Understanding how pollinators move across space is key to understanding plant mating patterns. Bees are typically assumed to search for flowers randomly or using simple movement rules, so that the probability of discovering a flower should primarily depend on its distance to the nest. However, experimental work shows this is not always the case. Here, we explored the influence of flower size and density on their probability of being discovered by bees by developing a movement model of central place foraging bees, based on experimental data collected on bumblebees. Our model produces realistic bee trajectories by taking into account the autocorrelation of the bee’s angular speed, the attraction to the nest (homing), and a gaussian noise. Simulations revealed a « masking effect » that reduces the detection of flowers close to another, with potential far reaching consequences on plant-pollinator interactions. At the plant level, flowers distant to the nest were more often discovered by bees in low density environments. At the bee colony level, foragers found more flowers when they were small and at medium densities. Our results indicate that the processes of search and discovery of resources are potentially more complex than usually assumed, and question the importance of resource distribution and abundance on bee foraging success and plant pollination.

<span><span style="font-family: Times New Roman;">Ferritic/Martensitic steels, with chromium contents ranging between 9 and 12%, were introduced into fusion material programs due to their better creep resistance and excellent thermal and nuclear properties compared to austenitic stainless steels. Reduced activation ferritic/martensitic (RAFM) steels are considered promising candidates for the test blanket modules of the future International Thermonuclear Experimental Reactor (ITER), being EUROFER steel is the EU reference material. It is a 9 % Cr RAFM steel which exhibits a tempered martensitic <span style="font-family: Times New Roman;">microstructure and presently allows operation up to 550 </span><span style="font-family: Cambria Math;">⁰</span><span style="font-family: Times New Roman;">C. This paper shows the work carried out</span></span><span style="font-family: Times New Roman;"><span style="font-family: Times New Roman;"> to develop at a pilot plant scale a Reduced Activation Ferritic/Martensitic (RAFM) steel, Asturfer </span><span style="font-family: Times New Roman; font-size: xx-small;"><span style="font-family: Times New Roman; font-size: xx-small;">®</span></span><span style="font-family: Times New Roman;">,</span></span><span style="font-family: Times New Roman;"> with chemical composition and mechanical properties very close to EUROFER steel. </span>

Understanding how pollinators move across space is key to understanding plant mating patterns. Bees are typically assumed to search for flowers randomly or using simple movement rules, so that the probability of discovering a flower should primarily depend on its distance to the nest. However, experimental work shows this is not always the case. Here, we explored the influence of flower size and density on their probability of being discovered by bees by developing a movement model of central place foraging bees, based on experimental data collected on bumblebees. Our model produces realistic bee trajectories by taking into account the autocorrelation of the bee's angular speed, the attraction to the nest, and a gaussian noise. Simulations revealed a « masking effect » that reduces the detection of flowers close to another, which may have critical consequences for pollination and foraging success. At the plant level, flowers distant to the nest were more often visited in low density environments, suggesting lower probabilities of pollination at high densities. At the bee colony level, foragers found more flowers when they were small and at medium densities, suggesting that there is an optimal flower size and density at which collective foraging efficiency is optimized. Our results indicate that the processes of search and discovery of resources are potentially more complex than usually assumed, and question the importance of resource distribution and abundance on plant-pollinator interactions.