Down scaling to regional assessment of greenhouse gas emissions to enable consistency in accounting for emissions reduction projects and national inventory accounts for northern beef production in Australia

This paper explores the effect of using regional data for livestock attributes on estimation of greenhouse gas (GHG) emissions for the northern beef industry in Australia, compared with using state/territory-wide values, as currently used in Australia’s national GHG inventory report. Regional GHG emissions associated with beef production are reported for 21 defined agricultural statistical regions within state/territory jurisdictions. A management scenario for reduced emissions that could qualify as an Emissions Reduction Fund (ERF) project was used to illustrate the effect of regional level model parameters on estimated abatement levels. Using regional parameters, instead of state level parameters, for liveweight (LW), LW gain and proportion of cows lactating and an expanded number of livestock classes, gives a 5.2% reduction in estimated emissions (range +12% to –34% across regions). Estimated GHG emissions intensity (emissions per kilogram of LW sold) varied across the regions by up to 2.5-fold, ranging from 10.5 kg CO2-e kg–1 LW sold for Darling Downs, Queensland, through to 25.8 kg CO2-e kg–1 LW sold for the Pindan and North Kimberley, Western Australia. This range was driven by differences in production efficiency, reproduction rate, growth rate and survival. This suggests that some regions in northern Australia are likely to have substantial opportunities for GHG abatement and higher livestock income. However, this must be coupled with the availability of management activities that can be implemented to improve production efficiency; wet season phosphorus (P) supplementation being one such practice. An ERF case study comparison showed that P supplementation of a typical-sized herd produced an estimated reduction of 622 t CO2-e year–1, or 7%, compared with a non-P supplemented herd. However, the different model parameters used by the National Inventory Report and ERF project means that there was an anomaly between the herd emissions for project cattle excised from the national accounts (13 479 t CO2-e year–1) and the baseline herd emissions estimated for the ERF project (8 896 t CO2-e year–1) before P supplementation was implemented. Regionalising livestock model parameters in both ERF projects and the national accounts offers the attraction of being able to more easily and accurately reflect emissions savings from this type of emissions reduction project in Australia’s national GHG accounts.

Effect of diet on phosphine toxicity, rate of development and reproduction of the rice weevil Sitophilus oryzae (Linnaeus)

One of the loci responsible for strong phosphine resistance encodes dihydrolipoamide dehydrogenase (DLD). The strong co-incidence of enzyme complexes that contain DLD, and enzymes that require thiamine as a cofactor, motivated us to test whether the thiamine deficiency of polished white rice could influence the efficacy of phosphine fumigation against insect pests of stored grain. Three strains of Sitophilus oryzae (susceptible, weak and strong resistance) were cultured on white rice (thiamine deficient), brown rice or whole wheat. As thiamine is an essential nutrient, we firstly evaluated the effect of white rice on developmental rate and fecundity and found that both were detrimentally affected by this diet. The mean time to reach adult stage for the three strains ranged from 40 to 43 days on brown rice and 50–52 days on white rice. The mean number of offspring for the three strains ranged from 7.7 to 10.3 per female over a three day period on brown rice and 2.1 to 2.6 on white rice. Growth and reproduction on wheat was similar to that on brown rice except that the strongly resistant strain showed a tendency toward reduced fecundity on wheat. The susceptible strain exhibited a modest increase in tolerance to phosphine on white rice as expected if thiamine deficiency could mimic the effect of the dld resistance mutation at the rph2 locus. The strongly resistant strain did not respond to thiamine deficiency, but this was expected as these insects are already strongly resistant. We failed, however, to observe the expected synergistic increase in resistance due to combining thiamine deficiency with the weakly resistant strain. The lack of interaction between thiamine content of the diet and the resistance genotype in determining the phosphine resistance phenotype suggests that the mode of inhibition of the complexes is a critical determinant of resistance.