Variability in the behavioural responses of three generalist herbivores to the most abundant coumarin in Daphne laureola leaves

We evaluated the responses of three generalist herbivores (Lepidoptera: Noctuidae) to the most abundant coumarin in young leaves of spurge-laurel, Daphne laureola L. (Thymelaeaceae), a perennial shrub consistently fed upon by several noctuid species. Pseudenargia ulicis Staud and Noctua janthe Borkhausen are natural herbivores of the species in southeastern Spain, whereas Spodoptera littoralis Boisduval is a model species frequently used to address the antifeedant role of secondary compounds. Discrimination between control and coumarin-coated D. laureola leaves was investigated by short-term choice experiments. We found species-specific behavioural responses to the treatment: P. ulicis preferred the control leaves, whereas S. littoralis did not discriminate between leaf treatments, although it clearly avoided coumarin when incorporated into an artificial diet, and N. janthe preferred the coumarin-coated leaves. Furthermore, N. janthe larvae reduced consumption when the proportion of treated leaves ingested increased and consumption of S. littoralis larvae was also reduced in coumarin-containing diet under no-choice conditions. Our results highlight that different herbivore species feeding simultaneously on the same host plant respond differently to a single chemical defence compound, likely constraining a directional response of the plant to selection.     

OCCURRENCE OF LOROXANTHIN,LOROXANTHIN DECENOATE,AND LOROXANTHIN DODECENOATE IN TETRASELMIS SPECIES (PRASINOPHYCEAE,CHLOROPHYTA)1

The pigment composition of six species of Tetraselmis (Prasinophyceae) was analyzed using improved HPLC methods. All pigment extracts showed three peaks corresponding to unknown carotenoids. The isolated pigments were analyzed using UV–Vis spectroscopy, electrospray ionization–mass spectrometry (ESI–MS), and when carotenoid esters were suspected, gas chromatography–mass spectrometry (GC–MS) of the methyl ester and dimethyloxazoline derivative of the corresponding fatty acid. The new pigments were determined to be loroxanthin, loroxanthin 19‐(2‐decenoate), and loroxanthin 19‐(2‐dodecenoate); this is the first time these pigments have been described in the genus Tetraselmis. Moreover, this is the first report of esterification of 2‐decenoic acid to loroxanthin. The relative contents of these pigments depended on the light regime, with the lowest proportions measured at the highest photon flux density assayed. The implications of the identification of these pigments in the genus Tetraselmis for the pigment types previously described in the class Prasinophyceae are discussed.     

Solar Drinking Water Disinfection (SODIS) to Reduce Childhood Diarrhoea in Rural Bolivia: A Cluster-Randomized,Controlled Trial

Background

Solar drinking water disinfection (SODIS) is a low-cost, point-of-use water purification method that has been disseminated globally. Laboratory studies suggest that SODIS is highly efficacious in inactivating waterborne pathogens. Previous field studies provided limited evidence for its effectiveness in reducing diarrhoea.

Methods and Findings

We conducted a cluster-randomized controlled trial in 22 rural communities in Bolivia to evaluate the effect of SODIS in reducing diarrhoea among children under the age of 5 y. A local nongovernmental organisation conducted a standardised interactive SODIS-promotion campaign in 11 communities targeting households, communities, and primary schools. Mothers completed a daily child health diary for 1 y. Within the intervention arm 225 households (376 children) were trained to expose water-filled polyethyleneteraphtalate bottles to sunlight. Eleven communities (200 households, 349 children) served as a control. We recorded 166,971 person-days of observation during the trial representing 79.9% and 78.9% of the total possible person-days of child observation in intervention and control arms, respectively. Mean compliance with SODIS was 32.1%. The reported incidence rate of gastrointestinal illness in children in the intervention arm was 3.6 compared to 4.3 episodes/year at risk in the control arm. The relative rate of diarrhoea adjusted for intracluster correlation was 0.81 (95% confidence interval 0.59–1.12). The median length of diarrhoea was 3 d in both groups.

Conclusions

Despite an extensive SODIS promotion campaign we found only moderate compliance with the intervention and no strong evidence for a substantive reduction in diarrhoea among children. These results suggest that there is a need for better evidence of how the well-established laboratory efficacy of this home-based water treatment method translates into field effectiveness under various cultural settings and intervention intensities. Further global promotion of SODIS for general use should be undertaken with care until such evidence is available.

Trial Registration

www.ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00731497","term_id":"NCT00731497"}}NCT00731497 Please see later in the article for Editors'' Summary     

Genetic diversity of chloroquine-resistant Plasmodium vivax parasites from the western Brazilian Amazon

The molecular basis of Plasmodium vivax chloroquine (CQ) resistance is still unknown. Elucidating the molecular background of parasites that are sensitive or resistant to CQ will help to identify and monitor the spread of resistance. By genotyping a panel of molecular markers, we demonstrate a similar genetic variability between in vitro CQ-resistant and sensitive phenotypes of P. vivax parasites. However, our studies identified two loci (MS8 and MSP1-B10) that could be used to discriminate between both CQ-susceptible phenotypes among P. vivax isolates in vitro. These preliminary data suggest that microsatellites may be used to identify and to monitor the spread of P. vivax-resistance around the world.     

Workers dominate male production in the neotropical bumblebee Bombus wilmattae (Hymenoptera: Apidae)

Background

Cooperation and conflict in social insects are closely linked to the genetic structure of the colony. Kin selection theory predicts conflict over the production of males between the workers and the queen and between the workers themselves, depending on intra-colonial relatedness but also on other factors like colony efficiency, sex ratios, cost of worker reproduction and worker dominance behaviour. In most bumblebee (Bombus) species the queen wins this conflict and often dominates male production. However, most studies in bumblebees have been conducted with only a few selected, mostly single mated species from temperate climate regions. Here we study the genetic colony composition of the facultative polyandrous neotropical bumblebee Bombus wilmattae, to assess the outcome of the queen-worker conflict over male production and to detect potential worker policing.

Results

A total of 120 males from five colonies were genotyped with up to nine microsatellite markers to infer their parentage. Four of the five colonies were queen right at point of time of male sampling, while one had an uncertain queen status. The workers clearly dominated production of males with an average of 84.9% +/- 14.3% of males being worker sons. In the two doubly mated colonies 62.5% and 96.7% of the male offspring originated from workers and both patrilines participated in male production. Inferring the mother genotypes from the male offspring, between four to eight workers participated in the production of males.

Conclusions

In this study we show that the workers clearly win the queen-worker conflict over male production in B. wilmattae, which sets them apart from the temperate bumblebee species studied so far. Workers clearly dominated male production in the singly as well the doubly mated colonies, with up to eight workers producing male offspring in a single colony. Moreover no monopolization of reproduction by single workers occurred.     

定量电子束显微分析中生物薄样品的质量损失

对多种生物薄样品和标样进行电子探针X射线能谱显微定量分析,分别以电子束轰击后样品的O Kα峰计数和介于4.2-6.2keV区间的连续X－射线计数变化监测质量损失,结果显示样品O Kα峰计数减少幅度大于连续X－射线计数减少幅度,在相同的分析条件下,各样品质量损失程度不相同（P＜0.05）。培养肝癌细胞冷冻干燥超薄切片、明胶冷冻干燥超薄切片、BSA薄膜、氨基塑料超薄切片、红细胞冷冻干燥超薄切片和卵黄高磷蛋白薄膜样品的质量损失分别为33％、28％、26％、18％、13％和13％,以上结果提示：以O Kα峰计数的减少监测样品的质量损失较敏感,在进行生物薄试样定量EPMA时应对各样品的质量损失进行相应校正。