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Integrated control of soft scale insect on Boronia megastigma Nees in Southern Tasmania


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Apriyanto, Enggar 1995 , 'Integrated control of soft scale insect on Boronia megastigma Nees in Southern Tasmania', Unspecified thesis, University of Tasmania.

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The commercial planting of boronia (Boroniu inegastigma Nees), which is
native to Western Australia, was established as an essential oil crop in Tasmania in
1985. In general, intensive cultural or monocultural practices are vulnerable to pest
problems due to lack of species diversity. While psyllid pests have now been
controlled, scale insects have become a serious pest in some boronia growers fields.
Two soft scale insects (Hemiptera: Coccidae) attack boronia and have been
identified as the black scale, Saissetiu oleae Oliver, and soft brown scale Coccus
hesperidum L. At this time, black scale is considered the most serious pest in
commercial plantations despite the occurrence of many natural enemies. Similarly,
black scale on citrus in California USA, has remained a problem despite a complex
of parasitoids and the repeated importation of new natural enemies (Daane and
Caltagirone, 1990; Lampson and Morse, 1992).
Saissetia oleue is an occasional pest insect and its distribution is mainly in
temperate and sub-tropical regions. Daane and Caltagirone (1990) noted that it is
common for orchards to have repeated outbreaks while neighbouring orchards do
not. Black scale occurs throughout Australia with South Australia, New South
Wales, and Victoria more affected due to their large citrus growing areas (Wilson,
Soft brown scale is of European origin (McLeod and Coppel, 1966). It is now
common in all tropical and subtropical regions of the world and in greenhouses in
cooler regions (Ebeling, 1959; McLeod et al, 1966). Again, South Australia,
Western Australia and New South Wales are more affected because of their large
citrus growing areas (Wilson, 1960).
Both scale species, S. oleue and C. hesperidum, are known to have a wide
range of host plants. When heavily infested parts of the plant, such as foliage,
shoots and fruit, are covered with sooty mould that develops on honeydew excreted
by scale insects. Damage to the plant can be either direct, i.e. by sucking sap from
the plant or indirect, i.e. by covering parts of the plant with sooty mould that
interferes with the efficiency of photosynthesis. Heavy infestation can result in
defoliation, fruit drop, twig dieback and in extreme cases, death of the plants
(Ebeling, 1959).
The application of insecticides to control scale insects without accurate
knowledge of pest population control mechanisms could disrupt any potential
regulation by natural enemies (Denach and Rosen, 1991; Paraskakis et al 1980).
Hely et al. (1982) and Beattie (1991) suggested that application of insecticides
against scale insects must be applied at an appropriate time and place in order to get
effective results. Boronia growers in Tasmania have relied on materials such as
petroleum spray oils and a mixture of these petroleum spray oils with maldison to
control black scale and soft brown scale without any sound knowledge of their
biology and ecology. This has led to unsuccessful results even though multiple
applications have been employed annually.
The aim of this study was to gain an understanding of the population dynamics
and the life-cycle of both scale species, to understand their biology and to assess a
range of insecticides for possible incorporation into an integrated program to control
these species.

Item Type: Thesis - Unspecified
Authors/Creators:Apriyanto, Enggar
Keywords: Scale insects, Boronia
Copyright Holders: The Author
Copyright Information:

Copyright 1995 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 (M.Ag.Sc.)--University of Tasmania, 1997. Includes bibliographical references

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