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Global climate change disrupts key ecological processes and biotic interactions. The recent increase in heatwave frequency and severity prompts the evaluation of physiological processes that ensure the maintenance of vital ecosystem services such as pollination. We used experimental heatwaves to determine how high temperatures affect the bumblebees' ability to detect floral scents. Heatwaves induced strong reductions in antennal responses to floral scents in both tested bumblebee species (Bombus terrestris and Bombus pascuorum). These reductions were generally stronger in workers than in males. Bumblebees showed no consistent pattern of recovery 24 h after heat events. Our results suggest that the projected increased frequency and severity of heatwaves may jeopardize bumblebee-mediated pollination services by disrupting the chemical communication between plants and pollinators. The reduced chemosensitivity can decrease the bumblebees' abilities to locate food sources and lead to declines in colonies and populations. [ABSTRACT FROM AUTHOR]

Global climate change disrupts key ecological processes and biotic interactions. The recent increase in heatwave frequency and severity prompts the evaluation of physiological processes that ensure the maintenance of vital ecosystem services such as pollination. We used experimental heatwaves to determine how high temperatures affect the bumblebees' ability to detect floral scents. Heatwaves induced strong reductions in antennal responses to floral scents in both tested bumblebee species (Bombus terrestris and Bombus pascuorum). These reductions were generally stronger in workers than in males. Bumblebees showed no consistent pattern of recovery 24 h after heat events. Our results suggest that the projected increased frequency and severity of heatwaves may jeopardize bumblebee-mediated pollination services by disrupting the chemical communication between plants and pollinators. The reduced chemosensitivity can decrease the bumblebees' abilities to locate food sources and lead to declines in colonies and populations. [ABSTRACT FROM AUTHOR]

Functional trait-based approaches have provided advances in the understanding of community assembly rules. Broad generalisations remain, however, limited due to the idiosyncratic nature of taxa and ecosystems, especially in tropical regions. We use fine scale resolution (30 m grid) environmental variables and community surveys from nearly 100 secondary tropical forest sites to study niche-based or neutral assembly mechanisms in ground dwelling ants. This provides a unique opportunity for understanding fine scale drivers of taxonomic, functional and phylogenetic diversity in a region characterized by large topographic and climatic differences on a relatively small geographic scale. Precipitation emerged as the most consistent environmental correlate, in shaping taxonomic, phylogenetic and functional aspects of the communities. Functional diversity was weakly associated with topography and temperature related variables. The fourth corner model revealed that femur, scape and mandible length were key traits in response to precipitation, and that communities showed a functional homogenization towards shorter appendages at wetter sites. Our results suggest that neutral and deterministic assembly processes act in concert to shape the taxonomic, phylogenetic and functional aspects of leaf litter ant assemblages. The use of multiple complementary metrics and approaches along environmental gradients are powerful to reveal the subtilities of assembly processes and provide insight into the ways future communities might change. [ABSTRACT FROM AUTHOR]

Knowledge on the distribution and abundance of organisms is fundamental to understanding their roles within ecosystems and their ecological importance for other taxa. Such knowledge is currently lacking for insects, which have long been regarded as the “little things that run the world”. Even for ubiquitous insects, such as ants, which are of tremendous ecological significance, there is currently neither a reliable estimate of their total number on Earth nor of their abundance in particular biomes or habitats. We compile data on ground-dwelling and arboreal ants to obtain an empirical estimate of global ant abundance. Our analysis is based on 489 studies, spanning all continents, major biomes, and habitats. We conservatively estimate total abundance of ground-dwelling ants at over 3 × 1015 and estimate the number of all ants on Earth to be almost 20 × 1015 individuals. The latter corresponds to a biomass of ∼12 megatons of dry carbon. This exceeds the combined biomass of wild birds and mammals and is equivalent to ∼20% of human biomass. Abundances of ground-dwelling ants are strongly concentrated in tropical and subtropical regions but vary substantially across habitats. The density of leaf-litter ants is highest in forests, while the numbers of actively ground-foraging ants are highest in arid regions. This study highlights the central role ants play in terrestrial ecosystems but also major ecological and geographic gaps in our current knowledge. Our results provide a crucial baseline for exploring environmental drivers of ant-abundance patterns and for tracking the responses of insects to environmental change. [ABSTRACT FROM AUTHOR]

Growing concern over rapid species declines and extinctions has led to considerable interest in the role of biodiversity for maintaining ecological processes. However, the loss of particular species has more pronounced effects on ecosystem services than others, highlighting the importance of key functional species traits and their relationships to ecosystem functioning. Human‐induced disturbances, such as species invasions, land use changes, or abiotic changes, appear to disproportionally impact larger species rather than smaller ones. The loss of large‐bodied species in the community diminishes key ecosystem services like seed dispersal, pest control, pollination and decomposition.Here, we use carrion, a nutrient‐rich ephemeral resource, to test the hypotheses that ants positively affect decomposition rates and that their role in the necrophilous community—as predator or decomposer—is mediated by body size. We further investigate the relative contribution of maggots versus ants to biomass decomposition.Our results show that ants contributed positively to the decomposition process. Moreover, decomposition was shaped by an intricate interplay between competition and predation among the guild of decomposer insects. As predicted, larger ants show a double action in increasing decomposition rate and predating on maggots, while small ants are rather inefficient decomposers and did not act as predators on other decomposer species.Our study shows that differentiating key taxonomic groups in function of their body size is key to untangle the diversity and directions of the various roles they play within complex ecological processes. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Agricultural intensification leads to wide ranging changes in habitats along with reduction in nesting site availability and flower resources for wild pollinators. Yet, little is known about the impact of these changes on functional traits of communal ground‐nesting bees.This study assesses the abundance and body size of a common and widespread North American ground‐nesting bee, Agapostemon virescens, throughout three consecutive years at three land use types: (i) unmowed meadows, (ii) conventional pesticide use and mowed agricultural and (iii) organic pesticide‐free mowed landscapes.We found no difference in abundance among the three land use types, but body size of spring bees was smaller at farmlands than meadow sites. Body size also varied among years, and bees were smaller in years that followed warm and dry summer seasons. Spring bees were particularly small at organic farms in years following dry and warm summers.Our results suggest that the smaller size of overwintering bees at agricultural lands could compromise their long‐term survival. This study indicates that a higher frequency of dry and warm summers as a consequence of climate change can impede bee populations in the future. [ABSTRACT FROM AUTHOR]

Wild bees provide invaluable ecosystem services in agricultural landscapes such as pollination. However, in recent decades, pollinator biodiversity, especially in wild bees, is declining on a global scale, with potentially far‐reaching consequences for crop production. Thus, there is an urgent need to determine whether wild bees are present in agricultural systems, such as fruit orchards.In the present study, we examined the wild bee fauna at species and community levels during the period of bee activity (May to August) in apple and high‐bush blueberry orchards in New England.Bee communities are crop‐specific and dominated by very few species, which fluctuate according to crop and season. The blueberry associated bee fauna was more diverse. In apple, communities were phylogenetically clustered at the genus level and dominated by solitary ground nesting bees within the genus Andrena. Species fluctuated widely in presence and abundance throughout the season, leading to differences in community composition and functional trait structure.The results obtained in the present study show that apple and blueberry harbour a distinct and diverse bee fauna that performs vital pollination services in orchards. Our results provide essential baseline data for wild bees in blueberry and apple orchards and this can be used to improve management and conservation strategies for wild bee preservation in these crops. [ABSTRACT FROM AUTHOR]

1. Agricultural intensification generally leads to large‐scale habitat changes marked by decreasing availability of nesting sites and flower resources for pollinators. However, little is known about how such changes impact wild bee maternal body size and foraging effort and, more importantly, whether there is a subsequent effect on their offspring. 2. Nests were collected from the common eastern North American stem nesting bee, Ceratina calcarata, across three land management types: (i) intensely managed conventional farms; (ii) moderately disturbed organic farmland; and (iii) least managed roadsides. The study assessed the effects of land use types on body size and wing wear (a proxy for foraging effort) of maternal bees, and on their offspring in terms of clutch size, survival, sex ratio and body size. 3. Findings revealed that more brood reached pupal stages from nests collected in conventional farmlands. This was due to the total lack of parasites, possibly because the host density is below the threshold that can support a brood parasite population in intensively farmed landscapes. A positive association between maternal bee size and clutch size was only found in least managed roadsides, while, in both farm types, body sizes for daughters and sons were smaller, barely reaching the predicted overwintering threshold. 4. The results suggest that the effects of intensified agricultural land use will be more pronounced in bee offspring, potentially leading to decreased fitness for subsequent generations. This implies far‐reaching consequences for agricultural pollination services and declines in wild bee populations. [ABSTRACT FROM AUTHOR]

Abstract: Animal mutualisms, which involve beneficial interactions between individuals of different species, are common in nature. Insect–insect mutualism, for example, is widely regarded as a keystone ecological interaction. Some mutualisms are anticipated to be modified by climate change, but the focus has largely been on plant–microbe and plant–animal mutualisms rather than those between animals. Ant–aphid mutualisms, whereby ants tend aphids to harvest their honeydew excretions and, in return, provide protection for the aphids, are widespread. The mutualism is heavily influenced by the quality and quantity of honeydew produced by aphids, which is directly affected by host plant quality. As predicted increases in concentrations of atmospheric carbon dioxide (eCO2) are widely reported to affect plant nutritional chemistry, this may also alter honeydew quality and hence the nature of ant–aphid mutualisms. Using glasshouse chambers and field‐based open‐top chambers, we determined the effect of eCO2 on the growth and nutritional quality (foliar amino acids) of lucerne (Medicago sativa). We determined how cowpea aphid (Aphis craccivora) populations and honeydew production were impacted when feeding on such plants and how this affected the tending behaviour of ants (Iridomyrmex sp.). eCO2 stimulated plant growth but decreased concentrations of foliar amino acids by 29% and 14% on aphid‐infested plants and aphid‐free plants, respectively. Despite the deterioration in host plant quality under eCO2, aphids maintained performance and populations were unchanged by eCO2. Aphids induced higher concentrations of amino acids (glutamine, asparagine, glutamic acid and aspartic acid) important for endosymbiont‐mediated synthesis of essential amino acids. Aphids feeding under eCO2 also produced over three times more honeydew than aphids feeding under ambient CO2, suggesting they were imbibing more phloem sap at eCO2. The frequency of ant tending of aphids more than doubled in response to eCO2. To our knowledge, this is the first study to demonstrate the effects of atmospheric change on an ant–aphid mutualism. In particular, these results highlight how impending changes to concentrations of atmospheric CO2 may alter mutualistic behaviour between animals. These could include positive impacts, as reported here, shifts from mutualism to antagonism, partner switches and mutualism abandonment. [ABSTRACT FROM AUTHOR]

While there has been longstanding interest in the factors that shape the composition and structure of insect assemblages, many fundamental questions remain. We compared species composition, and the distribution of feeding guilds within assemblages of two large insect orders (Coleoptera and Hemiptera) collected from nine plant species within three of the largest Australian plant families. We investigated the relative role of host plant family and architectural traits in explaining the characteristics of the insect assemblage. Assemblage composition varied significantly among plant species within families, as there was little commonality in Coleoptera and Hemiptera morphospecies among plants within each family. When the feeding guild structure of the Coleoptera and Hemiptera assemblages was considered as a whole, there was no consistency within host plant families and among plants with similar architectural traits (leaf size). In contrast, when the guild structure of only the phytophagous members of these two orders was considered, assemblage structure was found to be consistent among plant species with a similar leaf size. [ABSTRACT FROM AUTHOR]

Species-specific responses to climate change will lead to changes in species interactions across multiple trophic levels. Interactions between plants and their insect herbivores, in particular, may become increasingly disrupted if mobile herbivores respond more rapidly to climatic change than their associated host plants. We present a multispecies transplant experiment aimed at assessing potential climatic impacts on patterns of leaf herbivory. Four shrubby understorey plant species were transplanted outside their native range into a climate 2.5°C warmer in annual mean temperature. After 12 months, we assessed the types and amount of herbivore leaf damage, compared with plants transplanted to a control site within their native range. The overall amount of foliage loss to herbivores ranged from approximately 3-10% across species and sites, a range consistent with most estimates of leaf loss in other studies. The most common types of leaf damage were sucking and chewing and this pattern was consistent for all four plant species at all sites. There were no significant differences in levels and patterns of herbivory between control and warm sites for three out of four plant species. This suggests that with moderate climate warming, most herbivory will continue to be dominated by chewers and suckers, and that the overall level of foliage loss will be similar to that experienced presently. [ABSTRACT FROM AUTHOR]

Climate change will have profound impacts on the distribution, abundance and ecology of all species. We used a multi-species transplant experiment to investigate the potential effects of a warmer climate on insect community composition and structure. Eight native Australian plant species were transplanted into sites approximately 2.5°C (mean annual temperature) warmer than their native range. Subsequent insect colonisation was monitored for 12 months. We compared the insect communities on transplanted host plants at the warmer sites with control plants transplanted within the species' native range. Comparisons of the insect communities were also made among transplanted plants at warmer sites and congeneric plant species native to the warmer transplant area. We found that the morphospecies composition of the colonising Coleoptera and Hemiptera communities differed markedly between transplants at the control compared to the warmer sites. Community structure, as described by the distribution of feeding guilds, was also found to be different between the controls and transplants when the entire Coleoptera and Hemiptera community, including non-herbivore feeding guilds, was considered. However, the structure of the herbivorous insect community showed a higher level of consistency between plants at control and warm sites. There were marked differences in community composition and feeding guild structure, for both herbivores and non-herbivores, between transplants and congenerics at the warm sites. These results suggest that as the climate warms, considerable turnover in the composition of insect communities may occur, but insect herbivore communities may retain elements of their present-day structure. [ABSTRACT FROM AUTHOR]

The Australian desert ant Melophorus bagoti ( Formicidae) is a thermophilic, solitary foraging ant that inhabits the semi-arid regions of Australia. In recent years, it has become a model species for the study of navigation. However, its ecological traits are not well understood, especially on the level of the entire colony. Here, we investigated this species daily activity schedule and diet composition, and examined its foraging behaviour. Foraging activity is confined to a window of roughly 50-70°C soil surface temperature, and foragers reacted quickly to temperature changes. Consequently, the pattern of daily outbound traffic during summer is unimodal on warm days and bimodal on very hot days. Foragers are opportunistic scavengers; dead insects make up a large proportion of food items, but grass seeds are also occasionally brought back to the nest in large amounts. Diet composition changes with the seasonal availability of certain food groups. Melophorus bagoti foragers have the ability to recruit nestmates to profitable food sources. Recruitment seems to function without the use of pheromone trails, but the exact mechanism requires further investigation. [ABSTRACT FROM AUTHOR]

Australia harbours a very diverse phytophagous insect fauna, but little is known about the patterns of insect herbivory in dominant forest systems, especially in dry sclerophyll forests. Here, we assess variation in leaf herbivory in four species of narrow-ranged sclerophyllous shrubs across their geographical distribution. We assessed leaf herbivory as the percentage of missing leaf area, and estimated the proportion of damage types, such as chewing, sucking and mining. We found that the levels of leaf herbivory and the proportions of damage types were consistent among plant species but showed considerable variability within single plant species among sites and individual plants. This variability is most likely due to the patchy distribution of herbivorous insects in space and time. Leaf damage was dominated by chewing, but mining and sucking occurred on all plant four species. Sap sucking, although much less conspicuous, was found to be a major damage type, demonstrating that neglect of sap sucking damage in leaf herbivory assessments could lead to a considerable underestimation of the total herbivore damage inflicted on host plants. [ABSTRACT FROM AUTHOR]

Land use changes and accelerating deforestation rates impact biodiversity on a global scale. While it is well established that the loss of primary forests is devastating, considerably less is understood about the conservation value of sacred forests (e.g. Feng shui woods in China) as local biodiversity reservoirs in human influenced landscapes. When these forests were assessed, the focus was generally on floral diversity, while faunal aspects were neglected. Here we address this knowledge gap by evaluating several dimensions of faunal biodiversity in Hong Kong Feng shui woods. We compare taxonomic, phylogenetic and functional elements of the leaf litter dwelling ant fauna collected over five years among Feng shui woods and two woody habitats corresponding to two distinct successional stages. Ant assemblages in Feng shui woods presented higher species richness that were more resilient to invasions by tramp species, and encompassed specialist species with a distinct set of traits. Phylogenetic diversity was similar in Feng shui and successional woods, while functional diversity was clustered in early successional habitats. The scarcity of tramp species and presence of specialists in Feng shui woods despite their close proximity to human settlements highlights their conservation value for native species in highly degraded landscapes. Our results provide much needed insight on the faunal biodiversity of Feng shui woods. We highlight the conservation value and urgent need for a better protection of these widely overlooked sacred forests in highly disturbed landscapes. [ABSTRACT FROM AUTHOR]

Arthropod assemblages form a fundamental part of terrestrial ecosystems, underpinning ecosystem processes and services. Yet, little is known about how invertebrate communities, as a whole, respond to climatic and atmospheric changes, including predicted increases in carbon dioxide concentrations ( CO2)., To date, woodland Free Air CO2 Enrichment ( FACE) studies have focused entirely on northern hemisphere managed plantations. We manipulated atmospheric CO2 in a mature, native Eucalyptus woodland (0.15 ha, >32 000 m3) in Australia, using the Eucalyptus FACE ('EucFACE') facility. We used three complementary sampling methods (vacuum sampling, pitfall and sticky trapping) to record invertebrate abundances under ambient and elevated levels of CO2 (400 versus 550 ppm)., Based on the collection of over 83 000 invertebrates, we found significant declines in the overall abundance of ground-dwelling (14.7%) and aerial (12.9%) arthropods under elevated CO2, with significant decreases in herbivore, omnivore, scavenger and parasitoid functional groups. Even though several groups showed varying declines in abundance, elevated CO2 did not measurably affect community composition., The results of the present study indicate that atmospheric CO2 levels predicted within the next 35 years may cause declines in arthropod abundances in Eucalyptus woodland. Declines found in several functional groups suggest that elevated atmospheric CO2 has the potential to affect ecosystem processes, possibly including nutrient cycling by herbivores and omnivores, as well as biocontrol by parasitoids. [ABSTRACT FROM AUTHOR]

Ants use the panoramic skyline in part to determine a direction of travel. A theoretically elegant way to define where terrestrial objects meet the sky is to use an opponent-process channel contrasting green wavelengths of light with ultraviolet (UV) wavelengths. Compared with the sky, terrestrial objects reflect relatively more green wavelengths. Using such an opponent-process channel gains constancy in the face of changes in overall illumination level. We tested the use of UV wavelengths in desert ants by using a plastic that filtered out most of the energy below 400 nm. Ants, Melophorus bagoti , were trained to home with an artificial skyline provided by an arena (experiment 1) or with the natural panorama (experiment 2). On a test, a homing ant was captured just before she entered her nest, and then brought back to a replicate arena (experiment 1) or the starting point (the feeder, experiment 2) and released. Blocking UV light led to deteriorations in orientation in both experiments. When the artificial skyline was changed from opaque to transparent UV-blocking plastic (experiment 3) on the other hand, the ants were still oriented. We conclude that UV wavelengths play a crucial role in determining direction based on the terrestrial surround. [ABSTRACT FROM AUTHOR]

Ants are known to use the terrestrial visual panorama in navigation. Recent evidence has accumulated for the use of the currently perceived visual panorama to determine a direction to head in. The pattern of the height of the terrestrial surround, the skyline, is one key cue for the Central Australian red honey ant Melophorus bagoti in determining a direction of travel. But ants might also possess some mechanism to match the skyline heights encountered during training, which functions to steer away from regions whose skyline is too high and towards regions whose skyline is too low. We made an initial test of this hypothesis by training ants to visit a feeder centred between two experimentally constructed walls of black cloth. Trained ants were then tested for their initial homing direction with the walls retaining their heights as encountered in training (controls), with one of the walls lowered or raised in height, or with one wall lowered and the opposite wall raised. Wall-height manipulations deflected the initial headings of ants towards the lower wall, with combined wall lowering and wall raising changing the initial headings by ~30° when compared with controls. The results suggest that the ants combined the dictates of the panorama in determining the best direction of travel (a heading towards the nest) with some attractor mechanism that functions to establish the skyline heights of training conditions (a heading towards the lower wall). [ABSTRACT FROM AUTHOR]