The Jewel Beetle (Hylaeogena jureceki); a new biocontrol for cat’s claw creeper (Dolichandra unguis-cati) in Queensland

Cat’s claw creeper (Dolichandra unguis-cati (Bignoniaceae) is a serious environmental weed in Queensland and New South Wales. It presents a threat to riparian and rainforest ecosystems and is often found in inaccessible locations that are not suitable for chemical or physical control methods. This makes biological control an important tool for managing this weed. The jewel beetle Hylaeo¬gena jureceki was approved for release in Australia in May 2012. Since approval, approximately 35,000 insects have been released at 53 sites. Multiple and single releases have been made at sites with the number of insects released ranging from 20 to 1590. Post-release monitoring before and after winter found the beetle persisting at 73% of release sites in southeast Queensland. Within the release sites, the beetle appears to disperse widely, up to 100 m over a 15 month period. Based on these early field results, it appears that the beetle will establish and spread in Queensland and New South Wales. In addition to direct field releases, the beetle has been supplied to various community and Landcare groups for breeding and field release. This will hasten the spread of the insect to a wider area. It is expected that the jewel beetle will complement the leaf-sucking tingid (Carvalhotingis visenda) and leaf-tying moth (Hypocosmia pyrochroma) that were released in 2007

Temporal Variation of Phytophagous Insects of Calotropis gigantea (L.) in Southern Province of Sri Lanka

Calotropis gigantea is a native plant to Sri Lanka having an ayurvedic medicinal value. People use the plant to gain fodder, fiber, and fertilizer. Despite its benefits, the plant is considered as an invasive species in Australia, the USA, etc. As the plant is medicinally, agriculturally, and ecologically valuable, the study was designed to investigate phytophagous insects of C. gigantea and their temporal variation. The field visits were conducted fortnightly from August 2015 to August 2016 in eleven sites in Southern Province (SP). During sampling, the number of insect species, their abundance, and the number of Calotropis fruits were recorded in selected trees. Twentynine insect species were recorded from C. gigantea and among them twelve species were phytophagous. Dacus persicus and Paramecops farinosa were destructive phytophagous insects. D. persicus was recorded in all three districts of SP throughout the year and the mean abundance varies significantly (p= 0.002) among districts. P. farinosa was only recorded from Hambantota district. Sphaeroderma sp. was the most abundant phytophagous insect and varied widely across (p = 0.000) districts of Southern Province. Danaus chrysippus larva was observed in all selected sites of SP. None of the insect abundance correlated with Calotropis fruit density, month of year and monthly rainfall

Growth of Queensland Jatropha gossypifolia biotypes under varying water regimes

Bellyache bush (Jatropha gossypifolia L. (Euphorbiaceae)) is a serious weed of dry tropical regions of northern Australia, with the potential to spread over much of the tropical savannah. It is well adapted to the harsh conditions of the dry tropics, defoliating during the dry season and rapidly producing new leaves with the onset of the wet season. In this study we examined the growth and biomass allocation of the three Queensland biotypes Queensland Green, Queensland Bronze and Queensland Purple) under three water regimes (water-stressed, weekly watering and constant water). Bellyache bush plants have a high capacity to adjust to water stress. The impact of water stress was consistent across the three biotypes. Water stressed plants produced significantly less biomass compared to plants with constant water, increased their biomass allocation to the roots and increased biomass allocation to leaf material. Queensland Purple plants allocated more resources to roots and less to shoots than Queensland Green (Queensland Bronze being intermediate). Queensland Green produced less root biomass than the other two biotypes

The Impact of Parthenium Weed-Amended Substrates on the Germination and Early Growth of a Range of Pasture and Crop Species

Parthenium weed (Parthenium hysterophorus L.) is an internationally important invasive weed native to the tropical and sub-tropical Americas, and invasive in more than 30 countries. This weed has serious adverse influences on rangeland and agricultural crop production, on human and animal health, and on the biodiversity of natural communities. Parthenium weed leaf litter can reduce seedling emergence and affect the early growth of a wide range of pasture and crop species. Soil collected from a heavily infested parthenium weed area was shown to reduce seedling emergence of a wide range of test plants (lettuce (Lactuca sativa L.), maize (Zea mays L.), curly windmill grass (Enteropogon acicularis L.), and liverseed grass (Urochloa panicoides P.Beauv.)) by between 20 to 40%; however, the soil had no effect on the subsequent growth of the surviving test plants. Soil amended with dried parthenium weed leaf litter reduced the emergence of test species by ca. 20 to 40%, but it had no effect on the growth of the surviving test plants. One week after emergence, the growth of all test species was stimulated by 9 to 86% in the leaf litter-amended soil with the increased growth matching the increased amounts leaf litter amended. In parthenium weed-infested landscapes, the substrate (soil) is affected by the plant during the growing season by the release of allelopathic chemicals. However, the plant’s litter can affect the community outside of the growing season, first through a residual allelopathic activity, but also by a fertilizing effect as litter breakdown occurs. This study demonstrates the significant ability of parthenium weed to affect plant communities throughout the year and, when considered over several years, this may lead to the creation of a complete monoculture of the weed. View Full-Tex

Germination Biology and Occurrence of Polyembryony in Two Forms of Cats Claw Creeper Vine, Dolichandra unguis-cati (Bignoniaceae): Implications for Its Invasiveness and Management

Cat’s claw creeper vine, Dolichandra unguis-cati (L.) Lohmann (syn. Macfadyena unguis-cati (L.) Gentry), is a major environmental weed in Australia. Two forms of the weed with distinctive leaf morphology and reproductive traits, including varying fruit size, occur in Queensland, Australia. The long pod form occurs in a few localities in Queensland, while the short pod form is widely distributed in Queensland and northern part of New South Wales. This investigation aimed to evaluate germination behavior and occurrence of polyembryony (production of multiple seedlings from a single seed) in the two forms of the weed. Seeds were germinated in growth chambers set to 10/20°C, 15/25°C, 20/30°C, 30/45°C and 25°C, representing ambient temperature conditions of the region. Germination and polyembryony were monitored over a period of 12 weeks. For all the treatments in this study, seeds from short pod plants exhibited significantly higher germination rates and higher occurrence of polyembryony than those from long pod plants. Seeds from long pod plants did not germinate at the lowest temperature of 10/20°C; in contrast, those of the short pod form germinated under this condition, albeit at a lower rate (reaching a maximum 45% germination at week 12). Results from this study could explain why the short pod form of D. unguis-cati is the more widely distributed plants in Australia, while the long pod is confined to a few localities. The results have implication in predicting future range of both forms of the invasive D. unguis-cati, as well as inform management decisions for control of the weed

Insect diversity on Calotropis gigantea (L.) in Sri Lanka

Calotropis gigantea is a drought-resistant and salt-tolerant medicinal plant native to Sri Lanka. Although C. gigantea is widely distributed in Sri Lanka, information on insects associated with the plant is less understood. The objective of the study is to identify the diversity of insect fauna associated with C. gigantea. Surveys were conducted in 120 sites covering all provinces of Sri Lanka to document the insect fauna associated with C. gigantea and their biotic associations. The insects found in C. gigantea were cataloged as pests, pollinators, and occasional visitors. A total of thirteen morphospecies of phytophagous pests, six species of pollinators, and fourteen species of occasional visitors were documented. Dacus persicus and Paramecops farinosa were the highly damaging pests while Sphaeroderma sp. was more widespread. Xylocopa spp. were the most abundant insect pollinators. Dacus persicus and P. farinosa were identified as monophagous species of C. gigantea. Occasional visitors belonged to five orders and their diversity was very high. As the initial record from Sri Lanka, the findings of the study provide information on the identification of the insect fauna associated with Calotropis and their association with C. gigantea

The invasive Parthenium hysterophorus L. has limited impact on soil chemistry and enzyme activities but influences above and below ground bio-diversity

The invasive Parthenium hysterophorus L., a Weed of National Significance, is pervasive in agriculture, conservation and disturbed lands of central Queensland. In recent years, it has spread to the eastern and southern parts of the State and has the potential for incursion to the neighbouring States of New South Wales and Northern Territory, especially in view of climate change. However, very little work (most done overseas with inconsistent findings) has been reported on the weed’s impact on soil processes and native biodiversity. The work reported herein (involving soil sampling across multiple sites in central Queensland in parthenium weed infested and non-infested habitats) showed that due to the weed’s annual growth habit, a null effect was detected for soil chemistry (both micro- and macro-nutrients) and enzyme activities (β-glucosidase, fluorescein diacetate (FDA) hydrolysis and total microbial nitrogen and carbon). In contrast, significant negative impacts of parthenium weed infestation were observed for both below-ground (soil seed bank) and above-ground composition and diversity of co-occurring plant species. The results are discussed in terms of sampling methodology, adaptive pasture management, the weed’s growth habit and its ‘perceived’ position on Queensland weed list for risk assessment (based on impact, abundance and spread) and management