Further studies on cucumber mosaic virus infection of narrow-leafed lupin (Lupinus angustifolius): seed-borne infection, aphid transmission, spread and effects on grain yield

Four field trials were done with narrow-leafed lupins (Lupinus angustifolius) in 1988 - 1989, to examine the effect of sowing seed with 5% and 0.5% cucumber mosaic virus (CMV) infection on subsequent virus spread, grain yield and percentage of infection in harvested seed. A proportion of the CM V-infected seed failed to produce established plants and thus, plots sown with 5% and 0.5% infected seed contained 1.5-2.9% and 0.2-0.3% of seed-infected plants respectively. The rate of virus spread by aphids was faster and resulted in more extensive infection at maturity in plots sown with 5% infected seed than with 0.5% infected seed. In three trials, sowing 5% infected seed resulted in yield losses of 34 - 53% and CMV infection in the seed harvested of 6 - 13%. The spread of CMV infection resulting from sowing 0.5% infected seed did not significantly decrease yield. However, late CMV spread in these plots caused > 1% seed infection. In the fourth trial, which was badly affected by drought, CMV spread only slowly, there was no significant effect of CMV on grain yield and the percentage of infected seed harvested was 3–5 times less than that in the seed sown. When CMV-infected seed was sown at different depths, target depths of 8 and 11 cm decreased the incidence of seed-infected plants by c. 15% and c. 50% respectively compared with sowing at 5 cm. However, in glasshouse tests, treatment with the pre-emergence herbicide simazine failed to selectively cull out seed-infected plants. The field trials were colonised by green peach (Myzus persicae), blue-green (Acyrthosiphon kondoi) and cowpea (Aphis craccivora) aphids. When the abilities of these aphid species and of the turnip aphid (Lipaphis erysimi) in transmitting CMV from lupins to lupins were examined in glasshouse tests, short acquisition access times favoured transmission. With 5–10 min acquisition access times, overall transmission efficiencies were 10.8%, 9.4%, 6.1% and 3.9% for the green peach, cowpea, blue-green and turnip aphids respectively.     

Alien and native plant seed dispersal by vehicles

Vehicles play a significant role in spreading plants, both in terms of quantity and quality (species). This study was conducted in Southeast Queensland to determine the role of utility vehicles in spreading seeds. These vehicles were found to carry up to 397 seeds per vehicle and in all four seasons of the year, with the majority of these species being alien to Australia and/or Queensland. The largest seed loads were found in autumn in this summer rainfall environment. Seeds were shown to attach to all parts of the vehicle, often in mud picked up from the ground, affixed directly to the engine or radiator, or carried into the cabin by the driver. Therefore, much of the seed load is to be found on the underside, on the back and front mudguards while smaller collections were found in the cabin, on the radiator and engine, and on the tyres. Fewer viable seeds were found on the engine, presumably as desiccation and heat contributed more to their death on this part of the vehicle. One method used to reduce weed seed spread by vehicles in Queensland is washing and vacuuming of vehicles. From the present study, these procedures would need to be applied to all parts of the vehicle and in all seasons of the year.     

A trait‐based approach for predicting species responses to environmental change from sparse data: how well might terrestrial mammals track climate change?

Estimating population spread rates across multiple species is vital for projecting biodiversity responses to climate change. A major challenge is to parameterise spread models for many species. We introduce an approach that addresses this challenge, coupling a trait‐based analysis with spatial population modelling to project spread rates for 15 000 virtual mammals with life histories that reflect those seen in the real world. Covariances among life‐history traits are estimated from an extensive terrestrial mammal data set using Bayesian inference. We elucidate the relative roles of different life‐history traits in driving modelled spread rates, demonstrating that any one alone will be a poor predictor. We also estimate that around 30% of mammal species have potential spread rates slower than the global mean velocity of climate change. This novel trait‐space‐demographic modelling approach has broad applicability for tackling many key ecological questions for which we have the models but are hindered by data availability.     

Desiccation as a mitigation tool to manage biofouling risks: trials on temperate taxa to elucidate factors influencing mortality rates

The desiccation tolerance of biofouling taxa (adults and early life-stages) was determined under both controlled and ‘realistic’ field conditions. Adults of the ascidian Ciona spp. died within 24 h. Mortality in the adult blue mussel Mytilus galloprovincialis occurred within 11 d under controlled conditions, compared with 7 d when held outside. The Pacific oyster Crassostrea gigas was the most desiccation-tolerant taxon tested (up to 34 d under controlled conditions). Biofouling orientated to direct sunlight showed faster mortality rates for all the taxa tested. Mortality in Mytilus juveniles took up to 24 h, compared with 8 h for Ciona, with greater survival at the higher temperature (18.5°C) and humidity (~95% RH) treatment combination. This study demonstrated that desiccation can be an effective mitigation method for a broad range of fouling taxa, especially their early life-stages. Further work is necessary to assess risks from other high-risk species such as algae and cyst forming species.     

Modeling the risk of invasion and spread of Tuta absoluta in Africa

Tuta absoluta is an invasive insect that originated from South America and has spread to Europe Africa and Asia. Since its detection in Spain in 2006, the pest is continuing to expand its geographical range, including the recent detection in several Sub-Saharan African countries. The present study proposed a model based on cellular automata to predict year-to-year the risk of the invasion and spread of T. absoluta across Africa. Using, land vegetation cover, temperature, relative humidity and yield of tomato production as key driving factors, we were able to mimic the spreading behavior of the pest, and to understand the role that each of these factors play in the process of propagation of invasion. Simulations by inferring the pest’s natural ability to fly long distance revealed that T. absoluta could reach South of Africa ten years after being detected in Spain (Europe). Findings also reveal that relative humidity and the presence of T. absoluta host plants are important factors for improving the accuracy of the prediction. The study aims to inform stakeholders in plant health, plant quarantine, and pest management on the risks that T. absoluta may cause at local, regional and event global scales. It is suggested that adequate measures should be put in place to stop, control and contain the process used by this pest to expand its range.     

臭虫的再猖獗、生物学及防治研究进展

由于DDT等现代杀虫剂的问世,臭虫在20世纪40-50年代以后在全球大部分地区尤其是发达国家和地区销声匿迹,但近10多年来臭虫在部分国家和地区重新出现.本文对其再猖獗原因、生物学和行为、饲养、抗药性、监测与防治策略进行了综述,旨在引起国人的重视,对今后臭虫的监测和防治起到抛砖引玉的作用.本文分析了近15年有关温带臭虫Cimex lectulariusL.和热带臭虫C.hemipterus(F.)的研究文献.臭虫再猖獗被认为是因为它对目前使用的杀虫剂例如拟除虫菊酯类等产生抗性以及频繁的地区及国际交往等因素造成的.简单、经济和大规模臭虫种群饲养方法——人工膜饲喂法的研发为我们开展臭虫生物学和生态学研究提供了便利.控制和根除臭虫目前仍较困难,采用害虫综合治理(integrated pest management,IPM)策略,包括臭虫知识宣传、主动监测、非化学防治方法(例如:经常洗涤床上用品、蒸汽熏蒸、热处理、使用床垫罩、在家具腿下放置臭虫拦截装置)、有选择使用杀虫剂以及定期监测及反复防治等措施,可达到很好的防控效果.在我国部分地区,臭虫发生也呈上升趋势,工人宿舍和火车车厢是常见的臭虫为害环境.有必要对我国臭虫发生现状及其抗药性进行调查与监测.还应借鉴国际先进技术,研制出我国适用的、有效的监测工具和防治方法,并根据我国具体国情制定出切实可行的防治标准.同时积极开展臭虫科普宣传,做到早发现、早防治,防止臭虫再猖獗和扩散.     

Integrating species distribution models and interacting particle systems to predict the spread of an invasive alien plant

Aim We demonstrate how to integrate two widely used tools for modelling the spread of invasive plants, and compare the performance of the combined model with that of its individual components using the recent range dynamics of the invasive annual weed Ambrosia artemisiifolia L. Location Austria. Methods Species distribution models, which deliver habitat‐based information on potential distributions, and interacting particle systems, which simulate spatio‐temporal range dynamics as dependent on neighbourhood configurations, were combined into a common framework. We then used the combined model to simulate the invasion of A. artemisiifolia in Austria between 1990 and 2005. For comparison, simulations were also performed with models that accounted only for habitat suitability or neighbourhood configurations. The fit of the three models to the data was assessed by likelihood ratio tests, and simulated invasion patterns were evaluated against observed ones in terms of predictive discrimination ability (area under the receiver operating characteristic curve, AUC) and spatial autocorrelation (Moran’s I). Results The combined model fitted the data significantly better than the single‐component alternatives. Simulations relying solely on parameterized spread kernels performed worst in terms of both AUC and spatial pattern formation. Simulations based only on habitat information correctly predicted infestation of susceptible areas but reproduced the autocorrelated patterns of A. artemisiifolia expansion less adequately than did the integrated model. Main conclusions Our integrated modelling approach offers a flexible tool for forecasts of spatio‐temporal invasion patterns from landscape to regional scales. As a further advantage, scenarios of environmental change can be incorporated consistently by appropriately updating habitat suitability layers. Given the susceptibility of many alien plants, including A. artemisiifolia, to both land use and climate changes, taking such scenarios into account will increasingly become relevant for the design of proactive management strategies.