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Aim Environmental heterogeneity shapes species diversity by creating ecological niches (habitat heterogeneity hypothesis). Yet its role in driving behavioural diversity within species remains only partially understood. Behavioural diversity enhances a population's ability to exploit ecological niches and adapt to environmental change, making it critical to understand how behaviour is shaped by environmental factors. Here we test whether spatial and temporal heterogeneity predict behavioural diversity at population and individual levels across species and environments. Location Global. Methods We synthesised biologging data from five species of sea lions (15 colonies, 370 individuals, 927,000 dives) to test the relationship between population‐level behavioural variation and individual specialisation/flexibility metrics with bathymetric roughness, mean chlorophyll and interannual chlorophyll variability utilising GLMMs. Results We provide large‐scale, multi‐species evidence that environmental heterogeneity drives behavioural diversity. We show that populations foraging in structurally complex habitats and with greater resource variability exhibited more diverse dive and foraging behaviour, demonstrating that environmental heterogeneity, both in space and time, is associated with higher behavioural diversity. While habitat complexity fostered population‐level variation, environments with low productivity favoured specialisation on the individual level, suggesting a shift from generalist to specialist strategies under resource limitation. Main Conclusions The consistent pattern between environmental heterogeneity and population‐level behavioural diversity across species and environments suggests, in combination with observations from previous studies, a fundamental principle extending beyond species and habitat borders. We therefore suggest broadening the habitat heterogeneity hypothesis from species richness to within‐species variation. Our findings underscore two important conservation considerations: (1) conserving habitat complexity to help maintain behavioural diversity; and (2) prioritising protection for populations in low‐heterogeneity environments, where reduced behavioural flexibility may increase vulnerability to environmental change.

Summary Insect pollinators are essential for both the production of a large proportion of world crops and the health of natural ecosystems. As important pollinators, bumblebees must learn to forage on flowers to feed both themselves and provision their colonies. Increased use of pesticides has caused concern over sublethal effects on bees, such as impacts on reproduction or learning ability. However, little is known about how sublethal exposure to field‐realistic levels of pesticide might affect the ability of bees to visit and manipulate flowers. We observed the behaviour of individual bumblebees from colonies chronically exposed to a neonicotinoid pesticide (10 ppb thiamethoxam) or control solutions foraging for the first time on an array of morphologically complex wildflowers (Lotus corniculatus and Trifolium repens) in an outdoor flight arena. We found that more bees released from pesticide‐treated colonies became foragers, and that they visited more L. corniculatus flowers than controls. Interestingly, bees exposed to pesticide collected pollen more often than controls, but control bees learnt to handle flowers efficiently after fewer learning visits than bees exposed to pesticide. There were also different initial floral preferences of our treatment groups; control bees visited a higher proportion of T. repens flowers, and bees exposed to pesticide were more likely to choose L. corniculatus on their first visit. Our results suggest that the foraging behaviour of bumblebees on real flowers can be altered by sublethal exposure to field‐realistic levels of pesticide. This has implications for the foraging success and persistence of bumblebee colonies, but perhaps more importantly for the interactions between wild plants and flower‐visiting insects and ability of bees to deliver the crucial pollination services to plants necessary for ecosystem functioning. Lay Summary

1. Conservation biological control aims to control pests by promoting wild populations of natural enemies. One challenge is to attract and retain efficient natural enemies in crop fields, which often are a suboptimal environment. Towards this goal, the attract-and-reward strategy relies on combining attractive synthetically produced herbivore-induced plant volatiles (HIPVs) with companion plants (non-crop plants which provide alternative resources to the targeted natural enemies). Although severely overlooked, the spatial arrangement of HIPV dispensers and rewards inside crop fields may strongly influence the foraging behaviour and persistence of natural enemies and thus the success of this pest management strategy.2. We tested the impact of two contrasting spatial arrangements of HIPV dispensers and rewards, alternatively inside and around a block of target apple trees, on the efficacy of the biological control of Aphis citricola populations by the common predatory ladybird Propylea japonica in apple orchards in northern China. We used synthetic methyl salicylate (MeSA) as an attractant and the companion plant Calendula officinalis as a reward. To better understand how the spatial arrangement of MeSA dispensers and companion plants affected the attraction and foraging behaviour of adult ladybirds, we conducted indoor experiments in a flight mill, an olfactometer and a wind-tunnel.3. Blocks of target trees treated with MeSA dispensers inside and companion plants around provided the most efficient pest control in orchards, compared with the opposite spatial arrangement.4. The synthetic MeSA dispenser and the companion plant synergistically attracted ladybirds in the olfactometer and enhanced their flight activity in the flight mill. In the wind-tunnel, MeSA served as a spatial cue for ladybirds to find nearby prey, while companion plants were sought in the absence of prey.5. Synthesis and applications. The present study will help further improvements of aphid control in apple orchards through a careful spatial arrangement of herbivore-induced plant volatiles dispensers (HIPVs) and rewards (companion plants) in optimized attract-and-reward strategies. Without such assessment, these strategies may be hazardous even with well-identified targeted natural enemies. Associated lab experiments highlight that HIPVs and companion plants interactively influence ladybird foraging pattern, and that their spatial arrangement can modulate the ability of such key predators to find their prey. KEYWORDS attract-and-reward, foraging behaviour, integrated pest management, methyl salicylate, natural enemies, semiochemicals,synomone How to cite this article: Jaworski CC, Xiao D, Xu Q, et al. Varying the spatial arrangement of synthetic herbivore-induced plant volatiles and companion plants to improve conservation biological control. J Appl Ecol. 2019;00:1-13.

1. In Latin America, the common vampire bat Desmodus rotundus is the primary reservoir of rabies, a zoonotic virus that kills thousands of livestock annually and causes sporadic and lethal human rabies outbreaks. The proliferation of livestock provides an abundant food resource for this obligate blood-feeding species that could alter its foraging behaviour and rabies transmission, but poor understanding of the dietary plasticity of vampire bats limits understanding of how livestock influences rabies risk. 2. We analysed individual-and population-level foraging behaviour by applying δ¹³C and δ¹⁵N stable isotope analysis to hair samples from 183 vampire bats captured from nine colonies in Peru. We also assessed the isotopie distributions of realized prey by analysing blood meals extracted from engorged bats and samples collected from potential prey species. In two adjacent but contrasting areas of the Amazon with scarce and abundant livestock, we used questionnaires to evaluate the incidence of feeding on humans. 3. Population-level isotopie signatures suggested substantial among-site variation in feeding behaviour, including reliance on livestock in some colonies and feeding on combinations of domestic and wild prey in others. Isotopie heterogeneity within bat colonies was among the largest recorded in vertebrate populations, indicating that individuals consistently fed on distinct prey resources and across distinct trophic levels. In some sites, isotopie values of realized prey spanned broad ranges, suggesting that bats with intermediate isotopie values could plausibly be dietary specialists rather than generalists. 4. Bayesian estimates of isotopie niche width varied up to ninefold among colonies and were maximized where wildlife and livestock were present at low levels, but declined with greater availability of livestock. In the Amazon, the absence of livestock was associated with feeding on humans and wildlife. 5. Policy implications. We provide the first insights into the foraging behaviour of vampire bats in habitats with common depredation on humans and show how vampire bat foraging may respond to land-use change. Our results demonstrate risks of rabies transmission from bats to other wildlife and are consistent with the hypothesis that introducing livestock might reduce the burden of human rabies in high-risk communities.

Body size, bill length and shape determine foraging techniques, habitat selection and diet among shorebirds. In this study, water depth preferences of different shorebirds with different bill sizes in various habitats including mudflats, mangroves at Kadalundi‐Vallikkunnu Community Reserve (KVCR) (19 shorebird species) and adjacent agroecosystems at Vazhakkad (12 species) were studied between 2017 and 2020. The bill length of the shorebirds was significantly and positively associated with the average water depth, where shorebirds were observed to forage. Shorebirds with shorter bill lengths preferred shallow waters and those with longer bills preferred deep waters for their foraging activities. Habitat type also had a significant effect on the shorebird occurrence. Eurasian Curlews in both mangroves and mudflats were observed in areas with a higher water depth compared to other species. This is due to the fact that shorebirds tend to specialise in feeding habitats or in prey items to reduce intraspecific competition and distribute themselves in space and time in accordance with the availability of their resources. The occurrence of some species in agroecosystems is attributed to the reduced food availability, habitat quality and other disturbances for shorebirds on tidal flats, which are critical for sustaining migratory phenology. The differences in bill morphology are crucial in determining diet, water depth, niche preferences and segregation. Morphological characters and hydrological rhythms determine specialisation in diet and habitat preference in shorebirds. Body size, bill length and shape determine the foraging techniques, habitat selection and diet among shorebirds. In this study, water depth preferences of different shorebirds with different bill sizes in various habitats were investigated between 2017 and 2020. Average water depth, where shorebirds were observed, was significantly and positively associated with their bill lengths. This study underscores the need for conservation of wetlands with its diverse hydrological rhythms to preserve the biodiversity.

Summary Studies from the last decade clearly demonstrate that nectar is much more than just a simple alimentary reward for pollinators. Considerable progress has been made in recent years with regard to the chemical ecology of nectar, demonstrating unequivocally that its chemistry is strongly involved in the interactions between plants and a larger variety of organisms – from bacteria to fungi and animals – than previously thought. As far as plant–pollinator relationships are concerned, attention has recently been directed towards secondary compounds, mainly alkaloids that are able to induce a wide range of behavioural and physiological responses in floral visitors. Nonetheless the study of some other secondary compounds, such as non‐protein amino acids (NPAAs), has been neglected. The roles of these substances in nectar are still unknown although several ecological and physiological functions have been attributed to a number of NAAs in both animals and plants in several ecological and physiological contexts. The existence of NPAAs in floral nectar was first reported in early surveys of nectar composition dating from the 1970s. Since that time, only a very few papers have mentioned the presence of these compounds in nectar, but without any hypothesis relating to their ecological role and their putative effect on flower visitors. This appears surprising considering that interaction with other organisms is a recognized function of NPAAs in plants. Here, after exploring the multiple roles of NPAAs at the community level and focusing on the more recent advances in nectar chemistry and ecology, I review the small body of literature relating to the presence of NPAAs in nectar before outlining some ecological roles in the light of complex, nectar‐mediated, plant–animal interactions that have been recognized recently for other nectar secondary compounds based also on data and information obtained for other biological systems (from arthropods to humans). Synthesis. By integrating data obtained from both literature and field observations, I have arrived at the proposal that non‐protein amino acids in nectar may contribute to the plant–insect network of interactions in a number of ways: by affecting the physiology of the nervous system of the insect, regulating nectar intake through phagostimulation and promoting muscle function during flight. Confirmation of these hypotheses is needed in order to reinforce the concept that plants are able to affect the foraging behaviour of insects through nectar chemistry, thereby eventually optimizing their pollination effectiveness. The presence of non‐protein amino acids (NPAAs) in floral nectar is known from the 1970s, although no hypothesis was proposed until now regarding their role in interacting with nectar feeders. This paper proposes that they may contribute to the plant‐insect network of interactions in several ways: by affecting the physiology of the nervous system of the insect, by regulating nectar intake through phagostimulation and by promoting muscle function during flight. (Picture by Marta Galloni, University of Bologna).

1. We studied chick diet in a known-age, sexed population of a long-lived seabird, the Brünnich's guillemot (Uria lomvia), over 15 years (N = 136; 1993-2007) and attached time-depth-temperature recorders to examine foraging behaviour in multiple years (N = 36; 2004-07). 2. Adults showed specialization in prey fed to offspring, described by multiple indices calculated over 15 years: 27% of diet diversity was attributable to among-individual variation (within-individual component of total niche width = 0.73); average similarity of an individual's diet to the overall diet was 65% (mean proportional similarity between individuals and population = 0.65); diet was significantly more specialized than expected for 70% of individuals (mean likelihood = 0.53). These indices suggest higher specialization than the average for an across-taxa comparison of 49 taxa. 3. Foraging behaviour varied along three axes: flight time, dive depth and dive shape. Individuals showed specialized individual foraging behaviour along each axis. These foraging strategies were reflected in the prey type delivered to their offspring and were maintained over scales of hours to years. 4. Specialization in foraging behaviour and diet was greater over short time spans (hours, days) than over long time spans (years). Regardless of sex or age, the main component of variation in foraging behaviour and chick diet was between individuals. 5. Plasma stable isotope values were similar across years, within a given individual, and variance was low relative to that expected from prey isotope values, suggesting adult diet specialized across years. Stable isotope values were similar among individuals that fed their nestlings similar prey items and there was no difference in trophic level between adults and chicks. We suggest that guillemots specialize on a single foraging strategy regardless of whether chick-provisioning and self-feeding. With little individual difference in body mass and physiology, specialization likely represents learning and memorizing optimal feeding locations and behaviours. 6. There was no difference in survival or reproductive success between specialists and generalists, suggesting these are largely equivalent strategies in terms of evolutionary fitness, presumably because different strategies were advantageous at different levels of prey abundance or predictability. The development of individual specialization may be an important precursor to diversification among seabirds.

Contemporary climate change is altering temperature profiles across the globe. Increasing temperatures can reduce the amount of time during which conditions are suitable for animals to engage in essential activities, such as securing food. Behavioural plasticity, the ability to alter behaviour in response to the environment, may provide animals with a tool to adjust to changes in the availability of suitable thermal conditions. The extent to which individuals can alter fitness‐enhancing behaviours, such as food collection, to proximately buffer variation in temperature, however, remains unclear. Even less well understood are the potential performance advantages of flexible strategies among endotherms. We examined the degree to which individuals altered rates of food collection in response to temperature, and two potential benefits, using the American pika (Ochotona princeps), a temperature‐sensitive, food‐hoarding mammal, as a model. From July–September 2013–2015, we used motion‐activated cameras and in situ temperature loggers to examine pika food‐caching activity for 72 individuals across 10 sites in the central Rocky Mountains, USA. We quantified % nitrogen by cache volume as a metric of cache quality, and the number of events during which pikas were active in temperatures ≥25°C as a measure of potential thermoregulatory stress. We found a strong negative effect of temperature on the rate at which pikas cached food. Individual responses to temperature varied substantially in both the level of food‐collecting activity and in the degree to which individuals shifted activity with warming temperature. After accounting for available foraging time, individuals that exhibited greater plasticity collected a comparable amount of nitrogen, while simultaneously experiencing fewer occasions in which temperatures eclipsed estimated thermal tolerances. By varying food‐collection norms of reaction, individuals were able to plastically respond to temperature‐driven reductions in foraging time. Through this increased flexibility, individuals amassed food caches of comparable quality, while minimizing exposure to potentially stressful thermal conditions. Our results suggest that, given sufficient resource quality and availability, plasticity in foraging activity may help temperature‐limited endotherms adjust to climate‐related constraints on foraging time. By varying food‐collection norms of reaction, individual pikas responded to temperature‐driven reductions in foraging time. Flexible individuals amassed quality food caches, while minimizing exposure to potentially stressful thermal conditions. Given sufficient resource quality and availability, plasticity in foraging activity may help temperature‐limited endotherms adjust to climate‐related constraints on foraging time.

1.Recent studies unravelled the effect of climate changes on populations through their impact on functional traits and demographic rates in terrestrial and freshwater ecosystems, but such understanding in marine ecosystems remains incomplete.2.Here, we evaluate the impact of the combined effects of climate and functional traits on population dynamics of a long-l ived migratory seabird breeding in the southern ocean: the black- browed albatross (Thalassarche melanophris, BBA). We address the following prospective question: “Of all the changes in the climate and functional traits, which would produce the biggest impact on the BBA population growth rate?”3.We develop a structured matrix population model that includes the effect of cli-mate and functional traits on the complete BBA life cycle. A detailed sensitivity analysis is conducted to understand the main pathway by which climate and func-tional trait changes affect the population growth rate.4.The population growth rate of BBA is driven by the combined effects of climate over various seasons and multiple functional traits with carry- over effects across seasons on demographic processes. Changes in sea surface temperature (SST) during late winter cause the biggest changes in the population growth rate, through their effect on juvenile survival. Adults appeared to respond to changes in winter climate conditions by adapting their migratory schedule rather than by modifying their at- sea foraging activity. However, the sensitivity of the population growth rate to SST affecting BBA migratory schedule is small. BBA foraging activ-ity during the pre- breeding period has the biggest impact on population growth rate among functional traits. Finally, changes in SST during the breeding season have little effect on the population growth rate.5.These results highlight the importance of early life histories and carry- over ef-fects of climate and functional traits on demographic rates across multiple sea-sons in population response to climate change. Robust conclusions about the roles of various phases of the life cycle and functional traits in population response to climate change rely on an understanding of the relationships of traits to demo-graphic rates across the complete life cycle.

Summary Understanding the ecological function of an animal's pigmentation pattern is an intriguing research challenge. We used quantitative information on lizard foraging behaviour to search for movement correlates of patterns across taxa. We hypothesized that noticeable longitudinal stripes that enhance escape by motion dazzle are advantageous for mobile foragers that are highly detectable against the stationary background. Cryptic pigmentation patterns are beneficial for less‐mobile foragers that rely on camouflage to reduce predation. Using an extensive literature survey and phylogenetically controlled analyses, we found that striped lizards were substantially more mobile than lizards with cryptic patterns. The percentage of time spent moving was the major behavioural index responsible for this difference. We provide empirical support for the hypothesized association between lizard dorsal pigmentation patterns and foraging behaviour. Our simple yet comprehensive explanation may be relevant to many other taxa that present variation in body pigmentation patterns. Lay Summary