A stated preference valuation of the non-market benefits of pollination services in the UK

Using a choice experiment survey this study examines the UK public's willingness to pay to conserve insect pollinators in relation to the levels of two pollination service benefits: maintaining local produce supplies and the aesthetic benefits of diverse wildflower assemblages. Willingness to pay was estimated using a Bayesian mixed logit with two contrasting controls for attribute non-attendance, exclusion and shrinkage. The results suggest that the UK public have an extremely strong preference to avoid a status quo scenario where pollinator populations and pollination services decline. Total willingness to pay was high and did not significantly vary between the two pollination service outputs, producing a conservative total of £379M over a sample of the tax-paying population of the UK, equivalent to £13.4 per UK taxpayer. Using a basic production function approach, the marginal value of pollination services to these attributes is also extrapolated. The study discusses the implications of these findings and directions for related future research into the non-market value of pollination and other ecosystem services.

Chemical Communication in the Gregarious Psocid Cerastipsocus sivorii (Psocoptera: Psocidae)

The objectives of this study were: (1) to test the existence of an aggregation pheromone in the gregarious psocid Cerastipsocus sivorii; (2) to compare the attractiveness of odors from different aggregations; (3) to test whether nymphs are able to chemically recognize damage-released alarm signals. In a choice experiment conducted in the laboratory, we showed that psocids are able to detect chemical cues from groups of conspecifics. Laboratory experiments also showed that nymphs are capable of chemically recognizing the aggregations where they came from. Finally, in a field experiment, most aggregations dispersed when exposed to the body fluids of a crushed conspecific, but no aggregations dispersed upon exposure to a crushed termite. The implications of these results for the evolution of sociality in psocopterans are discussed.

Decision-making in a social welfare context

This paper presents analysis of the decision-making strategies adopted by respondents when confronted with potential policy options that include changes in both aggregate levels of welfare and equity in distribution. The analysis is based on the results of a choice experiment designed to estimate intergenerational distributional preferences. Non-linear welfare functions are employed within a conventional conditional logit framework. The heuristics employed by respondents in the stated preference context provide valuable insights into the application of welfare principles by respondents in determining trade-offs between the potential changes in the well-being of different generations.

Splash!: a prospective birth cohort study of the impact of environmental, social and family-level influences on child oral health and obesity related risk factors and outcomes

Background: Dental caries (decay) is the most prevalent disease of childhood. It is often left untreated and can impact negatively on general health, and physical, developmental, social and learning outcomes. Similar to other health issues, the greatest burden of dental caries is seen in those of low socio-economic position. In addition, a number of diet-related risk factors for dental caries are shared risk factors for the development of childhood obesity. These include high and frequent consumption of refined carbohydrates (predominately sugars), and soft drinks and other sweetened beverages, and low intake of (fluoridated) water. The prevalence of childhood obesity is also at a concerning level in most countries and there is an opportunity to determine interventions for addressing both of these largely preventable conditions through sustainable and equitable solutions. This study aims to prospectively examine the impact of drink choices on child obesity risk and oral health status.
Methods/Design: This is a two-stage study using a mixed methods research approach. The first stage involves qualitative interviews of a sub-sample of recruited parents to develop an understanding of the processes involved in drink choice, and inform the development of the Discrete Choice Experiment analysis and the measurement instruments to be used in the second stage. The second stage involves the establishment of a prospective birth cohort of 500 children from disadvantaged communities in rural and regional Victoria, Australia (with and without water fluoridation). This longitudinal design allows measurement of changes in the child’s diet over time, exposure to fluoride sources including water, dental caries progression, and the risk of childhood obesity.
Discussion: This research will provide a unique contribution to integrated health, education and social policy and program directions, by providing clearer policy relevant evidence on strategies to counter social and environmental factors which predispose infants and children to poor health, wellbeing and social outcomes; and evidence-based strategies to promote health and prevent disease through the adoption of healthier lifestyles and diet. Further, given the absence of evidence on the processes and effectiveness of contemporary policy implementation, such as community water fluoridation in rural and regional communities it’s approach and findings will be extremely
informative.

Economic value of mitigation of plant invaders in a subsistence economy : incorporating labour as a mode of payment

This paper presents the analysis of a choice experiment designed to estimate willingness-to-pay (WTP) to mitigate damages caused by invasive plant species in a rural community of Nepal. In order to address the cash constraints problem in a subsistence economy, two payment attributes, labour contribution and membership fee, were included in the choice sets. The results reveal that rural farmers have significant WTP for forest management activities, in terms of both cash and labour contributions. The results also suggest that rural farmers value their time in this context at a different rate from the current wage rate.

Estimating the benefits of managing invasive plants in subsistence communities

This thesis addresses the issue of estimating the willingness of members of low-income communities to contribute to the management of the invasion of exotic plant species by applying the stated preference method of a choice experiment in the buffer zone of Chitwan National Park in Nepal.

Geometry of compensatory feeding and water consumption in Drosophila melanogaster

Feeding behaviour is an expression of an animal’s underlying nutritional strategy. The study of feeding decisions can hence delineate nutritional strategies. Studies of Drosophila melanogaster feeding behaviour have yielded conflicting accounts, and little is known about how nutrients affect feeding patterns in this important model species. Here, we conducted two experiments to characterize nutrient prioritization and regulation. In a choice experiment, we allowed female flies to self-regulate their intake of yeast, sucrose and water by supplying individual flies with three microcapillary tubes: one containing only yeast of varying concentrations, another with just sucrose of varying concentrations, and the last with just water. Flies tightly regulated yeast and sucrose to a constant ratio at the expense of excess water intake, indicating that flies prioritize macronutrient regulation over excess water consumption. To determine the relative importance of yeast and sucrose, in a no-choice experiment, we provided flies with two microcapillary tubes: the first with one of the 28 diets varying in yeast and sucrose content and the other with only water. Flies increased total water intake in relation to yeast consumption but not sucrose consumption. Additionally, flies increased diet intake as diet concentration decreased and as the ratio of sugar to yeast equalized. Using a geometric scaling approach, we found that the patterns of diet intake can be explained by flies prioritizing protein and carbohydrates equally and by the lack of substitutability between the nutrients. We conclude by illustrating how our results harmonize conflicting results in the literature once viewed in a two-dimensional diet landscape.

Nonmarket valuation in developing countries: Incorporating labour contributions in environmental benefits estimates

There are limitations associated with the application of nonmarket valuation techniques, including choice experiments, in subsistence economies. In part, this is due to the concern that using money as a mode of contribution may not capture the potential contribution of low-income households. To address this limitation, respondents in this study were provided with the option of contributing towards the management of invasive plants in labour terms if they were unwilling to contribute in monetary terms. The results show that the existing practice of using dollar values to estimate willingness to contribute may disproportionately exclude the concerns of some groups within the community. The analysis also indicates that allowing respondents to express their willingness to contribute in labour increases their participation in environmental decision-making processes and hence increases the estimated value of forest ecosystem services. This study contributes to the limited empirical literature on the development of nonmarket valuation surveys, particularly choice experiments, in low-income countries in general and rural areas in particular. © 2014 Australian Agricultural and Resource Economics Society Inc.

Local population preferences toward restoring ecosystem services of a wetland in Thailand

This study reports the findings of a choice experiment designed to explore local population preferences toward wetland ecosystem restoration of Bung Khong Long Wetland in Thailand. By addressing ecological, socioeconomic and cultural dimensions of ecosystem services, the findings provide policy-makers with a richer insight into the interconnections among ecological, socioeconomic and cultural systems in explaining the value of ecosystem services. Gaining an understanding of the trade-offs associated with different interests in ecosystem uses in this community has the capacity to promote wetland management and enhance land use planning. The choice experiment application entails selecting attributes and their levels and developing an experimental design to create the choice sets or hypothetical scenarios for welfare assessment via the questionnaire. The study is based on household level data collected from 780 randomly drawn respondents living around the lake and the data are analysed using the Random Parameter Logit Model with interactions. The findings indicate that the local population derives positive and significant values from the restoration of wetland ecosystem services, indicating caution is needed in the decision-making processes involving sensitive environments faced with competing uses. Socioeconomic and attitudinal characteristics of respondents are important factors influencing willingness to pay, implying community preferences are important in the effectiveness of environmental conservation efforts in this community. The cultural values associated with the wetland are significant suggesting that incorporating culture preferences may be a key factor in supporting wetland conservation.

Toxicity of barbatimao to Apis mellifera and Scaptotrigona postica, under laboratory conditions

Two species of plants commonly known as barbatim (a) over tildeo occur in Brazil, Stryphnodendron adstringens (Fabaceae) (true barbatim (a) over tildeo) and Dimorphandra mollis (Caesalpiniaceae) (false barbatim (a) over tildeo). These two species have a similar flowering period and are considered by beekeepers to cause bee mortality during this period. Flowers were collected from both species, dehydrated, ground and incorporated into an experimental diet for bees of two different species, Apis mellifera and Scaptotrigona postica. Both plant species were toxic to A. mellifera, reducing their median survival. D. mollis was toxic to S. postica, and Stryphnodendron adstringens reduced median survival of this bee species even when used at a concentration of 2.5%. In a choice experiment carried out with A. mellifera and the two plant species, the honey bees could choose not to feed on the diets containing the flowers, and feed on sugar and honey instead, but they did not. This shows us that the flowers of S. adstringens were not repellent to the bees. The plants were more toxic to A. mellifera than to Scaptotrigona postica, a result that can be explained by the fact that A. mellifera was introduced into Brazil whereas S. postica is a native stingless bee.

Preferência alimentar de adultos de Diabrotica speciosa (Ger.) (Coleoptera: Chrysomelidae) por genótipos de feijoeiro

Tests were carried out to evaluate resistance of common bean (Phaseolus vulgaris L.) to Diabrotica speciosa (Ger.) with the genotypes Goiano Precoce, Jalo Precoce, PR 95105146, PR 95105142 (Andean domestication center, AN), Emgopa 201 Ouro and IAPAR 57 (Middle American domestication center, MA). The experiments were conducted in 1998 and 1999, at the farm of UNESP-FCAV, Jaboticabal, SP, Brazil. The genotypes were planted in pots and 20 day-old leaflets were collected and foliar disks were cut of for the test. Two trials, a no-choice test and a free-choice test, were set up in BOD. In free-choice test, two disks of each genotype were kept in a 140-mm-diameter petri dish (total of 12 disks), where 12 adults were confined. In no-choice test, two disks of one genotype and two insects were placed in a 60-mm-diameter petri dish. A field experiment was conducted when 400 adults of D. speciosa were released. Fifteen leaflets per plot were collected 30 days after planting and the leaf area consumption was evaluated. A no-choice experiment was carried out with 20 day-old genotypes protected in individual cages and infested by 10 adults, for 72h. The MA genotypes were the most preferred on feeding tests conducted at BOD, field and individual cages, while the AN genotypes were less eaten.

Effects of residential energy-saving lamps on the attraction of nocturnal insects

Many species of insects display a disposition to move towards light. As a consequence, nocturnal artificial lighting often contributes to an increase in insect population among humans. We tested the hypothesis that residential white lamps can evoke significantly different attraction to insects even when their light outputs are nearly indistinguishable to humans. In a two-choice experiment using insect traps equipped with either a compact fluorescent or a LED light source with similar photometric specifications, about three times more insects were captured in the trap with a compact fluorescent lamp than in the LED trap. The results suggest that LED lamps are preferable to compact fluorescent lamps when the objective is to avoid attracting nocturnal insects to households.

A Simple Artificial Life Model Explains Irrational Behavior in Human Decision-Making

Although praised for their rationality, humans often make poor decisions, even in simple situations. In the repeated binary choice experiment, an individual has to choose repeatedly between the same two alternatives, where a reward is assigned to one of them with fixed probability. The optimal strategy is to perseverate with choosing the alternative with the best expected return. Whereas many species perseverate, humans tend to match the frequencies of their choices to the frequencies of the alternatives, a sub-optimal strategy known as probability matching. Our goal was to find the primary cognitive constraints under which a set of simple evolutionary rules can lead to such contrasting behaviors. We simulated the evolution of artificial populations, wherein the fitness of each animat (artificial animal) depended on its ability to predict the next element of a sequence made up of a repeating binary string of varying size. When the string was short relative to the animats' neural capacity, they could learn it and correctly predict the next element of the sequence. When it was long, they could not learn it, turning to the next best option: to perseverate. Animats from the last generation then performed the task of predicting the next element of a non-periodical binary sequence. We found that, whereas animats with smaller neural capacity kept perseverating with the best alternative as before, animats with larger neural capacity, which had previously been able to learn the pattern of repeating strings, adopted probability matching, being outperformed by the perseverating animats. Our results demonstrate how the ability to make predictions in an environment endowed with regular patterns may lead to probability matching under less structured conditions. They point to probability matching as a likely by-product of adaptive cognitive strategies that were crucial in human evolution, but may lead to sub-optimal performances in other environments.

Sexual selection in Pomatoschistus – nests, sperm competition, and paternal care

Sexual selection arises through variation in reproductive success. This thesis investigates different aspects important in sexual selection, namely nest building, sperm competition, paternity and paternal care, and their mutual interrelationships. In the studied species, the sand goby (Pomatoschistus minutus) and the common goby (Pomatoschistus microps), sperm competition did arise when small males, so called sneakers, sneaked into other males nests and released sperm. They seemed to use female behaviour as their prime cue for a sneaking opportunity. However, also nest-holders, both with and without eggs, were found to fertilize eggs in the nests of other males. Clearly, nest-holding males tried to prevent other males from spreading their sperm in their nests, since they showed aggression towards such males. A nest building experiment indicated that the small nest-openings found in the sneaker male treatment were sexually selected through protection against sneaking or by female choice. Yet, no behavioural or genetical support for the hypothesis that the nest functions as a physical or visual defence, or that sneaker males prefer to sneak upon nests with wide nest-openings, were found in the other studies. Still, individual nest-holding males showed a higher mucus preparation effort inside the nest in the presence of a sneaker male than when alone. In close relatives, such mucus contains sperm, suggesting an importance in sperm competition. However, the mucus may also have pheromone and anti-bacterial functions and may constitute a mating effort, as found in other gobies. Both a behavioural and a mate choice experiment suggested that the males were not less eager to spawn in the presence of a sneaker male. Sneak intrusion did not affect nest defence, fanning or filial cannibalism, nor had paternity an effect on filial cannibalism. This and various life history aspects, together with the fact that the parasitic male only fertilized a fraction of the clutches, would predict females to ignore sneaker males. This was also the case, as the presence of sneaker males was found not to affect female spawning decision. Still, several females spawned in two nests, which coincided with parasitic spawnings, suggesting a cost of disturbance for the females and thus a substantial cost to the nest-holding males in terms of lost mating success. However, females paid attention to other traits in their choice of mate since spawning was associated with sand volume of the nest, but not with nest-opening width. Also, female (but not male) courtship was correlated with partial clutch filial cannibalism, indicating that females are able to anticipate future male cannibalism. In a partial correlation of nest opening, sand volume, male courtship display, displacement fanning and male size, a large number of traits were correlated both positively and negatively with regard to how we may expect them to be appreciated by females. For instance, males which fan well also build large nests or display intensely (but not both). Together with all the other results of this thesis, this shows the entangled selection pressures working on breeding animals, as well as the different male and female tactics employed to maximize their reproduction.

Social responsibility as a tool for destination competitiveness

Máster en Economía del Turismo, Transporte y Medio Ambiente