Jan-Eric Englund

Assessment of diet choice by the yellow fever mosquito Aedes aegypti

To investigate feeding‐related decisions in Aedes aegypti (L.), adults are presented with simple diets of paired gustatory stimuli conveying information concerning energy content, nutrient richness, osmotic balance and food toxicity in a two‐diet matrix assay. Assessment of mosquito gut contents indicates that both sexes accept single sugar diets in a dose‐dependent manner. When presented with a choice between two different yet equimolar sugar solutions, more individuals of both sexes accept the disaccharides, sucrose and trehalose, than the monosacharrides, fructose and glucose. The combination of pyranose and furanose sugars in solution, either physically associated (as in sucrose) or present as monomers (as glucose and fructose), is accepted over solutions containing a single sugar moiety. Using the two‐diet matrix assay, mosquito diet‐choice is also tested between two equimolar sucrose ‘driver’ solutions in which one is presented with various concentrations of another potential feeding cue ‘test’ compound (i.e. each of the 20 naturally‐occurring amino acids, sodium chloride, quinine or caffeine). Diet‐choice between the ‘driver’ sucrose‐only solution and the solution of the ‘driver’ sucrose containing a ‘test’ amino acid is influenced by sex, amino acid concentration and sucrose concentration. There is also an example of synergism between the diet components, leucine and sucrose. Mosquitoes demonstrate a dose‐dependent acceptance of sucrose‐only diets over sodium chloride‐containing sucrose when presented together. Interestingly, the sucrose‐only diet is accepted by more mosquitoes than all concentrations of the saline‐containing sucrose diets except those approximately isotonic to mosquito haemolymph, at which concentration mosquitoes show no clear choice between the diets. More individuals of both sexes accept sucrose‐only diets than the diets of caffeine‐containing sucrose in a dose‐dependent manner. Only females, however, respond to quinine‐containing sucrose diets and modulate this behaviour in relation to the energetic reward: more females imbibed quinine‐containing sucrose at the higher sucrose concentration (1 m). A systematic characterization of diet selection behaviour of A. aegypti is presented for 27 putative feeding cues potentially involved in nectar/honeydew feeding. This study will be used as a basis from which to investigate further the mosquitos assessment of food quality and ultimately host choice.

Effect on radish pests by application of insecticides in a nearby spring oilseed rape field

Chemical control of insect pests is often necessary to ensure high yields of field crops. The aim of the present study was to study whether field pesticide use influences amount of pest damage in neighbouring garden crops. Spring oilseed rape, OSR (Brassica napus L.), was established in Southern Sweden as an example of an agricultural field crop. One half of the OSR field was treated with insecticides to control flea beetles (Phyllotreta spp., Chrysomelidae) and pollen beetle (Meligethes aeneus Fab., Nitidulidae). Radish (Raphanus sativus L.) was used as an example of a common garden crop and it was sown as four replications at three different distances and on four occasions during the season. Care was taken to protect the radish plots from pesticide due to wind drift during applications. Damage to the radish by flea beetle and cabbage root fly (Delia radicum L., Anthomyiidae) along with unspecified leaf damage was recorded. Significantly lower damage by flea beetles was found on cotyledons of radish adjacent to the insecticide treated side of the OSR field compared to the untreated side in radishes from the first sowing. Unspecified damage to true leaves was also less abundant on radishes at the treated side of the OSR field as compared to the untreated side, in all three of the radish harvests analysed. However, radish plot distance from the OSR field did not influence leaf damage. Root fly damage rates in radish did not differ significantly between those adjacent to the treated and untreated sides of the OSR. Damage rates were, however, higher in the radish plots closest to the OSR field in the first sowing, which coincides with the appearance of the first ovipositing females after overwintering as pupae elsewhere. Generally, insecticide treatment in the agricultural field appeared to influence overall damage in the neighbouring garden crop, despite the fact that the garden crop was protected against wind drift of the insecticides during applications.

Outdoor Environments at Three Nursing Homes: Semantic Environmental Descriptions

Research suggests that the outdoor environment is an important source of variety and change as well as health and well-being for nursing home residents. However, not every outdoor environment has the potential to be a positive resource in the life of older persons at nursing homes, and in this respect we need to study the particular design and content of the outdoor environment. The semantic environmental description (SMB) is a quantitatively based standardized tool intended to systematically describe an environment through assessments of 8 dimensions, namely: pleasantness, complexity, unity, enclosedness, potency, social status, affection, and originality. In this study the SMB was used to compare the outdoor environment of an imagined ideal nursing home and the outdoor environments of 3 existing nursing homes. Furthermore, assessments of an imagined ideal nursing home by pensioners and by nursing home staff were compared. The environment that was the closest to the ideal environment according to the assessments was a park-like environment that was larger and had more variation in vegetation than the other environments. The article concludes by discussing the SMB dimensions in relation to important environmental qualities in nursing home gardens.

The Mississippi Problem

Abstract We present a tricky combinatorial problem, primarily intended for entertainment. Two more problems are given as a challenge to the reader at the end of the article.

Does insecticide application in a winter oilseed rape field influence the abundance of pollen beetle Meligethes aeneus in nearby ornamental flowers and vegetables

BACKGROUND Pollen beetle is a pest that attacks oilseed rape as well as many other brassicaceous crops, garden vegetables and ornamental flowers. The present study was primarily carried out to investigate whether insecticide application in brassicaceous field crops might influence the abundance of pollen beetles in nearby private garden flowers and vegetables. RESULTS At peak emergence of the new generation of pollen beetles, a significantly higher number of beetles were found in flowers, and in window traps, alongside untreated as opposed to alongside treated sections of the winter oilseed rape (WOSR) field. However, the type of flower played a role in the number of pollen beetles found in the flowers. The presence of pollen beetles in both ornamental and wild flowers was also significantly influenced by the direction of placement of the flowers. No pollen beetle, neither overwintering nor newly emerged, was observed in any of the brassicaceous vegetables placed along the field. CONCLUSION The number of pollen beetles in the WOSR field strongly influenced the number of pollen beetles in nearby flowers of preference to the beetles, and insecticide treatment with Biscaya (thiacloprid) against pollen beetle in oilseed rape may thus help, indirectly, to protect nearby garden flowers from damage.

Do humans really prefer semi-open natural landscapes? A cross-cultural reappraisal.

There is an assumption in current landscape preference theory of universal consensus in human preferences for moderate to high openness in a natural landscape. This premise is largely based on empirical studies of urban Western populations. Here we examine for the first time landscape preference across a number of geographically, ecologically and culturally diverse indigenous populations. Included in the study were two urban Western samples of university students (from southern Sweden) and five non-Western, indigenous and primarily rural communities: Jahai (Malay Peninsula), Lokono (Suriname), Makalero (Timor), Makasae (Timor), and Wayuu (Colombia). Preference judgements were obtained using pairwise forced choice assessments of digital visualizations of a natural landscape varied systematically on three different levels of topography and vegetation density. The results show differences between the Western and non-Western samples, with interaction effects between topography and vegetation being present for the two Swedish student samples but not for the other five samples. The theoretical claim of human preferences for half-open landscapes was only significantly confirmed for the student sample comprising landscape architects. The five non Western indigenous groups all preferred the highest level of vegetation density. Results show there are internal similarities between the two Western samples on the one hand, and between the five non-Western samples on the other. To some extent this supports the idea of consensus in preference, not universally but within those categories respectively.

The impact of the primary colours yellow, red and, blue on the perception of greenery

Abstract Colourful flowers and artefacts are frequently used in modern landscape architecture and in site-specific artwork. Despite this, there is limited empirically substantiated understanding of the impact of colour on perceptions of the soft, changing green colour palette of surrounding vegetation, and thus the overall colour perception of green spaces. Applying the CIE 1976 (L*a*b*) colour space, this study showed that the presence of artefacts with different primary colours, shape, size and position significantly changed perceptions of the lightness (L* spectrum) and blue-yellow spectrum (b*) of surrounding green vegetation, while perception of its green-magenta spectrum (a*) remained more or less unchanged. It also showed that colourful artefacts had different effects on different perennials. Overall, the results demonstrate that professionals should pay equal attention to the green hue of surrounding vegetation as to the colour of artefacts or flowers when researching or practising design.