The efficacy of Dryacide (diatomaceous earth coated with silica aerogels) on wheat was tested in the laboratory against adult and immature stages of 4 species of Coleoptera and against immature stages of 1 species of Lepidoptera. The minimum effective level of Dryacide increased in the following order: immature Ephestia cautella (Walker) ~ immature Tribolium castaneum (Herbst) < immature Rhyzopertha dominica (F) < adult R. dominica ~ adult T. castaneum < adult Sitophilus oryzae (L) < adult Sitophilus granarius (L) < immature Sitophilus species. When wheat treated with Dryacide was milled in the laboratory without prior cleaning, less than 3% of the Dryacide carried over into the flour. Commercial cleaning of wheat removed (�s.e.) about 98 � 1% of Dryacide, and no Dryacide could be detected in the flour. Dryacide treatment did not affect flour quality as determined by the volume of sponge cakes and the production of carbon dioxide by fermenting dough.

Predictive models of decay of dichlorvos residues and dichlorvos vapour concentrations were compared with breakdown observed in grain stored in six railway trucks and four commercial silos. Decay rates were adequately modelled by simple kinetic treatments and no variations in rate of decay caused by possible saturation of grain enzymes were observed. The discrepancies in various reported models for decay of dichlorvos may be due to pronounced differences in surface effects observed in commercial and laboratory applications.

The receival moisture content of wheat was raised experimentally from 12 to 13% (w/w, wet basis) at sites near Cowra and Forbes (New South Wales) and Port Giles (South Australia) that were fitted with cooling (aeration), during the 1989-90 and 1990-91 seasons. At Cowra and Forbes, no wheat was received above 12% moisture content. At Port Giles, large quantities of wheat were received in the range 12.1-13.0% moisture content, reaching a maximum of 56% of receivals in 1 bin. However, the average moisture content in each bin did not exceed 12.0% and changed, on average, only 0.01% during aerated storage. No significant effect on quality was detected from studies on viability, bread-making quality, and mycotoxins. All wheat was successfully passed for export, meeting all normal standards including the 'nil tolerance' for live insects.

Clay-based carriers of insecticides or 'dusts', e.g. talc or bentonite impregnated with fenitrothion, may either retain the protectant after admixture with wheat or release it into the surrounding grain. The amount of carrier was determined by mixing wheat with water or ethanol, subjecting to ultrasound, and determining absorbance of the supernatant at 580 nm. Swirling in water under ultrasound followed by decanting removed more than 90% of 9 tested carriers from water, was more efficient than sieving, and had no effect on fenitrothion levels in wheat that had previously been sprayed with an emulsifiable concentrate formulation. The amount of fenitrothion retained was measured by 3 methods, each duplicated, and was 0.5-5% for talc, 98-103% for Nuchart-Attaclay, 565-80% for Halloysite, and 96-97% for Steecoben.

High resolution oxygen and carbon isorope analyses of pare of a uniform diameter stalagmite from a cave in northern Tasmania have been used to study the climatic transitionfrom stadia! to interstadial conditions during the early Last Glacial (109-95 ka). A significant change in oxygen isotope values suggests that temperature warmed rapidly by approximately 2°-3°C between 100 and 97 ka. A decrease in carbon isotope values berween 10 I and 98 ka indicates that moisture availability was increasing slightly in advance of rising remperature.