Active Inferants: An Active Inference Framework for Ant Colony Behavior

In this paper, we introduce an active inference model of ant colony foraging behavior, and implement the model in a series of in silico experiments. Active inference is a multiscale approach to behavioral modeling that is being applied across settings in theoretical biology and ethology. The ant colony is a classic case system in the function of distributed systems in terms of stigmergic decision-making and information sharing. Here we specify and simulate a Markov decision process (MDP) model for ant colony foraging. We investigate a well-known paradigm from laboratory ant colony behavioral experiments, the alternating T-maze paradigm, to illustrate the ability of the model to recover basic colony phenomena such as trail formation after food location discovery. We conclude by outlining how the active inference ant colony foraging behavioral model can be extended and situated within a nested multiscale framework and systems approaches to biology more generally

Climate consequences for ecosystem functions, production and producer responses in coffee agroecosystems

Coffee is an important commodity crop, providing livelihoods for hundreds of millions worldwide. Like most plants and agricultural crops, coffee is anticipated to be strongly impacted by climate change forecasts. Grown at high altitudes and often accompanied by shade trees that provide additional ecosystem and conservation value, coffee is particularly climate sensitive requiring specific rainfall regimes for flower and fruit development. In this research I used ecological and interdisciplinary approaches to examine different effects of seasonality and climate change on coffee systems. In the first two chapters I examine the role of seasonality in predator-pest interactions of a tropical coffee agroforestry system in the highest coffee producing municipality of Chiapas, Mexico. Specifically, I use experiments and field manipulations to assess the impact of seasonal rainfall as a driver of changes to insect communities and predator-prey consumption patterns between natural biocontrol agents (ants) and coffee insect pests. I find that ant predation is affected by microclimate and seasonal rainfall and that reduced rainfall alters ecological communities and ecosystem functions. In the third chapter, I use environmental and socio-economic approaches to examine the impact of climate and price fluctuations on coffee production and producers in Mexico. Combining spatially-explicit historical climate, production and price data from all coffee-growing municipalities in Mexico, I examined trends of climate and coffee production and then further characterized and quantified coffee producer’s responses to changing conditions of climate and price. I found that coffee-specific climate variables contributed to a 60% decline in Mexican coffee production since its peak in the 1990s, and that farmers’ management responses to soaring temperatures, limited rainfall and price volatility are generally limited to reducing the proportion of planted area they harvest each year. In sum, my research examines seasonal climate impacts on coffee agroecosystem communities, functions and production. Specifically, I find (1) an unexplored potential effect of shifting seasonal climate on the natural biological control provided by ant predators; and that (2) climate change has already affected coffee production in Mexico, but producers have limited capacity to respond to changes. The findings of this research highlight the potential consequences of unmitigated global climate change for coffee agroecosystems and farmworker livelihoods

Behavioral and molecular mechanisms of pheromone transmission in the honey bee (Apis mellifera)

The European honey bee (Apis mellifera) has a sophisticated system of pheromonal signals that mediate a wide range of behaviors important for their fitness, including reproductive dominance, nest defense, and cooperative brood care. In honey bees, there are two distinct pheromones emitted by larvae, brood pheromone and (E)-beta-ocimene. By integrating behavior, chemical ecology, and transcriptomics, this dissertation analyzes several key stages in signal transmission in a systematic effort to understand how these two pheromones affect behavior, and in the process, generates a synthetic understanding of a highly complex system of communication. Previous studies have explored behavioral and gene expression patterns related to honey bee pheromones; however, none have compared the roles that two divergent pheromones from a common source play in rapid regulation of foraging behavior. Furthermore, while previous studies have investigated the mechanisms of pheromone detection and the factors involved in regulation of foraging behavior, it remains unclear how individual responses to pheromone exposure scales to colony-level changes in behavior. By investigating the behavioral, physiological, and genomic influences of honey bee chemical communication, this dissertation links phenotypic plasticity in behavior to gene expression profiles in the brain and provides insights into the evolution of a sophisticated chemical language.Ecology, Evolution and Behavio

Operation and planning of distribution networks with integration of renewable distributed generators considering uncertainties: a review

YesDistributed generators (DGs) are a reliable solution to supply economic and reliable electricity to customers. It is the last stage in delivery of electric power which can be defined as an electric power source connected directly to the distribution network or on the customer site. It is necessary to allocate DGs optimally (size, placement and the type) to obtain commercial, technical, environmental and regulatory advantages of power systems. In this context, a comprehensive literature review of uncertainty modeling methods used for modeling uncertain parameters related to renewable DGs as well as methodologies used for the planning and operation of DGs integration into distribution network.This work was supported in part by the SITARA project funded by the British Council and the Department for Business, Innovation and Skills, UK and in part by the University of Bradford, UK under the CCIP grant 66052/000000

Laboratory studies examining aspects of scent marking, traplining and remote detection of reward in the foraging bumblebee.

PhDEnergy from food is essential for the survival of all animals. For decades, bumblebees have been used as model organisms for studying animal foraging strategies. Here, I use bumblebees to examine two foraging strategies: scent marking and traplining. I find that experience and long term memory play an important role in both of these strategies. I show that bees interpret scent marks differently depending on context. They learn to rely on these scent marks to different degrees depending on flower handling time. Bees also learn to associate the same scent marks with high and low rewarding food, which means the same scent promotes and suppresses acceptance of flowers. Contrary to previous speculation, I find that these scent marks are not pheromonal signals specifically evolved to play a role in foraging. Rather they are incidental cues that bees learn to use to improve foraging performance and locate their nesting sites. Experience is also important in developing repeatable stable routes between food sites i. e. traplines. I show that bees required long term spatial memory to gradually form traplines. They reduced their travel distance by linking near neighbour flowers, which did not result in using the shortest routes. Traplining bees were also less likely to revisit emptied flowers and spent less time searching for these flowers. For decades, scientists have used water to control for remote effects of sucrose solution in experiments. I find that bees are able to detect the difference between these two liquids without contact chemoreception. The exact cue they use remains to be determined, but it is not humidity.University of London Central Research fun

Chemical based communication and its role in decision making within the social insects

This thesis investigates chemical communication and decision making in a stingless bee (Tetragonisca angustula) and two species of ants (Lasius flavus and L. niger). Complex chemical signalling and seemingly elaborate behavioural patterns based upon decisions made by individuals of a colony have facilitated the evolution of social living in these insects. This thesis investigates two important features of social living that involve these features: nest mate recognition and navigation. The first part of this thesis (Chapter 3 and Appendix 3) investigates nestmate recognition and nest defence in the Neotropical stingless bee T. angustula. In Chapter 3, two mechanisms are investigated which could potentially facilitate the extremely efficient nest mate recognition system, previously demonstrated in this bee species. Both are found to play no role which will enable further work to focus on the few remaining possibilities. The second part of this thesis (chapters 4-6) focuses on navigational decision making in two common British ant species with contrasting ecologies. Chapter 4 investigates how L. niger foragers adapt to foraging at night when the visual cues, so important to these ants for diurnal foraging, are unavailable. This study showed that nocturnal foraging is achieved in these ants by increasing trail pheromone deposition while concomitantly switching to a greater reliance on these cues to navigate. Chapter 5 contrasts the navigational strategies and capabilities of L. niger with another Lasius ant species, L. flavus, and demonstrates how these species can flexibly switch dependency between available navigational cues to cope with foraging within a fluxional ecological environment. Finally, Chapter 6 focuses on the glandular components and trail pheromone of L. flavus by measuring behavioural responses to glandular constituents and identifying the glandular source of the trail pheromone. The aim was to also identify the trail pheromone(s) but due to time constraints this was not possible. However, a new methodology that simplifies the process of identifying trail pheromone components was developed and is described. Furthermore, this study has laid the foundations for further work to establish if the compound prevalent in the Dufour glands’ of L. flavus does indeed serve as an antibacterial agent within the humid nest environment