The Terrestrial Isopod \u3ci\u3eHyloniscus Riparius\u3c/i\u3e (Isopoda: Oniscidea: Trichoniscidae) in Wisconsin

We examined seasonal reproductive patterns for the terrestrial isopod Hyloniscus riparius in Wisconsin. Samples collected from habitats in three Wisconsin regions were compared with regard to the reproductive status of population members. We also recorded differences in sex ratio and stage of female gravidity in all samples. Males were a minority in all samples. Southern samples showed the greatest reproductive capacity based on the proportion of females that were found to be gravid

Physiological and Agronomic Responses of Four Rice Varieties to Drought in the Rainforest.

The present investigation tested the hypothesis that there would be variation in physiological responses to water deficit among rice varieties from different production ecologies, with contrasting tolerance to water deficit under repeated cycle of soil moisture deficit, at reproductive growth stage. A screen house and a field trial were conducted at International Institute of Tropical Agriculture, Ibadan and Ikenne (Latitude 6° 52' N, Longitude 3° 43' E) respectively. Both experiments had rice varieties ('IR 64', 'WAB 56-104', 'IR 77298-1-2-B-10' and 'NERICA 4') and stress status (stress and control) as treatment factor's, arranged in a randomised complete block design with three replicates. In both trials, the physiological mechanism that underpins varietal differences with repeated cycles of water deficit at the reproductive growth stage was more balanced water status, improved foliar characters, efficient photosynthetic capacity and higher grain yield in comparatively drought tolerant upland rice varieties ('NERICA 4' and 'WAB 56-104'), as opposed with the results for the drought susceptible cultivar 'IR 64'. A converse pattern was observed on water stressed rice, despite fewer cycles of water deficit on the field. The results could have suggested that the initiation of water deficit is the rate limiting step rather than its intensity at the reproductive growth stage

Auto-spermatophore extrusion in male crickets

The reproductive cycle of the male cricket consists of the mating stage and the sexually refractory stage. The latter is further divided into the first refractory stage (RS1) from spermatophore extrusion in copulation to spermatophore preparation after copulation, and the second refractory stage (RS2) from spermatophore preparation to recommencement of a calling song. RS2 is time-fixed and unaffected by the female or by stress, hence RS2 is assumed to be controlled by the reproductive timer. Previously, we suggested that the timer is located in the terminal abdominal ganglion (TAG), because functional inactivation of the TAG by local cooling lengthened RS2 in proportion to cooling time. To obtain further evidence of timer localization and to examine the operation of the timer in dissected animals, we investigated the characteristics of auto-spermatophore extrusion, a phenomenon in which males eject the mature spermatophore themselves without any prior courtship. The occurrence of auto-spermatophore extrusion was 100% in dissected males with the TAG separated, compared to 1.7% in intact males. The time interval (SPaSE) between spermatophore preparation and autospermatophore extrusion was comparable to RS2 measured by the calling song. Spike recording from a genital motor neurone in the separated TAG indicated that burst discharge associated with auto-spermatophore extrusion occurred with a SPaSE comparable to RS2. Other efferent neurones, some of which were identified as dorsal unpaired median (DUM) neurones, showed a timedependent spike frequency increase during SPaSE. These results strengthen our previous conclusion that the reproductive timer is located within the TAG, and demonstrate that the timer functions normally even when the TAG is separated from the central nervous system.</p

Influence of Stage and Intensity of Reproductive Organs Pruning on Quality of Pepper (Capsicum annuum L.) At Humbo, Southern Ethiopia

Field experiment was conducted on farmer’s field from 2009 to 2010 at Humbo, Southern Ethiopia, to assess the effects of stage and intensity of reproductive organs pruning on quality of pepper. Four levels of pruning (control, one-reproductive organ, two-reproductive organs and three-reproductive organs) and three stages of pruning (bud, anthesis and fruit set), were arranged in factorial combination in Randomized Complete Block Design with three replications. Pepper cultivar called ‘Marekofana’ was used. The interaction effect of three- reproductive organs pruned treatment with fruit set stage gave the highest fruit length (14.64 cm), pericarp thickness (3.65 mm) and fruit diameter (2.98 cm) and the least values were obtained from the control. The interaction effect of three- reproductive organs pruned treatment with anthesis stage gave the highest fruit volume (33.98 cm3) and the least values were obtained from the control. Key words: Stage, intensity, reproductive organ, pruning, peppe

The effect of sex-allocation biasing on the evolution of worker policing in hymenopteran societies

Mutual policing is thought to be important in conflict suppression at all levels of biological organization. In hymenopteran societies (bees, ants, and wasps), multiple mating by queens favors mutual policing of male production among workers (worker policing). However, worker policing of male production is proving to be more widespread than predicted by relatedness patterns, occurring in societies headed by single-mated queens in which, paradoxically, workers are more related to the workers' sons that they kill than the queen's sons that they spare. Here we develop an inclusive-fitness model to show that a second reproductive conflict, the conflict over sex allocation, can explain the evolution of worker policing contrary to relatedness predictions. Among ants, and probably other social Hymenoptera, workers kill males to favor their more related sisters. Importantly, males are killed at the larval stage, presumably because workers cannot determine the sex of queen-laid eggs. Sex-allocation biasing favors worker policing because policing removes some males (the workers' sons) at low cost at the egg stage rather than at higher cost at the larval stage. Our model reveals an important interaction between two reproductive conflicts in which the presence of one conflict (sex allocation) favors the suppression of the other (male production by workers)

Reproductive value, the stable stage distribution, and the sensitivity of the population growth rate to changes in vital rates

The population growth rate, or intrinsic rate of increase, measures the potential rate of growth of a population with specified and fixed vital rates.The sensitivity of population growth rate to changes in the vital rates can be written in terms of the stable stage or age distribution and the reproductive value distribution. If the vital rate measures the rate of production of one type of individual by another, then the sensitivity of growth rate is proportional to the reproductive value of the destination type and the representation in the stable stage distribution of the source type. This formal relationship exists in three forms: one limited to age-classified populations, a second that applies to stage- or age-classified populations, and a third that uses matrix calculus. Each uses a different set of formal demographic techniques; together they provide a relationship that beautifully cuts across different types of demographic models.matrix population models, population growth, senescence, sensitivity

The effect of sex-allocation biasing on the evolution of worker policing in hymenopteran societies

Mutual policing is thought to be important in conflict suppression at all levels of biological organization. In hymenopteran societies (bees, ants, and wasps), multiple mating by queens favors mutual policing of male production among workers (worker policing). However, worker policing of male production is proving to be more widespread than predicted by relatedness patterns, occurring in societies headed by single-mated queens in which, paradoxically, workers are more related to the workers' sons that they kill than the queen's sons that they spare. Here we develop an inclusive-fitness model to show that a second reproductive conflict, the conflict over sex allocation, can explain the evolution of worker policing contrary to relatedness predictions. Among ants, and probably other social Hymenoptera, workers kill males to favor their more related sisters. Importantly, males are killed at the larval stage, presumably because workers cannot determine the sex of queen-laid eggs. Sex-allocation biasing favors worker policing because policing removes some males (the workers' sons) at low cost at the egg stage rather than at higher cost at the larval stage. Our model reveals an important interaction between two reproductive conflicts in which the presence of one conflict (sex allocation) favors the suppression of the other (male production by workers)

Evaluation of Argentine wild sunflower biotypes for drought stress during reproductive stage

As in several regions where sunflower production has moved to areas with limiting water availability, the search for water-stress tolerant genotypes has been intensified. Helianthus annuus ssp. annuus L. constitutes a potential genetic resource because it has naturalized in the semi-arid zone of central Argentina. The assessment of these genetic materials for water deficit tolerance is of interest because they may represent a source of genes for drought tolerance, useful to sunflower breeding. Drought resistant genotypes should be achieved using easily identified phenotypic traits. Parameters like leaf area are widely used to characterize the performance under stress. Leaf temperature is an easily measured physiological parameter that allows an indirect estimate of plant transpiration and is well correlated with water availability. Relative water content indicates the ability to retain water from the soil and expresses plant osmotic adjustment ability. Specific leaf area is a morphological parameter related to leaf thickness. The objectives of this study were to evaluate the drought tolerance of Argentine wild sunflower biotypes and identify morphological and physiological traits expressing differences between stressed biotypes. Wild biotypes were evaluated during three years in the experimental field of the Agronomy Department, Universidad Nacional del Sur, Argentina. Groups of 10-15 plants of each biotype were evaluated under two water conditions, drought (deficit supply) with drip irrigation to cover a half of the potential evapotranspiration during flowering, or with optimal water supply. Soil surface was covered with black polyethylene to exclude rainwater. Wild sunflower comprised five biotypes collected from different habitats in the semiarid region of Argentina. Crosses between the wild biotypes and inbred lines were also included every year. Inbred lines and a commercial hybrid (DK4000) were used as controls. Recorded traits were: plant height, stem diameter, petiole length, leaf area, leaf number, head number and reproductive surface. Leaf parameters were: relative water content (RWC), specific leaf area (SLA), canopy temperature (CT), and chlorophyll content (SPAD). A susceptibility index (SI) was obtained to compare the performance under water stress with that obtained in optimal conditions. Biotype evaluation and parameter characterization were performed separately for each year because water stress levels were different. Wild sunflower responses to water stress were different for all parameters among biotypes, except for plant height and petiole length. Wild biotypes had better RWC and lower SLA than cultivated biotypes. Under water stress wild biotypes showed higher values and greater range of RWC and SPAD than cultivated sunflower. Susceptibility index showed that leaf area of wild sunflower biotypes had lower stress susceptibility than cultivated sunflowers. Nevertheless, wild biotypes showed increased susceptibility to the remaining plant morpho-physiological parameters. RWC and CT had a significant relationship in wild sunflower biotypes under water stress. Drought tolerant type identification was complex because of the complex responses among parameters. Wild biotypes might have a physiological mechanism which allows higher RCA than cultivated sunflower under drought stress. The lower SLA under water deficit could be attributed to a greater leaf thickness and could be related with RCA. Lower leaf area reduction under stress in wild sunflower is an interesting trait that might be used to improve cultivated sunflower. As the RWC is related with CT under stress in wild biotypes, this trait evaluation allows the fast examination of a high number of plants. The assessment of Argentina wild sunflower biotypes for traits associated with drought tolerance has not yet been done. Their identification could increase sunflower crop yield under drought in semiarid regions.Fil: Fernández Moroni, Ivana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Fraysse, M.. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Presotto, Alejandro Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Cantamutto, Miguel Ángel. Instituto Nacional de Tecnología Agropecuaria; Argentin