Matching on-the-fly in Sequential Experiments for Higher Power and Efficiency

We propose a dynamic allocation procedure that increases power and efficiency when measuring an average treatment effect in sequential randomized trials. Subjects arrive iteratively and are either randomized or paired via a matching criterion to a previously randomized subject and administered the alternate treatment. We develop estimators for the average treatment effect that combine information from both the matched pairs and unmatched subjects as well as an exact test. Simulations illustrate the method's higher efficiency and power over competing allocation procedures in both controlled scenarios and historical experimental data.Comment: 20 pages, 1 algorithm, 2 figures, 8 table

Studies on breeding shorebirds at Medusa Bay, Taimyr, in summer 2001

In the Summer of 2001 a combined Dutch-Russian expedition took place to the Willem Barentz field station at Medusa Bay near Dikson in north-western Taimyr. The expedition was organized by Alterra, the Working Group for International Waterbird and Wetland Research (WIWO) and the Agricultural Department of the Dutch Embassy in Moscow. The results obtained by the Alterra team are presented in this report. Subjects of study generally concerned breeding biology of arctic breeding shorebirds, especially aspects related to timing of breeding and adult body condition. This report's purpose is not to discuss the findings thoroughly but merely to summarize the research questions addressed and present all basic information collected during the 2001 season. Topics included are spring arrival and autumn departure of waders from the tundra, breeding phenology, nest success, biometrics of adult waders, chick growth rate, return rates of adult shorebirds, and seasonal and weather-related variation in arthropod availability. Where useful, results are compared with data collected in a previous expedition in 2000. More elaborate analyses and discussion of the data will be made elsewhere

The use of kaolin to control Ceratitis capitata in organic citrus groves.

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera Tephritidae), is the key pest in some organically managed citrus orchards in Sicily. The effectiveness of processed kaolin (Surround WP) for control of C. capitata damage was tested in field trials carried out in 2003-2004 on two early ripening citrus species: satsuma (Citrus unshiu Markow.) and clementine (Citrus clementina Hort. ex Tan.). Although the number of males captured in trimedlure baited traps was high in both years and in both orchards, the percentage of damaged fruit varied greatly from almost 0% (satsuma 2003) to more than 60% (clementine, both years). Nevertheless, the application of processed kaolin significantly reduced damage caused by C. capitata on both citrus spe- cies on preharvest fruit on some dates and on harvested fruits in both years. The kaolin was easily removed from harvested fruit by washing. Processed kaolin has potential for reducing damage caused by C. capitata in organic and conventional citrus or- chards

Cold winters vs long journeys : adaptations of primary moult and body mass to migration and wintering in the Grey Plover Pluvialis Squatarola

Includes bibliographical references.The Grey Plover Pluvialis squatarola is a circumpolar breeding wader with a cosmopolitan winter distribution. Primary moult generally starts only when potential wintering sites are reached. Across the Palearctic-African region Grey Plovers experience an enormous variety of ecological and climatic conditions, which determine the development of different moult patterns, according to local conditions and timing of migration

Behavioral Ecology of an Invasive Species: Habitat and Mate Preference(s) in Drosophila Suzukii

The invasive Spotted-Wing fruit fly, Drosophila suzukii, has inflicted substantial economic losses to the soft-fruit agriculture industry worldwide due to the ability of females in this species to use a large, serrated ovipositor to cut the fruit’s skin and lay eggs directly into the mesocarp of ripening fruit. Once the eggs hatch, larvae consume the fruit flesh, ultimately leaving the fruit unmarketable. This species parasitizes numerous commercial fruit types (including blueberries, blackberries, strawberries, raspberries and occasionally grapes) as well as fruits from a variety of wild plant species. Since fruit types vary in their nutritional composition, as well as their spatial and temporal availability, this suggests that D. suzukii experiences considerable environmental heterogeneity. The environment can have a large influence on the development and evolution of morphological, physiological, and behavioural phenotypes and, thus, can have significant implications for individual variation and population growth and change over time. Thus to better understand success if this invasive species we have examined the behavioural and developmental and reproductive performance of D. suzukii as it relates to their local environment. Specifically we focused on the role of the nutritional developmental history (NDH), which can either hinder or support offspring growth and survival, and may be an important factor when selecting habitats. Secondly, as the juvenile NDH has the potential to greatly influence adult phenotypes, and consequently individual reproductive potential, we also examined if NDH influenced the operation of sexual selection. Here we report evidence that NDH is an important factor for D. suzukii females when choosing oviposition sites, and can have dramatic consequences for offspring development, mate-choice, offspring fitness, and ultimately population growth. Information on these two subject areas (habitat and mate choice) is of great potential importance to bettering future management strategies (e.g. by manipulating fly numbers based on host preference and reproductive strategies), which are currently limited by lack of knowledge on the biology of this species