Tracking mite trophic interactions by multiplex PCR

BACKGROUND A thorough knowledge of trophic webs in agroecosystems is essential to achieve successful biological pest control. Phytoseiid mites are the most efficient natural enemies of tetranychid mites, which include several important pests worldwide. Nevertheless, phytoseiids may feed on other food sources including other microarthropods, plants and even other phytoseiids (intraguild predation), which can interfere with biological control services. Molecular gut content analysis is a valuable tool for characterizing trophic interactions, mainly when working on microarthropods such as mites. We have designed new primers for Phytoseiidae, Tetranychidae and Thysanoptera identification and they have been multiplexed in a polymerase chain reaction (PCR) together with universal plant primers. Additionally, we have estimated prey DNA detectability success over time (DS50) considering the most probable events in Spanish citrus orchards: the phytoseiid Euseius stipulatus as a predator, the phytoseiid Phytoseiulus persimilis as intraguild prey, and the thrips Frankliniella occidentalis and Anaphothrips obscurus as alternative prey to Tetranychus urticae. RESULTS The designed multiplex PCR allows the identification of phytoseiids (both predator and intraguild prey) and detects alternative food sources mentioned above in the gut of the phytoseiid predator. DS50 for E. stipulatus as the predator were 1.3, 2.3 and 18.7 h post feeding for F. occidentalis, A. obscurus and P. persimilis as prey, respectively. CONCLUSION Tracking of the trophic relationships within the citrus acarofauna, and the unveiling of the role of alternative food sources will pave the way for enhancing T. urticae biological control. This multiplex PCR approach could be applicable for these purposes in similar agroecosystems

Ambulatory dispersal in Tetranychus urticae: an artificial selection experiment on propensity to disperse yields no response

Dispersal to new hosts is an important process for an invasive herbivore, such as the two-spotted spider mite. A recent study, using artificial selection experiments, has suggested that genetic variation and genetic trade-offs are present for propensity to disperse in this species. However, due to the experimental setup alternative explanations for the response to selection could not be ruled out. Using an altered setup, we investigated whether the propensity for ambulatory dispersal differs genetically between individuals and whether genetic correlations with life-history traits exist. Upward and downward selection on propensity to leave the colony was performed for seven generations in four replicate artificial selection experiments and the results were compared to control lines. No consistent responses to selection were found and no significant effect on life-history traits (oviposition rate, juvenile survival, development rate and number of adult offspring) or sex ratio was present across the replicates. The data suggest that our base population of spider mites harbours at best a low amount of additive genetic variation for this behaviour

"The Great Event of the Fortnight”: Steamship Rhythms and Colonial Communication

This paper engages with Tim Cresswell’s ‘contellations of mobility’ in order to contribute some understanding of historical maritime rhythms. The empirical focus is upon a steamship mail service in the post-emancipation Caribbean. In examining this communications network, it is stressed that while those managing the network valorised predictable efficiency, ‘friction’ was prized by mercantile groups at the steamers’ ports of call. Thus, the different aspects of mobility signified differently across the network, and this historical case study reinforces the resonance of slowness and stoppage time. The synchronisation of steamship arrivals with sociocultural norms in the Caribbean colonies also necessitated the adaptation of mail service rhythms. Through a focus on shipping operations, this paper proposes to temper our understanding of the role of steamship technology in empire. The influence of colonies on the metropole encompassed an alteration of the rhythms of imperial circulation, and it is within the maritime arena that these realities came into sharp focus

Crop Updates 2000 - Cereals part 1

This session covers eleven papers from different authors: PLENARY PAPERS 1. New Wheat for a Secure, Sustainable Future, Timothy G. Reeves, Sanjaya Rajaram, Maarten van Ginkel, Richard Trethowan, Hans-Joachim Braun, and Kelly Cassaday, International Maize and Wheat Improvement Centre (CIMMYT) 2. Managing Cereal Rusts - a National Perspective, R.A. McIntosh, University of Sydney Plant Breeding Institute, New South Wales 3. Managing Cereal Rusts in 2000 - a regional imperative, R. Loughman, Agriculture Western Australia 4. Is nutrition the answer to wheat after canola problems?Ross Brennan1, Bill Bowden1, Mike Bolland1, Zed Rengel2 and David Isbister2 1 Agriculture Western Australia 2University of Western Australia 5. Improved Sandplain Cropping Systems by Controlled Traffic, Dr Paul Blackwell, Agriculture Western Australia 6. Raised bed farming for improved cropping of waterlogged soils, Derk Bakker, Greg Hamilton, David Houlbrooke, Cliff Spann and Doug Rowe, Agriculture Western Australia 7. Banded Urea increased wheat yields, Patrick Gethin, Stephen Loss, Frank Boetel, and Tim O’Dea, CSBP futurefarm 8. Flexi N is as effective as Urea on wheat and canola, Frank Boetel, Stephen Loss, Patrick Gethin, and Tim O’Dea CSBP futurefarm 9. Why potassium may reduce cereal leaf disease, Noeleen Edwards, Agriculture Western Australia 10, Trace elements, Wayne Pluske CSBP futurefarm, and Ross BrennanAgriculture Western Australia 11. Historical Nutrient Balance at Paddock and Whole Farm scales for typical wheatbelt farms in the Dowerin - Wongan Hills area, M.T.F. Wong, K. Wittwer and H. Zhang Precision Agriculture Research Group, CSIRO Land and Wate

Loss and damage livelihood resilience

Climate change Loss and Damage has emerged as a key challenge of the 21st century. This Policy Brief first frames the challenge and then introduces the Resilience Academy, highlighting 5 key insights that both feed the debate and inform action. Finally, it provides 5 recommendations to the Executive Committee of the Warsaw International Mechanism (WIM ExCom) for its 5-year work plan

Crop Updates 2000 - Oilseeds

This session covers seventeen papers from different authors: Introduction, Paul Carmody, Centre for Cropping Systems CANOLA AGRONOMY 2. Genotype, location and year influence the quality of canola grown across southern Australia, PingSi1, Rodney Mailer2, Nick Galwey1 and David Turner1, 1Plant Sciences, Faculty of Agriculture, The University of Western Australia, 2Agricultural Research Institute, New South Wales Agriculture 3. Development of Pioneer® Canola varieties for Australian market,Kevin Morthorpe, StephenAddenbrooke, Pioneer Hi-Bred Australia Pty Ltd 4. Canola, Erucic Acid, Markets and Agronomic Implications, Peter Nelson, The Grain Pool of Western Australia 5. The control of Capeweed in Clearfield Production System for Canola, Mike Jackson and ScottPaton, Cyanamid Agriculture Pty Ltd 6. Responsiveness of Canola to Soil Potassium Levels: How Low Do We Have To Go? Ross Brennan, Noeleen Edwards, Mike Bolland and Bill Bowden,Agriculture Western Australia 7. Adaption of Indian Mustard (Brassica juncea) in the Mediterranean Environment of South Western Australia, C.P. Gunasekera1, L.D. Martin1, G.H. Walton2 and K.H.M. Siddique2 1Muresk Institute of Agriculture, Curtin University of Technology, Northam, 2Agriculture Western Australia 8. Physiological Aspects of Drought Tolerance in Brassica napus and B.juncea, Sharon R. Niknam and David W. Turner, Plant Sciences, Faculty of Agriculture, The University of Western Australia 9. Cross resistance of chlorsulfuron-resistant wild radish to imidazolinones, Abul Hashem, Harmohinder Dhammu and David Bowran, Agriculture Western Australia 10. Canola Variety and PBR Update 2000, From The Canola Association of Western Australia 11. Development of a canola ideotype for the low rainfall areas of the western Australian wheat belt, Syed H. Zaheer, Nick W. Galwey and David W. Turner, Faculty of Agriculture, The University of Western Australia DISEASE MANAGEMENT 12. Evaluation of fungicides for the management of blackleg in canola, Ravjit Khangura and Martin J. Barbetti, Agriculture Western Australia 13. Impact-IFÒ: Intergral in the control of Blackleg, Peter Carlton, Trials Coordinator, Elders Limited 14. Forecasting aphid and virus risk in canola, Debbie Thackray, Jenny Hawkes and Roger Jones, Agriculture Western Australia and Centre for Legumes in Mediterranean Agriculture 15. Beet western yellow virus in canola: 1999 survey results, wild radish weed reservoir and suppression by insecticide, Roger Jones and Brenda Coutts, Agriculture Western Australia 16. Are canola crops resilient to damage by aphids and diamond back moths? Françoise Berlandier, Agriculture Western Australia ECONOMIC OUTLOOK 17. Outlook for prices and implications for rotations, Ross Kingwell1,2, Michael O’Connell1 and Simone Blennerhasset11Agriculture Western Australia 2University of Western Australi