Aim: Habitat loss and alteration are widely considered one of the main drivers of current pollinator diversity loss. Yet little is known about habitat importance and preferences for major groups of pollinators, although this information is crucial to anticipate and mitigate the current decline of their populations. We aim to rank and assess the importance of different habitats for bees, to determine the preference for and avoidance of particular habitat types by different bees and to quantify the diversity of bees within and among habitats.Location: North-eastern USA. Time period:The sampling was done over 15 years (2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015).Major taxa studied: Apoidea. Methods:We used an unprecedented extensive dataset of >15,000 bee specimens, comprising more than 400 species collected across north-east USA. We extracted habitat information from the sample points and used network analyses, null models comparisons and beta-diversity analysis to assess habitat importance, habitat preference, use and diversity. Results:We found that natural habitats sustain higher bee diversity and a different set of species than agricultural and urban areas. Although many bee species used human-altered habitats, most species exhibited strong preferences for forested habitats and only a few preferred altered habitats over more natural habitats. In contrast to previous studies, landscape composition only had moderate buffer effects on diversity loss. The loss of biodiversity in human-altered environments could have been higher but it was partially compensated by the presence of human commensals and exotic species. Main conclusions:Although human-altered environments may harbour a substantial number of species, our work suggests that preserving natural areas is still essential to guarantee the conservation of bee biodiversity. K E Y W O R D Shabitat importance, habitat preference, habitat use, landscape, pollinators, urban | 925 COLLADO et AL.

Despite their miniature brains, insects exhibit substantial variation in brain size. Although the functional significance of this variation is increasingly recognized, research on whether differences in insect brain sizes are mainly the result of constraints or selective pressures has hardly been performed. Here, we address this gap by combining prospective and retrospective phylogenetic-based analyses of brain size for a major insect group, bees (superfamily Apoidea). Using a brain dataset of 93 species from North America and Europe, we found that body size was the single best predictor of brain size in bees. However, the analyses also revealed that substantial variation in brain size remained even when adjusting for body size. We consequently asked whether such variation in relative brain size might be explained by adaptive hypotheses. We found that ecologically specialized species with single generations have larger brains—relative to their body size—than generalist or multi-generation species, but we did not find an effect of sociality on relative brain size. Phylogenetic reconstruction further supported the existence of different adaptive optima for relative brain size in lineages differing in feeding specialization and reproductive strategy. Our findings shed new light on the evolution of the insect brain, highlighting the importance of ecological pressures over social factors and suggesting that these pressures are different from those previously found to influence brain evolution in other taxa.

When it comes to the brain, bigger is generally considered better in terms of cognitive performance. While this notion is supported by studies of birds and primates showing that larger brains improve learning capacity, similar evidence is surprisingly lacking for invertebrates. Although the brain of invertebrates is smaller and simpler than that of vertebrates, recent work in insects has revealed enormous variation in size across species. Here, we ask whether bee species that have larger brains also have higher learning abilities. We conducted an experiment in which field-collected individuals had to associate an unconditioned stimulus (sucrose) with a conditioned stimulus (coloured strip). We found that most species can learn to associate a colour with a reward, yet some do so better than others. These differences in learning were related to brain size: species with larger brains—both absolute and relative to body size—exhibited enhanced performance to learn the reward-colour association. Our finding highlights the functional significance of brain size in insects, filling a major gap in our understanding of brain evolution and opening new opportunities for future research.

A large brain is widely considered a distinctive feature of intelligence, a notion that mostly derives from studies in mammals. However, studies in inse cts demonstrates that cognitively sophisticated processes, such as social learning and tool use, are still possible with very small brains . Even after accounting for the allometric effect of body size , substantial variation in brain size still remains unexplained. A plausible advantage of a disproportionately larger brain might be an enhanced ability to learn new behaviors to cope with novel or complex challenges. While this hypothesis has received ample support from studies in birds and mammals, similar evidence is not available for small-brained animals like insects. Our objective is to compare the learning abilities of different bee species with their brain size investment. We conducted an experiment in which field-collected individuals had to associate an unconditioned stimulus (sucrose), with a conditioned stimulus (colored strip). We show that the probability of learning the reward-colour association was related to both absolute and relative brain size. This study shows that other bee species aside from the long studied honeybees and bumblebees , can be used in cognitive experiments and opens the door to explore the importance of relative brain sizes in cognitive tasks for insects and its consequences for species survival in a changing world.

Habitat loss and alteration is widely considered one of the main drivers of the current loss of pollinator diversity. Unfortunately, we still lack a comprehensive analysis of habitat importance, use and preference for major groups of pollinators. Here, we address this gap analysing a large dataset of 15,762 bee specimens (more than 400 species) across northeast USA. We found that natural habitats sustain the highest bee diversity, with many species strongly depending on such habitats. By characterizing habitat use and preference for the 45 most abundant species, we also show that many bee species can use human-altered habitats despite exhibiting strong and clear preferences for forested habitats. However, only a few species appear to do well when the habitat has been drastically modified. We conclude that although altered environments may harbor a substantial number of species, preserving natural areas is still essential to guarantee the conservation of bee biodiversity.

Behavioural innovation and problem solving are widely considered to be important mechanisms by which animals respond to novel environmental challenges, including those induced by human activities. Despite their functional and ecological relevance, much of our current understanding of these processes comes from studies in vertebrates. Understanding of these processes in invertebrates has lagged behind partly because they are not perceived to have the cognitive machinery required. This perception is, however, challenged by recent evidence demonstrating sophisticated cognitive capabilities in insects despite their small brains. Here, we studied innovation, defined as the capacity to solve a new task, of a solitary bee (Osmia cornuta) in the laboratory by exposing naive individuals to an obstacle removal task. We also studied the underlying cognitive and non-cognitive mechanisms through a battery of experimental tests designed to measure associative learning, exploration, shyness and activity levels. We found that solitary bees can innovate, with 11 of 29 individuals (38%) being able to solve a new task consisting of lifting a lid to reach a reward. However, the propensity to innovate was uncorrelated with the measured learning capacity, but increased with exploration, boldness and activity. These results provide solid evidence that non-social insects can solve new tasks, and highlight the importance of interpreting innovation in the light of non-cognitive processes.

Behavioural innovation is widely considered an important mechanism by which animals respond to novel environmental challenges, including those induced by human activities.Despite its functional and ecological relevance, much of our current understanding of the innovation process comes from studies in vertebrates. Understanding innovation processes in insects has lagged behind partly because they are not perceived to have the cognitive machinery required to innovate. This perception is however challenged by recent evidence demonstrating sophisticated cognitive capabilities in insects despite their small brains. Here, we study the innovation capacity of a solitary bee (Osmia cornuta) in the laboratory by exposing naïve individuals to an obstacle removal task. We also studied the underlying cognitive and noncognitive mechanisms through a battery of experimental tests designed to measure learning, exploration, shyness and activity levels. We found that solitary bees can innovate, with 11 of 29 individuals (38%) being able to solve a new task consisting in lifting a lid to reach a reward.The propensity to innovate was uncorrelated with learning capacities, but increased with exploration, boldness and activity. These results provide solid evidence that non-social insects can innovate, and highlight the importance of interpreting innovation in the light of noncognitive processes.

Las abejas son un grupo extremadamente diverso con más de 1000 especies descritas en la península ibérica. Además, son excelentes polinizadores y aportan numerosos servicios ecosistémicos fundamentales para la mayoría de ecosistemas terrestres. Debido a los diversos cambios ambientales inducidos por el ser humano, existen evidencias del declive de algunas de sus poblaciones para ciertas especies. Sin embargo, conocemos muy poco del estado de conservación de la mayoría de especies y de muchas de ellas ignoramos cuál es su distribución en la península ibérica. En este trabajo presentamos un esfuerzo colaborativo para crear una base de datos de ocurrencias de abejas que abarca la península ibérica e islas Baleares que permitirá resolver cuestiones como la distribución de las diferentes especies, preferencia de hábitat, fenología o tendencias históricas. En su versión actual, esta base de datos contiene un total de 87 684 registros de 923 especies recolectados entre 1830 y 2022, de los cuales un 87% presentan información georreferenciada. Para cada registro se incluye información relativa a la localidad de muestreo (89%), identificador y colector de la especie (64%), fecha de captura (54%) y planta donde se recolectó (20%). Creemos que esta base de datos es el punto de partida para conocer y conservar mejor la biodiversidad de abejas en la península ibérica e Islas Baleares. Se puede acceder a estos datos a través del siguiente enlace permanente: https://doi.org/10.5281/zenodo.6354502