The rusts on Proteaceae, including Puccinia grevilleae sp. nov. from northern Australia

The first rust fungus recorded on Grevillea in Australia is described as Puccinia grevilleae. A key is provided for all rusts occurring on the Proteaceae.

Intrapopulation variation in an Australian population of the North American thrips, Bagnalliella yuccae (Thysanoptera: Phlaeothripidae), a new record from Australia.

The genus Bagnalliella Karny is an endemic North American genus of Phlaeothripidae with 7 species associated with the New World plant genus Yucca; 2 Old World species currently placed in the genus are probably not congeneric. The number of sensoria on antennal segments III and IV has been used to distinguish the Bagnalliella species on Yucca, but an invasive population of Bagnalliella yuccae (Hinds) is reported here from Australia, at Brisbane, Queensland, in which the number of sensoria varied between individuals and even between left and right antennae of single individuals. These observations cast considerable doubt on the validity of some of the North American species of Bagnalliella. The Australian population was damaging young leaves of Yucca elephantipes, and indicates the ease with which thrips can be distributed by the horticultural trade.

Determination of management units for grey mackerel fisheries in northern Australia.

The requirement for Queensland, Northern Territory and Western Australian jurisdictions to ensure sustainable harvest of fish resources and their optimal use relies on robust information on the resource status. For grey mackerel (Scomberomorus semifasciatus) fisheries, each of these jurisdictions has their own management regime in their corresponding waters. The lack of information on stock structure of grey mackerel, however, means that the appropriate spatial scale of management is not known. As well, fishers require assurance of future sustainability to encourage investment and long-term involvement in a fishery that supplies lucrative overseas markets. These management and fisher-unfriendly circumstances must be viewed in the context of recent 3-fold increases in catches of grey mackerel along the Queensland east coast, combined with significant and increasing catches in other parts of the species' northern Australian range. Establishing the stock structure of grey mackerel would also immensely improve the relevance of resource assessments for fishery management of grey mackerel across northern Australia. This highlighted the urgent need for stock structure information for this species. The impetus for this project came from the strategic recommendations of the FRDC review by Ward and Rogers (2003), "Northern mackerel (Scombridae: Scomberomorus): current and future research needs" (Project No. 2002/096), which promoted the urgency for information on the stock structure of grey mackerel. In following these recommendations this project adopted a multi-technique and phased sampling approach as carried out by Buckworth et al (2007), who examined the stock structure of Spanish mackerel, Scomberomorus commerson, across northern Australia. The project objectives were to determine the stock structure of grey mackerel across their northern Australian range, and use this information to define management units and their appropriate spatial scales. We used multiple techniques concurrently to determine the stock structure of grey mackerel. These techniques were: genetic analyses (mitochondrial DNA and microsatellite DNA), otolith (ear bones) isotope ratios, parasite abundances, and growth parameters. The advantage of using this type of multi-technique approach was that each of the different methods is informative about the fish’s life history at different spatial and temporal scales. Genetics can inform about the evolutionary patterns as well as rates of mixing of fish from adjacent areas, while parasites and otolith microchemistry are directly influenced by the environment and so will inform about the patterns of movement during the fishes lifetime. Growth patterns are influenced by both genetic and environmental factors. Due to these differences the use of these techniques concurrently increases the likelihood of detecting different stocks where they exist. We adopted a phased sampling approach whereby sampling was carried out at broad spatial scales in the first year: east coast, eastern Gulf of Carpentaria (GoC), western GoC, and the NW Northern Territory (NW NT). By comparing the fish samples from each of these locations, and using each of the techniques, we tested the null hypothesis that grey mackerel were comprised of a single homogeneous population across northern Australia. Having rejected the null hypothesis we re-sampled the 1st year locations to test for temporal stability in stock structure, and to assess stock structure at finer spatial scales. This included increased spatial coverage on the east coast, the GoC, and WA. From genetic approaches we determined that there at least four genetic stocks of grey mackerel across northern Australia: WA, NW NT (Timor/Arafura), the GoC and the east Grey mackerel management units in northern Australia ix coast. All markers revealed concordant patterns showing WA and NW NT to be clearly divergent stocks. The mtDNA D-loop fragment appeared to have more power to resolve stock boundaries because it was able to show that the GoC and east coast QLD stocks were genetically differentiated. Patterns of stock structure on a finer scale, or where stock boundaries are located, were less clear. From otolith stable isotope analyses four major groups of S. semifasciatus were identified: WA, NT/GoC, northern east coast and central east coast. Differences in the isotopic composition of whole otoliths indicate that these groups must have spent their life history in different locations. The magnitude of the difference between the groups suggests a prolonged separation period at least equal to the fish’s life span. The parasite abundance analyses, although did not include samples from WA, suggest the existence of at least four stocks of grey mackerel in northern Australia: NW NT, the GoC, northern east coast and central east coast. Grey mackerel parasite fauna on the east coast suggests a separation somewhere between Townsville and Mackay. The NW NT region also appears to comprise a separate stock while within the GoC there exists a high degree of variability in parasite faunas among the regions sampled. This may be due to 1. natural variation within the GoC and there is one grey mackerel stock, or 2. the existence of multiple localised adult sub-stocks (metapopulations) within the GoC. Growth parameter comparisons were only possible from four major locations and identified the NW NT, the GoC, and the east coast as having different population growth characteristics. Through the use of multiple techniques, and by integrating the results from each, we were able to determine that there exist at least five stocks of grey mackerel across northern Australia, with some likelihood of additional stock structuring within the GoC. The major management units determined from this study therefore were Western Australia, NW Northern Territory (Timor/Arafura), the Gulf of Carpentaria, northern east Queensland coast and central east Queensland coast. The management implications of these results indicate the possible need for management of grey mackerel fisheries in Australia to be carried out on regional scales finer than are currently in place. In some regions the spatial scales of management might continue as is currently (e.g. WA), while in other regions, such as the GoC and the east coast, managers should at least monitor fisheries on a more local scale dictated by fishing effort and assess accordingly. Stock assessments should also consider the stock divisions identified, particularly on the east coast and for the GoC, and use life history parameters particular to each stock. We also emphasise that where we have not identified different stocks does not preclude the possibility of the occurrence of further stock division. Further, this study did not, nor did it set out to, assess the status of each of the stocks identified. This we identify as a high priority action for research and development of grey mackerel fisheries, as well as a management strategy evaluation that incorporates the conclusions of this work. Until such time that these priorities are addressed, management of grey mackerel fisheries should be cognisant of these uncertainties, particularly for the GoC and the Queensland east coast.

Assessing the biological control potential of an adventitiously-established "pest", Scirtothrips aurantii (Faure), on a weed, Bryophyllum delagoense (Eckl. & Zeyh.), in Queensland

South African citrus thrips (Scirtothrips aurantii) established adventitiously in Australia. Although it is a major horticultural pest in Africa, it is now advocated as a possible biological control agent against Bryophyllum delagoense Eckl. & Zeyh. (Crassulaceae). To evaluate the biocontrol potential of S. aurantii a two year field study was conducted on the western Darling Downs of southern Queensland. Imidacloprid insecticide was applied to two quadrats at each of 18 field sites to assess, in the absence of S. aurantii, the persistence of individual plants and to quantify propagule production and recruitment by this declared weed. A third quadrat was left, as a control, to be infested naturally by S. aurantii. When released from herbivory by thrips in the field, plants grew significantly more, flowered more, and were significantly more fecund than plants in the quadrats with S. aurantii. Increases in growth and fecundity translated into significantly increased plant numbers but not increased recruitment. Recruitment even declined in experimental quadrats, through the indirect effects of releasing plants from herbivory. Field sampling also revealed that S. aurantii may be sensitive to seasonal climatic fluctuations. These and other local climatic influences may limit the biological control potential of the insect.

Reducing the incidence of under-skin browning in 'Honey Gold' mango (Mangifera indica L.) fruit

'Honey Gold' mango is a relatively new cultivar in Australia, with an appealing skin colour and a sweet fibre-free flesh. However, fruit can develop 'under-skin browning' (USB), which appears several days after packing as a distinct 'bruise'-like discolouration under the epidermis and can affect large areas of the fruit surface. We investigated the anatomy of USB and the impact of post-harvest fruit handling conditions on the disorder. Starch accumulated around the resin canals and discoloured cells in the affected area, with no visible change to the cuticle or epidermis. Delays of 1 d at ambient temperature (27 degrees - 35 degrees C) before packing, and 2 d at 18 degrees - 20 degrees C (after packing), before placing fruit at 12 degrees - 14 degrees C and road transportation, reduced the incidence of USB by 83% compared to placing fruit at 12 degrees - 14 degrees C within 13 h of picking. The incidence of USB was 88 100% higher in fruit that were cooled to 12 degrees - 14 degrees C within 13 h of picking, then commercially road-freighted for 4 d at 12 degrees - 14 degrees C, than in fruit held under similar temperature conditions, but not road-freighted. Wrapping each fruit in bubble-wrap to minimise direct contact with other fruit, with the plastic insert, or with the cardboard tray, reduced the incidence of USB by 84% after road-freight compared to not using bubble-wrap. These results suggest that USB is a unique disorder of mango skin associated with a rapid post-harvest reduction in temperature, from high ambient temperatures to 12 degrees - 14 degrees C, and with physical damage during road-freight.