The collection and selection in Europe of isolates of Phragmidium violaceum (Uredinales) pathogenic to species of European blackberry naturalised in Australia

Phragmidium violaceum is a rust fungus with potential for the biological control of European blackberry (Rubus fruticosus) in Australia. The collection, selection, purification and multiplication in Europe of isolates of the rust is described. Species of European blackberry naturalised in Australia showed different levels of susceptibility when inoculated with a pool of 15 isolates highly pathogenic to Rubus procerus. Selection of individual isolates on the four most widespread blackberry species showed that only two of the isolates would be required to obtain the best attack on these four species.     

A new method for sampling eriophyoid mites from architecturally complex plant structures

Abstract: In this study the effectiveness of the sticky tape method of eriophyoid mite extraction (H arvey and M artin , J. Econ. Entomol. 81, 731–734, 1988) was evaluated with and without the addition of a new method – a supplementary synthetic pyrethroid spray – for estimating the critical abundance of eriophyoid mites from within architecturally complex plant structures. To do so the eriophyoid mite, Acalitus essigi (Hassan) was sampled from within the architecturally complex fruit of blackberries ( Rubus fruticosus L. aggregate). Even though damage symptoms were not observed, sticky tape extraction supplemented with a synthetic pyrethroid spray was the significantly most successful method of mite extraction, with on average over twice the number of mites extracted from blackberry fruit using this method compared with sticky tape alone. Visual counts of A. essigi on the receptacle region of blackberry fruit were correlated to the number of mites extracted using the sticky tape method both with and without a spray treatment. However, due to the low numbers that were visually assessed, the use of visual methods alone appears limited.     

The host specificity ofHartigia albomaculatus (Hym.: Cephidae] and its potential effectiveness in the biological control of European blackberry

The host specificity of the cephid stem-borerHartigia albomaculatus (Stein), was studied to determine its suitability for the biological control of European blackberry (Rubus fruticosus L. agg.) in Australia. Field observations indicated that the insect was specific toR. fruticosus, however laboratory tests showed that it can attack some cultivatedRubus and garden rose (Rosa spp.) varieties. Raspberry (R. idaeus L.) the most importantRubus crop in Australia, was not attacked, nor were 4Rubus spp. endemic to Australia. Observations in the Montpellier area, France, indicate thatH. albomaculatus has no significant detrimental effect on the vegetative reproduction of its host.     

Biological studies of the Australian predatory mite Typhlodromalus lailae (Schicha) (Acari: Phytoseiidae)

Abstract The biology of the Australian phytoseiid mite Typhlodromalus lailae is described from material collected in Western Australia and New South Wales in 1994. At 25°C, when fed on cumbungi ( Typha sp.) pollen, the life cycle is completed in approximately 6 days, with an intrinsic rate of natural increase ( r _m ), of 0.38. Female−male pairs produced a mean total of 44.6 eggs within 22 days of oviposition, with 39% of these females living in excess of 29 days. Females that were deprived of males after first mating stopped laying eggs after 4−9 days, but if another male was added they resumed egg laying and produced close to a full complement of eggs (mean 42 eggs). At 25°C, fecundity on a diet of cumbungi pollen or thrips larvae (first-instar Frankliniella schutzei Trybom) was high, averaging 3.71 and 3.33 eggs per day, respectively, over a 3-day period. The sex ratio was approximately 1.5 females to 1 male. Consumption rate of thrips was also high, with an average of approximately seven first-instar or two second-instar F. schultzei larvae eaten per day. The species was also observed to feed on broad mite, Polyphagotarsonemus latus (Banks), and tomato russet mite, Aculops lycopersici (Massee). No diapause was observed under conditions of 25°C 8 h light and 10°C 16 h dark. Eggs were sensitive to low humidity, with 50% failing to hatch below 71.1% relative humidity. This species is of interest as a candidate biological control agent for thrips, broad mite and tomato russet mite in protected crops.     

Separation of three Rubus-feeding species of aphid — Sitobion fragariae (Wlk.), Macrosiphum funestum (Macch.) and Amphorophora rubi (Kalt.) (Hemiptera: Aphididae) — by electrophoresis

Four species of aphid infest wild and cultivated blackberry (Rubus fruticosus agg., R. lachiatus, etc) and other Rubus species in Britain and Continental Europe, - Sitobion fragariae (Walker), Macrosiphum funestum (Macchiati), Amphorophora rubi (Kaltenbach) and Aphis ruborurn (Bösrner). The nymphs, especially the early instars, of the first three species are fairly difficult to differentiate morphologically. However, they can clearly be separated using electrophoresis. The present paper describes diagnostic enzyme/isoenzyme banding patterns which allow differentiation of the first three species as apterous and alate adults and their instars using two enzymes - carboxylesterase (EST) and phosphatase (PHOS).     

Dispersal of Acalitus essigi to blackberry (Rubus fruticosus agg.) fruit

The eriophyoid mite, Acalitus essigi (Hassan), is hypothesised to be responsible for redberry disease of blackberry (Rubus fruticosus L. agg.) fruit. Infested fruit ripen unevenly with affected drupelets becoming hard, inedible and bright red, whereas unaffected drupelets ripen evenly. As a first step toward possible control of this disease, the method and timing of dispersal of A. essigi onto developing blackberry fruit was examined. No mites were found on unopened flower buds or open flowers. However, infestation of fruit was found to commence during the green stage of fruit development and significantly increase during the red fruit stage. Although redberry symptoms were not observed, experimental exclusion of A. essigi to prevent the mite moving up the pedicel of open flowers by a sticky barrier significantly reduced A. essigi populations within the resultant fruit by over five fold that of control fruit. Although very low levels of aerial dispersal onto fruit cannot be discounted it was concluded that non-aerial or crawling dispersal via the fruit pedicel was the dominant method of blackberry fruit infestation.     

Native faunal communities depend on habitat from non-native plants in novel but not in natural ecosystems

Invasive non-native plants are a major driver of native biodiversity loss, yet native biodiversity can sometimes benefit from non-native species. Depending on habitat context, even the same non-native species can have positive and negative effects on biodiversity. Blackberry (Rubus fruticosus aggregate) is a useful model organism to better understand a non-native plant with conflicting impacts on biodiversity. We used a replicated capture-mark-recapture study across 11 consecutive seasons to examine the response of small mammal diversity and abundance to vegetation structure and density associated with non-native blackberry (R. anglocandicans) in native, hybrid and blackberry-dominated novel ecosystems in Australia. Across the three habitat types, increasing blackberry dominance had a positive influence on mammal diversity, while the strength and direction of this influence varied for abundance. At a microhabitat scale within hybrid and native habitat there were no significant differences in diversity, or the abundance of most species, between microhabitats where blackberry was absent versus dominant. In contrast, in novel ecosystems diversity and abundances were very low without blackberry, yet high (comparable to native ecosystems) within blackberry as it provided functionally-analogous vegetation structure and density to the lost native understory. Our results indicate the ecological functions of non-native plant species vary depending on habitat and need to be considered for management. Comparative studies such as ours that apply a standardized approach across a broad range of conditions at the landscape and habitat scale are crucial for guiding land managers on control options for non-native species (remove, reduce or retain and contain) that are context-sensitive and scale-dependent.     

Biological studies of the Australian predatory mite Typhlodromips montdorensis (Schicha) (Acari: Phytoseiidae), a potential biocontrol agent for western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae)

Abstract The biology of the Australian phytoseiid mite Typhlodromips montdorensis is described from material collected in Queensland and South Australia in 1994−1996. At 25°C, when fed on cumbungi ( Typha sp.) pollen, the life cycle was completed in approximately 7 days, with an intrinsic rate of natural increase ( r _m ) of 0.32. Female−male pairs produced a mean total of 52.7 eggs within 28 days of oviposition. Females that were deprived of males after first mating stopped laying eggs after 7−19 days; however, if another male was added, they resumed egg laying and produced, on average, a total of 49.4 eggs. The sex ratio was 2.24 females to one male. At 25°C, fecundity on a diet of thrips larvae (first-instar Frankliniella schultzei Trybom) was high, ranging from 2.72 to 3.58 eggs per day on the third day, depending on previous diet. Consumption rate of thrips was also high, with an average of 7.23−14.44 first-instar larvae eaten per day on the third day, depending again on previous diet and also on number of thrips larvae made available. The species was also observed to feed on: (i) broad mite, Polyphago­tarsonemus latus (Banks); (ii) tomato russet mite, Aculops lycopersici (Massee); and (iii) two-spotted mite, Tetranychus urticae Koch. No diapause was observed under conditions of 25°C, 8 h light and 10°C, 16 h dark. Eggs were sensitive to low humidity, with 50% failing to hatch below 70.8% relative humidity. This species is of interest as a candidate biological control agent for thrips, broad mite and tomato russet mite in protected crops.     

Dynamics of Introduced Populations of Phragmidium violaceum and Implications for Biological Control of European Blackberry in Australia

Phragmidium violaceum causes leaf rust on the European blackberry (Rubus fruticosus L. aggregate). Multiple strains of this pathogen have been introduced into southern Australia for the biological control of at least 15 taxa of European blackberry, a nonindigenous, invasive plant. In climates conducive to leaf rust, the intensity of disease varies within and among infestations of the genetically variable host. Genetic markers developed from the selective amplification of microsatellite polymorphic loci were used to assess the population genetic structure and reproductive biology of P. violaceum within and among four geographically isolated and diseased infestations of the European blackberry in Victoria, Australia. Despite the potential for long-distance aerial dispersal of urediniospores, there was significant genetic differentiation among all populations, which was not associated with geographic separation. An assessment of multilocus linkage disequilibrium revealed temporal and geographic variation in the occurrence of random mating among the four populations. The presence of sexual spore states and the results of genetic analyses indicated that recombination, and potentially random migration and genetic drift, played an important role in maintaining genotypic variation within populations. Recombination and genetic differentiation in P. violaceum, as well as the potential for metapopulation structure, suggest the need to release additional, genetically diverse strains of the biocontrol agent at numerous sites across the distribution of the Australian blackberry infestation for maximum establishment and persistence.     

Genetic diversity in the invasive <Emphasis Type="Italic">Rubus phoenicolasius</Emphasis> as compared to the native <Emphasis Type="Italic">Rubus argutus</Emphasis> using inter-simple sequence repeat (ISSR) markers

Invasive species are one of most significant factors in human-influenced global change. Management actions that prevent the spread and impacts of invasive species require knowledge of their ecological and genetic characteristics. The genetic characteristics of the invasive wine raspberry, Rubus phoenicolasius Maxim. (Rosaceae) and the native sawtooth blackberry, Rubus argutus Link, were examined in two forest habitats on the Maryland Coastal Plain. Using inter-simple sequence repeat (ISSR) markers we quantified the genetic diversity of both species. We analyzed genetic diversity using analysis of molecular variance (AMOVA) and found less genetic diversity in the invasive species, R. phoenicolasius, with variation between sites was 0.418 between sites and 0.075 within sites as compared to the native, R. argutus, where the variation between sites was 1.538 and 0.370 within sites. The lower genetic diversity in the invasive may be due to a history of limited introductions or frequent self-fertilization and clonal reproduction.     

Comparison of genetic diversity of the invasive weed Rubus alceifolius poir. (Rosaceae) in its native range and in areas of introduction, using amplified fragment length polymorphism (AFLP) markers

Theory predicts that colonization of new areas will be associated with population bottlenecks that reduce within-population genetic diversity and increase genetic differentiation among populations. This should be especially true for weedy plant species, which are often characterized by self-compatible breeding systems and vegetative propagation. To test this prediction, and to evaluate alternative scenarios for the history of introduction, the genetic diversity of Rubus alceifolius was studied with amplified fragment length polymorphism (AFLP) markers in its native range in southeast Asia and in several areas where this plant has been introduced and is now a serious weed (Indian Ocean islands, Australia). In its native range, R. alceifolius showed great genetic variability within populations and among geographically close populations (populations sampled ranging from northern Vietnam to Java). In Madagascar, genetic variability was somewhat lower than in its native range, but still considerable. Each population sampled in the other Indian Ocean islands (Mayotte, La Réunion, Mauritius) was characterized by a single different genotype of R. alceifolius for the markers studied, and closely related to individuals from Madagascar. Queensland populations also included only a single genotype, identical to that found in Mauritius. These results suggest that R. alceifolius was first introduced into Madagascar, perhaps on multiple occasions, and that Madagascan individuals were the immediate source of plants that colonized other areas of introduction. Successive nested founder events appear to have resulted in cumulative reduction in genetic diversity. Possible explanations for the monoclonality of R. alceifolius in many areas of introduction are discussed.     

Movement patterns of Rhyssomatus lineaticollis Say (Coleoptera: Curculionidae) within and among Asclepias syriaca (Asclepiadaceae) patches in a fragmented landscape

Abstract.  1. Dispersal capabilities of organisms are critical in determining the landscape population structure of species as well as their likelihood of survival in fragmented landscapes. Using mark–recapture techniques on the monophagous weevil Rhyssomatus lineaticollis Say (Curculionidae), within- and between-patch dispersal capabilities, landscape level population structure, and the role of beetle density and host patch characteristics in setting distances, amounts, and timing of dispersal were studied.
2. The data indicate that R. lineaticollis is sedentary, with 50% of recaptured beetles moving < 1 m and the maximum distance moved < 1 km. Within- and between-patch movement of beetles was unrelated to host plant patch characteristics and beetle densities.
3. Despite limited dispersal, R. lineaticollis probably functions as a patchy population in east-central Iowa, U.S.A. because dispersals between patches are common and because all host patches surveyed contained this herbivore, indicating a lack of suitable vacant patches, a prerequisite for metapopulation structure.
4. Between-patch distances are well within the dispersal capabilities of R. lineaticollis , although this may be the result of an increase in the density of patches of its host, Asclepias syriaca , in the landscape over the last 150 years as a result of human disturbance and this species' weedy habit.
5. Metapopulation structure in monophagous prairie herbivores may be most likely in species whose non-weedy host plants form highly predictable resources in space and time, but which are now widely scattered in habitat fragments.     

Phylogeny of Rubus (rosaceae) based on nuclear ribosomal DNA internal transcribed spacer region sequences

We used nuclear ribosomal DNA internal transcribed spacer region (ITS 1 - 5.8S - ITS 2; ITS) sequences to generate the first phylogeny of Rubus based on a large, molecular data set. We sampled 57 taxa including 20 species of subgenus Rubus (blackberries), one to seven species from each of the remaining 11 subgenera, and the monotypic and closely related Dalibarda. In Rubus, ITS sequences are most informative among subgenera, and variability is low between closely related species. Parsimony analysis indicates that Rubus plus Dalibarda form a strongly supported clade, and D. repens may nest within Rubus. Of the subgenera with more than one species sampled, only subgenus Orobatus appears monophyletic. Three large clades are strongly supported: one contains all sampled species of nine of the 12 subgenera; another includes extreme Southern Hemisphere species of subgenera Comaropsis, Dalibarda, and Lampobatus; and a third clade consists of subgenus Rubus plus R. alpinus of subgenus Lampobatus. Rubus ursinus appears to be a hybrid between a close relative of R. macraei (subgenus Idaeobatus, raspberries) and an unidentified subgenus Rubus species. ITS sequences are generally consistent with biogeography and ploidy, but traditionally important morphological characters, such as stem armature and leaf type, appear to have limited phylogenetic value in Rubus.     

Winter mortality of Aceria chondrillae, a biological control agent released to control rush skeletonweed (Chondrilla juncea) in the western United States

Abstract:  Classical biological control of weeds is based on the assumptions that: (1) plant species are in part invasive in their introduced range because of the absence of coevolved specialist herbivore arthropods and plant pathogens; and (2) that these specialist herbivores can regulate host-plant populations. Although the need for quantitative post-release monitoring studies testing these assumptions has been acknowledged repeatedly, the number of assessments is still remarkably small and usually restricted to systems with notable impact of an agent species. However, studying systems where biological control agents cause no observable target weed reductions may be important to identifying factors that limit the population size or impact of biological control agents. Three biological agents were released for the control of the herbaceous perennial rush skeletonweed, Chondrilla juncea in North America between 1975 and 1977. Although all three species are widely established, weed densities are increasing and there is little quantitative information on factors limiting biological control efficacy. We examined the winter biology and survivorship of the rush skeletonweed gall mite Aceria chondrillae at two rush skeletonweed field sites in south-western Idaho over 2 years. Gall mite winter mortality was high (>90%) in both years and for both sites. Gall mites were more abundant on plants that produced rosettes in fall and rush skeletonweed plants growing on southern aspect were 3.4 times more likely to produce rosettes than those growing on northern aspects. Our data suggest that A. chondrillae population densities are limited by its high winter mortality. The gall mites may require fall rosettes to successfully survive the winter, which are commonly absent on north-facing aspects, impairing the efficacy of A. chondrillae to control rush skeletonweed in the intermountain western United States.     

DNA fingerprinting reveals significant amounts of genetic variation in a wild raspberry Rubus idaeus population

Establishing the genotypic distribution in natural plant populations is an important part of ecological studies concerning plant growth, reproduction and turn-over. Restriction enzyme-digested DNA samples, isolated from 24 plants of a natural Rubus idaeus population, were analysed with DNA fingerprinting using the M13 repeat sequence as well as a synthetic (AC)/(TG) polydinucleotide as hybridization probes. All the examined samples exhibit unique DNA fingerprint patterns, suggesting that vegetative reproduction may be considerably more restricted in wild R. idaeus populations than previously assumed. By comparison, all samples of the apomictic blackberry species Rubus nessensis, collected on the same location, were completely identical.     

Mite populations on grapevines in south-eastern Australia: Implications for biological control of grapevine mites (Acarina: Tenuipalpidae,Eriophyidae)

Pest and predatory mite populations were monitored over a 2 year period on grapevines in three viticultural regions of southern Australia (The Riverlands, Sunraysia and Murrumbidgee Irrigation Area [MIA]). The mite pestsBrevipalpus spp..Colomerus vitis (Pagenstecher) andCalepitrimerus vitis (Nalepa) occurred in each region with a predatory mite fauna which showed considerable interregional variation in incidence, abundance and composition. Nine species of Phytoseiidae, the dominant predatory mite family, were recorded inhabiting grapevines. In the Riverlands, mite populations were apparently suppressed by two phytoseiids (Typhlodromus doreenae Schicha,Amblyseius victoriensis (Womersley)) in vineyards on which no insecticide was used and on which sulphur and copper were used to control vine diseases. In Sunraysia and MIA, vineyards which generally had greater inputs of synthetic pesticides, particularly fungicides, five to eight phytoseiid species were recorded. However, they were less abundant and appeared to have less impact on mite (particularlyBrevipalpus spp.) populations. The population dynamics of pest and predatory mites on grapevines in southern Australia and implications for mite management based on biological control are discussed with respect to pesticide (particularly fungicide) inputs and phytoseiid biology/ecology.     

Unusual filamentous virus-like particles in symptomless blackberry associated with severe leaf curling in the virus indicator Rubus macraei, and anomalous data using a degenerate badnavirus primer in PCR of Rubus species

Electron microscopy of ultrathin sections of leaves of symptomless Himalaya Giant blackberry and of the virus indicator species, Rubus macraei, showing severe leaf curl symptoms following graft inoculation with scions from this blackberry, detected highly flexuous virus‐like particles with an unusual ‘beaded’ structure. Such particles were restricted to a few vascular cells and were distinct from P‐protein common in some such cells. This virus, provisionally named Hawaiian rubus leaf curl virus (HRLCV), symptomlessly infected a wide range of Rubus species and cultivars. Badnavirus‐like bacilliform particles were observed in some cells of a single R. macraei plant showing leaf curl symptoms following graft inoculation with the causal agent of this disease symptom from Himalaya Giant blackberry after passage through red raspberry, but not in any other material. PCR with primer sets for the badnaviruses Rubus yellow net virus and Gooseberry veinbanding associated virus, showed that no Rubus sources studied contained these viruses. However, using a sequence‐specific primer set designed from the sequence of the product generated with a badnavirus degenerate primer set, a specific product was amplified from healthy plants of all of 16 raspberry cultivars and two Rubus species, but not from 16 blackberry cultivars (including cv. Himalaya Giant). All of these sources were free from viruses known to occur in Rubus. Sequence analysis of this product showed no homology with any known badnavirus, or with any other published sequences. It seems most likely therefore that a region of the raspberry genome has been amplified using the degenerate badnavirus primer set and that it is absent from the blackberry genome.     

The hymenopteran parasitoids of light brown apple moth, Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae) in Australia

Abstract  Epiphyas postvittana (Walker) is a serious pest of a number of horticultural crops including grapes in Australia and New Zealand. This study brings together information on the parasitoid complex associated with E. postvittana that previously was fragmented and largely inaccessible. We include species reared during a 3-year study of the parasitoids of E. postvittana in the vineyards of the Coonawarra region, South Australia, material from several Australian agricultural insect collections and records from the literature. An illustrated key is presented for 25 species of parasitoids and hyperparasitoids associated with E. postvittana , along with information on the taxonomy, identification, distribution and biology of each species. Taxa newly recorded from this host are Perilampus sp. (Perilampidae), and six species of Ichneumonidae: Euceros sp., Labium sp., Netelia sp., Plectochorus sp., Temalucha minuta (Morley) and Eriborus epiphyas sp. n., the latter species being described in full.     

Interaction between organophosphate insecticides and the parasitic mite Acarophenax lacunatus (Prostigmata: Acarophenacidae) on Rhyzopertha dominica (Coleoptera: Bostrichidae)

The interaction between the organophosphate insecticides fenitrothion and pirimiphos-methyl with Acarophenax lacunatus (Cross & Krantz) (Prostigmata: Acarophenacidae), an egg parasite of the stored grain pest Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae), was assessed in a range of doses for each compound. The number of physogastric females of A. lacunatus and egg parasitism (%) decreased with increasing insecticide doses and mite density for both organophosphates. Lower insecticide doses for fenitrothion and pirimiphos-methyl and lower mite densities led to higher instantaneous rates of increase of the mite population. Overall lower instantaneous rates of increase of A. lacunatus were obtained with the insecticide pirimiphos-methyl. The sustained presence of the mite species in all insecticide doses suggest that this biological control agent may be used together with insecticide applications for controlling R. dominica, but high insecticide doses, mainly of pirimiphos-methyl, compromise mite population growth. The high rates of egg parasitism obtained with the biological control agent may aid the insecticide effect on the adult pest population preventing its outbreaks in wheat grains, constituting a potential tactic for pest management of stored wheat.     

The leaf-tying moth Hypocosmia pyrochroma (Lep., Pyralidae), a host-specific biological control agent for cat's claw creeper Macfadyena unguis-cati (Bignoniaceae) in Australia

Abstract:  Cat's claw creeper, Macfadyena unguis-cati , a major environmental weed in coastal and sub-coastal areas of Queensland and New South Wales, Australia is a target for classical biological control. Host specificity of Hypocosmia pyrochroma Jones (Lep., Pyralidae), as a potential biological control agent was evaluated on the basis of no-choice and choice larval feeding and survival, and adult oviposition preference tests, involving 38 plant species in 10 families. In no-choice tests, larval feeding and development occurred only on cat's claw creeper. In choice tests, oviposition and larval development was evident only on cat's claw creeper. The results support the host-specificity tests conducted in South Africa, and suggest that H. pyrochroma is a highly specific biological control agent that does not pose any risk to non-target plants tested in Australia. This agent has been approved for field release by relevant regulatory authorities in Australia.