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A genetic basis to the destruction of Eucalyptus globulus seed by wasps from the genus Megastigmus


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McGowen, MH, Potts, BM, Vaillancourt, RE, Gore, PL and Williams, DR 2004 , 'A genetic basis to the destruction of Eucalyptus globulus seed by wasps from the genus Megastigmus', paper presented at the Eucalyptus in a Changing World. International IUFRO Conference, 11-15 October 2004, Aveiro, Portugal.

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Megastigmus spp. are tiny wasps (bodies 2.5-
6.5mm in length) from the hymenopteran family
Torymidae that destroy the seed of forest trees
(Elliott and deLittle 1984). Many studies have
examined their destructive effect on seed
production in conifers, such as: Pseudotsuga;
Abies; Cedrus; Cupressus; Juniperus; Larix and
Picea (Roques and Skrzypczynska 2003). In
Australia, they have been reported to feed on
the seed of at least seven eucalypt species.
However, despite reports of losses both in openpollinated
seed orchard and controlled crossed
seed of Eucalyptus globulus extending over
many years, little is known of the biology and
taxonomy of these insect species, nor the extent
of the decrease in seed production they cause.
The only study available suggests that the
female wasps lay their eggs in eucalypt flowers
(Drake 1974). After hatching, each small larva
tunnel down into the developing seeds and
gradually consume the content of a seed. The
larva goes through several instars and the pupa
develops within the seed coat. Fully-grown adult
wasps emerge from the seed coat through a
circular exit hole, and then exit through the top
or side of the capsule usually before it opens. In
this study we quantified the percentage of seed
damaged by Megastigmus spp. predation in 384
seedlots of Eucalyptus globulus and examined
whether there was a genetic basis to differences
in the levels of seed predation observed.

Item Type: Conference or Workshop Item (Paper)
Authors/Creators:McGowen, MH and Potts, BM and Vaillancourt, RE and Gore, PL and Williams, DR
Additional Information:

BM Potts.

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