Papers by Kunjithapatham Dhileepan
Journal of Biological Control, 2014
Social Science Research Network, 2022
Data on the field release and establishment of cat's claw creeper leaf tying moth (Hypocosmia... more Data on the field release and establishment of cat's claw creeper leaf tying moth (Hypocosmia pyrochroma) as a weed biological control agent in Australia.
Biological Control, Sep 1, 2022
Biocontrol Science and Technology, Jun 22, 2022
Calotropis gigantea is a plant native to Sri Lanka with an Ayurvedic medicinal value, yet it is k... more Calotropis gigantea is a plant native to Sri Lanka with an Ayurvedic medicinal value, yet it is known to be invasive in countries where it has been introduced. Dacus persicus and Paramecops farinosus (Aak weevil) are monophagous insects that feed on C. gigantea. Present study is aimed to elucidate the life history aspects of D. persicus and P. farinosus with their damage to the plant, in order to assess the potential of them to be used as a bio-control agent against C. gigantea in countries where the plant is invasive. The field sampling was done throughout the island covering 108 sampling sites during December 2014 to October 2015, and C. gigantea fruits were examined for life stages of the two insect species, and any signs of damage to the fruit. D. persicus eggs were found in seed chamber as only one cluster of eggs per fruit, and three larval instars were recorded feeding on Calotropis seeds. Infected fruits drop pre-maturely with fully developed larvae inside. Subsequent pupation takes place in soil, and cocoons are creamy white and cylindrical in shape. Similarly, P. farinosus lay yellowish, oval and mostly one-clustered eggs in the inner-pericarp fibrous layer of the Calotropis fruit. Newly emerged larvae were apodous, pale yellowish-white with brown head capsule whereas developing larvae were creamy-white, curved and stout. P. farinosus larvae voraciously feed on Calotropis seeds while adults feed on leaves, buds and flowers. Fifth larval instar of Aak weevil pupated by forming silky cocoons within seed chamber of Calotropis fruits. Both species being seed predators highly damage reproductive structures of C. gigantea thus directly influences on reproductive output of the plant. These results provide baseline information needed in adopting D. persicus and P. farinosus as potential bio-control agents against C. gigantea.
Prickly acacia (Vachellia nilotica) is a landscape level weed problem affecting large areas of we... more Prickly acacia (Vachellia nilotica) is a landscape level weed problem affecting large areas of western Queensland and other areas of the state. Following high rainfall related mass germination events of 2010 – 2012, the Department of Agriculture and Fisheries (DAF) launched the War on Western Weeds (WoWW) initiative in 2013. WoWW focussed on three key areas: refining new tools and approaches; improving biosecurity systems; and, exploring biocontrol opportunities. Notable outcomes have included: refinement of misting, weed sniper and skattergun as control options; two Good Neighbour Program case studies demonstrating the practicalities of property boundary weed-free buffer zones; ecological studies as a basis for seed spread prevention actions; and, renewed biological control investigations involving searches for prospective agents in India and North Africa. Initiative results have been extended through forums, field days and publication of a decision support tool factsheet series. The increased capacity, skills, tools and motivation from the WoWW initiative are helping to achieve practical and cost-effective outcomes for prickly acacia management – helping land managers to help themselves.
Journal of entomology and zoology studies, Nov 1, 2017
Calotropis species are categorized under the family of Apocynaceae in the plant kingdom. Calotrop... more Calotropis species are categorized under the family of Apocynaceae in the plant kingdom. Calotropis plants grow as a small tree or spread as a shrub. It is drought resistant, salt tolerant and prefers disturbed sandy soils (Kumar et al, 2013). These species are distributed throughout the tropical regions. They are native to Asia and Africa (Sigh et al, 2013). Three species are recorded namely: C.procera, C.acia and C.gigantea (Bebawi et al, 2015). C.gigantea and C.procera are more common and have wider distribution than C.acia (Bebawiet al, 2015).
Bellyache bush (Jatropha gossypifolia L. (Euphorbiaceae)) is a serious weed of dry tropical regio... more 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.
Ceylon Journal of Science, Sep 6, 2021
Calotropis gigantea (Crown flower, Giant milkweed or Wara) is a native medicinal plant in Sri Lan... more Calotropis gigantea (Crown flower, Giant milkweed or Wara) is a native medicinal plant in Sri Lanka. It is recorded as an invasive plant in Australia, Brazil, USA, etc. Dacus persicus is recorded as a highly destructive monophagous pest of C. gigantea in Sri Lanka. Larvae of D. persicus feed on developing fruits and seeds and reduce the reproductive output of the plant significantly making it a suitable candidate for biocontrol. Therefore, the present study was aimed to investigate the distribution and reproductive biology of Dacus persicus to assess the potential as a biocontrol agent for Calotropis species. D. persicus distributed in six provinces in Sri Lanka. The duration of mating and ovipositing of D. persicus was 54 and 92 minutes, respectively. It laid eggs in the seed chamber of developing fruits and the fruit size is highly correlated (p < 0.001, r = 0.990) with the number of laid eggs. Only one egg cluster of D. persicus found within a single fruit having 18.5 (± 0.85) eggs per cluster and the eggs hatched in 3 days. The duration of larval and pupal stages for D. persicus were 24 and 12 days, respectively. These results provide essential information needed in adopting D. persicus as a biocontrol agent of C. gigantea.
Biological Control, Apr 1, 2021
Prickly acacia (Vachellia nilotica) has been the target of biological control programmes in Austr... more Prickly acacia (Vachellia nilotica) has been the target of biological control programmes in Australia for over three decades, with little success. Control efforts may have been hindered by poor characterisation of the plants in Australia, and the ambiguous taxonomy of the species. Nine subspecies of this weed have been described, with only one subspecies identified in Australia (subsp. indica), though previous genetic screening identified a unique genotype in Australia that allegedly did not match any of the previously described subspecies (dubbed the “Pakistan genotype”). We used gene sequencing to characterise this weed in Australia, and to assess the native range distribution of the invasive subspecies. Two widespread ITS1 haplotypes were identified from 25 localities across northern Australia, corresponding to subsp. indica and the undescribed “Pakistan genotype”. Many plants were heterozygous at the ITS1 locus, indicating plants with the distinct genotypes are freely interbreeding. The “Pakistan genotype”, which has no defining morphological characters, was found across the native range of subsp. indica (including Ethiopia, where this subspecies has only recently been detected). The “Pakistan genotype” is not, in other words, a distinct subspecies, but simply represents genetic variation within subsp. indica. No genetic structuring was found across the native distribution of subsp. indica, so the precise provenance of the Australian plants could not be determined. Future studies should use microsatellites or genotyping-by-sequencing approaches to provide a finer-scale assessment of the provenance of the Australian plants.
Ruhuna Journal of Science, Dec 31, 2021
Journal of Biological Control, Jul 12, 2012
CABI eBooks, 2019
In East and South-east Asia, parthenium weed (Parthenium hysterophorus) has invaded many countrie... more In East and South-east Asia, parthenium weed (Parthenium hysterophorus) has invaded many countries, including Vietnam in 1922, Southern China in 1926, Japan in 1972, Taiwan in 1988, Korea in 1993, a new second introduction has been identified in Northern China (Shandong Province) in 2004, and it has been found in peninsular Malaysia and Sarawak in 2013 and Thailand in 2016. This chapter discusses the history of invasion, background, spread and management (using chemical, cultural, physical and biological control methods) of pathenium weed in East and South-east Asian countries. Only a limited amount of information is available on the incidence of parthenium weed in these countries. More survey work is suggested to determine the full extent of the parthenium weed invasion. Although some countries have reported the presence of the weed and have some knowledge of its spread, legislative frameworks to help prevent further invasion and spread of parthenium weed are still needed. Also, educational tools need to be developed to raise public awareness. Methods to prevent further spread need to be implemented, including restrictions on the movement of seed lots and food products from infested to non-infested weed-free regions, and the potential for future biological control investigated.
CABI eBooks, 2019
Parthenium weed (Parthenium hysterophorus) is now recognized as a major invasive weed worldwide. ... more Parthenium weed (Parthenium hysterophorus) is now recognized as a major invasive weed worldwide. Yet in the 1950s, when it was first discovered in Australia, it was an almost unknown plant. International research on parthenium weed did not start until the 1970s, after reports of increasing health problems caused by the dense infestations in central India. Australian policy makers in 1973-75 were therefore working in an information vacuum when trying to manage this new weed, which was rapidly spreading south from the northern cattle zone. Their response was to establish one of the largest long-term and well-funded weed management programmes ever seen against a single weed, and the outcome has been startlingly successful. This chapter outlines the history and background of parthenium in Australia and the management tools used to produce this success. It shows that the management programme in place from 1975 to the present day, along with the simultaneous development of on-ground methods to reduce spread and a well-funded biological control programme to reduce the impact of existing infestations, has proved highly effective. Parthenium weed is no longer a major threat to farmers and landholders in Australia, and no longer rates as one of the top weeds, even in the worst-affected areas.
Parthenium (Parthenium hysterophorus L.), a serious weed of grazing areas in central Queensland (... more Parthenium (Parthenium hysterophorus L.), a serious weed of grazing areas in central Queensland (Qld) and a Weed of National Significance in Australia, has spread into parts of southern Qld. The isolated nature of the southern Qld infestations, probably resulting from the movement of contaminated stock feed, livestock and machinery, has meant many of the effective biological control agents established in core infested areas of central Qld have not extended their distribution at the same pace as the weed. As a result, a program to redistribute these agents from central Qld to southern Qld was initiated. The seed-feeding weevil (Smicronyx lutulentus Dietz), the stem-boring weevil (Listronotus setosipennis (Hustache), and the root-boring moth (Carmenta nr. ithacae Beutenmuller), the winter rust (Puccinia abrupta var. partheniicola Dietel & Holway), and the summer rust (Puccinia xanthii var. parthenii-hysterophorae Seier, Evans & Romero) were prioritised for redistribution. Since late 2015, prioritised agents have either been bulk collected from central Qld, or reared in glasshouse facilities in Brisbane, and released at 19 sites across 10 geographically isolated areas in southern Qld. Periodic surveys of release sites have indicated strong evidence of establishment of the winter rust and the Smicronyx weevil at most of the sites and preliminary signs of establishment of the summer rust and the Listronotus weevil at a few sites. Redistribution of field-collected and glasshouse-reared agents and monitoring of their establishment status in the field will continue over the next year.
Parthenium (Parthenium hysterophorus L.), a noxious weed of grazing areas in Queensland (Qld), is... more Parthenium (Parthenium hysterophorus L.), a noxious weed of grazing areas in Queensland (Qld), is a Weed of National Significance in Australia. Eleven biological control agents (nine insect species and two rust pathogens) have been released against parthenium in Australia. The majority of these agents have become established and have proven effective against the weed in central Qld. Parthenium is spreading further into southern Qld, where many of the widespread and effective biological control agents in central Qld are not present. Hence, a program to redistribute these agents from central Qld to the south and south east of the state has been initiated. The seed-feeding weevil (Smicronyx lutulentus Dietz), the stem-boring weevil (Listronotus setosipennis (Hustache)), and the root-boring moth (Carmenta nr. ithacae Beutenmuller), the winter rust (Puccinia abrupta var. partheniicola Dietel & Holway), and the summer rust (Puccinia xanthii var. parthenii-hysterophorae Seier, Evans & Romero) have been identified as priority agents for redistribution. So far, field collected winter rust, the Listronotus weevil, the Smicronyx weevil, the Carmenta moth and the leaf-feeding beetle (Zygogramma bicolorata Pallister) have been field released at ten sites in south and south east Qld. Field releases of the winter rust from glasshouse cultures were also made at several sites. So far there is evidence of field establishment of the winter rust and the Smicronyx weevil in some of the release sites. Cultures of the summer rust and Listronotus weevil have recently been established at the Ecosciences Precinct for future mass rearing and field releases. Redistribution of field collected and glasshouse cultured biological control agents and monitoring their establishment status in the field will continue over the next three years.
The Proceedings of the Royal Society of Queensland
The invasive liana cat's claw creeper, Macfadyena unguis-cati, native to tropical Central and Sou... more The invasive liana cat's claw creeper, Macfadyena unguis-cati, native to tropical Central and South America, is a major environmental weed in Queensland and New South Wales (NSW). Two morphologically distinct cat's claw creeper varieties occur in Australia, a 'short-pod' variety that is widespread through Queensland and NSW and a 'long-pod' variety restricted to a few sites in southeast Queensland. In this study we report the differences in the above-ground morphological, phenological and reproductive traits between the two varieties. The 'long-pod' variety has significantly larger leaves, larger pods, and larger number of seeds per pod than the 'short-pod' variety. The 'short-pod' variety has a slightly wider pods, and thicker leaves than the 'long-pod' variety. Both varieties have a yellow trumpet shaped flower, but the flower of the 'long-pod' variety has a deeper hue of yellow than the 'short-pod' flower. The fruits of the 'short-pod' variety mature in late summer to early autumn while the fruits of 'long-pod' variety mature in late winter to early spring. The more widespread nature of the 'short-pod' variety could potentially be due to a preference for this variety as an ornamental plant, due to its more presentable foliage characteristics and shorter pods, in contrast to the 'long-pod' variety.
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Papers by Kunjithapatham Dhileepan