Green vegetable bug, Nezara viridula L., is a serious pest of many fruiting crops (especially legumes and Solanaceae). Adult bugs and nymphs suck sap from stems, fruit, and petioles causing death of tissue, malformation, or fruit drop. In Australia, pests cause serious damage to pecan nuts, and also soybean resulting in yield loss, reduced numbers of seeds per pod, premature pod fall, reduced oil content, and reduced ability for seeds to germinate. In PNG, the bug attacks soybean, pigeon pea, sorghum, maize, green snake beans, rice and horticultural crops including tomatoes and eggplant.
Some biological control has been achieved with the parasitic wasp Trissolcus basalis which attacks eggs. However, success has not been recorded in all crops, so natural enemies are needed, particularly those that attack more advanced pests. Evidence from overseas suggests a group of parasitic flies (Trichopodaspp.) are particularly useful natural enemies, but none of these are established in Australia.
The objectives of this ACIAR project are: to determine the natural enemies of Green vegetable Bug (GVB) in Papua New Guinea (PNG); to assess and the level of biological control being achieved; to evaluate the potential for introduction of further natural enemies especially Trichopoda giacomellii, or other Tachinidae; to introduce these natural enemies into PNG with appropriate precautions, as considered desirable, and rear them for field release; and to monitor the establishment, build-up and impact of the newly introduced natural enemies.
The first stage of the project will involve assessment of the tachinid parasite Trichopoda giacomellii for introduction to Australia. Pending quarantine and importation arrangements, host specificity testing and population studies on the parasite will be carried out under quarantine at CSIRO Long Pocket Laboratories, Brisbane. Researchers may investigate the introduction of further natural enemies when results of the natural enemy effectiveness studies are known. Importation of natural predators into PNG will be subject to PNG Government approval and post-entry testing will be carried out at the quarantine laboratory at Laloki, PNG.
Researchers at Markham Valley, PNG (Bubia Agricultural Research Station) will carry out field studies in soybean and other crops to collect eggs, nymphs, and adults of GVB to determine population structure. They will also assess the effectiveness of the natural enemies of GVB in the area including the egg parasite Trissolcus basalis and various other predators (including spiders) of the nymphal stages. If quarantine permission for the release of Trichopoda giacomellii is obtained, the researchers will monitor the establishment of the new parasite and its impact on GVB populations. Similar field trials will be carried out in pecan orchards in Moree, Australia.
Links:
[1] http://www.aciar.gov.au/country/Papua New Guinea
[2] http://www.aciar.gov.au/programarea/Crop Protection