Genetic variation of Eucalyptus globulus in relation to autumn gum moth Mnesampela privata (Lepidoptera: Geometridae) oviposition preference

The autumn gum moth Mnesampela privata Guenée is a major defoliator of Australia’s commercially important pulpwood plantation species, Eucalyptus globulus Labill. However, little is known about genetic variability of E. globulus to M. privata oviposition preference. We examined oviposition preference by exposing juvenile foliage sprigs of different genetic origins to gravid female moths in cage bioassays. Foliage sprigs were collected from 40 E. globulus families grown in a common environment field trial in southern Tasmania. These families were derived from open-pollinated seed collected in native stands and represented four geographic races of E. globulus. Significant differences in the level of oviposition was detected between foliage sprigs from the different races, with those from the Furneaux race receiving over twice as many egg batches compared to those from either the Strzelecki Ranges or northeastern Tasmania races. The southern Tasmania race received an intermediate egg load. No significant variability in oviposition preference was identified between different localities within races or between different open-pollinated families within localities. Selections from both the Strzelecki Ranges and Furneaux races comprise a large component of the Australian E. globulus breeding population. There is therefore likely to be significant genetic variation for M. privata oviposition preference within the breeding population and by screening before deployment gains in plantation productivity in areas subject to M. privata outbreaks may be possible.