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Biological Control of Eucalyptus Pests with the Southern Ladybird - A Possibility?

Sustainable Farming Fund application (2004/2005):

What is the problem/opportunity the project will address?

Species in the genus Eucalyptus are a vital component of farm forestry across New Zealand, with numerous species fulfilling many end needs (timber, pulp, veneer, carbon credits etc). Universal acceptance of these species is restricted by health problems, many of which are caused by insect and pathogens from their native Australian range. Under natural conditions potential Eucalyptus pests are regulated by natural enemies or competition, which is removed when a pest establishes in New Zealand. The use of natural enemies, or classical biological control, is one of the few sustainable and ecologically friendly methods to redress this balance.

Among the most serious of these pests is the Eucalyptus tortoise beetle, Paropsis charybdis. In 1987 the egg parasitoid Enoggera nassaui was introduced, and partially succeeded in controlling Paropsis. However, Enoggera is now attacked and suppressed by an obligate hyperparasitoid, Baeoanusia albifunicle, which was first detected in 2001. This new agent is linked to severe Eucalyptus defoliation as Enoggera is now unable to regulate Paropsis.

A new self established wasp species (Neopolycystus) also specifically attacks Paropsis eggs. A remarkable development with Neopolycystus was the gathering, breeding and release of the beneficial wasp by industry to improve its establishment in New Zealand. Biological control, even if only with a limited impact can reduce the need for chemical inputs into farm forestry, improving productivity and sustainability.

Following this development, the environment is right for work on the Southern Ladybird, Cleobora mellyi. Introduced in 1977, only one population of this Australian predator is believed to be established in the Marlborough Sounds. A conclusion from this well documented work was that there were insufficient psyllid species to supplement the diet of Cleobora, which was not nutritionally satisfied on Paropsis larvae alone. Since that time over 8 psyllid (and 3 Paropsis-related) species have established on Eucalyptus and Acacia in New Zealand. The collection, rearing and distribution of Cleobora could be beneficial in improving the biological control of a large number of Eucalyptus and Acacia pests. Any reduction in the use of harmful chemical insecticides is of positive and sustainable benefit, one which would recover the relatively small cost of the programme in a short time.

What previously completed work is relevant to this proposal?

The initial scientific programme to collect, rear and release Cleobora in New Zealand is well documented with several published and unpublished papers available from Forest Research. This covers all rearing requirements even down to an artificial diet. The action to collect, rear and release Neopolycystus has shown the determination and responsibility of Eucalyptus growers to participate in similar programmes with enthusiasm.

The Eucalyptus Action Group has the following support:

Brendan Murphy and Mark Ross from MAF Forest BA support this programme. Brendan has extensively studied Paropsis species and their natural enemies. John Bain, an entomologist with Forest Research who was involved with rearing and releasing Cleobora in 1980, is also very supportive of the idea of finding and rearing Cleobora for release and will supervise the programme to rear Cleobora. Dick Bashford, an entomologist with Forestry Tasmania, is currently researching mass rearing of Cleobora to control outbreaks of Paropsis species in Tasmania has been approached and will act as an advisor to the programme.

The Farm Forestry Association have launched on their website a site providing information and photos relating to the proposal.

What is the project going to do and how will it help to solve the problem or take advantage of the opportunity?

This project proposes a two step plan. The initial step is to request a small amount of funding for search/collection of Cleobora mellyi. If unsuccessful, the project was stop and not request further funding. If successful, the second part of the funding would be requested to support the rearing and release programme. This funding would cover up to two years of rearing and release and some field monitoring at release sites. This project will take advantage of the farm forestry community as a network to facilitate distribution at minimal cost. The project could fund a post-graduate study to take care of the rearing and experimental aspects as required. Successful delivery of this project would be an excellent model for advancement of sustainable farm forestry.



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