Prospects for biopesticides for aphid control

Diseases form an important component of the natural enemy complex of aphids. The most common and obvious of these diseases are entomophthoran fungi such asErynia neoaphidis Remaudiere & Herbert,Entomophthora planchoniana Cornu,Zoophthora radicans (Brefeld) Batko andConidiobolus obscurus (Hall & Dunn) Remaudiere & Keller. The pest status of some aphids such as the pea aphid,Acyrthosiphon pisum (Harris), is considerably reduced by natural epizootics of fungal disease. However, disease may contribute little to practical control as it is mainly effective in high density populations when weather conditions are suitable. Introduction of exotic diseases for classical biological control is only rarely possible since most diseases, like their aphid hosts, are distributed world-wide. One exception was the successful introduction into Australia of a strain ofZ. radicans for control of spotted alfalfa aphid,Therioaphis trifolii (Monell) f.maculata in 1979. Attempts to manipulate entomophthoran fungi have had limited success because of problems with mass production, the fragility of the conidia and the need for suitably moist conditions. Hyphomycete fungi such asVerticillium lecanii (Zimm.) Viegas,Metarhizium anisopliae (Metsch.) Sorokin,Beauveria bassiana (Bals.) Vuill. andPaecilomyces spp. are more suitable for development as mycoinsecticides as they are cheap to mass produce and form stable conidia. “Vertalec?”, a formulation ofV. lecanii, has been sold in small quantities commercially in Britain and parts of Europe for many years and used mainly in glasshouses. Recently promising results have been obtained with use ofM. anisopliae for control of lettuce root aphid,Pemphigus bursarius (L.) in the UK. Laboratory studies on selected isolates ofB. bassiana andPaecilomyces spp. show a promising level of activity. Problems may occur with these species as they can kill aphid predators such as coccinelids. In addition, more research is needed on developing improved formulations which enable control to be achieved under low humidity conditions.     

寻找黑脸琵鹭觅食地

黑脸琵鹭的觅食地在哪里?民以食为天,鸟为食而亡。弄清黑脸琵鹭的食物来源,对保护它们至关重要。     

Risk factors for rejection for morphological reasons of heart valves for transplantation

The study aim was to identify risk factors for morphological rejection of aortic and pulmonary valves for transplantation that could be used to optimize donor selection. The files of all Dutch heart valve donors, donating in a 2.5 years period, whose hearts were processed at Heart Valve Bank Rotterdam, were reviewed for all factors that could be relevant for valve rejection and related to outcome of morphological assessment of the valves. Valves were retrieved from 813 deceased Dutch donors, 24.1% also donating organs. For 797 aortic and 767 pulmonary valves, who met retrieval criteria, morphological assessment was done. 69.5% of aortic and 37.5% of pulmonary valves were considered unsuitable for transplantation at morphological assessment. Backward stepwise multivariate logistic regression analysis, showed age, cardiac cause of death, cerebrovascular accident as cause of death or in medical history, and number of cardiovascular risk factors in a donor to be independent risk factors for morphological rejection of aortic valves. Age, sex, weight >100 kg and ruptured aortic aneurysm as cause of death were independent risk factors for morphological rejection of pulmonary valves. Being an organ donor was an independent predictor of morphological approval of aortic and pulmonary valves, while hypertension was an independent predictor for morphological approval of aortic valves. Thus, independent factors were identified that are associated with morphological rejection of aortic and pulmonary valves for transplantation, and that could be used to optimize donor selection by preventing unnecessary retrievals, limiting costs, while improving yield per donor with minimal compromise for availability.     

Competition for water for the food system

Although the global agricultural system will need to provide more food for a growing and wealthier population in decades to come, increasing demands for water and potential impacts of climate change pose threats to food systems. We review the primary threats to agricultural water availability, and model the potential effects of increases in municipal and industrial (M&I) water demands, environmental flow requirements (EFRs) and changing water supplies given climate change. Our models show that, together, these factors cause an 18 per cent reduction in the availability of worldwide water for agriculture by 2050. Meeting EFRs, which can necessitate more than 50 per cent of the mean annual run-off in a basin depending on its hydrograph, presents the single biggest threat to agricultural water availability. Next are increases in M&I demands, which are projected to increase upwards of 200 per cent by 2050 in developing countries with rapidly increasing populations and incomes. Climate change will affect the spatial and temporal distribution of run-off, and thus affect availability from the supply side. The combined effect of these factors can be dramatic in particular hotspots, which include northern Africa, India, China, parts of Europe, the western US and eastern Australia, among others.