Fourteenth Australian Weeds Conference

What happens when a biocontrol agent attacks exotic but desired ornamentals?

Philip E. Maher1, Brett J. Davis1, Michael D. Day2, A. Peter Mackey2, William A. Palmer2 and Elizabeth L. Snow2 1 Queensland Department of Natural Resources, Mines and Energy, GPO 2454, Brisbane, Queensland 4001, Australia 2 Alan Fletcher Research Station, Queensland Department of Natural Resources, Mines and Energy, PO Box 36, Sherwood, Queensland 4075, Australia

Summary Signifi cant damage to non-target plant unpublished estimate of the total cost indicates it ex- species by a biological control agent could be in- ceeds $20 million annually (Department of Natural imical to the future of biocontrol, particularly if it Resources, Mines and Energy 2004). is associated with widespread community concern. Aconophora compressa (Walker) (Homoptera: When an agent attacks exotic non-target species that Membracidae) was the 27th species released are valued by some members of the community, then in Australia as a biocontrol agent for . It is a the issues become clouded and diffi cult to address. sap-sucking bug imported from Mexico and was fi rst Aconophora compressa (Walker) was approved for released for the Queensland Department of Natural release as an agent for biocontrol of Resources, Mines and Energy (NRM and E) in 1995 L. in 1995, after 21 state and federal environmental by the Alan Fletcher Research Station (AFRS) (Palmer and agricultural agencies reviewed and supported the et al. 1996). The last release in Queensland was in submission. November 2001 at Helidon. Aconophora compressa established in the fi eld All quarantine protocols for the import, testing and since 1999, when A. compressa populations be- and release of A. compressa were met. Aconophora came locally high, it has also attacked the introduced compressa was extensively tested against a total of ornamentals fi ddlewood, L. 62 potential host plant species, representing numerous and duranta, Duranta erecta L. Both plant species plant families. The list of host plants for testing, and are popular garden plants, although fi ddlewood is the results of the testing were reviewed by 21 state and no longer widely planted. Adults were also found on federal agencies across the country. Final approval for several other closely related species in the same family release of the insect was given by the Australian Quar- or closely related families. While rural landholders antine Inspection Service (AQIS) and the Department and land managers were demanding agents to assist of Environment and Heritage. in the management of lantana, Australia’s worst envi- Aconophora compressa was widely released in ronmental weed, residents in south-east Queensland Queensland and New South Wales from 1995 to 2001 were concerned that A. compressa was damaging their and established at several sites in both states, including garden plants. The situation was both challenging and south-east Queensland and central NSW. complex – placating angry homeowners, while trying Since late 1999, researchers at AFRS have become to control a Weed of National Signifi cance. This paper aware that A. compressa populations were locally high discusses the issues, processes and outcomes involved around Brisbane, and the insect was found to attack with the handling of the A. compressa situation in the introduced ornamental tree fi ddlewood, Citharexy- south-east Queensland, covering science, extension, lum spinosum L. () and the introduced, communication, policy and media. ornamental shrub duranta, Duranta erecta L. (Verben- Keywords Non-target, Aconophora, lantana, com- aceae). However, heatwaves over the following sum- munication strategy, public concern. mer caused the insect to disappear from fi ddlewoods and no further study of the insect was possible. Insect INTRODUCTION populations again increased slowly during 2002. The Lantana, Lantana camara L. (Verbenaceae) is a summer of 2002/2003 was relatively mild and popula- Weed of National Signifi cance (WONS) and as such, tions persisted and built up to very large numbers on is regarded as one of Australia’s worst weeds (Day lantana and fi ddlewood, especially around the Brisbane et al. 2003). Lantana was estimated to cost Australia bayside suburbs (Day et al. 2003), the Gold Coast and $7 million per annum in lost production for primary higher altitude areas around Mount Tamborine and industries and more than $10 million per annum Springbrook in the Gold Coast hinterland, causing in control costs (Culvenor 1985). A more recent concern for homeowners.

187 Fourteenth Australian Weeds Conference

Fiddlewood, a rapidly growing exotic tree from Aconophora compressa also fed upon other plant the West Indies, which grows up to 20 metres, has species, both exotic and native, the highest profi le of been sporadically planted throughout Brisbane as which was jacaranda, Jacaranda mimosifolia (D. Don a screening/feature tree in suburban backyards and pers. comm.). Although fi eld observations ultimately parks. Local government and energy generation indicated that the effects on jacaranda and these other companies (such as Energex in Brisbane) now regard plant species were minor (Palmer et al. 2004), and that fi ddlewood as an undesirable species, as its shallow, they were very marginal hosts, the appearance of the aggressive root system interferes with underground insect on these plants caused understandable concern services and plumbing and its vigorous growth can for homeowners. damage overhead powerlines. DEPARTMENTAL APPROACH TO PROBLEM THE 2003 OUTBREAK The major problem for the Department was how to deal NRM and E received its fi rst phone call from a con- with the issue of an introduced biocontrol agent that cerned homeowner regarding A. compressa damaging was causing substantial damage to one of Australia’s their fi ddlewoods in late 2002 and by early April 2003, worst weeds and the public perception that the Depart- was receiving about 1–2 calls per week. The Depart- ment had released ‘another cane toad’ that attacked ment fi rst received signifi cant media attention and high ornamentals, which themselves were exotics. levels of public enquiry regarding A. compressa in Other diffi culties encountered included: the ability late April 2003. While a vast majority of calls related to produce public information materials; indications of to damage to fi ddlewoods, there were a signifi cant possible legal action; demands for compensation and/ number that suggested the insect was attacking ‘every or solving the problem for homeowners; signifi cant plant in the garden’. public reaction, i.e. ‘gardens being trashed’, ‘bug at- By the end of February 2004, NRM and E had tacking everything’; polarised opinion between science received 59 radio and seven television mentions, a and communication issues; delay between research signifi cant number of print media articles and a total staff knowing of a potential problem and the com- of 1732 telephone enquiries regarding A. compressa. munication of the issue to the broader departmental The number of calls NRM and E received clearly body; in-house resources to manage the problem of demonstrated that these non-target impacts of A. high volumes of public callers seeking information compressa attacking fi ddlewood and possibly other about the problem; and no registered control method species concerned a signifi cant number of homeown- for the insect being available for use on large trees. ers in south-east Queensland. These concerns were Once the problem of A. compressa attacking fuelled by media activity from one particular outlet fi ddlewood and possibly other garden species was that likened the insect to ‘another cane toad’. established, the Department adopted a coordinated Many fi ddlewood trees were affected, with some public relations strategy. A management group was trees being completely defoliated by the stress brought established and met regularly to discuss and formulate on by large numbers of feeding . To compound communications plans that were updated as required. the issue, when large numbers of A. compressa oc- The following actions were initiated and updated on curred on fi ddlewood and the tree began to lose leaves, a regular basis at a cost to the department of approxi- the insects migrated to other garden plants. These mately $175,000. ‘overfl ow’ populations sometimes fed on other species • Two part time staff were appointed to offer techni- but, in most cases, the insects were merely resting and cal and extension advice to the general public and did not feed or damage these other plants. to visit concerned homeowners. Like other sap-sucking insects (e.g. aphids, psyl- • A fact sheet for A. compressa was produced, re- lids, scales), A. compressa exudes copious quantities viewed and updated several times. of processed sap known as honeydew, a sugar–water • Fact sheets were mailed with covering letters to all solution in which black sooty moulds often thrive. The retail nurseries, garden centres, hardware outlets production of honeydew by A. compressa was found to and tree surgeons in south-east Queensland includ- dirty plants, paths, patios, drying laundry, and parked ing Toowoomba. Supplies of the brochure were cars and, because of its high concentration of sugars, also made available to affected local governments also caused yellowing of some lawns. While the hon- and to members of the public at targeted extension eydew and sooty mould problems can be resolved by events such as ‘Gardening Australia Live’ and on removing the bug, washing down paths, vehicles and the internet. giving lawns extra water, its presence was unsightly • Media releases were issued with only one nomi- and a major concern for some homeowners. nated spokesperson.

188 Fourteenth Australian Weeds Conference

• Media appearances, including the Brisbane nightly control one of Australia’s worst environmental weeds news and a gardening show, were made. and on the other the damage to exotic ornamentals in • Question and Answer items were posted to the gardens. When such a confl ict arises, it is critical that NRM and E web site. an adequate management plan is quickly activated, so • Presentations were made to local governments. that neither the Department nor the public is caught • Presentations were made to the Horticultural with insuffi cient information. This information should Media Association. include the status of the problem, the decision-making • A half-day industry forum was held at AFRS. processes involved, the benefi ts of the particular action • Ministerial and Director General briefs were pre- and any possible negative impacts to certain groups. pared. The communications and extension strategies • Media monitoring was implemented to issue developed for A. compressa have since been adapted transcripts of electronic media and press cuttings and applied to other more recent problems, in particu- on the same day. lar to the seizing of a Class 1 incursion (the • On-going situation updates were prepared for local red-eared slider turtle) and to breaches of the Land government and industry. Protection Act involving a wild animal park in far The Department also proceeded to resolve several sci- north Queensland. entifi c issues. It was necessary to distinguish plants that were actually being threatened by the insect from REFERENCES plants subject to minor feeding or plants on which the Culvenor, C.C.J. (1985). Economic loss due to poi- insects were simply resting. In this regard, the status of sonous plants in Australia. Proceedings of the mangrove species was of particular importance (Palm- Australia–USA poisonous plants symposium, er et al. 2004). Research into control methods for use eds A.A. Seawright, M.P. Hegarty, L.F. James and on large trees that could be registered nationally was R.F. Keeler, pp. 3-13. (Queensland Department of initiated. The relationship between high temperatures Primary Industries, Yeerongpilly). and insect mortality was investigated. The phenology Day, M.D., Broughton, S. and Hannan-Jones, M.A. of insect populations over time and on various plant (2003). Current distribution and status of Lantana species including mangroves, the mapping of the camara and its biological control agents in Aus- spread of infestations, and the infl uence of predators tralia, with recommendations for further biocon- and parasites were also investigated. This research is trol introductions into other countries. Biocontrol presently continuing and will develop a greater under- News and Information 24, 63N-76N. standing of the behaviour of A. compressa and provide Department of Natural Resources, Mines and Energy accurate information on the plants affected. (2004). Lantana control manual: current manage- Insect populations have declined substantially ment and control options for lantana (Lantana on lantana and fi ddlewoods after heatwaves during camara) in Australia. (Department of Natural the 2003–4 summer. Consequently, public and media Resources, Mines and Energy, Brisbane). comment has also reduced dramatically. Despite the re- Palmer, W.A., Day, M.D., Dhileepan, K., Snow, E.L. duced populations, A. compressa is fi rmly established and Mackey, A.P. (2004). Analysis of the non- in parts of Queensland and NSW and is continuing target attack by the lantana sap-sucking bug, to spread and contribute to the biocontrol of lantana. Aconophora compressa and its implications for However, it is likely that insect populations will again biological control in Australia. Proceedings of increase and that there will be further attack on fi d- the 14th Australian Weeds Conference, eds B.M. dlewoods, with the possibility of overfl ow populations Sindel and S.B. Johnson, pp. 341-4. (Weed Society again moving onto other ornamental species. As a re- of New South Wales, Sydney). sult, public concern and media activity and interest is Palmer, W.A., Willson, B.W. and Pullen, K.R. (1996). expected to follow. The host range of Aconophora compressa Walker (Homoptera: Membracidae): a potential biologi- CONCLUSION cal control agent for Lantana camara L. (Verben- The main concern with A. compressa was one of per- aceae). Proceedings of the Entomological Society ception and impact. On one hand, there is a need to of Washington 98, 617-24.

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