Beetle adhesive hairs differ in stiffness and stickiness: in vivo adhesion measurements on individual setae

Leaf beetles are able to climb on smooth and rough surfaces using arrays of micron-sized adhesive hairs (setae) of varying morphology. We report the first in vivo adhesive force measurements of individual setae in the beetle Gastrophysa viridula, using a smooth polystyrene substrate attached to a glass capillary micro-cantilever. The beetles possess three distinct adhesive pads on each leg which differ in function and setal morphology. Visualisation of pull-offs allowed forces to be measured for each tarsal hair type. Male discoidal hairs adhered with the highest forces (919?±?104?nN, mean?±?SE), followed by spatulate (582?±?59?nN) and pointed (127?±?19?nN) hairs. Discoidal hairs were stiffer in the normal direction (0.693?±?0.111?N?m^?1) than spatulate (0.364?±?0.039?N?m^?1) or pointed (0.192?±?0.044?N?m^?1) hairs. The greater adhesion on smooth surfaces and the higher stability of discoidal hairs help male beetles to achieve strong adhesion on the elytra of females during copulation. A comparison of pull-off forces measured for single setae and whole pads (arrays) revealed comparable levels of adhesive stress. This suggests that beetles are able to achieve equal load sharing across their adhesive pads so that detachment through peeling is prevented.     

Honeybees learn floral odors while receiving nectar from foragers within the hive

Recent studies showed that nectar odors brought back by honeybee foragers can be learned associatively inside the hive. In the present study, we focused on the learning abilities of bees, which directly interact via trophallaxis with the incoming nectar foragers: the workers that perform nectar-receiving tasks inside the hive. Workers that have received food directly from foragers coming back from a feeder offering either unscented or scented sugar solution [phenylacetaldehyde (PHE) or nonanal diluted] were captured from two observational hives, and their olfactory memories were tested using the proboscis extension response paradigm. Bees that have received scented solution from incoming foragers showed significantly increased response frequencies for the corresponding solution odor in comparison with those that have received unscented solution. No differences in the response frequencies were found between food odors and colonies. The results indicate that first-order receivers learn via trophallaxis the association between the scent and the sugar solution transferred by incoming foragers. The implications of these results should be considered at three levels: the operational cohesion of bees involved in foraging-related tasks, the information propagation inside the hive related to the floral type exploited, and the putative effect of these memories on future preferences for resources.     

The development of self‐efficacy during aviation training

Given that self‐efficacy has been shown to be positively related to training outcomes, a better understanding of factors that affect self‐efficacy in complex training contexts is needed. This study examined the development of self‐efficacy in a flight‐training programme. Results indicate that training performance and self‐esteem predicted self‐efficacy for post‐training flight performance. Furthermore, prior flight experience moderated the relationships between training performance and self‐efficacy, and between self‐esteem and self‐efficacy. Implications regarding the development of self‐efficacy and the design of training programmes are discussed. Copyright © 2000 John Wiley & Sons, Ltd.     

Monitoring Changes in Stressed Ecosystems Using Spatial Patterns of Ant Communities

We examined the feasibility of using changes in spatial patterns of ants-distribution on experimental plots as an indicator of response to environmental stress. We produced contour maps based on relative abundances of the three most common genera of ants based on pit-fall trap captures. Relative abundance of Conomyrma spp. decreased, relative abundance of Solenopsis spp. increased, and relative abundance of Pogonomyrmex spp. remained relatively unchanged. The contour maps showed long-term changes in foraging activity and/or distribution of colonies of ants in response to grazing by domestic livestock. This study demonstrated that analysis of spatial patterns of ant activity derived from relative abundances of ants in pit-fall traps provided interpretable data for developing an indicator of exposure to ecosystem stress.     

Vegetation, Soil, and Animal Indicators of Rangeland Health

We studied indicators of rangeland health on benchmark sites with long, well documented records of protection from stress by domestic livestock or histories of environmental stress and vegetation change. We measured ecosystem properties (metrics) that were clearly linked to ecosystem processes. We focused on conservation of soil and water as key processes in healthy ecosystems, and on maintenance of biodiversity and productivity as important functions of healthy ecosystems. Measurements from which indicators of rangeland health were derived included: sizes of unvegetated patches, cover and species composition of perennial grasses, cover and species composition of shrubs and herbaceous perennials, soil slaking, and abundance and species composition of the bird fauna. Indicators that provided an interpretable range of values over the gradient from irreversibly degraded sites to healthy sites included: bare patch index, cover of long-lived grasses, palatability index, and weighted soil surface stability index. Indicators for which values above a threshold may serve as an indicator of rangeland health include: cover of plant species toxic to livestock, cover of exotic species, and cover of increaser species. Several other indicator metrics were judged not sensitive nor interpretable. Examples of application of rangeland health indicators to evaluate the success of various restoration efforts supported the contention that a suite of indicators are required to assess rangeland health. Bird species diversity and ant species diversity were not related to the status of the sample site and were judged inadequate as indicators of maintenance of biodiversity.     

The consequences of (not) seeing eye-to-eye about the past: The role of supervisor–team fit in past temporal focus for supervisors' leadership behavior

This study seeks to advance our understanding of the leadership consequences that may ensue when supervisors and their teams have similar versus differing orientations toward the past. Integrating a leader–team fit perspective with functional leadership theory, we cast incongruence between supervisor and team past temporal focus as a key antecedent of supervisors' active (i.e., task-oriented and relationship-oriented) and passive (i.e., laissez-faire) leadership behaviors toward the team. We tested our hypotheses in a team-level study that included a field sample of 84 supervisors and their teams using polynomial regression and response surface analyses. Results illustrated that supervisors demonstrated more task-oriented and relationship-oriented leadership when supervisors' and their team's past temporal focus were incongruent rather than aligned. Furthermore, in situations of supervisor–team congruence, supervisors engaged in less task-oriented and relationship-oriented leadership and more laissez-faire leadership with higher (rather than lower) levels of supervisor and team past temporal focus. In sum, these findings support a complex (mis)fit model such that supervisors' attention to the past may hinder their productive leadership behaviors in some team contexts but not in others. Hence, this research advances a novel, multiple-stakeholder perspective on the role of both supervisors' and their team's past temporal focus for important leadership behaviors.     

Residues of legacy organochlorine pesticides and DDT metabolites in highly consumed fish from the polluted Guanabara Bay,Brazil: distribution and assessment of human health risk

Abstract

Organochlorine (OCP) pesticides were determined in samples of sardine (Sardinella brasiliensis), whitemouth croaker (Micropogonias furnieri), and mullet (Mugil liza) from Guanabara Bay (state of Rio de Janeiro, Brazil). OCP concentrations and fish consumption were linked with acceptable daily intake values in order to assess the human health risk for the Brazilian population. The total concentrations of OCPs (Σ OCP) was 6.6?ng/g f.w., 7.5?ng/g f.w., and 2.8?ng/g f.w. for sardines, corvina, and mullet, respectively. There was a significant difference (P?<?0.05) among the species related to o,p’-DDD and o,p’-DDT concentrations. Both DDT-related compounds were 5 and 76 times more abundant in sardines than in whitemouth croaker and mullet. Newly discovered DDT metabolite, o-Cl-DDMU, was frequently detected in the fish. None of the samples exceeded the maximum limits for acceptable levels of OCP residues. According to the data of average intake of Brazilian population, none of three species exceeded toxicological parameter. The investigated fishes are considered as safe for human consumption in regard to exposure of the studied OCPs. However, fish may be a intake source of OCP metabolites such as o-Cl-DDMU whose toxicity is still unknown.     

Combining land-use planning and tenure security: a tenure responsive land-use planning approach for developing countries

There is tenure insecurity around land ownerships and land rights in most developing countries. There are also many land-use planning projects being implemented in these countries. Often, land-use planning exists in these countries but is not formally linked with tenure security. This study argues that combining them by conducting land-use planning in a way that promotes tenure security presents a new approach. A central premise for the rationale of this intervention is that processes of land-use planning may inadvertently increase tenure security. By way of methodology, it evaluates land-use planning case studies from Africa, Asia and South America. It uses the three case study examples to build a case for making tenure security one of the major planned outcomes of a land-use planning process and provides a detailed framework for operationalising the concept. Its main contribution to the literature is that it introduces the concept of tenure responsive land-use planning.     

Survival of Cryptosporidium parvum oocysts in calf housing facilities in the New York City watersheds

Pathogen contamination of the public drinking water supply in the New York City watersheds is a serious concern. New York City's Watershed Agriculture Program is working with dairy farms in the watersheds to implement management practices that will reduce the risk of pathogens contaminating the water supply. Solar calf housing (SCH) was suggested as a best management practice (BMP) to control Cryptosporidium parvum, a common protozoan parasite that causes disease in humans. This BMP targets young calves because they are the primary source of C. parvum in dairy herds. The objective of this project was to assess and compare the survivability of C. parvum in SCH and in conventional calf housing (CCH), usually located in the main barn. C. parvum oocysts were secured in sentinel chambers and placed in SCH and CCH bedding on four farms. The chambers were in thermal, chemical, and moisture equilibrium with their microenvironments. An oocyst-filled control chamber, sealed from its surroundings, was placed near each chamber. Chambers and controls were sampled after 4, 6, and 8 wk. Oocyst viability in the chambers decreased to less than 10% in warm months and between 15 and 30% in the winter months. The viability of the control oocysts was similar to the chambers during warm months and generally higher during winter months. There was no significant (P > 0.05) difference in the viability decrease between SCH and CCH. Although oocyst viability was similar in both types of calf housing, SCH allow contaminated calf manure to be isolated from the main barn manure and potentially managed differently and in a way to decrease the number of viable oocysts entering the environment during field spreading.