moved to the long-term traps by late November, and that only adult females had overwintered in the traps. These females began to move and reproduce in early May. By that time immature developmental stages of T. vulgaris were also recorded in the short- and long-term Phyto traps. Our results confirmed that the Phyto trap was a useful tool for estimating overwintering phenology of phytoseiid mites on trees.     

Grape downy mildew Plasmopara viticola, an alternative food for generalist predatory mites occurring in vineyards

Generalist phytoseiids are often observed for long periods on plants in the absence of prey, feeding on alternative foods and reaching high population levels. The persistence of generalist predatory mites on plants with a scarcity or absence of prey is a requirement for successful biocontrol strategies of herbivore mites. The importance of pollen as an alternative food for the support of generalist predatory mite populations is widely recognized. However, on grape the presence of pollen is often limited and thus other food sources should contribute towards generalist predatory mite persistence on perennial plants. Previous field observations reported the relationships between the population increases of generalist phytoseiids with late-season spread of grape downy mildew (GDM) Plasmopara viticola. In this study, we test the hypothesis that GDM could be a suitable food source for the predatory mites Amblyseius andersoni and Typhlodromus pyri. In the laboratory we compared the development times, oviposition rates and life-table parameters of predatory mites feeding on pollen or GDM mycelium and spores. Grape downy mildew supported the survival, development and oviposition of T. pyri and A. andersoni. Life-table parameters showed that GDM was a less suitable food source than pollen for both phytoseiid species and that it was more favorable for A. andersoni than for T. pyri. Implications for predator–prey interactions and conservation biological control in vineyards are discussed.     

Abundance of phytoseiid mites on Vitis species: effects of leaf hairs,domatia, prey abundance and plant phylogeny

We observed the number of predatory mites (Phytoseiidae:Typhlodromus caudiglans) on the foliage of 20 North American species of grapes (Vitis spp) plus the domesticated EuropeanVitis vinifera, all grown in a common garden. We found relatively few phytophagous mites. The numbers of phytophagous mites were not correlated with the plant characteristics that we measured. We found approximately five times as many predatory mites as phytophagous mites and the numbers of these phytoseiid predators were not affected by the availability of prey. Similarly, numbers of phytoseiids were unaffected by plant gender and, hence, the availability of pollen, another source of food. The numbers of phytoseiids were not clustered according to the taxonomic grouping of the tested plant species. Leaf surface characteristics explained over 25% of the variance in the numbers of phytoseiids. Numbers of phytoseiids were positively associated with the density of vein hairs, the density of bristles in leaf axils, and the presence of leaf domatia. These results suggest that sheltered habitats rather than food availability may limit the numbers of phytoseiid mites on grapevines.     

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.     

Feeding behavior ofEuseius stipulatus andTyphlodromus phialatus on the citrus red mitePanonychus citri [Acari: Phytoseiidae,Tetranychidae]

Observations were made on the feeding behavior of the two main phytoseiid species in Spanish Citrus orchards,Euseius stipulatus (Athias-Henriot) andTyphlodromus phialatus Athias-henriot. The experiences were carried out by rearing the predatory mites on excised orange leaves, and always with an excess of the prey the Citrus Red Mite (=CRM)Panonychus citri (McGregor). In experiments with all stages of CRM, the number of prey killed per hour was 5.12 and 2.00, the percentage of successful attacks, 58% and 21%, and the mean time spent feeding on each prey was 5.1 and 12.2 minutes for starving females ofE. stipulatus andT. phialatus respectively.E. stipulatus feeds on all stages of the prey except eggs, andT. philatus, on all stages, except males. Both species attack much less successfully females ofP. citri rather than immatures. In experiments with adult females and eggs ofP. citri as prey, the mean number of prey killed daily was 4.51 females forE. stipulatus, and 2.01 females and 2.12 eggs forT. philatus. Considering this killing rate and the number of eggs laid by the predators in the same period, it can be concluded thatE. stipulatus consumes only 30% of the content of the preys killed, whereasT. philatus consumes a percentage of prey variable between individuals and ranging from 40% to 100%. These differences in feeding behavior between the two species could partly explain differences in their efficiency as biocontrol agents ofP. citri observed in the field.      

Interactions among phytophagous mites, and introduced and naturally occurring predatory mites, on strawberry in the UK

In choice test experiments on strawberry leaf disc arenas the phytoseiid mites Neoseiulus californicus and N. cucumeris were more effective than Typhlodromus pyri as predators of the phytophagous mites Tetranychus urticae and Phytonemus pallidus. There were no preferences shown for either prey by any of these predators. In multiple predator leaf disc experiments both Phytoseiulus persimilis and N. cucumeris significantly reduced numbers of T. urticae eggs and active stages; this effect was seen when the two species were present alone or in combination with other predator species. Neoseiulus californicus was less effective at reducing T. urticae numbers, and T. pyri was not effective; no interaction between predator species was detected in these experiments. When T. urticae alone was present as prey on potted plants, P. persimilis and N. californicus were the only phytoseiids to significantly reduce T. urticae numbers. These two predator species provided effective control of T. urticae when P. pallidus was also present; however, none of the predators reduced numbers of P. pallidus. There were no significant negative interactions when different species of predators were present together on these potted plants. In field experiments, releases of both P. persimilis and N. cucumeris significantly reduced T. urticae numbers. However, there was a significant interaction between these predator species, leading to poorer control of T. urticae when both species were released together. These results show the importance of conducting predator/prey feeding tests at different spatial scales.     

Distortion of the spermathecae of phytoseiid mites (Acari: Phytoseiidae) in slide preparation

The shape and dimensions of the spermathecae are taxonomically important characteristics in phytoseiid mites. In experiments with Neoseiulus californicus (McGregor) and Typhlodromus pyri Scheuten, the shape of the cervix of the spermatheca changed considerably and its diameter was increased by 42–49% when mites were flattened, compared to being mounted with 140m spacers underneath the coverslips. Dimensions of the dorsal shield were also affected by flattening, increasing by 3–5%.     

Survey of natural enemies of spider mites (Acari: Tetranychidae) in citrus orchards in eastern Spain

Field surveys were conducted from 2004 to 2007 to determine the species composition and relative abundance of natural enemies associated with colonies of either the citrus red mite, Panonychus citri, or the two spotted spider mite, Tetranychus urticae, in Valencian citrus orchards (eastern Spain). Fourteen species were recorded, six phytoseiid mites and eight insect predators. Two of them are reported for the first time on citrus in Spain and two more are first reports as predators associated with T. urticae. The community of predators associated with T. urticae and P. citri was almost identical, and the Morisita–Horn index of similarity between both natural enemy complexes was close to one, suggesting that predators forage on both pest species. Quantifying the presence of many known spider mites predators in Valencian citrus orchards is an important first step towards spider mite control. A challenge for future studies will be to establish conservation and/or augmentation management strategies for these predators, especially to improve T. urticae biological control.     

Phytophagous and predatory mites (Acari: Tetranychidae,Eriophyidae, Phytoseiidae,Stigmaeidae) in South Moravian vineyards,Czechoslovakia, treated with various types of chemicals

Communities of phytophagous and predatory mites on vine can be influenced by the type of chemical treatment. Ten species of phytoseiid mites inhabit vines in the region of South Moravia. Populations ofTyphlodromus pyri Scheuten play leading roles in effective suppression of tetranychid and eriophyid mites in commercial vineyards sprayed with pesticides, except synthetic pyrethroids and mancozed, which are considered to be detrimental to the predatory phytoseiid mites.     

Hedges as potential sources ofTyphlodromus pyri,the most important predatory mite in vineyards of Northern Switzerland

This paper presents the results of an acarological survey started in 1984 in hedges bordering vineyards in Northern Switzerland where natural populations of the economically important predatory miteTyphlodromus pyri occur. The objective of these investigations was to identify those plant species in the hedges and forest margins adjacent to vineyards that carry high populations of this important predator, and to evaluate the potential role of hedges as ecological refuges and sources ofT. pyri. We found high and consistent densities ofT. pyri onRubus fruticosus, and less regularly onCornus sanguinea, Corylus avellana andLonicara xylosteum. We conclude that hedges can provide ecological refuges and sources of this economically important predatory mite where earlier applications of inappropriate pesticides have eliminated these important antagonists. However, the inoculative release ofT. pyri along with the increase of the internal ecological diversity of the vineyard achieved by proper management of the green over plants (“weed”) will have a strong influence on predator densities within the vineyards.      

Role of the egg parasitoid Trichogramma minutum in biological control of the grape berry moth, Endopiza viteana

During a survey for natural enemies of thegrape berry moth (GBM) Endopiza viteana(Clemens) in northwestern Pennsylvania, wefound that Trichogramma minutum Riley isthe only native egg parasitoid with thepotential to limit berry damage by preventingegg hatch. Natural parasitism, however, wasfound to be unreliable for providing economicpest suppression. Early season populations ofthe parasitoid are extremely low and may be theresult of inadequate alternative host eggs foroverwintering. Also, wild grapes and theirwooded habitats were found to be favored byT. minutum. Parasitism was low incultivated grapes and in wild grapes growingclose to commercial vineyards (possibly due tothe deterrent effect of insecticides) andhighest in sites 1.5 km from commercialvineyards. Adult T. minutum emergingfrom GBM eggs were exceptionally small andshowed little vigor. Parasitized eggs oftenfailed to produce adult parasitoids. Pre-adults in such eggs had poorly formed mouth-parts or lacked them altogether. Inundativereleases of laboratory-reared T. minutumin border rows of vineyards are suggested as apossible alternative to the current practice ofapplying carbamate and organophosphateinsecticides, which are inimical to beneficialarthropods.     

Cannibalism and Interspecific Predation in a Phytoseiid Predator Guild from Cassava Fields in Africa: Evidence from the Laboratory

Interspecific predation and cannibalism are common types of interaction in phytoseiid predator guilds, but the extent and nature of these interactions have not been determined yet in phytoseiid guilds composed of African native and neotropical exotic phytoseiid predators found in cassava habitat in southern Africa. We determined in laboratory experiments the level of cannibalism and interspecific predation among the three phytoseiid mite species Euseius fustis, Iphiseius degenerans, and Typhlodromalus aripo in the absence of food and in the presence of limited or abundant quantities of two food types – Mononychellus tanajoa and maize pollen – commonly found on cassava in Africa. When confined without food, only two T. aripo females laid each two eggs within 5 days, and this species survived longer than I. degenerans and E. fustis. In the presence of con- or hetero-specific larvae or protonymphs, the three species fed more on the former than on the latter, and more on hetero-specifics than on con-specifics. Oviposition rates of the three species did not exceed 0.7 egg/female/day on con- and hetero-specific immatures. Typhlodromalus aripo and E. fustis survived longer on con-specific and hetero-specific larvae and on hetero-specific protonymphs than in the absence of any food, while T. aripo survived longer than the two other species on the same diets. Provision of limited quantity of food decreased interspecific predation rate by I. degenerans and T. aripo, but not by E. fustis, and increased oviposition rate and longevity of all three species. Provision of abundant food, however, eliminated cannibalism by all three species and further reduced interspecific predation rates, but their oviposition and longevity remained relatively unchanged compared with limited food provision. Potential consequences of cannibalism and interspecific predation among phytoseiid mites on cassava for the biological control of M. tanajoa are discussed.     

Search for effective natural enemies of Tetranychus evansi in south and southeast Brazil

Tetranychus evansi Baker & Pritchard is an important pest of Solanaceae in several countries. Introduced accidentally to Africa, it presently occurs in many countries of that continent. In some of them, it is considered a key pest. The suspected area of origin of this mite is South America. The objective of the present study was to identify phytoseiid mites on solanaceous plants in association with T. evansi in south and southeast Brazil for introduction in the African continent for use in a classic biological control program. Almost 1,400 predatory mites of the family Phytoseiidae were collected, on 22 solanaceous species. The Amblyseiinae were the most diverse group in this study. Twenty-three of the species found belong to this subfamily, while only three belong to the Typhlodrominae and two to the Phytoseiinae. The most abundant and most frequent phytoseiid species were Phytoseius guianensis De Leon and Galendromus annectens (De Leon) of the Phytoseiinae and Typhlodrominae, respectively. The most frequent and abundant species of Amblyseiinae was Neoseiulus tunus (De Leon). Phytoseius guianensis and N. tunus were never found in association with T. evansi and G. annectens was found only once in association with it. Two factors suggested Phytoseiulus longipes Evans as the most promising predator found in this study. It could walk very well on tomato leaves infested by T. evansi, without being hampered by the profuse webbing produced by the prey and by the trichomes. In addition, several specimens of both sexes including eggs and nymphs of the predator were found associated with T. evansi on three different plant species and in two different periods of the year, when T. evansi was the only arthropod present on the leaves.     

The spatial and temporal distribution of predatory and phytophagous mites in field-grown strawberry in the UK

Extensive sampling of strawberry plants in everbearing and June-bearing strawberry plantations and on potted plants showed that different species of mites were spatially separated. Of the two phytophagous species recorded, Tetranychus urticae was most abundant on old leaves and Phytonemus pallidus on folded leaves and flower/fruit clusters. Predatory phytoseiid mites were found on all plant parts but different species were spatially separated; Neoseiulus cucumeris and N. aurescens were found mostly on folded leaves and clusters, and N. californicus and Phytoseiulus persimilis on old and medium aged leaves. No Typhlodromus pyri were found in the field plantations. These patterns of distribution did not change over sampling dates in summer and early autumn. An understanding of this within-plant zonation of mite species is important when studying predator–prey interactions and when designing sampling strategies for strawberry. A programme to sample the entire mite system on strawberry should be stratified to include all the above mentioned parts of the plant. Different sampling protocols, as appropriate, are required for sampling different pest species and their associated predators.     

Diurnal and spatial patterns of Phytoseiidae in the citrus canopy

Phytoseiid mites were sampled in a grapefruit orchard at various times of the day to study their diurnal and seasonal distributions in the tree canopy. Samples were collected on 14, 20 and 28 October 1999 at 2 h intervals from 0600 to 2200 h. Similar samples were collected in a grapefruit orchard at 3 h intervals from 0600 to 2100 h on 9 and 16 March and on 17 and 24 August 2000 for phytoseiid mites. No differences in numbers of phytoseiid motiles were observed among the hours sampled in any of the three months. However, significant differences were observed in the number of phytoseiids per leaf based on location within the tree (eastern, western sides of the canopy or interior). Interior leaves collected in March and August 2000 had higher numbers of phytoseiids than exterior leaves taken from either the eastern or western sides of the tree canopy. Phytoseiids were more abundant in the March 2000 samples (mean = 1.10 phytoseiids/leaf) than in either October 1999 or August 2000 samples (mean = 0.16 and 0.19 phytoseiids/leaf, respectively). Prevalent phytoseiid species were Typhlodromalus peregrinus (Muma) (42.1%) and Iphiseiodes quadripilis (Banks) (50.4%) in October 1999, Typhlodromalus peregrinus (Muma) (76.2%) in March 2000, and Euseius mesembrinus (Dean) (54%) in August 2000.