Rob Emery

Since 1968, the Australian Dung Beetle Project has carried out field releases of 43 deliberately introduced dung beetle species for the biological control of livestock dung and dung-breeding pests. Of these, 23 species are known to have become established. For most of these species, sufficient time has elapsed for population expansion to fill the extent of their potential geographic range through both natural and human-assisted dispersal. Consequently, over the last 20 years, extensive efforts have been made to quantify the current distribution of these introduced dung beetles, as well as the seasonal and spatial variation in their activity levels. Much of these data and their associated metadata have remained unpublished, and they have not previously been synthesized into a cohesive dataset. Here, we collate and report data from the three largest dung beetle monitoring projects from 2001 to 2022. Together, these projects encompass data collected from across Australia, and include records for all 23 species of established dung beetles introduced for biocontrol purposes. In total, these data include 22,718 presence records and 213,538 absence records collected during 10,272 sampling events at 546 locations. Most presence records (97%) include abundance data. In total, 1,752,807 dung beetles were identified as part of these data. The distributional occurrence and abundance data can be used to explore questions such as factors influencing dung beetle species distributions, dung beetle biocontrol, and insect-mediated ecosystem services. These data are provided under a CC-BY-NC 4.0 license and users are encouraged to cite this data paper when using the data.

The rice weevil, Sitophilus oryzae (L.) (Curculionidae), is a globally distributed pest of stored grain, but despite having functional wings it is considered a reluctant flier. An analysis of the population genetics of S. oryzae from all major regions in Australia where grain is grown and stored in bulk revealed limited population structure nationally, despite our expectation that the low levels of flight in this species would impose considerable population structure geographically. Little genetic structure detected in nuclear DNA yet strong mitochondrial DNA structure was found among populations within the growing regions suggesting greater dispersal in males than females. Also, there were low levels of mitochondrial DNA diversity within and among Australian S. oryzae populations. Anthropogenic movement is most likely the reason for the observed lack of isolation-by-distance pattern of gene flow, especially in eastern Australia. The extent of gene flow demonstrated in our study has potential implications for the development and spread of phosphine resistance in Australia. Undoubtedly, selection for phosphine resistance in S. oryzae is occurring in all grain growing regions because of the widespread use of phosphine fumigation, but the level of gene flow demonstrated in Australian S. oryzae suggests that we can expect some spread of resistant insects geographically despite the apparent limited flight in this species.

Kenya and some other African countries are threatened by a serious pest Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), the false codling moth. The detection of T. leucotreta is quite difficult due to the cryptic nature of the larvae during transportation and is therefore a concern for Australia. This insect is a known pest of agriculturally important crops. Here, Maxent was used to assess the biosecurity threat of T. leucotreta to Australia. Habitat suitability and risk assessment of T. leucotreta in Australia were identified based on threatened areas under suitable climatic conditions and the presence of hosts in a given habitat. Modeling indicated that Australia is vulnerable to invasion and establishment by T. leucotreta in some states and territories, particularly areas of western and southern Australia. Within these locations, the risk is associated with specific cropping areas. As such, invasion and establishment by T. leucotreta may have serious implications for Australia’s agricultural and horticultural industries e.g., the fruit and vegetable industries. This study will be used to inform the government and industry of the threat posed by T. leucotreta imported via the cut flower industry. Targeted preventative measures and trade policy could be introduced to protect Australia from invasion by this pest.

Export celery (Apium graveolens var. dulce) from Australia has been affected by a natural infestation of purple scum springtails (Hypogastrura vernalis). These insects live inside the celery head, contaminating fresh celery, but do not cause any visible damage. As a result, purple scum springtail-infested celery has led to rejection for export with an impact on market value for fresh produce. In this study, fumigation with ethyl formate (EF), phosphine (PH3), and their combination on mortality of purple scum springtails in naturally infested celery was evaluated. Laboratory experiments were conducted using concentrations of 50, 60, and 90mg.L‑1 of EF for 1, 2, and 4 hours; 1, 1.5, 2, and 2.5mg.L‑1 ofPH3 for2, 4, and 6 hours; and 20, 30, and 40mg.L‑1 of EF combined with 1mg.L‑1 of PH3, for 2and 4 hours at the laboratory temperature 25 ºC. Complete control was achieved at 90 mg.L‑1 of EF for 2 hours; however, phytotoxicity was observed in celery treated by EF at all concentrations. PH3 at 2.5 mg.L‑1 achieved 100% mortality within 6 hours, and no phytotoxicity was evident. Mortality of 100% was achieved also at 30 and 40 mg.L‑1 EF combined with 1 mg.L‑1 of PH3 for 2 and 4 hours exposure time; however, phytotoxicity occurred with EF alone treatments and with the combination. From these data, we conclude that PH3 alone has potential as a fumigant for the preshipment treatment of celery infested with purple scum springtails.

Khapra beetle (Trogoderma granarium) is one of the major quarantine pest of Australia. The economic consequences of an incursion of this species would be very serious as the pest is difficult to control by existing methods, threatening an estimated $1.83 billion in Australian annual export revenue. Australia would also lose our premium (Khapra-free) market reputation, which is valued at $4.9 billion. The risk of incursion and establishment of this species is increasing significantly as Australia continues to grow imports of grain, grain products and animal products.

European House Borer (EHB) Hylotrupes bajulus Linnaeus, is considered a serious invasive threat because it is a destructive pest of seasoned coniferous timber including pine, fir and spruce. If allowed to become established it can cause major structural damage to buildings. The pest is able to live in a variety of climatic conditions however it prefers temperate habitats. Methyl bromide is widely used for quarantine treatment but it is being phased out due to its listing as an ozone depleting substance. Furthermore, complete control of EHB with methyl bromide in timber at low temperatures and high moisture content is difficult. Currently, there are no known chemical or biological controls for EHB larvae in timber and wood packaging and the obvious way to reduce the quarantine threat posed by EHB is to develop reliable and effective means to disinfest wooden materials at the source. There is an urgent requirement for an alternative effective fumigant for the control of EHB larva in timber and wood. Ethanedinitrile (EDN) is a new fumigant (patented under the chemical name “cyanogen”) and it is known to be highly toxic to insect pests of timber and is fast acting. It is believed to have particular potential as a quarantine treatment for timber. EHB larvae of differing lengths were found to have varying tolerance to both EDN and methyl bromide with the larger EHB found to be more tolerant. In all experimental fumigations with larvae of a range of lengths and at varying exposure times (6 and 24 hours), EDN showed more toxicity than methyl bromide. EDN achieved 100% mortality at 40 mg/L, 25°C and 70% r.h. for 24 hours of exposure with timber blocks artificially infested with EHB. However, under the same experimental conditions, methyl bromide at 48 mg/L only achieved a mortality range of 97.3-100%.

Murdoch University Stored Grain Research Laboratory investigated the fate of 32P labelled phosphine in grain and grain fractions. Radioactively-labelled phosphine is a useful and sensitive tool to study residues of phosphine in grains and their fractions. This research will assist industry to improve phosphine fumigation practice. Five representative grains (wheat, barley, oats, canola and lupins) were fumigated with 32P labelled phosphine at 700 ppm and 25±2°C for two weeks exposure. Two types of residues were formed in grains from phosphine fumigation – phosphine residue and phosphine converted non-volatile residues. After one week exposure to atmosphere, the levels of 32P radioactive residue in the grains and their fractions were analysed. The results show that more than 85% of absorbed phosphine which was converted to non-volatile compounds cannot be removed by ventilation. Furthermore, 80-90% of non-volatile 32P residues were present in water and acid soluble extractions. Radiation imagery shows that more than 80% of 32P residues were located or distributed in the embryo, testa, pericarp and husk of wheat, barley, canola, lupins and oats. However, 90% of absorbed phosphine will be desorbed after one week exposure to the atmosphere.