See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/321759098 AT LAST, BIOLOGICAL CONTROL OF BELLYACHE BUSH Conference Paper · December 2017 CITATIONS READS 0 53 4 authors: Dianne Bronwyn Jean Taylor Elizabeth Louise Snow Queensland Government Queensland Government 7 PUBLICATIONS 29 CITATIONS 13 PUBLICATIONS 163 CITATIONS SEE PROFILE SEE PROFILE Kerri James Moore Kunjithapatham Dhileepan The Commonwealth Scientific and Industrial Research Organisation Queensland Government 1 PUBLICATION 0 CITATIONS 163 PUBLICATIONS 1,658 CITATIONS SEE PROFILE SEE PROFILE Some of the authors of this publication are also working on these related projects: Biological control of Navua sedge: feasibility studies View project Invasive species View project All content following this page was uploaded by Kunjithapatham Dhileepan on 13 December 2017. The user has requested enhancement of the downloaded file. AT LAST, BIOLOGICAL CONTROL OF BELLYACHE BUSH Dianne B. J. Taylor, Elizabeth L. Snow, Kerri Moore and Kunjithapatham Dhileepan Biosecurity Queensland, Department of Agriculture and Fisheries, Ecosciences Precinct, Boggo Road, Dutton Park, Queensland 4102, Australia. ABSTRACT Jatropha gossypiifolia , commonly known as bellyache bush, is a serious weed of rangelands and riparian zones of northern Australia. Since bellyache bush became a target for biological control in 1997, only one agent has been released and this failed to establish. A renewed biological control effort has identified a number of potential agents. A small leaf-mining moth, Stomphastis sp. (Lepidoptera: Gracillariidae), was imported from Peru into quarantine for further research in 2014. Newly emerged larvae mine directly into a leaf and remain there until pupation. No-choice host specificity testing of Stomphastis sp. has been completed for 43 test plant species. The moth laid eggs on numerous non- target species; however development of the agent only occurred on bellyache bush and its congener J. curcas , which is also a weed. Quarantine testing has thus confirmed that the leaf miner is highly host specific and suitable for release in Australia. An application to release this agent will be submitted to the Australian government in the near future. A second agent, Sciota divisella (Lepidoptera: Pyralidae) from India, was imported into quarantine in 2015. The larvae of this moth feed on the leaves, stems and fruit of bellyache bush. No-choice host specificity testing of this agent is in progress. To date, complete development has occurred on five exotic species and two natives. The potential use of the two native species as hosts is being investigated further. Other prospective agents under consideration include a gall midge from Bolivia and a leaf-feeding midge from Paraguay. Keywords: Jatropha gossypiifolia, Stomphastis, Sciota, Australia INTRODUCTION Jatropha gossypiifolia L. (Euphorbiaceae) , commonly known as bellyache bush, is a serious weed of rangelands and riparian zones of northern Australia, and it has the potential to invade much of northern Australia (Heard et al. 2012). It forms dense thickets, reducing the usefulness of land for pastoral and grazing purposes. Monotypic stands supress seedling recruitment of native species, reducing biodiversity and impacting fire regimes due to reduced fuel load. The shallow root system causes increased erosion along creek and river banks (Bebawi et al. 2007). All parts of the plants are toxic to stock and humans. Biological control is an important component of the long-term management strategy for J. gossypiifolia in Australia. Biological control of bellyache bush was initiated in 1999. Since then, only one agent, the jewel bug, Agonosoma trilineatum (F.) has been released and there is no evidence of its establishment (Heard et al. 2012). A renewed biological control effort, involving exploration in South America, identified a 4 number of potential biological control agents (Dhileepan et al. 2014). The most promising was a small leaf-mining moth Stomphastis sp. (Lepidoptera: Gracillariidae) which was imported from Peru into quarantine in 2014 for further research. A second agent, Sciota Page divisella (Duponchel) (Lepidoptera: Pyralidae), was found on bellyache bush during opportunistic surveys conducted in India and was imported into quarantine in 2015. The larvae of this moth feed on the leaves, stems and fruit of bellyache bush. In this paper, we discuss the progress of quarantine testing for both of these species and future actions. MATERIALS AND METHODS Stomphastis sp. Stomphastis sp. was imported into our quarantine facility in Brisbane in November 2014 (Taylor et al. 2016). Adult Stomphastis sp. are small moths (less than 1 cm long) and live for an average of 10 days under quarantine conditions. Females lay eggs singly on leaves. Newly emerged larvae mine directly into the leaf and remain in the leaf as they develop. Larvae exit the leaf to pupate, mainly on the leaf. A generation from adult to adult takes around 22 days under quarantine conditions (Taylor et al. 2016). The host test list for Stomphastis sp. contains 43 species from the Euphorbiaceae and closely related families; 33 are native species and 10 are exotic species (Table 1). All test plants were subjected to no-choice oviposition/larval development trials, with at least five replicates conducted for most species. Twenty newly emerged, unsexed Stomphastis sp. adults were released into a 45 x 45 x 90 cm gauze covered cage, containing a single potted test plant. With each round of testing, at least one bellyache bush plant was also included as a control, however only ten newly emerged adults were released into this cage. Test plants were maintained until a new generation of adults were recovered from bellyache bush, at which time they are disposed of. Test species on which Stomphastis sp. completed development, were subject to choice oviposition/larval development trials with bellyache bush. Sciota divisella In India, S. divisella was observed feeding on bellyache bush, J. curcas and Euphorbia grantii Oliv., (Snow et al. 2016). A colony was established in quarantine in July 2015, with a further importation in October 2015 to augment the colony. Female S. divisella lay eggs in clumps or rows on leaves and the upper portions of stems of bellyache bush plants (Snow et al. 2016). Native, crop and ornamental species from the Euphorbiaceae and closely-related families were included in the host testing. Initially test plants were subject to no-choice larval development trials, with at least five replicates for each species. Ten newly-hatched S. divisella larvae were carefully placed onto each potted test plant which were each enclosed in a 45 x 45 x 90 cm gauze covered cage. With each round of testing, at least one bellyache bush plant was also included as a control. Test plants were maintained until a new generation of adults were recovered from bellyache bush, at which time they are disposed of. Native species on which complete development occurred will be subject to further testing including oviposition and choice trials. RESULTS Stomphastis sp. 5 Under no-choice conditions, Stomphastis sp. females laid eggs on 29 of the 43 test species, predominantly on leaves at the top of the plants. Egg hatch occurred on 24 of Page these species. However, in all cases except on bellyache bush and J. curcas , the 1st instar larvae died shortly after emerging (Figures 1 and 2). When female Stomphastis sp. were provided with both bellyache bush and J. curcas , they oviposited at an equal rate on both species. The proportion of eggs that developed into adults was also similar for the two species. Sciota divisella To date larval development trials have been completed for 13 test species and partially completed for further 22 species (Table 1). These include 25 native and ten exotic species. Complete larval development has occurred on seven non-target species – five exotic species ( J.curcas, J. podagrica Hook. , Manihot esculenta Crantz., Euphorbia nerifolia L. and E. grantii ) and two native species ( Macaranga tannarius (L.) Müll.Arg. and E. plumerioides Teijsm. ex Hassk.) (Figure 3). In no-choice oviposition trials females have laid eggs on M. tannarius. Euphorbia plumerioides is yet to be tested. DISCUSSION No-choice tests are rigorous tests and identify the absolute host range; insects either feed/lay eggs on the test plant or die. Host specificity test results for Stomphastis sp. provide strong evidence that it is highly host specific and suitable for release in Australia. The non-target species on which eggs were laid have been shown to be unsuitable hosts by the absence of any larval development. Larval development only occurred on bellyache bush and J. curcas. Though not declared as a weed in Queensland, J. curcas is regarded as invasive and is an approved target for biological control in Australia. Utilisation of this species in the field by Stomphastis sp. would thus be beneficial. Jatropha curcas was the only congener of three tested to support any development of the insect past the first instar. Biological studies conducted in quarantine demonstrated that Stomphastis sp. has both a short generation time and high fecundity. This bodes well for its future as a biological control agent. It is expected that like other Gracillaridae, Stomphastis sp. will be an adept disperser, a desirable characteristic given the expansive areas across which bellyache bush occurs. A release application will be submitted to the relevant regulatory bodies later this year. If approved for release, the release effort for Stomphastis sp. will be focussed in areas with major bellyache bush infestations, such as along the Burdekin River from Charters Towers to Home Hill, Hughenden and Gulf of Carpentaria, along the Gregory River and Normanton, and along the Palmer River in Cape York. Given the ease with which the insect can be reared, there will be an opportunity to explore partnerships with various community and NRM groups. Insects will also be supplied to stakeholders in the Northern Territory and Western Australia (in partnership with the respective government bodies).