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Taxonomic and ecological studies of the Tasmanian Eucalyptus-defoliating paropsids (coleoptera: chrysomelidae), with particular reference to Chrysophtharta bimaculata (Olivier)

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De Little, DW (1979) Taxonomic and ecological studies of the Tasmanian Eucalyptus-defoliating paropsids (coleoptera: chrysomelidae), with particular reference to Chrysophtharta bimaculata (Olivier). PhD thesis, University of Tasmania.

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Abstract

This study investigates the taxonomy and ecological relationships
of the Tasmanian Eucalyptus-defoliating paropsid beetles of the family
Chrysomelidae. In particular, the host-plant relationships, life
history and population ecology of Chrysophtharta bimaculata (Olivier)
a major forest pest in Tasmania, are investigated.
A survey of eucalypt forest and woodland over much of the
island revealed the presence of at least thirty-six paropsid species
which fed on the foliage of eucalypts. These species belonged to
five genera, viz: Paropsis Olivier (sensu stricto) (nine species),
Trachymela Weise (eight species), Chrysophtharta Weise (thirteen
species), Paropsisterna Motschulsky (three species) and Sterromela
Weise (three, or possibly four species).
All species were described and indicated by a code, but it was
only possible to positively identify twenty-three species. No
attempt was made to name new species, since it was considered that
in the absence of a recent revision of the entire paropsid fauna,
this would only serve to increase nomenclatural confusion within
the group. Keys to adults and fourth instar larvae are provided.
Records of Eucalyptus species on which each species of Paropsis was
found at each collecting locality are given. The Tasmanian island paropsid fauna on eucalypts is compared and contrasted to that of
mainland Australia in the light of current limited knowledge.
Ecological relationships of the more common paropsids are
discussed in relation to r and K strategy and niche differentiation.
The host-plant relationships of two very common, highly r-selected
species, Chrysophtharta bimaculata and C. agricola (Chapuis) were
studied in detail in the field, insectary and laboratory.
C. bimaculata showed a field preference for Monocalyptus species of
the series Obliquae, while C. agricola preferred Symphyomyrtus
species. In laboratory larval feeding trials, C. bimaculata
performed better on a Monocalyptus species (E. delegatensis) than
on a Symphyomyrtus species (E. dalrympleana) while C. agricola
performed equally well on both species. C. bimacutata developed
faster but was a less efficient feeder than C. agricola on
E. delgatensis. It was therefore inferred that C. bimaculata
was more highly r-selected than C. agricola, competitively
displacing the latter species from E. delegatensis.
Detailed studies were made of the life history and
population ecology of C. bimaculata. This species was shown to be
univoltine at least in N.W. Tasmania,and not bivoltine as previously
considered. Partial population budgets were prepared for three
populations. A major mortality factor in populations of immature
C. bimaculata was the predatory coccinellid, Cleobora mellyi
Mulsant which accounted for up to 74 percent of egg mortality.
Egg parasitization and larval parasitization by the braconid
species Eadya paropsidis were described for the first time.
The pest potential of C. bimaculata is discussed in the light of
its host-plant relationships, ecological strategies of its
preferred hosts, and other population determinants.

Item Type: Thesis (PhD)
Keywords: Chrysomelidae, Beetles, Eucalyptus
Copyright Holders: The Author
Copyright Information:

Copyright 1979 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).

Additional Information:

Thesis (Ph.D.)--University of Tasmania, 1980. Bibliography: l. 407-437

Date Deposited: 08 Dec 2014 23:54
Last Modified: 10 May 2016 02:47
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