Phenological fate of plant-acquired pyrrolizidine alkaloids in the polyphagous arctiid Estigmene acrea

Summary. The alkaloid profiles of the life history stages of the highly polyphagous arctiid Estigmene acrea were established. As larvae individuals had free choice between a plain diet (alkaloid-free) and a diet that was supplemented with Crotalaria-pumila powder with a known content and composition of pyrrolizidine alkaloids (PAs). Idiosyncratic retronecine esters (insect PAs) accounted for approximately half of the PAs recovered from the larvae. These alkaloids were synthesized by the larvae through esterification of dietary supinidine yielding the estigmines, and esterification of retronecine yielding the creatonotines. The retronecine is derived from insect-mediated degradation of the sequestered pumilines (macrocyclic PAs of the monocrotaline type). With one exception, the PA profiles established for larvae were found almost unaltered in all life-stages as well as larval exuviae and pupal cocoons. The exception is the males, which in comparison to pupae and adult females, showed a significantly decreased quantity of the creatonotines and pumilines. These data support the idea that the creatonotines are direct precursors of the PA-derived male courtship pheromone, hydroxydanaidal. Crosses of PA-free males with PA-containing females and vice versa confirmed an efficient trans-mission of PAs from males to females and then from females to eggs. In single cases a male bestowed almost his total PA load to the female, and a female her total load to the eggs. The results are discussed with respect to pheromone formation, PA transmission between life-stages, and the defensive role of PAs against predators and parasitoids     

USING INFILTRATION ENHANCEMENT AND SOIL WATER MANAGEMENT TO REDUCE DIAZINON IN RUNOFF1

ABSTRACT: Pesticide runoff from dormant sprayed orchards is a major water quality problem in California's Central Valley. During the past several years, diazinon levels in the Sacramento and San Joaquin Rivers have exceeded water quality criteria for aquatic organisms. Orchard water management, via post‐application irrigation, and infiltration enhancement, through the use of a vegetative ground cover, are management practices that are believed to reduce pesticide loading to surface waters. Field experiments were conducted in Davis, California, to measure the effectiveness of these management practices in reducing the toxicity of storm water runoff. Treatments using a vegetative ground cover significantly reduced peak concentrations and cumulative pesticide mass in runoff for first flush experiments compared with bare soil treatments. Post‐application irrigation was found to be an effective means of reducing peak concentrations and cumulative mass in runoff from bare soil treatments, but showed no significant effect on vegetated treatments.     

Nikinake: the mobilization of labour and skill development in rural Ethiopia

A public mobilization approach known as nikinake drives implementation and technology upscaling in Ethiopia's agricultural extension. This study investigates and describes the processes and effectiveness of nikinake as an extension method used for natural resource management (NRM). The paper draws on empirical field research conducted in Oromia and the southern region of Ethiopia by looking at nikinake in the context of a watershed management campaign in 2015 and 2016. Nikinake is used as an approach to mobilize the public and to promote the skills of farmers and development actors. In principle, the implementation of NRM is voluntary; however, it is largely planned top‐down and enforced through state actors and informal institutions. This study suggests effective integration of social mobilization with reliable extension and a paradigm shift in emphasis from spatial coverage to an effective outcome. Additionally, sustainability and scalability of NRM interventions could be ameliorated by improving experts’ technical skills, raising farmers’ awareness, improving an incentive system, building trust, and better integrating past watershed management and future planning activities. We reflect on the significance of the nikinake experience in Ethiopia for a broader theory of extension‐as‐mobilization for rural development. From the Ethiopian case, a more general recommendation emerges for extension‐as‐mobilization schemes. For long‐term development, it is worthwhile to consider the fit between yearly campaigns as ad hoc project organizations and the existing pattern of actors and institutions responsible for rural development.     

<Emphasis Type="Italic">Ceroplastes albolineatus</Emphasis>, the first scale insect shown to sequester pyrrolizidine alkaloids from its host-plant <Emphasis Type="Italic">Pittocaulon praecox</Emphasis>

Summary. The occurrence of pyrrolizidine alkaloids (PAs) in Pittocaulon (ex Senecio) praecox (Asteraceae) a species endemic to Mexico was established. The aboveground plant organs contain the 1,2-saturated monoester 7-angeloyl-dihydroxyheliotridane together with a small proportion of its 9-angeloyl isomer as major alkaloid. The monoesters are accompanied by the macrocyclic otonecine derivative senkirkine. Roots contain only related macrocyclic PAs with senecionine, senkirkine and platyphylline as major components; monoesters are absent. The broom-like succulent stems of P. praecox are infested by the scale insect Ceroplastes albolineatus conspicuously visible by its huge wax cover. All life-history stages, i.e. females, eggs, first instar nymphs (crawlers) and the wax cover were found associated with PAs. The measured PA concentrations clearly indicate sequestration. The highest PA concentrations (mg / g dry weight) reached are: mature females, 0.44; eggs, 0.58; crawlers, 0.37; wax cover, 0.08. The host plant as well as in the infesting scale insect contain the PAs exclusively as free bases. As a phloem-feeder C. albolineatus must acquire the PAs with the ingested phloem sap. This appears plausible since in Senecio species PA are transmitted and circulated through the phloem path. It is suggested that PAs may protect particularly the crawlers as the most endangered stage in the life-cycle of the scale insect.     

The flavo-enzyme xanthine oxidase is under circadian control in the marine alga Gonyaulax

The activity of xanthine oxidoreductases (xanthine oxidase, XO, EC 1.2.3.2 and xanthine dehydrogenase, XDH, EC 1.1.1.204) in partially purified extracts of Gonyaulax polyedra was measured over 24 h both in a light:dark cycle and in constant light. This is the first demonstration of xanthine oxidoreductase in a unicellular alga. The activity of the O₂-dependent form (XO) was found to be 15 times higher in light than in darkness. The same time-of-day specific differences persisted in constant light, demonstrating a control of XO by the circadian clock. In contrast, the activity of the NAD-dependent form (XDH) is not under circadian control. Because pharmacological inhibition of XO also blocks the effect of blue light on the Gonyaulax circadian clock, the possible relationship between XO and light reception in this unicellular alga will be discussed.     

Dynamics of land change: insights from a three-level intensity analysis of the Legedadie-Dire catchments,Ethiopia

Earlier studies on land change (LC) have focused on size and magnitude, gains and losses, or land transfers between categories. Therefore, these studies have failed to simultaneously show the complete LC processes. This paper examines LCs in the Legedadie-Dire catchments in Oromia State, Ethiopia, using land-category maps with intensity analysis (IA) at three points in time. We comprehensively analyze LC to jointly encompass the rate, intensity, transition, and process. Thirty-meter US Geological Survey (USGS) Landsat imagery from 1986, 2000, and 2015 (<?10% cloud) is processed using TerrSet-LCM and ArcGIS. Six categories are identified using a maximum likelihood classification technique: settlement, cultivation, forest, water, grassland, and bare land. Then, classified maps are superimposed on the images to statistically examine changes with an IA. Considerable changes are observed among categories, except for water, between 1986–2000 and 2000–2015. Overall land change occurred quickly at first and then slowly in the second time interval. The total land area that exhibited change (1st?≈?54% and 2nd?≈?51%) exceeded the total area of persistence (1st?≈?46% and 2nd?≈?49%) across the landscape. Cultivation and human settlements were the most intensively increased categories, at the expense of grassland and bare ground. Hence, when grassland was lost, it tended to be displaced by cultivation more than other categories, which was also true with bare land. Annual intensity gains were active for forest but minimal for cultivation, implying that the gains of forest were associated with in situ reforestation practices and that the gains in cultivation were caused by its relatively large initial area under a uniform intensity concept. This study demonstrates that IA is valuable for investigating LC across time intervals and can help distinguish dormant vs. active and targeted vs. avoided land categories.     

Are you an ambitious cyclist? Results of the cyclist profile questionnaire in Germany

Abstract

Objective: A number of studies have already grouped cyclists according to different aspects of their mobility behavior. This could be used e.g., to improve the bicycle infrastructure planning, to detect critical spots and, to reduce obstacles for cycling. This wide, preexisting, range of cyclist typologies usually concentrates on one or two influence factors and differs, content-wise, in both factors used, as well as, methodically. Based on existing cyclist typologies we extracted all possible influence factors to integrate them in one single questionnaire. The objective of this study, using an empirical, based approach, is to compare this typology of cyclists with existing ones, integrating all known influence factors of recent studies.

Methods: To address these issues, we conducted a Germany-wide online survey on cycling behavior, covering all relevant aspects we derived from both literature and especially, former cyclist typology studies including: social factors; the impact of environmental, individual; and route factors; as well as motives. The main goal was to identify distinct types of cyclists, and describe them as detailed as possible. The heterogeneous sample included a total of 10,294 responses.

Results: Using factor and cluster analyses, a multidimensional typology with four groups of cyclists was derived which were interpreted as: ambitious, functional, pragmatic, and passionate cyclists. In addition, socio-economic factors, cyclist’s motivation, and crash history were analyzed.

Conclusion: The results produced by grouping different characteristics of cyclists can lead to policy recommendations or communal bicycle traffic planning. Policy planners can estimate reactions of the different types on interventions and adjust their decisions which can serve to support already passionate cyclists or, encourage normally under-represented infrequent cyclists to cycle more. The extent of perceived safety plays here an important role in the classification, e.g., the handling of high-risk areas for crashes.