Control Agents In Australia Research Articles

Practical Suggestions for Assessing Rabbit Haemorrhagic Disease Virus 2 Risk to Endangered Native Lagomorphs in North America and Southern Africa.

A new form of the rabbit haemorrhagic disease virus, RHDV2, first observed in European rabbits, has spread widely among different species of hares in Europe, jackrabbits and cottontails in North America, and hares in southern Africa. However, only limited surveillance studies have been undertaken so far. It is suggested that methods developed for controlling the disease in farmed rabbits in Europe and studying the efficacy of RHDV as a biological control agent in Australia could facilitate epidemiological research on those recently affected lagomorph species. This would enable the assessment of the risk of RHDV2 to native lagomorphs, including endangered species, and the determination of the main host species of RHDV2. Because RHDV2 has not spread equally through all lagomorph species, epidemiological studies could give insights into factors important for determining host susceptibility.

Effectiveness of classical weed biological control agents released in Australia

The historical record of releases of 288 species of weed biological control agents in Australia was analysed to examine if considering the damage/host type relationship of agents can offer insights into why some agents and not others have proved to be effective in producing partial or complete control of the target weed. Specifically, the effectiveness of agents released in Australia was examined in relation to their feeding guild and the functional group (growth form) of the target weed. Biotrophic pathogens (rusts/smuts), sap feeders and root/crown feeders were effective in producing control more often than other guilds. Effectiveness of biological control across weed functional groups was somewhat similar, although herbaceous biennials/perennials tended to be more effectively controlled than other functional groups. Significant biological control was recorded for at least one case in each of the 31 of the 37 feeding-guild/weed functional group combinations for which there were data. Possible explanations for the greater success of some guilds are explored, as are caveats with using such inductive approaches to predict effectiveness in classical weed biological control.

Decline of the invasive plant Asparagus asparagoides within the first seven years after release of biological control agents in Australia

There is ample anecdotal evidence and expert opinion on the adverse impact of imported biological control agents on populations of invasive plants, but still a paucity of quantitative data. Asparagus asparagoides (bridal creeper), a perennial climber with an extensive below-ground network of rhizomes and tubers, was considered one of the most invasive plants of natural ecosystems in southern Australia in the 1990s. A long-term experiment was conducted at 15 sites invaded by A. asparagoides across Australia to determine whether its growth and reproduction declined following the release of two biological control agents: a leafhopper (undescribed Erythroneurini formerly referred to as Zygina sp.) and rust fungus (Puccinia myrsiphylli). Data on A. asparagoides were collected annually at each site for up to 3 years before the release of one or both agents in 2000 or 2001, and up to 7 years after release to capture spatial and temporal variability. Our results showed a steady decrease in A. asparagoides seedling and shoot density, and total above-ground biomass in quadrats across all sites in the years following the release of the leafhopper and/or rust fungus. The number of fruits produced in quadrats greatly varied between sites, although for most sites, fruit numbers before the release of agents were higher than after release. Changes in A. asparagoides climbing onto standardized trellises, however, were not consistent across sites during the same period, with major reductions in plant measurements recorded at some sites but not others. Differences in climatic conditions between sites during A. asparagoides growing season did not explain these variable results. Incidence of leafhopper damage on A. asparagoides cladodes in quadrats and trellises was generally lower than that of rust infection.

Broad and narrow host ranges in resolved species of Cintractia limitata s. lat. (Anthracoideaceae, Ustilaginomycotina) on Cyperus

Cintractia (Anthracoideaceae, Ustilaginomycotina) is a widespread genus of smut fungi that parasitizes species of Cyperaceae. Specimens of Cintractia spp. on species of Cyperus s. lat. were examined to resolve their taxonomy, including a species on Cyperus aromaticus, which is an invasive weed in Australia. A phylogenetic species concept was used to show that Cintractia limitata s. lat. contains three different species, Cintractia limitata, C. tangensis, and a new species C. kyllingae. The proposed taxonomy is based on phylogenetic analyses of the ITS rDNA region and on the position of the sori in diverse parts of inflorescences examined in approximately 100 specimens of Cintractia. A morphological synapomorphy in C. tangensis is sori with firmly agglutinated spore masses around the base of the peduncles, rarely in the spikelets. Cintractia limitata forms powdery spore masses between flowers and is known only to occur on Cyperus species with spikelets in capitate heads. Cintractia kyllingae was found on Cy. aromaticus and may have potential as a biological control agent in Australia.

Insect Herbivores Associated with Lycium ferocissimum (Solanaceae) in South Africa and their Potential as Biological Control Agents in Australia

Lycium ferocissimum Miers (Solanaceae) is an indigenous shrub in South Africa but has become invasive in several countries including Australia, where chemical and mechanical control methods have proved costly and unsustainable. In Australia, biological control is being considered as a management option, but the herbivorous insects associated with the plant in its native range are not well known. The aim of this study was to survey the phytophagous insects associated with L. ferocissimum in South Africa and prioritise promising biological control agents. In South Africa, the plant occurs in two geographically distinct areas, the Eastern and Western Cape provinces. Surveys for phytophagous insects on L. ferocissimum were carried out repeatedly over a two-year period in these two regions. The number of insect species found in the Eastern Cape Province (55) was higher than that in the Western Cape Province (41), but insect diversity based on Shannon indices was highest in the Western Cape Province. Indicator species analysis revealed eight insect herbivore species driving the differences in the herbivore communities between the two provinces. Based on insect distribution, abundance, feeding preference and available literature, three species were prioritised as potential biological control agents. These include the leaf-chewing beetles Cassida distinguenda Spaeth (Chrysomelidae) and Cleta eckloni Mulsant (Coccinellidae) and the leaf-mining weevil Neoplatygaster serietuberculata Gyllenhal (Curculionidae).

Biological control of Ziziphus mauritiana (Rhamnaceae): feasibility, prospective agents and research gaps

AbstractThe tropical fruit tree, Ziziphus mauritiana (Rhamnaceae), a native of the Indian subcontinent, is a pasture and environmental weed in northern Australia and Fiji. In their native range, Ziziphus spp., including commercially cultivated Z. mauritiana and Z. jujuba, are subjected to a wide range of pests and diseases. The feasibility of classical biological control of this weed has not been explored to date. Effective biological control could reduce plant vigour and seed output, thereby limiting the spread of Z. mauritiana in Australia. Two Ziziphus species are native to Australia, hence, any prospective biological control agent should be specific to Z. mauritiana. Opportunistic field surveys and literature searches identified 133 species of phytophagous insects, 9 species of phytophagous mites and 12 plant pathogens on Ziziphus spp. Host records suggest the following are possibly specific to Z. mauritiana and hence are prospective biological control agents in Australia: the seed‐feeding weevil Aubeus himalayanus; the leaf‐feeding gracillariid moth Phyllonorycter iochrysis; the leaf‐mining chrysomelid beetle Platypria erinaceus; the leaf‐folding crambid moth Synclera univocalis; the leaf‐galling midge Phyllodiplosis jujubae; and the gall‐mites Aceria cernuus and Larvacarus transitans. Host range of the rust Phakopsora zizyphi‐vulgaris includes many Ziziphus species, including the native Z. oenoplia and hence would not be a suitable biological control agent in Australia. The powdery mildew Pseudoidium ziziphi, with a host range restricted to Ziziphus species, has not been reported on Z. oenoplia. All available information on the pests and diseases of Z. mauritiana are from cultivated varieties. Hence, future surveys should focus on wild Z. mauritiana in the Indian subcontinent in areas that are climatically similar to the regions of northern Australia, where it is currently most abundant.

Development of cat’s claw creeper leaf-tying moth Hypocosmia pyrochroma (Lepidoptera: Pyralidae) at different temperatures: Implications for establishment as a biological control agent in Australia and South Africa

The leaf-tying moth Hypocosmia pyrochroma Jones (Lepidoptera: Pyralidae), a native of sub tropical South America, has been introduced as a biological control agent for cat’s claw creeper, Dolichandra unguis-cati (L.) Lohman (Bignoniaceae), in Australia and South Africa. So far there has been no evidence of its field establishment in either country. A narrow temperature tolerance is a potential limiting factor for the establishment of weed biological control insects in novel habitats. In this study, we evaluated the effect of seven constant temperatures (12–40°C) on the survival and development of H. pyrochroma in temperature-controlled cabinets. Temperatures between 20 and 30°C were the most favorable for adult survival, oviposition, egg hatching, and larval and pupal development. Adult survival (12–40°C) and egg development (15–35°C) showed tolerance for wider temperature ranges than oviposition, and larval and pupal development, which were all negatively affected by both high (>30°C) and low (<20°C) temperatures. The degree-day (DD) requirement to complete a generation was estimated as 877 above a threshold temperature of 12°C. Based on DD requirements and an obligatory winter diapause of pupae from mid-autumn to mid-spring, the potential number of generations (egg to adult) the leaf-tying moth can complete in a year in Australia or South Africa range from one to three. A climate-matching model predicted that the inland regions of both Australia and South Africa are less favorable for H. pyrochroma than the coastal areas. The study suggested that H. pyrochroma is more likely to establish in the coastal areas of Australia where most of the cat’s claw creeper infestations occur, than in South Africa where most of the cat’s claw creeper infestations are inland.

A new species of Aceria (Acari: Eriophyidae) damaging sowthistles, Sonchus spp. (Asteraceae), in Australia with notes on Aceria sonchi (Nalepa, 1902)

A new species of eriophyoid mite from Australia is described and illustrated. Aceria thalgi sp. n. causes severe curling and rolling of leaves of common introduced sowthistle, Sonchus oleraceus L. It also affects introduced Sonchus asper (L.) Hill and native Sonchus hydrophilus Boulos. The native species may be the original host for this mite. Aceria thalgi sp. n. is shown to be a separate species to Aceria sonchi (Nalepa), which forms distinctive leaf galls on Sonchus spp. in southern Europe. English translations of past descriptions of A. sonchi are included for comparison. Historical observations and records from New South Wales suggest that A. thalgi sp. n. has been known for at least 80 years prior to its recent rediscovery in Western Australia. This implies that the newly described species may be widespread across the continent. There is also a past record of similar damage symptoms occurring on sowthistles in New Zealand. Aceria thalgi sp. n. has the potential to be a useful biological control agent in Australia and Canada, where sowthistles are major weeds of agriculture.

TADPOLES OF FOUR COMMON AUSTRALIAN FROGS ARE NOT EFFECTIVE PREDATORS OF THE COMMON PEST AND VECTOR MOSQUITO CULEX ANNULIROSTRIS

In a laboratory investigation of tadpoles of 4 Australian frogs, Limnodynastes peronii, Limnodynastes tasmaniensis, Litoria aurea, and Litoria peronii, there was no evidence of active predation on larvae of Culex annulirostris. The mortality of larvae was greatest when exposed to the tadpoles of Litoria spp., which may have been the result of specific foraging behavior. Results indicate that Litoria spp. tadpoles may have a minor impact on mosquito populations, but they are unlikely to be useful biological control agents in Australia.

Alcidodes sedi (Col.: Curculionidae), a natural enemy of Bryophyllum delagoense (Crassulaceae) in South Africa and a possible candidate agent for the biological control of this weed in Australia

The Madagascan endemic, Bryophyllum delagoense (Crassulaceae), is a major weed in Queensland, Australia. Despite having first been recorded in Australia in the 1940s, it is far more invasive there than on the African mainland where it was introduced more than 170 years ago. This may be due to a number of factors, one of which could be the occurrence of new natural enemy associations in southern Africa. Among the insects of crassulaceous plants that have extended their host ranges, a stem-boring weevil, Alcidodes sedi, was studied to elucidate its status as a natural enemy of B. delagoense in southern Africa and as a candidate biological control agent for introduction to Australia. Laboratory studies indicated that damage inflicted by adult and larval feeding caused significant reductions in stem length and number of leaves. Preliminary host-range trials revealed that A. sedi can complete its development on other species in the Crassulaceae, including most of the introduced Bryophyllum species and some Kalanchoe species native to South Africa. Despite the oligophagous nature of A. sedi and the fact that it can complete its development on a number of ornamental species in the Crassulaceae, it should be considered a potential biological control agent in Australia. All of the native Crassulaceae in Australia are in the genus Crassula, most of which are very small and therefore unlikely to support the development of a large weevil like A. sedi. However, additional host-range trials will have to be undertaken in Australia to determine whether the weevil can be considered safe for release.

Current distribution and status of Lantana camara and its biological control agents in Australia, with recommendations for further biocontrol introductions into other countries

Abstract The results of surveys conducted in Australia over a five-year period (1996-2001) to determine the distribution of Lantana camara (lantana) and its introduced biological control agents are reviewed and discussed. The relative merits and drawbacks of each species are summarized for the benefit of other countries wishing to consider biological control programmes against lantana. Lantana is found in coastal and sub-coastal areas from far-north Queensland to southern New South Wales (NSW), Australia. Small populations of the weed have been reported around Darwin in the Northern Territory and Perth in Western Australia. For the purpose of this review, lantana is classified into five varietal groups, based on flower colour. The pink flowering group is the most common and widespread. It is the only variety found in southern NSW and in high altitude subtropical areas. The pink-edged red flowering varietal group is the next most common, being found from central NSW to far-north Queensland. The three remaining varietal groups, red, white and orange, are less common and limited in their distribution. Of the 30 biological control agents that have been introduced into Australia, 16 have established. The most widespread and damaging agents are Octotoma scabripennis , Uroplata girardi , and Teleonemia scrupulosa . Leptobyrsa decora is very damaging to lantana seasonally but has a very limited distribution, being found at only a few sites in high altitude tropical regions. Two agents, Plagiohammus spinipennis and Teleonemia harleyi previously reported as established, were not found in the surveys. Despite the establishment of 16 agents, lantana is not under adequate control in Australia. Climate is probably the major factor that prevents populations of insects from being maintained at consistently high enough levels to control the weed.

Host specificity, release, and establishment of the gorse spider mite, Tetranychus lintearius Dufour (Acarina: Tetranychidae), for the biological control of gorse, Ulex europaeus L. (Fabaceae), in Australia

Abstract The gorse spider mite, Tetranychus lintearius , is widespread on Ulex europaeus in Europe and its foliage-feeding activities can cause severe damage to plants. It has been released as a biological control agent for U. europaeus in New Zealand, the United States, and Chile following tests on over 100 plant species or cultivars confirming its host specificity to Ulex species. The suitability of T. lintearius for release in Australia was tested on an additional 32 plant species or cultivars from the family Fabaceae that occur in Australia. The tests confirmed that T. lintearius was a genus-level specialist and would be unable to survive on any plant other than U. europaeus in Australia. The first Australian field releases were carried out in Tasmania and Victoria in December 1998. Since then, field releases from laboratory cultures at 116 sites in Tasmania and 90 sites in Victoria have resulted in T. lintearius initially becoming well established in both states. However, examination of T. lintearius colonies in Tasmania and Victoria has shown that predation by the introduced Chilean predatory mite, Phytoseiulus persimilis and the native coccinellid, Stethorus histrio , is already widespread. These predators have the potential to significantly suppress populations of T. lintearius and severely restrict its usefulness as a biological control agent in Australia.

Impact of the Seed-Fly, Ophiomyia lantanae (Froggatt) (Diptera: Agromyzidae), on the Viability of Lantana Fruit in South-East Queensland, Australia

The seed-fly Ophiomyia lantanae (Froggatt) (Dip.: Agromyzidae) is one of the most widely established biological control agents for lantana. Larvae of O. lantanae are found in the lantana fruit, in which they attack the fleshy endosperm and pupate in either the seed receptacle or a chamber within the fruit. This paper questions the impact of the seed-fly as a biological control agent in Australia. Fruit were dissected and tested with tetrazolium chloride to assess the viability of embryos. Of 3300 fruit dissected, none of the embryos were affected. Dissections and testing of fruit of different ages suggest that embryos are viable for a short period, regardless of whether the fruit is fly-infested.

Biology and climatic requirements of Perapion antiquum (Coleoptera: Apionidae) in southern Africa: implications for the biological control of Emexspp. in Australia

AbstractThe potential distribution of the South African weevil, Perapion antiquum (Gyllenhal), a biological control agent for the weeds Emex spp., was deter mined by the computer program CLIMEX, using its native distribution, phenology and abundance together with development parameters. The predicted distribution included parts of Hawaii where the weevil successfully controlled Emex australis and E. spinosa. In Australia, sites of past unsuccessful releases have climates that this analysis indicates are unsuitable for the insect. The most favourable regions for establishment of the weevil are near the coast in the southern half of Australia, but most of these do not overlap with regions where Emex spp. are a problem. In western Cape Province, South Africa, E. australis plants are abundant and the weevil attacks the plant after seeds have formed. In Hawaii, a fortuitous combination of climatic conditions favours the weevil during the period after seed germination, and this may be the key to its control of the weed. Sites with climatic conditions similar to successful control sites in Hawaii are not found in Australia. It was concluded that P. antiquum will be of limited use as a biological control agent in Australia even in areas suitable for its establishment.

Acigona infusella (Walker) (Lepidoptera: Pyralidae), an agent for biological control of waterhyacinth (Eichhornia crassipes) in Australia

AbstractThe biology and host specificity of a South American moth, Acigona infusella (Wlk.), were studied in quarantine facilities in Australia. In choice tests on the host specificity of A. infusella, slight feeding by larvae occured on ginger, lettuce, banana, bullrush (Typha orientalis) and water primrose (Ludwigia peploides), but in starvation tests only waterhyacinth (Eichhornia crassipes) and pickerel weed (Pontederia cordata) supported complete development. A decrease in larval mortality and increase in egg-mass size of A. infusella occured when a microsporidian, Vairimorpha sp.; infecting the colony was eliminated, suggesting that these insects may then perform more effectively as biological control agents in Australia than in South America. The damage to waterhyacinth cause bu larvae of A. infusella may complement attack by other biological control agents already established in Australia.

Life histories and host specificities of theEchium flea beetlesLongitarsus echii andL. Aeneus [Col. Chrysomelidae

Two halticine flea beetles,Longitarsus echii Koch andLongitarsus aeneus Kutsch, occurring on the boraginaceous plantEchium plantagineum L. in the western Mediterranean region are potential biological control agents in Australia where the plant has become a weed (Paterson's curse). The adults of both species feed by making “shot holes” in the leaves. The larvae of both species attack the roots ofEchium, those ofL. echii feeding more centrally in the root than those ofL. aeneus which attack the outer cortex and rootlets. Both species are univoltine. The host restrictions of both flea beetles as adults and as larvae were tested using the criteria already established for theEchium leaf minerDialectica scalariella Zeller (Wapshere & Kirk, 1977). This testing established that it would be safe to introduce the 2 insects into Australia for the biological control ofE. plantagineum and they are now under quarantine.

The biology and host specificity of the Echium leaf miner Dialectica scalariella (Zeller) (Lepidoptera: Gracillariidae)

AbstractThe gracillariid leaf miner Dialectica scalariella (Zell.), which occurs in Mediterranean Europe, North Africa, the Middle East and the Canaries, is a potential biological control agent for the weed Echium plantagineum in Australia. The moth has a high fecundity and oviposits on the leaves of Echium spp. and other Boraginaceae. The larvae destroy the leaves by forming large bulbous blotch mines. There are 5-7 generations per year. Host restriction of D. scalariella to Boraginaceae was tested by exposing a wide range of cultivated plants considered to be most at risk from it because of their close relation to Boraginaceae, because they were of Australian or non-European origin, because they did not occur in the same ecoclimatic region as D. scalariella, because their entomological fauna was poorly known, and because they or related plants were known to be attacked by insects closely related to D. scalariella. The host restriction of the moth was confirmed as only boraginaceous plants were attacked. It was concluded that both in terms of effectiveness and specificity D. scalariella could serve as a biological control agent in Australia for E. plantagineum.