Target For Biological Control Research Articles

Assessment of a stenophagous weevil, Osphilia tenuipes (Coleoptera: Curculionidae), as a potential biological control agent for weedy Bryophyllum spp. (Crassulaceae) in Australia

Bryophyllum delagoense (Crassulaceae) is a serious weed in Australia and a target for biological control. Following preliminary testing in South Africa, the host range of a Madagascan conderine weevil, Osphilia tenuipes, was determined within a quarantine facility in Queensland, Australia. The primary test consisted of exposing potted plants, selected from an approved host test list, to attack by the weevil in a no-choice design. Tests of oviposition on cut stems and adult preference in a choice design were also undertaken. Osphilia tenuipes used all Bryophyllum spp. found in Australia as hosts and also several other exotic species of Crassulaceae, including Kalanchoe blossfeldiana, Kalanchoe spathulata and Echeveria sp. Native Australian species of Crassulaceae, all Crassula spp., were not attacked, nor were any plant species outside the family Crassulaceae. The preference test showed that the weevil fed on and oviposited in Bryophyllum pinnatum, K. blossfeldiana (two varieties) and Kalanchoe sexangularis in the presence of B. delagoense. The climate matching software CLIMEX was used to develop models that indicated that much of Australia, including southern states, would be climatically suitable for both B. delagoense and O. tenuipes, and that the predicted distribution of both organisms would move southward with climate change. Because the conflicts of interest attributed to the non-target attack are thought to be resolvable, the insect is to be assessed for release under the provisions of Australia’s Biological Control Act.

A history of biological control in Canadian forests, 1882–2014

AbstractBiological control has been an important tactic in the management of Canadian forests for over a century, but one that has had varied success. Here, we review the history of biological control programmes using vertebrate and invertebrate parasitoids and predators against insects in Canadian forests. Since roughly 1882, 41 insect species have been the target of biological control, with approximately equal numbers of both native and non-native species targeted. A total of 161 species of biological control agents have been released in Canadian forests, spanning most major orders of insects, as well as mites and mammals. Biological control has resulted in the successful suppression of nine pest species, and aided in the control of an additional six species. In this review, we outline the chronological history of major projects across Canadian forests, focussing on those that have had significant influence for the development of biological control. The historical data clearly illustrate a rise and fall in the use of biological control as a tactic for managing forest pests, from its dominance in the 1940s and 1950s to its current low level. The strategic implementation of these biological control programmes, their degree of success, and the challenges faced are discussed, along with the discipline’s shifting relationship to basic science and the environmental viewpoints surrounding its use.

Impacts on silkworm larvae midgut proteomics by transgenic Trichoderma strain and analysis of glutathione S-transferase sigma 2 gene essential for anti-stress response of silkworm larvae

Lepidoptera is a large order of insects that have major impacts on humans as agriculture pests. The midgut is considered an important target for insect control. In the present study, 10 up-regulated, 18 down-regulated, and one newly emerged protein were identified in the transgenic Trichoderma-treated midgut proteome. Proteins related to stress response, biosynthetic process, and metabolism process were further characterized through quantitative real-time PCR (qPCR). Of all the identified proteins, the glutathione S-transferase sigma 2 (GSTs2) gene displayed enhanced expression when larvae were fed with Trichoderma wild-type or transgenic strains. Down regulation of GSTs2 expression by RNA interference (RNAi) resulted in inhibition of silkworm growth when larvae were fed with mulberry leaves treated with the transgenic Trichoderma strain. Weight per larva decreased by 18.2%, 11.9%, and 10.7% in the untreated control, ddH2O, and GFP dsRNA groups, respectively, at 24h, while the weight decrease was higher at 42.4%, 28.8% and 32.4% at 72h after treatment. Expression of glutathione S-transferase omega 2 (GSTo2) was also enhanced when larvae were fed with mulberry leaves treated with the transgenic Trichoderma strain. These results indicated that there was indeed correlation between enhanced expression of GSTs2 and the anti-stress response of silkworm larvae against Trichoderma. This study represents the first attempt at understanding the effects of transgenic organisms on the midgut proteomic changes in silkworm larvae. Our findings could not only broaden the biological control targets of insect at the molecular level, but also provide a theoretical foundation for biological safety evaluation of the transgenic Trichoderma strain.

Is Chinese Tallowtree, Triadica sebifera, an Appropriate Target for Biological Control in the United States?

AbstractBiological control is one of the most common approaches used to manage invasive weeds of wetlands and other natural areas. Before candidate agents can be released, research is conducted to support biological control, which can be protracted and expensive, leading to a scientific and potentially lengthy regulatory review. To increase biological control safety, efficacy, and transparency, we suggest that during the early phases of a weed project, the feasibility of the invasive plant as a target should be studied explicitly. Our purpose here is to summarize information of an important invasive weed that can serve to judge whether the project is appropriate. Chinese tallowtree, Triadica sebifera, is one of the worst invasive species invading coastal wetlands and other riparian areas of the southeastern United States. Current management practices have not controlled the spread of this weed into these sensitive habitats. Initial surveys in the plant's native Chinese range for potential biological control agents have recovered several herbivore species that could be developed. These potential agents include defoliators, root and foliage feeders, and gall formers, whose biology, apparent host specificity, and impacts on plant fitness suggest that biological control offers great promise against Chinese tallowtree. When conducted during the initial phase of a project, this type of feasibility study can address potential conflicts of interest and risks, ultimately producing projects that are more effective and safer for biological control.

Potential for biological control of the weed Angled Onion (Allium triquetrum) by the fungus Stromatinia cepivora in Australia

The fungus Stromatinia cepivora (Berk.) Whetzel, which causes white rot of cultivated Allium species, was assessed as a biological control agent for Angled Onion (Allium triquetrum L.), a widespread noxious invasive environmental weed in southern Australia. A. triquetrum showed relatively little genetic diversity, suggesting it was a suitable target for biological control. Genetic analysis of plants from 23 sites in the three main infested Australian states by internal transcribed spacer (ITS) and randomly amplified polymorphic DNA (RAPD) analysis suggested biotypes of A. triquetrum in Australia grouped by state, except for samples from Westernport Bay and Ararat (Victoria). Pathogenicity and virulence of two S. cepivora isolates were assessed on up to 13 A. triquetrum provenances, 6 cultivated Allium species and 9 Australian endemic monocotyledons in test-tube and pot trials. In test-tubes, sclerotia killed plants from all provenances. In pot trials with sclerotia and mycelium, the more pathogenic isolate killed plants from all but one provenance. No A. triquetrum provenance was resistant to S. cepivora, nor were common cultivated Allium species, but common Australian endemic monocotyledons from habitats infested with A. triquetrum showed no disease symptoms 90 days post-inoculation. S. cepivora thus has potential as a biological control agent for A. triquetrum in native bushland in Australia where the risk of it spreading to horticulturally important Allium species is low and can be controlled.

The Leaf-Feeding Geometrid Isturgia disputaria (Guenee)-A Potential Biological Control Agent for Prickly acacia , Vachellia nilotica subsp. indica (Benth.) Kyal. & Boatwr. (Mimosaceae) in Australia

Prickly acacia ( Vachellia nilotica subsp. indica ), a native multipurpose tree in India, is a weed of National significance, and a target for biological control in Australia. Based on plant genetic and climatic similarities, native range surveys for identifying potential biological control agents for prickly acacia were conducted in India during 2008-2011. In the survey leaf-feeding geometrid, Isturgia disputaria Guenee (syn. Tephrina pulinda ), widespread in Tamil Nadu and Karnataka States, was prioritized as a potential biological control agent based on field host range, damage potential and no choice test on non target plant species. Though the field host range study exhibited that V. nilotica ssp. indica and V. nilotica ssp. tomentosa were the primary hosts for successful development of the insect, I. disputaria , replicated no - choice larval feeding and development tests conducted on cut foliage and live plants of nine non-target acacia test plant species in India revealed the larval feeding and development on three of the nine non-target acacia species, V. tortilis , V. planiferons and V. leucophloea in addition to the V. nilotica ssp. indica and V. nilotica ssp. tomentosa . However, the proportion of larvae developing into adults was higher on V. nilotica subsp. indica and V. nilotica subsp. tomentosa , with 90% and 80% of the larvae completing development, respectively. In contrast, the larval mortality was higher on V. tortilis (70%), V. leucophloea (90%) and V. planiferons (70%). The no-choice test results support the earlier host specificity test results of I. disputaria from Pakistan, Kenya and under quarantine in Australia. Contrasting results between field host range and host use pattern under no-choice conditions are discussed.

Genetic diversity in Pareuchaetes insulata and its implications for biological control of Chromolaena odorata

Chromolaena odorata (L.) King & H.E. Robins. (Asteraceae) threatens several economic and environmental activities in the eastern subtropical regions of South Africa and is a target for biological control. Three populations of Pareuchaetes insulata (Walker) (Lepidoptera: Erebidae) originating from Florida (USA), Cuba and Jamaica were released at 30 separate sites in KwaZulu-Natal, South Africa. Subsequent overlapping of two of these populations in the field and the likelihood of interbreeding posed a potential risk of establishment failure. To explore the genetic diversity of the different P. insulata populations and test for the existence of pre- and post-zygotic reproductive isolation between them, molecular analyses and cross-mating experiments were conducted. Mitochondrial DNA sequences revealed significant genetic similarity between them. Cross-mating trials between Floridian and Jamaican populations of P. insulata revealed no significant pre- and post-zygotic isolation, with no demonstrable differences in measured parameters between the ‘parental’ populations, the F1 ‘hybrids’ and the backcrosses. These results suggest that P. insulata populations released in South Africa are part of the same ‘parental’ population. Genetic incompatibility is, therefore, relatively unlikely to be the cause of any failure in establishment of P. insulata at any of the release sites.

Biology of Polypedilum n. sp. (Diptera: Chironomidae), a promising candidate agent for the biological control of the aquatic weed Lagarosiphon major (Hydrocharitaceae) in Ireland

Lagarosiphon major (Ridl.) Moss ex Wager (Hydrocharitaceae), an aquatic macrophyte native to Southern Africa that has become invasive in several countries worldwide, is a potential target for biological control. Biology studies were conducted on Polypedilum (Pentapedilum) n. sp. near reei Oyewo & Sæther (Diptera: Chironomidae), a midge whose larvae were discovered mining the plant's shoot tips in its native range. Field surveys indicated that the midge occurred only at a small number of sites but attained high densities (up to 370 shoots damaged/m2) that prevented further growth from the shoot tips. A population of the midge was imported into quarantine in Ireland to evaluate its potential as a candidate biological control agent. The adult stage is terrestrial and short-lived (4–5 d), with females depositing one–two egg packets into the water bodies. First-instar larvae fed externally on the stems and leaflets. Later instars fed on the apical meristems and burrowed into the shoot tips, with resultant damage stunting the apical growth. Larvae moved readily between shoots to complete their development and pupated within the tunnels excavated by the late instar larvae. Developmental time to adulthood ranged from 31 to 49 days at 20.7°C and a 15 L:9-D cycle. This is the first time that a chironomid has been imported and successfully cultured for consideration as a classical biological control agent. Several aspects of the midge's biology suggest that host specificity testing is warranted to determine its potential as a biocontrol agent of L. major.

First Report of Pilidium concavum causing Leaf Necrosis on Fallopia japonica in the United States.

Fallopia japonica (Houtt.) Ronse Decr. (= Polygonum cuspidatum Siebold & Zucc.; Japanese knotweed, JKW) is an invasive perennial forb in the Polygonaceae. It has been identified as a target for biological control in many parts of the world, including the United States. Several potted JKW plants in an outdoor study at the Oregon Department of Agriculture, Salem (44.93° N, 122.99° W) developed leaf spots. Samples collected on August 20, 2007, were sent to the FDWSRU for identification of the disease. The necrotic leaf spots were brown and large, 1 to 3 cm in diameter, and in some cases occupying 30% of the leaf area. Both hemispherical and discoid conidiomata with gloeoid spore masses (3) developed in necrotic areas of all leaves placed in moist chambers. Discoid conidiomata had dark, pedicellate bases subtending a fimbriate disc on which pale brown to brown gloeoid conidial masses were produced. Hemispherical conidiomata were black, circular, sessile, and somewhat flattened, within which similar, gloeoid conidial masses were produced. Conidia from each type of conidioma were unicellular, cylindrical to fusiform, hyaline, and 4.5 to 7.2 × 0.9 to 1.8 μm (mean 5.7 × 1.33). Artificial inoculation of 15 plants was made on two occasions with a suspension of 106 conidia per ml, followed by two 16-hr dew periods at 25°C that were separated by an 8-hr "day;" a similar set of 15 non-inoculated plants served as controls each time. Symptoms similar to those in the original sample developed within 2 months after inoculation. The fungus was easily reisolated, and conidia from each type of conidioma produced similar growth on artificial media and similar disease after inoculation. The characteristics of conidial size and distinctly different conidiomata are diagnostic of Pilidium concavum (Desm.) Höhn (3,4). A sequence of the ITS1-5.8S-ITS2 region DNA, extracted using a DNeasy Plant Mini Kit (QIAGEN), was found identical to that of P. concavum from Rosa sp. (BPI 1107275; GenBank Accession No. AY487094), using BLAST. This isolate, FDWSRU 07-116, has been deposited in the US National Fungus Collection (BPI 883546) and at the Centraalbureau voor Schimmelcultures (CBS 132725). Sequence data have been deposited in GenBank (JQ790789). To our knowledge, this is the first report of P. concavum causing disease on a member of the Polygonaceae in North America (1), a disease clearly different from a Japanese Mycosphaerella sp. under consideration for biological control of JKW in the United Kingdom (2).

Detection of PLC- From Testis of Rattus Argentiventer(RiceField Rat) Using RT-PCR and qRT-PCR

Rattus argentiventer (Rice Field Rat) is responsible for destruction of paddy. The mammal is known for its rapid reproductive potential which can be a target for biological control of this species. Phospholipase C-zeta (PLC ζ) is a specific enzyme found in sperm of mammals responsible for triggering calcium oscillations leading to egg activation during fertilization. It facilitates the first step of egg activation causing egg division and subsequent development into an embryo. The method used in this study was to identify PLC gene fragments from the testis of Rattus argentiventer using two-step Reverse Transcriptase Polymerase Chain Reaction (PCR) and quantified with Real Time Reverse Transcriptase Polymerase Chain Reaction (qRT-PCR). Following that, sequencing of PLC was performed. The identified sequence was then keyed in into the BLAST portal in NCBI (National Centre of Bioinformatics) for comparison with a standard PLC sequence from Rattus norvegicus for sequence alignment. The result showed that PLCζ was present in Rattus argentiventer and qRTPCR could quantify the amount of PLCζ available.As such this would give additional information of detection and quantification techniques for rapid identification and detection of PLCζ to be carried out in the approach of controlling the rapid growth of Rattus argentiventer population.

Cat's claw creeper leaf‐mining jewel beetle Hylaeogena jureceki Obenberger (Coleoptera: Buprestidae), a host‐specific biological control agent for Dolichandra unguis‐cati (Bignoniaceae) in Australia

AbstractCat's claw creeper, Dolichandra unguis‐cati (L.) L.G. Lohman (syn: Macfadyena unguis‐cati (L.) A.H. Gentry) (Bignoniaceae), a major environmental weed in Queensland and New South Wales, is a Weed of National Significance and an approved target for biological control. A leaf‐mining jewel beetle, Hylaeogena jureceki Obenberger (Coleoptera: Buprestidae), first collected in 2002 from D. unguis‐cati in Brazil and Argentina, was imported from South Africa into a quarantine facility in Brisbane in 2009 for host‐specificity testing. H. jureceki adults chew holes in leaves and lay eggs on leaf margins and the emerging larvae mine within the leaves of D. unguis‐cati. The generation time (egg to adult) of H. jureceki under quarantine conditions was 55.4 ± 0.2 days. Host‐specificity trials conducted in Australia on 38 plant species from 11 families supplement and support South African studies which indicated that H. jureceki is highly host‐specific and does not pose a risk to any non‐target plant species in Australia. In no‐choice tests, adults survived significantly longer (>32 weeks) on D. unguis‐cati than on non‐target test plant species (<3 weeks). Oviposition occurred on D. unguis‐cati and one non‐target test plant species, Citharexylum spinosum (Verbenaceae), but no larval development occurred on the latter species. In choice tests involving D. unguis‐cati, C. spinosum and Avicennia marina (Avicenniaceae), feeding and oviposition were evident only on D. unguis‐cati. The insect was approved for field release in Australia in May 2012.

Using Biological-Control Research in the Classroom to Promote Scientific Inquiry & Literacy

Scientists researching biological control should engage in education because translating research programs into classroom activities is a pathway to increase scientific literacy among students. Classroom activities focused on biological control target all levels of biological organization and can be cross-disciplinary by drawing from subject areas such as ecology, molecular biology, physiology, and chemistry. We evaluate published “how-to” biological-control activities to determine whether they meet National Science Education Standards and use a constructivist pedagogical approach. We also provide an example classroom activity developed from our research that scientists can use as a template to develop their science-education activities.

Introduction, Establishment, and Potential Geographic Range of <I>Carmenta</I> sp. nr <I>ithacae</I> (Lepidoptera: Sesiidae), a Biological Control Agent for <I>Parthenium hysterophorus</I> (Asteraceae) in Australia

Parthenium (Parthenium hysterophorus L.), a major weed causing economic, environmental, and human and animal health problems in Australia and several countries in Asia, Africa, and the Pacific, has been a target for biological control in Australia since the mid-1970s. Nine species of insects and two rust fungi have been introduced as biological control agents into Australia. These include Carmenta sp. nr ithacae, a root feeding agent from Mexico. The larvae of C. sp. nr ithacae bore through the stem-base into the root where they feed on the cortical tissue of the taproot. During 1998-2002, 2,816 larval-infested plants and 387 adults were released at 31 sites across Queensland, Australia. Evidence of field establishment was first observed in two of the release sites in central Queensland in 2004. Annual surveys at these sites and nonrelease sites during 2006-2011 showed wide variations in the incidence and abundance of C. sp. nr ithacae between years and sites. Surveys at three of the nine release sites in northern Queensland and 16 of the 22 release sites in central Queensland confirmed the field establishment of C. sp. nr ithacae in four release sites and four nonrelease sites, all in central Queensland. No field establishment was evident in the inland region or in northern Queensland. A CLIMEX model based on the native range distribution of C. sp. nr ithacae predicts that areas east of the dividing range along the coast are more suitable for field establishment than inland areas. Future efforts to redistribute this agent should be restricted to areas identified as climatically favorable by the CLIMEX model.

Classical Biological Control for the Management of Alien Invasive Plants in Ireland

As a consequence of the sustained interest in exotic plants we now face the challenge of dealing with the economic and ecological impacts of many environmental weeds. Exotic ornamental plants can often flourish as they have been imported without their natural enemies that suppress the plant’s growth and reproduction in the native range. The aim of classical biological control is to re-establish the natural regulation provided by host-specific primary consumers from the native range of the weed. In contrast to the long history of arthropod biological control in Europe, environmental weed biological control is only now gaining some momentum. Ireland stands to benefit from developments made in other EU member states and other parts of the world as it shares many of the same environmental weed problems. Both terrestrial and aquatic weeds are good targets for biological control, and developments relevant to Ireland are described in this paper to illustrate the potential benefits of this management option.

Suitability of a New Plant Invader as a Target for Biological Control in Florida

AbstractThe suitability of a target weed for classical biological control should be considered early in the process of plant invasion. Concerns have been raised about the recent arrival ofMikania micranthaKunth in south Florida and its potential to spread and invade natural and managed ecosystems. This weed is native to the neotropics, and has been introduced into many Asian countries and, more recently, into Australia. In Asia,M. micranthais particularly problematic in plantation crops, but also threatens natural areas and disturbed ecosystems. Several aspects of the biology and ecology ofM. micranthaare discussed in this review to evaluate its suitability as a target of biological control in Florida. Based on an ecological niche model, the climate in southern and central Florida is highly favorable for the invasion of this weed. Previous biological control programs provide valuable information for Florida scientists about the availability of natural enemies and potential areas for future foreign surveys. Genetic comparison of the Florida population and native range populations, in addition to climate matching, should be considered when selecting areas for foreign exploration. Finally, the authors used a scoring system and risk-benefit–cost analysis to evaluateM. micranthaas a potential target for biological control in Florida. We suggest that similar feasibility evaluations should be conducted not only for well-established problematic weeds but also for new invaders with a known history of invasiveness.

Biological Control ofSolanum mauritianumScop. (Solanaceae) in South Africa: Will Perseverance Pay off?

Solanum mauritianum Scop. (Solanaceae), a fast-growing tree with a high reproductive capacity, threatens several commercial activities and natural habitats in the higher rainfall regions of South Africa. Biological control efforts spanning 26 years have previously been confined to South Africa, but have recently been extended to New Zealand. The weed is a particularly challenging target for biological control, largely because of its taxonomic relatedness to economically important and native plant species which resulted in the rejection or shelving of the majority of candidate agents tested thus far. Despite these problems, two insect agents, the sap-sucking Gargaphia decoris Drake (Hemiptera: Tingidae) and flowerbud-feeding Anthonomus santacruzi Hustache (Coleoptera: Curculionidae), have been released in South Africa. Gargaphia decoris was first released in 1999 and has become established in several regions of the country. Although large outbreaks and extensive damage have been observed in the field, to date these have been erratic and insufficient to inflict meaningful damage on the weed populations. Anthonomus santacruzi was released in early 2009 and so far appears to have established at two sites in KwaZulu-Natal. This paper is a review of the biological control programme against S. mauritianum in South Africa, including (i) aspects of the weed that are pertinent to its invasiveness and management, (ii) the current status of the two prominent insect agents, and (iii) the direction of future research efforts.

CLASSICAL BIOLOGICAL CONTROL FOR THE MANAGEMENT OF ALIEN INVASIVE PLANTS IN IRELAND

As a consequence of the sustained interest in exotic plants we now face the challenge of dealing with the economic and ecological impacts of many environmental weeds. Exotic ornamental plants can often flourish as they have been imported without their natural enemies that suppress the plant's growth and reproduction in the native range. The aim of classical biological control is to re-establish the natural regulation provided by host-specific primary consumers from the native range of the weed. In contrast to the long history of arthropod biological control in Europe, environmental weed biological control is only now gaining some momentum. Ireland stands to benefit from developments made in other EU member states and other parts of the world as it shares many of the same environmental weed problems. Both terrestrial and aquatic weeds are good targets for biological control, and developments relevant to Ireland are described in this paper to illustrate the potential benefits of this management option.

Studies to assess the suitability ofUromyces pencanusas a biological control agent forNassella neesiana(Poaceae) in Australia and New Zealand

Nassella neesiana (Chilean needle grass), a South American species, is an intractable weed invading managed pastures and natural grasslands that has become a target for biological control in Australia and New Zealand. Studies have been carried out to assess the potential of three rusts naturally infecting this grass species in Argentina: Uromyces pencanus, Puccinia graminella and P. nassellae, as biocontrol agents. Of the three, U. pencanus was recognised as the most promising candidate. It causes significant damage to its host in the field and there is an isolate that can infect most Australian populations of the weed tested. Herein are described methods for: maintaining the rust in the glasshouse; storing urediniospores over 12 months; and, for inoculating urediniospores in order to test the host-specificity of selected isolates of the rust. Evidence from the literature, and a preliminary host range test indicates that U. pencanus is sufficiently host-specific for use as a classical biocontrol agent. Attempts at elucidating the life cycle of U. pencanus were unsuccessful as teliospores did not germinate. It appears that these have become redundant and the rust cycles as urediniospores on its grass host.

Additions to the mycobiota of the invasive weed Miconia calvescens (Melastomataceae)

Miconia calvescens (Melastomataceae) is a shrub or small tree native to the Neotropics that has become one of the worst invaders of forest ecosystems, particularly in Pacific islands such as Hawaii and French Polynesia. It has been a target for biological control for more than 10 y, both with arthropod and pathogen natural enemies. Until now Colletotrichum gloeosporioides f. sp. miconiae was the only organism to be used in biological control against this weed. This fungus was introduced both in Hawaii and in French Polynesia in the late 1990s/early 2000s, where it has caused some damage to the weed, but it became evident that additional agents are needed to achieve adequate control. Exploratory surveys for plant pathogens as potential biocontrol agents of M. calvescens were undertaken in Brazil, Costa Rica and Ecuador and yielded a diverse list of pathogens, including one phytoplasma, two nematodes, one oomycete and numerous fungi. A study including the description of five fungal species found attacking M. calvescens was published recently. Herein the following additional fungi also belonging to the mycobiota of M. calvescens are described: Hyalosphaera ornata sp. nov, Microsphaeropsis miconiae sp. nov., Myrothecium miconiae sp. nov., Phyllachora miconiiphila sp. nov., as well as Hyalosphaera miconiae, Lembosia melastomatum and Microsphaeropsis clidemiae, which are recorded here for the first time on this host. Although preliminary our observations of damage to M. calvescens caused by these seven fungal species did not indicate any potential for use in classical biological control.

Prioritising potential guilds of specialist herbivores as biological control agents for prickly acacia through simulated herbivory

AbstractUnderstanding plant response to herbivory facilitates the prioritisation of guilds of specialist herbivores as biological control agents based on their potential impacts. Prickly acacia (Acacia nilotica ssp. indica) is a weed of national significance in Australia and is a target for biological control. Information on the susceptibility of prickly acacia to herbivory is limited, and there is no information available on the plant organ (i.e. leaf, shoot and root in isolation or in combination) most susceptible to herbivory. We evaluated the ability of prickly acacia seedlings, to respond to different types of simulated herbivory (defoliation, shoot damage, root damage and combinations), at varying frequencies (no herbivory, single, two and three events of herbivory) to identify the type and frequency of herbivory that will be required to reduce the growth and vigour. Defoliation and shoot damage, individually, had a significant negative impact on prickly acacia seedlings. For the defoliation to be effective, more than two defoliation events were required, whereas a single bout of shoot damage was enough to cause a significant reduction in plant vigour. A combination of defoliation + shoot damage had the greatest negative impact. The study highlights the need to prioritise specialist leaf and shoot herbivores as potential biological control agents for prickly acacia.