Toxicity effects of an insecticidal soap on the green peach aphid [Homoptera: Aphididae]

Effects of an insecticidal soap on the survival, development and reproduction of the green peach aphid, Myzus persicae, were studied. Twenty-four hours after application at a concentration of 37.50 g L-1, the soap caused 100% mortality in all aphid instars, and LC50 (lethal concentrations causing 50% mortality in the population) were 1.50, 3.25 and 5.50 g L-1 for first and second instars, third and fourth instars, and adult M. persicae, respectively. Aphids that survived the LC50 had a shorter longevity than the controls. Both insecticidal soap and parasitoids could be used on a crop but, as the LC50 of the third and fourth instars and adult M. persicae are higher than that of the aphid parasitoid Aphidius colemani (2.75 g L-1), it is essential to avoid treating aphids with insecticidal soap when adult parasitoids are present in the crop.Les effets d'un savon insecticide sur la survie, le développement et la fécondité du puceron vert du pêcher, Myzus persicae, ont été étudiés. Vingt-quatre heures après son application à une concentration de 37,50 g L-1, le savon a causé 100 % de mortalité chez tous les stades de pucerons et les CL50 (concentrations létales causant 50 % de mortalité dans la population) pour M. persicae étaient de 1,50, 3,25 et 5,50 g L-1 pour les premier et deuxième stades, pour les troisième et quatrième stades et pour le stade adulte, respectivement. Les pucerons ayant survécu aux CL50 n'ont pas vécu aussi longtemps que ceux du traitement témoin. Il est possible d'utiliser le savon insecticide et des parasitoïdes sur des cultures, mais comme les CL50 des troisième et quatrième stades et des adultes de M. persicae sont plus élevées que celles du parasitoïde Aphidius colemani (2,75 g L-1), il est important de ne traiter les pucerons avec du savon que lorsque les parasitoïdes adultes sont absents de la culture

Modeling the depuration potential of blue mussels (Mytilus spp.) in response to thermal shock

When contaminated, most molluscs destined for human consumption require a depuration regime lasting 48 h at a minimum temperature of 5 °C to ensure elimination of coliforms. However, this regime is unsatisfactory in northern temperate regions, where temperatures are frequently below 5 °C. A series of tests were undertaken to determine the filtration activity of mussels (Mytilus spp.) under cold temperatures. We used physiological measures rather than the more traditional method of bacterial analysis to evaluate mussel acclimation to cold temperatures. Mussels were acclimated for 4 weeks at three different temperatures (8, 4, and − 1 °C) and their scope for growth was evaluated each week to determine the level of acclimation. Mussels were then exposed to a thermal shock and clearance rates were measured after 2 h and 72 h. We observed a clearance rate of 2.45 l h− 1 g− 1 (g DW) for the 8 °C control group. Thus, within a 48-h depuration period, Mytilus spp. could filter a standard volume of 117.47 l. We used a von Bertalanffy exponential model to estimate the time required for an individual from each thermal shock treatment to filter that standard volume. We found that thermal shock had an important effect on the volume filtered by a mussel in 48 h. For example, mussels acclimated at 8 °C were able to filter the standard volume of 117.47 l in an average of 75 h at 4 °C, whereas those acclimated at 4 °C and transferred to 8 °C required only 23 h on average

The effect of habitat quality on foraging patterns, provisioning rate and nestling growth in Corsican blue tits Parus caeruleus.

Many bird species face seasonal and spatial variation in the availability of the specific food required to rear chicks. Caterpillar availability is often identified as the most important factor determining chick quality and breeding success in forest birds, such as tits Parus spp. It is assumed that parents play an important role in mediating the effect of environment on chick development. A reduction in prey availability should therefore result in increased foraging effort to maintain the amount of food required for optimal chick development. To investigate the capacity of adults to compensate for a reduction in food supply, we compared the foraging behaviour of Blue Tits Parus caeruleus breeding in rich and poor habitats in Corsica. We monitored the foraging effort of adults using radiotelemetry. We also identified and quantified prey items provided to nestlings by using a video camera mounted on the nest. We found that the mean travelling distance of adults was twice as great in the poor habitat as it was in the rich. Despite the marked difference in foraging distance, the proportion of optimal prey (caterpillars) in the diet of the chicks and the total biomass per hour per chick did not differ between the two habitats. We argue that relationships between habitat richness, offspring quality and breeding success cannot be understood adequately without quantifying parental effort

A food web model for the Baffin Bay coastal and shelf ecosystem. Part 1 : Ecopath Technical Report

This work was undertaken as part of a multidisciplinary research project funded by the Marine Observation Prediction and Assessment Network - MEOPAR (at ULaval), Canadian Institute of Health Research – CIHR (at University of Ottawa), and Sentinel North (at ULaval), and hosted at Université Laval, in Canada. The objective of the overall project is to support the food security (i.e., the availability and access to sufficient, safe, nutritious food that meets dietary preference) of Inuit communities of the Eastern Canadian Arctic, as well as to explore ways to adapt to effects of climate change. Inuit fish and hunt local marine species, from invertebrates to fish and marine mammals, which make a large part of their diet and are central to their food security. With temperatures increasing twice as fast as the global average and sea ice becoming thinner and forming later, climate change effects on the distribution and abundance of Arctic marine species are already taking place. To better understand the effects of climate change in important subsistence species, a multi-species model (Ecopath with Ecosim) will be used to inform the development of an integrated ecosystem assessment. The model will be used as a tool to co-create scenarios of ecosystem change with the community of Qikiqtarjuaq, Nunavut, to inform adaptation strategies regarding food security (e.g., potential of new fisheries in the region). This report describes the development of an Ecopath model of the Baffin Bay coastal and shelf ecosystem. The methodology, data used to construct the model, data gaps and limitations are described

The Astropy Problem

The Astropy Project (http://astropy.org) is, in its own words, "a community effort to develop a single core package for Astronomy in Python and foster interoperability between Python astronomy packages." For five years this project has been managed, written, and operated as a grassroots, self-organized, almost entirely volunteer effort while the software is used by the majority of the astronomical community. Despite this, the project has always been and remains to this day effectively unfunded. Further, contributors receive little or no formal recognition for creating and supporting what is now critical software. This paper explores the problem in detail, outlines possible solutions to correct this, and presents a few suggestions on how to address the sustainability of general purpose astronomical software