Protein feeding of Queensland fruit fly Bactrocera tryoni and cucumber fly Zeugodacus cucumis (Diptera: Tephritidae) on non-host vegetation: effect of plant species and bait height

Perimeter-baiting of non-crop vegetation using toxic protein baits was developed overseas as a technique for control of melon fly, Zeugodacus (Zeugodacus) cucurbitae (Coquillett) (formerly Bactrocera (Zeugodacus) cucurbitae), and evidence suggests that this technique may also be effective in Australia for control of local fruit fly species in vegetable crops. Using field cage trials and laboratory reared flies, primary data were generated to support this approach by testing fruit flies' feeding response to protein when applied to eight plant species (forage sorghum, grain sorghum, sweet corn, sugarcane, eggplant, cassava, lilly pilly and orange jessamine) and applied at three heights (1, 1.5 and 2 m). When compared across the plants, Queensland fruit fly, Bactrocera tryoni (Froggatt), most commonly fed on protein bait applied to sugarcane and cassava, whereas more cucumber fly, Zeugodacus (Austrodacus) cucumis (French) (formerly Bactrocera (Austrodacus) cucumis), fed on bait applied to sweet corn and forage sorghum. When protein bait was applied at different heights, B. tryoni responded most to bait placed in the upper part of the plants (2 m), whereas Z. cucumis preferred bait placed lower on the plants (1 and 1.5 m). These results have implications for optimal placement of protein bait for best practice control of fruit flies in vegetable crops and suggest that the two species exhibit different foraging behaviours.

Preliminary evaluation of macadamia rootstocks for yield and tree height

Rootstock has profound effects on traits such as yield and tree size in various horticultural industries, however relatively little is known about rootstock effects for macadamia. In this study, 12 cultivars were propagated as open-pollinated seedling and clonal rootstocks, and own-rooted cuttings. The same cultivars were also used as scions, and grafted to a subset of rootstocks, then planted at four trial locations. In this preliminary analysis, rootstock accounted for 19% of the variance in yield compared with 72% for scion, and 23% in height compared with 72% for scion. There was no interaction between rootstock and scion for yield, and only a small effect for height. The interaction between rootstock and propagation method (seedling, clonal, own roots) was not significant for height. A small effect was observed for yield, with the own roots treatment producing significantly lower yield than grafted trees for all rootstock cultivars except 'HAES 849'. 'H2' seedling rootstock produced a cumulative yield to age 10 years of 11.1 kg tree -1 compared to the highest yield of 13.6 kg tree -1 for 'Beaumont' clonal rootstocks. 'H2' seedling rootstock produced 4.8 m trees at age 11 years, compared to the smallest grafted tree which was 'HAES 849' seedling at 4.7 m.