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Population phenology and natural enemies of paropsis atomaria Olivier (Coleoptera: Chrysomelidae) in South-East Queensland

Duffy, Michael Patrick (2007) Population phenology and natural enemies of paropsis atomaria Olivier (Coleoptera: Chrysomelidae) in South-East Queensland. Masters by Research thesis, Queensland University of Technology.

Abstract

Paropsis atomaria Olivier (Coleoptera: Chrysomelidae: Paropsini), is a major pest of commercially grown eucalypts in South-East Queensland. Current management of

paropsine beetles involves regular inspection and the application of chemical sprays if defoliation is severe. However, non-chemical control of plantation pests is highly desirable given the requirement to certify forest practices for sustainability, and community concerns over the use of pesticides. One way of reducing pesticide use is through conservation biological control, which requires detailed knowledge of the life history of the pest and its natural enemies. This thesis documents aspects of P. atomaria phenology, including life tables, sex ratios and damage estimates; identifies the predators, parasites, and egg and larval parasitoids of P. atomaria; and examines the ecology of the most promising natural enemy, Neopolycystus Girault sp. (Hymenoptera: Pteromalidae) in South-East Queensland.

P. atomaria adults are active from September until April and can complete up to four generations in a season. Field mortality between egg and fourth instar larvae is approximately 94%. A large proportion of this mortality can be attributed to natural enemies. The most abundant predators in eucalypt plantations were spiders, comprising 88% of all predators encountered.

Egg parasitoids exerted the greatest influence on P. atomaria populations, emerging from around 50% of all egg batches, and were responsible for mortality of almost one third of all eggs in the field. Only about one percent of larvae were parasitised in the field, in contrast to paropsine pests in temperate Australia, where egg parasitism rates are low and larval parasitism rates high.

Neopolycystus sp. was the only primary parasitoid reared from P. atomaria eggs, along with three hyperparasitoid species; Baeoanusia albifunicle Girault (Encyrtidae), Neblatticida sp. (Encyrtidae) and Aphaneromella sp. (Platygasteridae). This is the first record of B. albifunicle hyperparasitising Neopolycystus spp. B. albifunicle emerged from one-third of all parasitised egg batches and could pose a potential problem to the efficacy of Neopolycystus sp. as a biological control agent. However, within egg batches, hyperparasitoids rarely killed all Neopolycystus sp. with only 9% of hyperparasitised egg batches failing to produce any primary parasitoids. Total field mortality of P. atomaria through direct and indirect effects of parasitism by Neopolycystus sp. was 28%. The proportion of egg batches parasitised increased with exposure time in the field, but within-batch parasitism rate did not. In general, there was no significant correlation between parasitism rates and distance from landscape features (viz. water sources and native forest).

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ID Code: 16467
Item Type: QUT Thesis (Masters by Research)
Supervisor: Clarke, Anthony& Lawson, Simon
Keywords: Paropsis atomaria, Neopolycystus sp., Eucalyptus cloeziana, parasitioids, natural enemies, habitat manipulation, conservation biological control
Divisions: Past > Schools > Biogeoscience
Past > QUT Faculties & Divisions > Faculty of Science and Technology
Department: Faculty of Science
Institution: Queensland University of Technology
Copyright Owner: Copyright Michael Patrick Duffy
Deposited On: 03 Dec 2008 14:04
Last Modified: 29 Oct 2011 05:48

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