Historical tests of the toxicity of pesticides to Typhlodromus pyri (Acari: Phytoseiidae) and their relevance to current pest management in New Zealand apple orchards 1. Laboratory tests with eggs and larvae

A two-part review is presented relating historical tests of the toxicity of pesticides to Typhlodromus pyri and their relevance to modern pest management in New Zealand pome-fruit orchards. Over the past thirty years, the initial need for T. pyri resistance to broad-spectrum pesticides has substantially declined as a growing array of new selective chemicals have come into use. In Part 1, a laboratory bioassay is described for determining the toxicity of pesticides to the eggs and larvae of an organophosphate (OP)-resistant strain of Typhlodromus pyri from New Zealand. Apple leaves bearing T. pyri and its prey Panonychus ulmi were collected from the field. Leaf discs with known numbers of eggs (no active stages) of T. pyri and prey were cut from the leaves and sprayed with selected pesticides at recommended field rates to simulate field application. The survival of eggs, and the larvae which hatched from them, were recorded for seven days. Thirteen acaricides, 16 fungicides and 15 insecticides were evaluated. Toxic chemicals were aminocarb, amitraz, benomyl, binapacryl, chlordimeform, ethion, omethoate, oxamyl, permethrin, pirimiphos-methyl and triazophos. Slight and variable toxicity was caused by azinphos-methyl, chlorpyrifos, dinocap, mancozeb + dinocap, metiram + nitrothal-isopropyl, and sulphur. No toxicity was detected with the other 24 pesticides. A comparison of the test results with those from field trials in New Zealand showed good agreement, except that the laboratory tests failed to detect the known field toxicity of dithiocarbamate fungicides and the insecticide vamidothion. Most of the chemicals tested are no longer used in commercial pome-fruit orchards in New Zealand, all of which now practise integrated (IFP) or organic (OFP) fruit production based on selective pest management methods. The tested pesticides of continuing importance are identified, and a summary is presented of the international literature describing the impact on T. pyri of the current pesticides used in New Zealand IFP and OFP. The changes in pesticide use in New Zealand are paralleled by similar changes in most pome-fruit growing areas of the world.     

A laboratory study on the predatory mite,Typhlodromus pyri (Acarina: Phytoseiidae). II The effect of temperature and prey consumption on the numerical reponse of adult females

The numerical response of adult female T. pyri feeding on different levels of ERM larvae, and at a range of temperatures was examined. The duration of the pre-oviposition period decreased as larval consumption increased, and the rate of oviposition was linearly related to the rate of consumption of larvae. Mathematical models were used to describe these relationships in terms of temperature and consumption of ERM larvae. The results were discussed in relation to the nature of the T. pyri/ERM interaction in New Zealand apple orchards.     

Laboratory evaluation of resistance to pesticides in the phytoseiid predator Typhlodromus pyri from English apple orchards

Typhlodromus pyri, reared on plate cultures and fed on pollen of Vicia faba, were bioassayed using a taped-slide technique. Mite stocks from isolated unsprayed orchards were used to establish base-line susceptibility to azinphos-methyl, parathion, carbaryl and permethrin. Stocks from English orchards with a spray history of organophosphates and carbaryl showed resistance of 4 to 6x to azinphos-methyl, c 50 x to parathion, >20x to carbaryl, and no resistance to permethrin. An orchard population derived from T. pyri imported from New Zealand in 1977 responded similarly. In other tests, mites exposed to spray residues on glass and on apple leaves were killed by lower concentrations than in taped-slide tests (glass < apple leaf < taped-slide technique); but for all three assay techniques the resistance factors to azinophos-methyl and carbaryl, comparing two stocks, were similar. All stocks from sprayed orchards were resistant to both azinphos-methyl and carbaryl, suggesting cross-resistance; and resistance to both these pesticides appeared to be stable in the field when selection pressure was relaxed. The results are discussed in relation to earlier work on T. pyri and two other resistant orchard-inhabiting phytoseiid species.     

Toxicity of a number of pesticides to strains ofTyphlodromus pyri andAmblyseius andersoni (Acari: Phytoseiidae)

Side effects of ten pesticides used in orchards and vineyards were tested with a laboratory method on several Dutch and Italian strains of the predatory mitesTyphlodromus pyri Scheuten andAmblyseius andersoni (Chant). Resistant and susceptible strains of both species were studied. Results showed that a test which evaluates mortality of various developmental stages and fecundity of adult females is better than one that measures only survival of adult females. A definite resistance to certain pesticides was found in ItalianT. pyri andA. andersoni. The level of resistance to parathion, azinphos-methyl and carbaryl was particularly high in some strains ofA. andersoni. The high level of resistance to certain pesticides was often associated with a marked reduction in fecundity.      

Effects of acaricides,pyrethroids and predator distributions on populations of <Emphasis Type="Italic">Tetranychus urticae</Emphasis> in apple orchards

We sampled mites in three apple orchards in Nova Scotia, Canada, that had been inoculated with pyrethroid-resistant Typhlodromus pyri and had a history of Tetranychus urticae outbreaks. The objective of this study was to monitor populations of T. urticae and phytoseiid predators on the ground and in trees and to track dispersal between the two habitats. Pesticides were the chief cause of differences in mite dynamics between orchards. In two orchards, application of favourably selective acaricides (abamectin, clofentezine) in 2002, coupled with predation by T. pyri in trees and Neoseiulus fallacis in ground cover, decreased high T. urticae counts and suppressed Panonychus ulmi. By 2003 phytoseiids kept the tetranychids at low levels. In a third orchard, application of pyrethroids (cypermethrin, lambda-cyhalothrin), plus an unfavourably selective acaricide (pyridaben) in 2003, suppressed phytoseiids, allowing exponential increases of T. urticae in the ground cover and in tree canopies. By 2004 however, increasing numbers of T. pyri and application of clofentezine strongly reduced densities of T. urticae in tree canopies despite high numbers crawling up from the ground cover. Another influence on T. urticae dynamics was the distribution of the phytoseiids, T. pyri and N. fallacis. When harsh pesticides were avoided, T. pyri were numerous in tree canopies. Conversely, only a few N. fallacis were found there, even when they were present in the ground cover and on tree trunks. Low numbers were sometimes due to pyrethroid applications or to scarcity of prey. Another factor was likely the abundance of T. pyri, which not only competes with N. fallacis, but also feeds on its larvae and nymphs. The scarcity of a specialist predator of spider mites in trees means that control of T. urticae largely depends on T. pyri, a generalist predator that is not particularly effective in regulating T. urticae. The Canadian Crown's right to retain a non-exclusive, royalty-free licence in and to any copyright is acknowledged.     

Integrated control of apple pests in New Zealand 16. Progress with integrated control of European red mite

Abstract

Studies were made in an orchard near Nelson from 1974 to 1978 on integrated control of Panonychus ulmi (Koch) using the organophosphate-resistant predator Typhlodromus pyri Scheuten. Correct timing of selective acaricides during the October-January period is essential, and can be achieved by close observation of P. ulmi development. When the majority of winter eggs have hatched (late October to early November), or the majority of the summer eggs laid by the first generation (very late November to early or mid December), there is a short period when a maximum of immature mites occurs. This is before many adult females have matured, and is the most effective time for application of an acaricide such as cyhexatin. The development of P. ulmi, in particular the incubation period of the summer eggs, is controlled by temperature, and in seasons when mean temperatures are well below average in November and December the delayed mite development makes accurate timing of the December spray more difficult. Other factors which also affect mite development are the use of dormant oil, cultivar, and orchard aspect and shelter.

On the block of trees where no acaricides were used since 1968, although regular applications of azinphos-methyl were made, T. pyri maintained P. ulmi at acceptable levels over the 5 years 1973-78, a maximum of P. ulmi occurring each season in January with the third generation. In three seasons the peak was well below the threshold for commercial spraying; in two seasons this threshold was exceeded, but despite the absence of acaricides P. ulmi numbers soon fell.

A further experiment demonstrated the utility of mineral oil and cyhexatin as selective acaricides in integrated programmes. Cycloprate, tricyclotin, and fenbutatin oxide were shown to be as effective and selective as cyhexatin, a single application in early December giving good survival of T. pyri and season-long control of P. ulmi. In another experiment propargite was as effective and selective as cyhexatin; amitraz was more toxic to T. pyri and less persistent against P. ulmi, and resulted in a poor P. ulmi : T. pyri ratio; and chlorpyrifos, though not more toxic than cyhexatin to T. pyri, was less effective against P. ulmi.

Mancozeb, and dinocap + mancozeb, used in a summer-long programme of 12 treatments, were more toxic to T. pyri than were binapacryl or dinocap alone.     

Effects of 37 fungicides on the rove beetleAleochara bilineata (Col.: Staphylinidae) in the laboratory

Effects of 37 fungicides — several of which were mixtures — on adult females of the rove beetle,Aleochara bilineata, were investigated in the laboratory. The pesticides were tested in concentrations equivalent to the highest recommended dosages for practical use. Mortality, egg production and hatch of the eggs were recorded. Most fungicides had no serious effect on any of the parameters measured. Among the morpholine and dithiocarbamate fungicides, several had adverse effects on egg production and/or hatch of the eggs laid. Furthermore, chinomethionate and pyrazophos were found to be toxic at the dosages used. Results are compared to results obtained with other species of beneficial arthropods in the laboratory. The importance of including several species in the assessment of pesticide side effects as well as the importance of measuring sublethal effects are stressed.

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Résumé Des expériences de laboratoire ont été faites pour étudier les effets de 37 fongicides (dont plusieurs étaient des mélanges) sur les femelles adultes d'Aleochara bilineata. Les pesticides ont été testés à des concentrations équivalant aux plus fortes doses recommandées pour l'usage agricole. La mortalité, la production et l'éclosion des œufs ont été étudiées. La plupart des fongicides n'ont pas d'effet important sur aucun des paramètres retenus. Parmi les fongicides à base de morpholine et de dithiocarbamate, plusieurs avaient un effet contraire sur la production et l'éclosion des œufs. En outre le chinométhionate et le pyrazophos se sont révélés toxiques aux doses utilisées. Les résultats ont été comparés à d'autres résultats obtenus avec d'autres espèces d'auxiliaires au laboratoire. L'importance d'inclure plusieurs espèces dans l'évaluation des effects secondaires des pestieides ainsi que l'importance de mesurer les effets sublétaux sont soulignées.

     

Is the predatory mite <Emphasis Type="Italic">Kampimodromus aberrans</Emphasis> a candidate for the control of phytophagous mites in European apple orchards?

The most important biocontrol agents of phytophagous mites (mainly Tetranychidae) in European apple orchards are the predatory mites Amblyseius andersoni, Typhlodromus pyri and Euseius finlandicus (Phytoseiidae). A similar situation is found in Trentino (north-eastern Italy), an important apple production area in Europe. Another phytoseiid mite, Kampimodromus aberrans, can be dominant in neglected fruit orchards but is rare in commercial orchards because of its susceptibility to pesticides. However, pesticide resistant strains of K. aberrans have recently been found in vineyards. In the late 1990s, one of these resistant strains was successfully released on an experimental farm in Trentino. Kampimodromus aberrans spread to an apple orchard, despite the fact that it was colonized by T. pyri, A. andersoni and E. finlandicus, and became the dominant species. Since K. aberrans’ colonization appeared to be affected by apple cultivars, experiments were conducted on potted plants of three selected apple cultivars (Golden Delicious, Red Chief, Reinette du Canada). The results stressed the effect of cultivars on apple colonization by K. aberrans and suggested the role of leaf morphology in influencing this phenomenon. Field releases of K. aberrans were successfully performed in four commercial apple orchards. The incidence of K. aberrans in the total phytoseiid population increased over time and the predator became dominant in the season following its release in two orchards. Kampimodromus aberrans persists in these orchards as the dominant species. The adaptation of K. aberrans to varying environmental conditions, its tolerance to pesticides, and its competitiveness towards other phytoseiid species suggest a potential role of this species in the biological control of phytophagous mites in European apple orchards. Handling editor: Eric Lucas.     

A comparative study of the effect of some pesticides on three predacious mite species:Typhlodromus pyri,Amblyseius potentillae andA. bibens [Acarina: Phytoseiidae]

Toxicological responses to 10 different pesticides were determined for 3 species of typhlodromid mites,Typhlodromus pyri Scheuten,Amblyseius potentillae Garman, andA. bibens Blommers, in order to investigate whether or notA. bibens might be used as a substitute for the 2 other species as a testing object for measuring adverse effects of pesticides. T. pyri andA. potentillae are important predators in orchards on phytophagous mites. These species can be reared on the common spider mite,Tetranychus urticae Koch, but they seem averse to the webbing of the spider mite. When placed on detached bean leaves on moist cotton wool withT. urticae present as prey, these typhlodromids tend to run off the leaves, especially when in addition such leaves have been treated with pesticides.A. bibens on the other hand will stay on the leaves when prey is present; it seems to be attracted by the webbing of the spider mite. This makesA. bibens an attractive testing object. In the present study the 3 species mentioned were tested comparatively in closed cells to see whether or not there might be differences in intrinsic susceptibility to pesticides. Mortality of adults, the effect on reproduction, and the mortality of eggs and juveniles were determined. It was found thatA. bibens can reasonably well replace other typhlodromids as a testing objeot for obtaining information on adverse effects of pesticides in orchards.

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Résumé Les effets toxiques de 10 pesticides sur 3 espèces de typhlodromes,Typhlodromus pyri Scheuten,Amblyseius potentillae Garman etA. bibens Blommers ont été examinés afin de déterminer si on peut employer ou nonA. bibens à la place des 2 autres espèces en tant qu'espèce test pour la mesure des effets nocifs des pesticides. t. pyri etA. potentillae sont d'importants prédateurs d'acariens phytophages en vergers. Ces espèces peuvent être élevées sur l'acarien commun,Tetranychus urticae Koch, mais présentent des réactions de répulsion à la soie de ce tetranyque. Placés sur des feuilles de haricot plantées dans du coton humide avecT. pyri comme proie, ces typhlodromes ont tendance à quitter les feuilles, surtout si elles ont été traitées par des pesticides.A. bibens, par contre, demeure sur les feuilles en présence de la proie et semble attiré par le tissage de l'acarien. Ce fait rend intéressantA. bibens. Dans ce travail les 3 espèces ont été étudiées comparativement dans des cellules fermées, afin de montrer si elles font preuve de différences dans leur sensibilité intrinsèque aux pesticides, d'après la mortalité des adultes, la reproduction et la mortalité des œufs et des jeunes. On a trouvé queA. bibens peut très bien remplacer les autres typhlodromes comme espèce-test.

     

Seasonal history ofTyphlodromus pyri (Acari: Mesostigmata: Phytoseiidae) in a commercial apple orchard in Czechoslovakia

The seasonal history and phenology of an indigenous field population ofTyphlodromus pyri Scheuten inhabiting a commercial apple orchard in South Bohemia are described. Data on population dynamics, number of generations, feeding, mating and reproductive habits as well as seasonal distribution within the apple tree canopy are discussed. Recommendations for mass retrieval ofT. pyri from apple orchards, their transfer to, and release in other orchards, are given. The conclusions and recommendations can be used for improving integrated pest management strategies in commercial apple orchards.     

Gene flow measured by allozymic analysis in pesticide resistant Typhlodromus pyri occurring within and near apple orchards

Electrophoresis of allozymes was used to estimated gene flow among populations of Typhlodromus puri Scheuten from apple orchards and nearby blackberry plants from two valleys of western Oregon, USA. Four allozyme loci unaffected by pesticides were tested. Wright's coefficient of inbreeding, F _ST, for all populations was 0.115 and the proportion of populations that migrated per generation, Nm, was 2.08. These values were higher than expected for such locally collected mites. No allelic patterns could be discerned for populations among or within valleys: however, more variation was found for mites collected within than between valleys. From other studies of dispersal and pesticide resistance, we concluded that T. pyri had a low dispersal rate, but these data from allozymic analysis indicated there was moderate gene flow among populations. We concluded that the unique features of the population dynamics of T. pyri may account for the differences seen in estimating gene flow when using different types of population assessment (i.e., dispersal distances, resistance rates and allozyme frequency studies).     

Comparison of the responses of two predaceous mites,Typhlodromus pyri and Zetzellia mali,to variation in prey density

The ability of a predator to respond to prey density in a patchy habitat has been the focus of much study in biological control systems and elsewhere. Here we look at the response of two species of predatory mite commonly found in commercial apple orchards, Typhlodromus pyri Scheuten and Zetzellia mali Ewing. The two species differ in several characteristics: T. pyri is a more successful biological control agent, is more mobile, has a slightly narrower breadth of diet and prefers the target prey, Panonychus ulmi Koch. We measured resisdence time as a function of prey density, both under field and laboratory conditions. Both predators showed a wide variation in behaviour; however, Z. mali increased residence time in response to the presence of prey, while T. pyri did not show a significant response. Both predators usually left a patch before all prey were consumed. Patterns from the field and laboratory were similar, although residence time was shorter under field conditions.     

Dispersal and gene flow of pesticide resistance traits in phytoseiid and tetranychid mites

Dispersal and gene flow of pesticide resistance traits in phytoseiid and tetranychid mites are discussed relative to their biologies and resistance management. The focus is on deciduous fruit-tree crops whereTyphlodromus pyri Scheuten andMetaseiulus occidentalis (Nesbitt) can effectively control spider mite pests. Oregon populations ofM. occidentalis were more dispersive thanT. pyri, as evidenced by movement to small apple trees placed inside and outside of commercial apple orchards. This difference was corroborated by the spatial distributions of organophosphate resistance in populations from sprayed orchards and nearby unsprayed habitats:T. pyri showed patchy, local patterns of resistance whileM. occidentalis showed more regional, homogeneous trends. Gene flow among populations was estimated from allozymic variation ofT. pyri. Intra- and inter-population genetic variation was high enough to prevent population differentiation. Thus, allozymic estimates of gene flow were higher than that indicated by pesticide resistance patterns.Dispersal inTetranychus urticae Koch is also discussed relative to resistance evolution. Immigration of resistant phenotypes from crops or other sprayed habitats can increase the frequency of resistance. Immigration of susceptible individuals from surrounding unsprayed habitat into a sprayed crop can slow resistance or lead to its reversion, depending on the level of gene flow between populations. Dispersal within crops can have the same effect if susceptibles come from a refuge. In pears, immigration of susceptibleT. urticae from nearby habitat and groundcover aided in reversion of organotin resistance. Experiments on resistance management tactics forT. urticae are discussed.     

Resistance to chlorpyriphos in the predatory mite Kampimodromus aberrans

The predatory mite Kampimodromus aberrans (Oudemans) is a key biocontrol agent in vineyards in Italy and Southern Europe. Its susceptibility to common pesticides (e.g., organophosphates) has been considered an important factor in preventing successful biocontrol of phytophagous mites. Nevertheless, populations of K. aberrans apparently resistant to organophosphates (OPs) have been reported to occur in Northern Italian vineyards. The resistance of K. aberrans to fungicides (e.g., mancozeb) has been demonstrated in the laboratory in France, but little is known about the toxicity of insecticides towards K. aberrans. Of these pesticides, the OP chlorpyriphos is extensively used in viticulture to control lepidopterans and homopterans. The present study investigated the dose–response effect of chlorpyriphos in four K. aberrans strains characterized by different levels of exposure to OP insecticides in the past: from never to frequently exposed. Resistance to chlorpyriphos is demonstrated for populations collected from vineyards and apple orchards. Resistance factors exceeded 145,000× for the three strains collected in vineyards and orchard. LC₅₀ values for resistant strains were 1.85–6.83 times higher than the recommended field dose of chlorpyriphos for vineyards and orchards (525 mg a.i./l).     

Sublethal effects of esfenvalerate residues on pyrethroid resistant Typhlodromus pyri (Acari: Phytoseiidae) and its prey Panonychus ulmi and Tetranychus urticae (Acari: Tetranychidae)

The effect of residues of esfenvalerate on oviposition of the resistant strain of the predatory mite Typhlodromus pyri and its main prey, European red mite Panonychus ulmi and two-spotted spider mite Tetranychus urticae, were investigated. T. pyri showed a significant linear reduction in oviposition after 24h in the presence of increasing levels of esfenvalerate residue applied at the field rate. Furthermore, when given a choice, T. pyri preferred to lay eggs on residue-free surfaces. Of the two prey species, only P. ulmi showed significant avoidance of increasing levels of residues of the field rate concentration of esfenvalerate, as measured by runoff mortality, however both P. ulmi and T. urticae, when given a choice, showed a preference for esfenvalerate-free surfaces. As with the predatory mite T. pyri, both prey species showed a significant linear reduction of oviposition with increasing esfenvalerate residues and a preference to lay eggs on esfenvalerate-free surfaces. Esfenvalerate residues as high as 15X field rate were not repellent to pyrethroid-resistant T. pyri. The possible effects of these sublethal effects on predator-prey dynamics and implications for integrated mite control programmes in apple orchards are discussed.     

Molecular Identification of Sphaceloma perseae (Avocado Scab) and its Absence in New Zealand

Avocado scab was recorded as present in New Zealand in international databases on the basis of one isolate (ICMP 10613) identified by morphological features as Sphaceloma perseae. However, sequence analysis of the rDNA internal transcribed spacer (ITS) region showed that this isolate was dissimilar to the ITS region of other Sphaceloma species, and to S. perseae. By phylogenetic analysis, isolate ICMP 10613 was identified as a species of Phaeosphaeria. To identify S. perseae reliably and quickly, specific polymerase chain reaction (PCR) primers were developed and tested. These PCR primers detected the authentic strain and another strain available from international collections, but did not detect isolate ATCC 11190, or the New Zealand isolate ICMP 10613 which were deposited as S. perseae. No other fungi commonly present in New Zealand avocado orchards were amplified by these primers, nor were three other species of Elsinoë (E. ampelina, E. fawcettii and E. pyri). By phylogenetic analysis of ITS sequence, the atypical isolate ATCC 11190 was identified as Elsinoë araliae, whereas isolate ICMP 10613 was identified as Phaeoseptoria sp. (anamorphic Phaeosphaeria). Re‐examination of the scar symptoms on New Zealand avocado fruit showed they were dissimilar to herbarium specimens of S. perseae from Florida and from Cuba. Leaf symptoms typical of this disease have not been found in New Zealand, and isolations from over 1000 scars on fruit onto selective media yielded no fungi identifiable as S. perseae. These results show that ICMP 10613 was mis‐identified as S. perseae. The record of avocado scab in New Zealand was shown to be incorrect, and there is no evidence that the causal fungus occurs in New Zealand.     

Integrated control of apple pests in New Zealand 8. Commercial assessment of an integrated control programme against European red mite using an insecticide-resistant predator

Abstract

An integrated control programme against Panonychus ulmi (Koch) is described which uses a phytoseiid predator, Typhlodromus pyri Scheuten, known to be common in commercial orchards and to be highly resistant to azinphos-methyl. The programme was tested in commercial export orchards in Nelson in the 1975–76 and 1976–77 seasons. By regular monitoring of the levels and ratios of T. pyri and P. ulmi the application of miticides was confined to occasions when specified population thresholds were exceeded. At these times a selective miticide, cyhexatin, was applied to improve predator: prey ratios. No other changes were made to normal commercial spray practices for pest and disease control in the monitored orchards. The integrated mite control programme saved an average of N.Z.$75–80/ha in spray materials each season. No fruits were rejected from export grade because of contamination with mite eggs. Procedures for the wider implementation of integrated mite control in commercial orchards are described and the response of growers is noted. The role of selective miticides in the integrated control of P. ulmi is discussed.     

Toxicity of pesticides to <Emphasis Type="Italic">Tamarixia radiata</Emphasis>, a parasitoid of the Asian citrus psyllid

Sixteen pesticides including two fungicides were evaluated for toxicity to adult Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae), a parasitoid of the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae). Percentage mortality data were evaluated to generally assess IPM-compatibility of the pesticides with adult parasitoids. The following were found to be least compatible with (most toxic to) adult T. radiata based on the toxicity of direct sprays and potential long residual life on leaves: carbaryl, chlorpyrifos, and fenpropathrin. Although highly toxic to the parasitoid as direct sprays or freshly dried residues, each of the following was more compatible with T. radiata because the toxicity of residues of these pesticides was either low at one to three days after application or relatively non-persistent: abamectin, chenopodium oil, fenpyroximate, and spirotetramat. Depending on environmental conditions, imidacloprid (foliar-applied), phosmet, pyridaben, sulfur and 435 spray oil might also be somewhat more compatible for the same reasons. The pesticides that consistently appeared to be most compatible with T. radiata were aluminum tris, copper hydroxide, diflubenzuron, and kaolin clay (Surround WP).     

Population density of the predatory mite <Emphasis Type="Italic">Typhlodromus pyri</Emphasis> (Acari: Phytoseiidae) on various pear cultivars in organic and integrated orchards

During an experiment carried out in 2009–2010 we observed different population densities of Typhlodromus pyri in three monitored pear cultivars in Organic Pest Management (OPM) as well as Integrated Pest Management (IPM) orchards. In both years the population density of T. pyri was the highest in the cultivar Conference (organic orchard). The lowest population density was found in 2009 on the cultivar Dicolor (IPM orchard) and in 2010 on the cultivar Bohemica. Factors involved are discussed.     

The effects of some commonly-used foliar fungicides on Collembola in winter barley: laboratory and field studies

Four commonly-used cereal foliar fungicides were screened for their laboratory toxicity against the symphypleone collembolan, Sminthurinus aureus. A proportional hazards analysis of time-survival curves following the fungicide treatments showed that carbendazim, propiconazole, pyrazophos and triadimenol significantly increased the laboratory mortality of S. aureus. The organophosphorus fungicide pyrazophos caused high levels of mortality of S. aureus in the laboratory so a field evaluation of the effects of this fungicide on a wider range of Collembola was undertaken in winter barley. Comparison of the effects of pyrazophos with those of the broad-spectrum insecticide dimethoate in the field revealed both compounds to have similar activity against some Collembola. Of the 11 species caught only the four symphypleone species exhibited these effects but the numbers of three symphypleone species were reduced to zero 4 wk after treatment with pyrazophos. The effects of pyrazophos and dimethoate were, however, not detectable in individual species after 11 wk.