Survivorship and fecundity of Argulus bengalensis (Crustacea; Branchiura) under laboratory conditions

The Life table features and the fecundity schedule of the fish louse Argulus bengalensis (Branchiura: Argulidae) were estimated under laboratory conditions using Cirrhinus mrigala as the model host. The cohort-based Life table revealed that survival of A. bengalensis declines as a function of age. Life expectancy was observed to be 34?days for a newly emerged adult. The mean number of eggs produced per egg strip was 86 (±8.89 S.E.). The sex ratio 2:1 was biased towards males. The net reproductive rate (R₀) varied between 50 and 487 while the cohort generation time (T_c) ranged between 24 and 26?days. The intrinsic rate of increase (r) was 0.14–0.23, while the finite rate of increase (λ) remained between 1.16 and 1.28. The Life table features and the fecundity schedule of A. bengalensis are comparable with congenerics of temperate regions. Early reproduction (between 21 and 23?days) and an extended postreproductive phase (47?days) of females are characteristic of A. bengalensis and a reflection for survival under uncertain conditions and a parasitic mode of life.     

Vocabulary of Definitions of Life Suggests a Definition

Abstract

Analysis of the vocabulary of 123 tabulated definitions of life reveals nine groups of defining terms (definientia) of which the groups (self-)reproduction and evolution (variation) appear as the minimal set for a concise and inclusive definition: Life is self-reproduction with variations.     

Demographic parameters of Brachionus calyciflorus Pallas (Rotifers) exposed to sublethal endosulfan concentrations

The effects of sublethal levels of endosulfan (0, 1, 1.5, 2.5 and 3.3 mg 1^–1) on the demography of the rotifer Brachionus calyciorus were studied. Life expectancy at birth (e _o), net reproductive rate (Ro), generation time (T) and intrinsic rate of natural increase (r) were significant differentes between blank controls and controls with acetone. The effective endosulfan concentration at which a given parameter value was reduced to 50% of the controls (EC50) was calculated for life expectancy.     

Elevational trends in life histories: revising the pace‐of‐life framework

Life‐history traits in birds, such as lifespan, age at maturity, and rate of reproduction, vary across environments and in combinations imposed by trade‐offs and limitations of physiological mechanisms. A plethora of studies have described the diversity of traits and hypothesized selection pressures shaping components of the survival–reproduction trade‐off. Life‐history variation appears to fall along a slow–fast continuum, with slow pace characterized by higher investment in survival over reproduction and fast pace characterized by higher investment in reproduction over survival. The Pace‐of‐Life Syndrome (POLS) is a framework to describe the slow–fast axis of variation in life‐history traits and physiological traits. The POLS corresponds to latitudinal gradients, with tropical birds exhibiting a slow pace of life. We examined four possible ways that the traits of high‐elevation birds might correspond to the POLS continuum: (i) rapid pace, (ii) tropical slow pace, (iii) novel elevational pace, or (iv) constrained pace. Recent studies reveal that birds breeding at high elevations in temperate zones exhibit a combination of traits creating a unique elevational pace of life with a central trade‐off similar to a slow pace but physiological trade‐offs more similar to a fast pace. A paucity of studies prevents consideration of the possibility of a constrained pace of life. We propose extending the POLS framework to include trait variation of elevational clines to help to investigate complexity in global geographic patterns.     

The Judicious Use of Instructional Technology in Science Education

It is natural to study astronomy outdoors, but it is not quite as natural to study astronomy during the daytime. This lesson uses the Earth's closest star as a subject of study within the schoolyard. The importance of the rising sun is combined with hands-on inquiry in which students explore the properties of shadows. Students (a) complete a modified Know and Need to Know (KNK) chart about shadows, (b) complete task cards to help direct their inquiry, (c) develop two rules about shadows and the sun, and (d) reflect upon the experience through a writing assignment.     

Speciation across the Tree of Life

Much of what we know about speciation comes from detailed studies of well-known model systems. Although there have been several important syntheses on speciation, few (if any) have explicitly compared speciation among major groups across the Tree of Life. Here, we synthesize and compare what is known about key aspects of speciation across taxa, including bacteria, protists, fungi, plants, and major animal groups. We focus on three main questions. Is allopatric speciation predominant across groups? How common is ecological divergence of sister species (a requirement for ecological speciation), and on what niche axes do species diverge in each group? What are the reproductive isolating barriers in each group? Our review suggests the following patterns. (i) Based on our survey and projected species numbers, the most frequent speciation process across the Tree of Life may be co-speciation between endosymbiotic bacteria and their insect hosts. (ii) Allopatric speciation appears to be present in all major groups, and may be the most common mode in both animals and plants, based on non-overlapping ranges of sister species. (iii) Full sympatry of sister species is also widespread, and may be more common in fungi than allopatry. (iv) Full sympatry of sister species is more common in some marine animals than in terrestrial and freshwater ones. (v) Ecological divergence of sister species is widespread in all groups, including ~70% of surveyed species pairs of plants and insects. (vi) Major axes of ecological divergence involve species interactions (e.g. host-switching) and habitat divergence. (vii) Prezygotic isolation appears to be generally more widespread and important than postzygotic isolation. (viii) Rates of diversification (and presumably speciation) are strikingly different across groups, with the fastest rates in plants, and successively slower rates in animals, fungi, and protists, with the slowest rates in prokaryotes. Overall, our study represents an initial step towards understanding general patterns in speciation across all organisms.     

Resource division by perlid stoneflies (Plecoptera) in a lake outlet ecosystem

In a stream draining a productive lake, two abundant (250/m²) stoneflies Calineuria californica and Hesperoperla pacifica differed in population size structure, habitat use and food although overlap in resource use was extensive. Life cycles of two (Calineuria) and three years (Hesperoperla) were indicated. A multivariate analysis of habitat use demonstrated size dependent habitat selection in both species and between species habitat differences. Feeding habits differed although only the largest Hesperoperla had a food refuge. Diets of individual nymphs represented an interaction of species, size and habitat.     

Assessing the Sensitivity of Seabed Species and Biotopes – The Marine Life Information Network (MarLIN)

Science-based approaches to support the conservation of marine biodiversity have been developed in recent years. They include measures of ‘rarity’, ‘diversity’, ‘importance’, biological indicators of water ‘quality’ and measures of ‘sensitivity’. Identifying the sensitivity of species and biotopes, the main topic of this contribution, relies on accessing and interpreting available scientific data in a structured way and then making use of information technology to disseminate suitably presented information to decision makers. The Marine Life Information Network (MarLIN) has achieved that research for a range of environmentally critical species and biotopes over the past four years and has published the reviews on the MarLIN Web site (www.marlin.ac.uk). Now, by linking the sensitivity database and databases of survey information, sensitivity mapping approaches using GIS are being developed. The methods used to assess sensitivity are described and the approach is advocated for wider application in Europe.     

Natural enemies implicated in the regulation of an invasive pest: a life table analysis of the population dynamics of the emerald ash borer

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Life tables ofProctolaelaps deleoni Nawar,Childers and Abou-Setta (Gamasida: Ascidae) at different temperatures

Life tables were constructed for the predatory mite,Proctolaelaps deleoni, fed on the free-living nematodeRhabditis scanica at 20, 25, 28, 30 and 32°C. The intrinsic rate of increase (r _m ) and the net reproduction rate (R _o ) reach maximum values at 28°C. Mean generation time (t _g ) decreases with increasing temperature reaching its lowest value at 32°C.     

Two new species of Exobasidium causing Exobasidium diseases on Vaccinium spp. in Japan

Two new Exobasidium species on Vaccinium spp. in Japan are described and discussed. Exobasidium kishianum, which causes Exobasidium leaf blight on V. hirtum var. pubescens and V. smallii, is characterized by its ellipsoid to ovoid basidiospores with (0–)1–3 septa. Its systemic infection is also observed. Exobasidium inconspicuum, causing Exobasidium leaf blister on V. hirtum var. pubescens, is characterized by its obovoid or ellipsoid to oval basidiospores with 0–4 septa. Mode of germination of the basidiospores is by germ tube in both species. Contribution no. 199, Laboratory of Plant Parasitic Mycology, Graduate School of Life and Environmental Sciences, University of Tsukuba, Japan     

Effects of live animals vs. preserved specimens on student learning

Fourth-grade students (292 in all) were tested to determine if handling live animals influences cognitive and affective learning to a greater extent than handling preserved specimens. Live and dried exoskeletons of horseshoe crabs (Limulus polyphemus) and sea stars (Asterias forbesi) were used as contact animals. All students were 1) pre- and posttested; 2) participants in a teacher-directed, “touch-and-feel” lecture; and 3) given a “retention” test 6 weeks following contact. Results indicated that short- and long-term cognitive learning took place when students handled either live or dried animals. However, gains in short- and long-term affective learning (measured by changes in attitude) were achieved only when students handled live animals.     

Web-based weight management programs in an integrated health care setting: a randomized, controlled trial

Objective: To assess the efficacy of a Web‐based tailored behavioral weight management program compared with Web‐based information‐only weight management materials. Research Methods and Procedures: Participants, 2862 eligible overweight and obese (BMI = 27 to 40 kg/m²) members from four regions of Kaiser Permanente's integrated health care delivery system, were randomized to receive either a tailored expert system or information‐only Web‐based weight management materials. Weight change and program satisfaction were assessed by self‐report through an Internet‐based survey at 3‐ and 6‐month follow‐up periods. Results: Significantly greater weight loss at follow‐up was found among participants assigned to the tailored expert system than among those assigned to the information‐only condition. Subjects in the tailored expert system lost a mean of 3 ± 0.3% of their baseline weight, whereas subjects in the information‐only condition lost a mean of 1.2 ± 0.4% (p < 0.0004). Participants were also more likely to report that the tailored expert system was personally relevant, helpful, and easy to understand. Notably, 36% of enrollees were African‐American, with enrollment rates higher than the general proportion of African Americans in any of the study regions. Discussion: The results of this large, randomized control trial show the potential benefit of the Web‐based tailored expert system for weight management compared with a Web‐based information‐only weight management program.     

Use of image analysis software as a tool to visualize non-radioactive signals in plantin situ analysis

In situ hybridization (ish) allows the visualization of gene expression in tissues at high microscopic resolution. Interference by plant tissue pigments generally confers higher sensitivity to radioactiveish, relative to non-radioactiveish using hapten labeled probes. The increased resolution is partially due to image acquisition methods in radioactiveish experiments. However, radioactiveish has many drawbacks including short probe life, safety concerns associated with the use of radioactive materials, and slow development of signal. In this report, we show how commercially available image analysis software can be used to extract data from non-radioactiveish images to gain a substantial increase in resolution. We provide a comparison between detecting a probe (CELLULOSE SYNTHASE) that is expected to produce a consistent, detectable signal in all growing tissues with detection of a probe (LEAFY)that is expected to produce a signal only in specific tissues. Although the scientific content of this article has been reviewed,the full-text Web publication has not been edited in detail.     

The Effect of a Canine-assisted Activity on College Student Perceptions of Family Supports and Current Stressors

Using data from a previously published study on effects of a canine-assisted activity (CAA) on college student stress the week before final examinations, we examined whether participation in this activity had effects on perceptions of 1) family supports (i.e., emotional distance to family members and pets) and 2) current stressors. A total of 74 students completed the Family Life Space Diagram (FLSD), which uses an individual's structured drawings of distances between symbols of self and living entities, organizations, and stressors to reflect “emotional distances.” Participants were randomly assigned to order of CAA or FLSD, which was the intervention study control condition. Groups completed the FLSD after participating in CAA (Group A, n = 34) or prior to CAA (Group B, n = 40). Participants were primarily white (56.8%) females (75.7%) with a mean age of 19.38 years (SD = 1.75). Significant differences with large effect sizes were found for both groups in distances between 1) self-closest and self-average family member (Group A: t = 7.02, df = 33, p < 0.001, d = 1.205; Group B: t = 6.25, df = 39, p < 0.001, d = 0.987) and 2) self-closest personal stressor (t = 2.93, df = 18, p = 0.009, d = 1.311) and self-average personal stressor (t = 2.54, df = 18. p = 0.020, d = 1.138). In both cases, Group A (FLSD following CAA) placed personal stressors in closer proximity to self. Although CAA did not affect students’ current perceptions of family and pet relationships, the intervention may have increased their abilities to cope with personal stressors. Modified stress theory supports the proposition that positive emotions associated with CAA engage positive coping strategies, resulting in more positive perceptions of stressors.     

Comparison of life table parameters for Maconellicoccus hirsutus, Anagyrus kamali, Cryptolaemus montrouzieri and Scymnus coccivora

The pink mealybug Maconellicoccushirsutus Green (Homoptera: Pseudococcidae) wasrecently introduced to Trinidad. M.hirsutus almost immediately attained peststatus and despite the implementation ofcultural and chemical control measures, thepopulation increased above the economic injurylevel. Three natural enemies, Anagyruskamali Moursi (Hymenoptera: Encyrtidae), Cryptolaemus montrouzieri Mulsant (Coleoptera:Coccinellidae) and Scymnus coccivoraAyyar (Coleoptera: Coccinellidae) were introduced.Life fecundity tables were constructed for thepest-natural enemies complex in the hope ofunderstanding the interaction of each naturalenemy with its host, and, in so doing, form acomparative approach to assessing theeffectiveness of each natural enemy. Thestudies were carried out in the laboratory at27.0 ± 3.0 °C and 58.0 ± 3.0%RH, which is within the average field conditions in Trinidad.The net reproductive rates (R_o), theinnate capacity for increase (r_m) and thefinite rate of increase () were found to behigher for the natural enemies compared to thepest. The doubling time for M. hirsutuswas 8.83 days, while A. kamali, C.montrouzieri and S. coccivora populationsdoubled in 2.09, 5.13 and 4.45 daysrespectively. The significantly higherpopulation parameters of the natural enemies,coupled with their shorter doubling times, meanthat their populations can grow faster and thusexert a controlling effect on pest numbers.     

Doing Something about the Weather

Mealworms, yum yum! Insects are an exciting way for middle school students to acquire science process skills. A teacher eating a mealworm will certainly capture the attention of students, and explaining the common practice of insect eating among people in other countries is a great way to include culture in a science lesson. This article provides the teacher with basic information on: (a) how to set up and maintain a mealworm colony, (b) instructions on setting up an observational journal as well as a sample organizational template, and (c) a number of explorations and activities to do with mealworms.     

Biological control ofAleurocanthus woglumi [Homoptera: Aleyrodidae] in El Salvador

The citrus blackfly,Aleurocanthus woglumi Ash., was first observed in El Salvador in 1965. Its dispersal was followed during a three-year period (1969–1972) in which it infested most citrus orchards in the country. Indigenous natural enemies as the predatorsDelphastus sp. andChrysopa sp., and the pathogenic fungusAschersonia aleyrodis Web. are unable to exert any economic control of the pest. The introduction of the parasiteProspaltella opulenta Silvestri from Mexico brought about the successful biological control of the pest. Life table studies carried out before and after introduction of the parasite helped to assess the value ofP. opulenta as an effective natural enemy of the citrus blackfly.

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Résumé L'Aleurode des citrus,Aleurocanthus woglumi Ash. a été observé pour la première fois en Salvador en 1965. Son extension a été suivie pendant trois ans de 1969 à 1972, au cours desquels il a envahi la plupart des vergers d'agrumes du pays. Les ennemis naturels indigènes, tels que les prédateursDelphastus sp. etChrysopa sp. ainsi que le champignon pathogèneAschersonia aleyrodis Web. ne sont pas capables d'avoir un effet économiquement satisfaisant. L'introduction du Mexique du parasiteProspaltella opulenta Silvestri a été un succès pour la lutte biologique contre ce ravageur. L'étude des tables de vie effectuée avant et après cette introduction confirme la valeur deP. opulenta comme ennemi naturel officace de l'Aleurode des citrus.

     

Ecological interactions in Aedes species on Reunion Island

Two invasive, container‐breeding mosquito species, Aedes aegypti (Stegomyia aegypti) and Aedes albopictus (Stegomyia albopicta) (Diptera: Culicidae), have different distribution patterns on Reunion Island. Aedes albopictus occurs in all areas and Ae. aegypti colonizes only some restricted areas already occupied by Ae. albopictus. This study investigates the abiotic and biotic ecological mechanisms that determine the distribution of Aedes species on Reunion Island. Life history traits (duration of immature stages, survivorship, fecundity, estimated finite rate of increase) in Ae. aegypti and Ae. albopictus were compared at different temperatures. These fitness measures were characterized in both species in response to competitive interactions among larvae. Aedes aegypti was drastically affected by temperature, performing well only at around 25 °C, at which it achieved its highest survivorship and greatest estimated rate of increase. The narrow distribution of this species in the field on Reunion Island may thus relate to its poor ability to cope with unfavourable temperatures. Aedes aegypti was also more negatively affected by high population densities and to some extent by interactions with Ae. albopictus, particularly in the context of limited food supplies. Aedes albopictus exhibited better population performance across a range of environmental conditions. Its ecological plasticity and its superior competitive ability relative to its congener may further enhance its invasion success on Reunion Island.     

Length–weight relationships of eight Asian freshwater fish species in Nam Theun 2 Reservoir (Laos PDR)

Length–weight relationships (LWRs) were determined for eight Asian freshwater fish species that were not yet recorded in any peer‐reviewed journal indexed in the Web of Science or the FishBase database. Fish specimens from Nam Theun 2 reservoir in Lao PDR, were collected from April 2012 to August 2016 using several methods to cover a large size‐spectrum for each species. For LWRs using the general equation from Beckman (1948), the parameter b (slope value on the growth pattern) ranges from 2.908 (Puntius brevis) to 3.429 (Rasbora paviana). This study provides an update in maximum lengths for two species and first LWRs for eight common freshwater species found mainly in reservoirs, and thus represents a means for further population dynamic evolution analyses and local fisheries management.