Biological control of bellyache bush: Native range surveys in South America

Bellyache bush (Jatropha gossypiifolia), a deciduous shrub introduced as an ornamental from tropical America, is a major and expanding weed of rangelands and riparian zones in northern Australia. Biological control that complements existing control techniques (e.g. herbicide, mechanical and fire) is needed for cost-effective and long-term control of the weed. Surveys in Mexico, Central and northern South America and the Caribbean for potential biological control agents resulted in release of the seed feeding bug Agonosoma trilineatum (which failed to establish) and prioritisation of a leaf-rust Phakopsora arthuriana (previously known as P.jatrophicola) for host-specificity testing (ongoing). Prospects of gaining new agents from Mexico, Central America and the Caribbean are unlikely. Hence, further surveys were conducted in South America, at 42 sites in Peru, 15 sites in Bolivia and 16 sites in Paraguay. Natural populations of bellyache bush (green leaf form) were seen only in the arid regions of Bolivia. Ornamental populations (purple leaf form) were seen in Peru, Paraguay and Bolivia. A total of 14 agents (12 species of insects, one mite species and one rust fungi) were collected from Peru, Bolivia and Paraguay. The insects were exported to a quarantine facility in South Africa, where they were reared through to adults and sent to relevant taxonomic experts for identification. Identifications of the leaf-mining gracillariid moth Stomphastis thraustica from Bolivia and Peru and the leaf-feeding cecidomyiid Prodiplosis sp. near longifila from Paraguay have been confirmed, while the identification of the shoot-tip/leaf galling cecidomyiid (?Prodiplosis sp.) from Bolivia is in progress. None of the notodontid larvae from Paraguay developed into adults in the quarantine facility in South Africa. A leaf-rust was also recorded from both Bolivia and Peru. The leaf was exported to CABI (UK) and DAFF (Brisbane) where it was identified as P. arthuriana. The limited number of insect species found on bellyache bush in the arid regions in Bolivia was probably due to the timing of surveys which were undertaken late in the dry season. Further exploration needs to be conducted in Bolivia during the wet season to study the field host range and damage levels of the previously identified agents and to look for any new agents. Based on the restricted field host range in South America, an application to import the Jatropha leaf-miner (S. thraustica) in to a quarantine in Brisbane, Australia for host-specificity testing has been submitted to relevant regulatory authorities in Australia

How widespread is Parthenium hysterophorus and its biological control agent Zygogramma bicolorata in South Asia?

Parthenium hysterophorus is a weed of global significance causing severe economic, environmental, human and animal health problems in Asia, Africa, Australia and the Pacific. In South Asia, P. hysterophorus occurs in India, Pakistan, Sri Lanka, Bangladesh and Nepal. A host-specific leaf-feeding beetle Zygogramma bicolorata from Mexico was introduced into India in 1984, as a biological control agent for P. hysterophorus. In this study, a GIS-based distribution map of P. hysterophorus and its biological control agent Z. bicolorata in South Asia based on meta-analysis is presented. The map highlights the limited published information on P. hysterophorus incidence in many of the states and territories in India, as well as in neighbouring Bangladesh, Bhutan, Nepal and Pakistan. Incidence of Z. bicolorata was recorded as three distinct clusters, covering many states in India. In Pakistan, Z. bicolorata was recorded in the Punjab region bordering India. A CLIMEX model based on the current distribution of Z. bicolorata in India suggests that the geographic range of this agent in India and Pakistan can extend to other P. hysterophorus-infested areas in the region. The CLIMEX model also suggests that all of Bangladesh and Sri Lanka, and parts of Nepal are climatically suitable for Z. bicolorata

Thrips-fimgus association with special reference to the sporophagous Bactrothrips idolomorphus (Karny). (Tubulifera: Thysanoptera)

Aspects of feeding and fungal spore preference in terms of the percentage of gut-spore composition, and the relative preference of sporophagous Tubulifera to Coelomycetes, Ascomycetes, Hyphomycetes are highlighted. A positive correlation between the width of the maxillary stylets and the fungal spore size indicates the relationship between the two in the choice of the spore type for feeding. The incidence of reproductive polymorphism among the majority of large spore feeding thrips and their absence in hyaline spore feeders, the role of abiotic factors such as temperature and relative humidity in determining the type of reproduction and their influence on the post-embryonic development inBactrothrips idolomorphus are discussed. Numerical variation in the pre-vitellogenic, vitellogenic and developing oocytes during oviparity, ovoviviparity and viviparity is also discussed

Thermal tolerance and potential distribution of Carvalhotingis visenda (Hemiptera: Tingidae), a biological control agent for cat's claw creeper, Macfadyena unguis-cati (Bignoniaceae)

The specialist tingid, Carvalhotingis visenda, is a biological control agent for cat's claw creeper, Macfadyena unguis-cati (Bignoniaceae). Cat's claw creeper is an invasive liana with a wide climatic tolerance, and for biological control to be effective the tingid must survive and develop over a range of temperatures. We evaluated the effect of constant temperatures (0-45°C) on the survival and development of C. visenda. Adults showed tolerance for wider temperature ranges (0-45°C), but oviposition, egg hatching and nymphal development were all affected by both high (>30°C) and low (<20°C) temperatures. Temperatures between 20°C and 30°C are the most favourable for adult survival, oviposition, egg hatching and nymphal development. The ability of adults and nymphs to survive for a few days at high (40°C and 45°C) and low (0°C and 5°C) temperatures suggest that extreme temperature events, which usually occur for short durations (hours) in cat's claw creeper infested regions in Queensland and New South Wales states are not likely to affect the tingid population. The potential number of generations (egg to adult) the tingid can complete in a year in Australia ranged from three to eight, with more generations in Queensland than in New South Wales

Prickly acacia biocontrol phase II: host specificity testing of agents from India

Prickly acacia (Vachellia nilotica ssp. indica), a multipurpose tree native to the Indian subcontinent, is a Weed of National Significance and is widespread throughout the grazing areas of northern Australia. Biological control of prickly acacia has been in progress since the early 1980s, but with limited success to date. Based on genetic and climate matching studies, native surveys for potential biological control agents were conducted in India, resulting in the prioritisation of several species. The brown leaf-webber, Phycita sp. A, was imported into quarantine in January 2011 and host specificity testing commenced in June 2011. In no-choice larval development trials the leaf-webber completed development on 16 out of 27 non-target plant species tested. Despite occurring only on prickly acacia in the field, testing of the brown leaf-webber was terminated in December 2012 due to unacceptable non-target feeding. The second leaf-webber, Phycita sp. B, was imported into quarantine in October and December 2013 and host-specificity testing commenced in May 2014 after colony establishment, though maintaining the colony has proved difficult due to issues with stimulating reproduction. Host-specificity testing of a scale insect, Anomalococcus indicus, commenced in July 2011. The scale insect completed development on 17 of the 83 non-target plant species tested during no-choice trials. However, when provided with a choice, prickly acacia was the preferred host. In view of the field host specificity of the scale insect in India, choice trials under field conditions in India involving non-target test plants on which the scale insect completed development in no-choice tests in quarantine are in progress. Results to date suggest that Neptunia major and Vachellia sutherlandii are likely to be susceptible to the scale insect attack under field conditions. Tests for the susceptibility of other non-target plants for the scale insect under field conditions in India are in progress. The green leaf-webber larvae completed development on 10 out of 19 test plant species under no-choice conditions but in no-choice oviposition trials egg have been laid only on prickly acacia and N. major. However, in paired choice oviposition trials, eggs were laid only on prickly acacia and not on N. major. No further progress on screening the remaining test plants for the green leaf-webber was made due to difficulties in maintaining a culture of the insect in quarantine. b.bA colony of the leaf-weevil Dereodus denticollis could not be established in the quarantine due to difficulties with its oviposition and larval feeding. Three promising gall-inducing biocontrol insects (a thrips gall, a mite gall and a midge gall) have been identified in Ethiopia. Based on damage potential, field host range and geographic range, the gall thrips, Acaciothrips ebneri (Karny) (Thysanoptera: Phlaeothripidae), inducing rosette galls in shoot tips and sprouting axillary buds resulting in shoot tip dieback, was imported into high-security quarantine in Brisbane, Australia and host specificity tests are in progress. No-choice tests on 14 non-target test plant species so far suggest that the gall thrips is highly host specific with no galls on any of the non-target plant species

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