Showing papers in "Ecological Entomology in 2021"
TL;DR: It is argued that studies using established habitat‐selection methods are essential to properly identify nesting‐habitat preferences of ground‐nesting species and to determine how best to support this diverse group of bees and the vital ecosystem service they provide.
Abstract: About 3/4 of all wild bee species nest in the soil and spend much of their life cycle underground. These insects require suitable environmental conditions for nest construction and for the development and survival of their offspring. However, there is little quantitative information on the nesting habitat requirements and preferences of ground‐nesting bees. Moreover, there are almost no data on the effects of nesting conditions on these bees' fitness. Here, to better understand the factors that influence nest‐site selection in ground‐nesting bees, we synthesise the literature on the nesting‐habitat associations of these important pollinators. We also review techniques that can be used to study the nesting preferences of ground‐nesting bees. Our review reveals enormous variation among bee species in their associations with such nesting‐habitat attributes as soil texture, compaction, moisture, temperature, ground surface features, and proximity to conspecifics or floral resources. However, more studies—particularly experimental ones—are needed to segregate the influence of each factor on bees' choices of nesting location, since multiple factors are often correlated. It is also unclear whether nesting‐habitat associations vary geographically or seasonally within species, or phylogenetically among ground‐nesting bee species, partly because we lack information on nesting habitat for many species. We argue that studies using established habitat‐selection methods are essential to properly identify nesting‐habitat preferences of ground‐nesting species. Finally, more research on nesting ecology is needed (especially in agroecosystems) to determine how best to support this diverse group of bees and the vital ecosystem service they provide.
63 citations
TL;DR: How insects provide opportunities both to understand the ecological effects of global change and to enhance environmental conservation is considered.
Abstract: 1. Insects have emerged as causes célèbres for widespread concern about human effects on global biodiversity. Here, we consider how insects provide opportunities both to understand the ecological effects of global change and to enhance environmental conservation.
52 citations
39 citations
TL;DR: Efforts to reverse insect declines will only succeed if they correctly identify and address their major causes, if they are correctly identified and addressed.
Abstract: 1. With evidence of significant global insect declines mounting, urgent calls to mitigate such declines are also increasing. Efforts to reverse insect declines will only succeed, however, if we correctly identify and address their major causes.
36 citations
TL;DR: The decline in insect abundance and diversity observed in many ecosystems is of major concern because of the long‐term consequences for ecosystem function and stability.
Abstract: 1. The decline in insect abundance and diversity observed in many ecosystems is of major concern because of the long-term consequences for ecosystem function and stability.
2. Species in ecological communities are connected through interactions forming complex networks. Therefore, initial extinctions can cause further species losses through co-extinctions and extinction cascades, where single extinctions can lead to waves of secondary extinctions. Such knock-on effects can multiply the initial impact of disturbances, thereby largely adding to the erosion of biodiversity. However, our knowledge of their importance for the current insect decline is hampered because secondary extinctions are challenging to both detect and predict.
3. In this review, we bring together theory and knowledge about secondary extinctions in the light of the main drivers of insect decline. We evaluate potential and evidence for cascading extinction for the different drivers and identify major pathways. By providing selected examples we discuss how habitat loss, pollution, species invasions, climate change and overexploitation can cause cascading extinctions. We argue that habitat loss and pollution in particular have the largest potential for such extinctions by changing community structure, the physical environment, and community robustness.
4. Overall, cascading extinction are part of an ecosystems' response to anthropogenic drivers but are so far not explicitly measured in their contribution when evaluating biodiversity loss. This knowledge is necessary to predict biodiversity loss and find strategies to buffer against the devastating long-term impact of habitat loss, pollution, species invasions, and climate change.
34 citations
TL;DR: Analysis of geographic patterns of extinction must be accompanied by knowledge of biodiversity patterns in insects given three shortfalls, which means the accelerated loss of insect species likely surpasses the rate at which the authors are discovering new species.
Abstract: 1. Analysis of geographic patterns of extinction must be accompanied by knowledge of biodiversity patterns. Such analysis is not yet available in insects given three shortfalls. First, knowledge of insect species' distribution is poor. Second, insect inventories have taxonomic, geographical, temporal and habitat biases. Third, the accelerated loss of insect species likely surpasses the rate at which the authors are discovering new species.
30 citations
TL;DR: Spiders were found to consume one another more than expected, indicating their propensity towards intraguild predation, but also consumed common pest families, and primers show promise for application to the diets of other spider families such as Agelenidae and Pholcidae.
Abstract: Money spiders (Linyphiidae) are an important component of conservation biological control in cereal crops, but they rely on alternative prey when pests are not abundant, such as between cropping cycles. To optimally benefit from these generalist predators, prey choice dynamics must first be understood.
Money spiders and their locally available prey were collected from cereal crops 2 weeks pre‐ and post‐harvest. Spider gut DNA was amplified with two novel metabarcoding primer pairs designed for spider dietary analysis, and sequenced.
The combined general and spider‐exclusion primers successfully identified prey from 15 families in the guts of the 46 linyphiid spiders screened, whilst avoiding amplification of Erigone spp. The primers show promise for application to the diets of other spider families such as Agelenidae and Pholcidae.
Distinct invertebrate communities were identified pre‐ and post‐harvest, and changes in spider diet and, to a lesser extent, prey choice reflected this. Spiders were found to consume one another more than expected, indicating their propensity towards intraguild predation, but also consumed common pest families.
Changes in spider prey choice may redress prey community changes to maintain a consistent dietary intake. Consistent provision of alternative prey via permanent refugia should be considered to sustain effective conservation biocontrol.
25 citations
TL;DR: Dung beetles are an important group of insects that use excrement for feeding and reproductive purposes and the increasing number of investigations that use them as the focal group.
Abstract: 1. Dung beetles are an important group of insects that use excrement for feeding and reproductive purposes. The interest of the scientific community in dung beetles is highlighted by the increasing number of investigations that use them as the focal group.
21 citations
TL;DR: 1. Hyphantria cunea is a problematic invasive species that has caused considerable damage to agricultural and forestry ecosystems in China.
Abstract: 1. Hyphantria cunea is a problematic invasive species that has caused considerable damage to agricultural and forestry ecosystems in China.
20 citations
TL;DR: It has been shown that eggs of the dark bush‐cricket, Pholidoptera griseoaptera, which experienced an insufficient warm treatment (shorter and/or colder), had a longer development time and hatched predominantly after the second diapause.
Abstract: 1. Phenotypic plasticity and/or genetic adaptation may allow species to live in a variable environment. It has been shown that eggs of the dark bush‐cricket, Pholidoptera griseoaptera, which experienced an insufficient warm treatment (shorter and/or colder), had a longer development time and hatched predominantly after the second diapause.
20 citations
TL;DR: The bidirectional nature of plant‐mediated interactions between the PGPR and insect communities associated with plants, including effects of beneficial rhizobacteria via modification of plant defence traits on insects, is discussed and how such knowledge can be used in the development of sustainable crop‐protection strategies is discussed.
Abstract: 1. Plants interact with various organisms, aboveground as well as belowground. Such interactions result in changes in plant traits with consequences for members of the plant-associated community at different trophic levels. Research thus far focussed on interactions of plants with individual species. However, studying such interactions in a community context is needed to gain a better understanding. 2. Members of the aboveground insect community induce defences that systemically influence plant interactions with herbivorous as well as carnivorous insects. Plant roots are associated with a community of plant-growth promoting rhizobacteria (PGPR). This PGPR community modulates insect-induced defences of plants. Thus, PGPR and insects interact indirectly via plant-mediated interactions. 3. Such plant-mediated interactions between belowground PGPR and aboveground insects have usually been addressed unidirectionally from belowground to aboveground. Here, we take a bidirectional approach to these cross-compartment plant-mediated interactions. 4. Recent studies show that upon aboveground attack by insect herbivores, plants may recruit rhizobacteria that enhance plant defence against the attackers. This rearranging of the PGPR community in the rhizosphere has consequences for members of the aboveground insect community. This review focusses on the bidirectional nature of plant-mediated interactions between the PGPR and insect communities associated with plants, including (a) effects of beneficial rhizobacteria via modification of plant defence traits on insects and (b) effects of plant defence against insects on the PGPR community in the rhizosphere. We discuss how such knowledge can be used in the development of sustainable crop-protection strategies.
TL;DR: This study presents a probabilistic approach to estimating the impact of climate change on herbivores and their interactions with host plants in the context of drought.
Abstract: 1. Frequently changing climatic conditions can cause recurring droughts which often subject plants to tremendous amounts of stress, leaving biologists to wonder about its impact on the associated herbivores and their interactions with host plants.
TL;DR: Artificial pollen diets were created using five different ratios of commercially available clover and rose pollen and results show that clover pollen provides a higher quality diet for larval development and survival of the native small carpenter bee.
Abstract: As native bee populations decrease, there is a need to better understand their nutritional requirements to sustain healthy pollinator populations. A common native bee to eastern North America is the small carpenter bee, Ceratina calcarata. Previous studies have shown that the primary pollen sources for C. calcarata consist of clover and rose. The aim of this study is to compare the effects of diet composition on body size, development and survival. Artificial pollen diets were created using five different ratios of commercially available clover and rose pollen. Diets containing higher ratios of clover pollen produced larger individuals with increased survival rates and faster development times. To examine this further, the macronutrient profiles of clover and rose pollen were characterised comparing: protein, sugar, fatty acid, and amino acid content. Results indicated that rose pollen contained significantly higher protein and sugar content, while clover pollen had higher concentrations of essential amino acids. These are crucial to bee health and development, which helps to explain the increased survivorship observed on high clover diet treatments. Taken together, these results show that clover pollen provides a higher quality diet for larval development and survival of the native small carpenter bee. This research indicates that diet has a significant effect on the health of the native pollinator community and more research is needed to further explore the balance between pollen quality and availability, including essential macronutrients and the availability of these floral sources for wild bees.
TL;DR: Dung beetles are capable of providing a variety of ecosystem services and can be used as bioindicators and have been identified as one of the main drivers of global biodiversity loss.
Abstract: 1. Changes in land use have been identified as one of the main drivers of global biodiversity loss, and also negatively affect ecosystem services. Dung beetles are capable of providing a variety of ecosystem services and can be used as bioindicators.
TL;DR: This work states that changes in the environment are likely to have a stronger effect on phylogenetic lineages that depend on intimate and specialised ecological interactions, such as most herbivorous insects.
Abstract: 1. One of the main challenges faced by ecologists today is to understand and predict how species interactions will respond to the current environmental change. It is likely that these changes will ...
TL;DR: Entomologists interested in trait analyses should critically evaluate how intraspecific variation could affect their inference, especially when evaluating species that are highly sexually dimorphic, phenotypically plastic, and/or distributed across broad environmental and spatial clines.
Abstract: Intraspecific variation plays important roles in ecology and evolution. Yet, information on how species and populations vary remains scarce, particularly for insects and regarding functional traits. This lack of knowledge can be problematic in trait‐based ecology because traditional approaches assume negligible intraspecific variation, even for analyses that assess highly variable taxa. We measured 291 Arctic fritillary butterflies (Boloria chariclea) to assess the intraspecific variation in one population of this species, evaluating (i) how wingspan of Arctic fritillaries varies in relation to the other species of its community, and (ii) how well wingspan, a measure of body size, predicts weight, a measure of body mass. Wingspan of Arctic fritillaries varied between 2.62 and 4.07 cm, with the 95% interval range, including ∼33% (14/42) of the species in the community, and ∼30% (84/279) of the butterflies of Canada. The relationship between wingspan and weight was significant (βwingspan = 0.002, SE = 0.0008, P < 0.001), but relatively weak (R2adj = 0.31, F2,288 = 67.82, P < 0.001). We discuss our findings in relation to the assumption of species homogeneity and the use of proxies in the analysis of species traits, complementing our case study with simulations to illustrate how intraspecific and interspecific variation interact in determining when traditional trait analyses are robust. We suggest entomologists interested in trait analyses should critically evaluate how intraspecific variation could affect their inference, especially when evaluating species that are highly sexually dimorphic, phenotypically plastic, and/or distributed across broad environmental and spatial clines.
TL;DR: Patterns have generally been analysed at species level without taking into account possible differences between populations, which, when they are noted, are mostly attributed to large‐scale climate differences across a latitudinal gradient.
Abstract: In recent decades, efforts have been made to understand how global warming affects biodiversity and in this regard butterflies have emerged as a model group. The most conspicuous sign that warming is affecting the ecology of butterflies are the phenological advances occurring in many species. Moreover, rising temperatures are having a notable impact – both negative and positive – on population abundances. To date, patterns have generally been analysed at species level without taking into account possible differences between populations, which, when they are noted, are mostly attributed to large-scale climate differences across a latitudinal gradient. In this work, we use a long-term database of butterflies from the island of Menorca (Balearic Islands, Spain) to investigate how phenology and population dynamics have been affected by climate warming during the past two decades. In addition, we assess how responses are modulated by habitat characteristics and by species’ biological cycles. Our results show that species respond differently to warming at a local scale depending on season and habitat, and that coastal habitats in the Mediterranean region are particularly sensitive to the effects of climate change. Furthermore, our findings suggest that the effects of temperature could be partially offset in more inland habitats such as forests and deep ravines. The positive effect of temperature on ravine populations during the summer suggests that butterflies disperse across habitats as a response to rising temperatures during the season. This type of dispersal behaviour as a response to warming could be especially important in island ecosystems where the possibilities of modifying altitudinal or latitudinal distributions are often severely limited.
TL;DR: Alternative hypotheses are tested to determine if the invasive red imported fire ant, Solenopsis invicta, is a ‘driver’ or simply a ’passenger’ of ecological change in a longleaf pine ecosystem.
Abstract: 1. Invasive species and habitat disturbance are among the most important drivers of biodiversity loss and ecological change. Their individual effects, however, are difficult to disentangle because invasion and disturbance are often intimately linked. Here we test alternative hypotheses to determine if the invasive red imported fire ant, Solenopsis invicta, is a ‘driver’ or simply a ‘passenger’ of ecological change in a longleaf pine ecosystem.
TL;DR: Tsetse flies are K‐strategist species and deposit a single larva at 10‐day intervals in specific sites, and the selection of larviposition sites is unlikely to be random and will be subject to strong selective processes, probably mediated by specific cues.
Abstract: 1. Tsetse flies (Diptera: Glossinidae) are K‐strategist species and deposit a single larva at 10‐day intervals in specific sites. As larviposition site selection strongly impacts reproductive success, the selection of larviposition sites is unlikely to be random and will be subject to strong selective processes, probably mediated by specific cues. 2. This study was designed to assess the existence of an aggregation effect in the palpalis group and to test its potential chemical nature (contact or volatile compounds). The larviposition site selection of Glossina palpalis gambiensis was studied according to the presence of conspecific and heterospecific larvae (morsitans group) buried in substrates. Three sets of experiments were performed with either individual or grouped gravid females and with or without physical access to the substrate. 3. In individual larviposition experiments, females were more likely to select trays with buried larvae than unconditioned sand (63.2% and 36.8%, respectively; P < 0.05). In the grouped experiment with substrate contact, females were more likely to larviposit in trays with conspecific (40%) or heterospecific (33%) buried larvae than in unconditioned sand (22%) or empty trays (5%; P < 0.05). The results were similar without substrate contact, but more pupae were deposited in empty trays (19%). 4. These results provide the first evidence for larval aggregation in G. p. gambiensis and suggest that larviposition site selection is mediated by volatile semiochemicals of larval or pupal origin. However, this larval aggregation does not seem to be species specific and therefore offers new options for the behavioural manipulation of these vectors.
TL;DR: A major component of biomass burning smoke is fine particulate matter (PM2.5), which has been shown to generate impacts on insect population dynamics and development, and potentially migration and ecosystem services such as pollination.
Abstract: 1. A major component of biomass burning smoke is fine particulate matter (PM2.5), which has been shown to generate impacts on insect population dynamics and development. However, little is known about its effect on insect flight behaviour, even though this will influence insect dispersal and distribution, and potentially migration and ecosystem services such as pollination.
TL;DR: This data indicates that circular bare patches occur in high numbers among the vegetation of the Namib Desert margin and are likely to be the result of localised herbivory by sand termites of the genus Psammotermes (family Rhinotermitidae).
Abstract: 1. Circular bare patches occur in high numbers among the vegetation of the Namib Desert margin. There is an ongoing scientific debate on the origin of these so‐called “fairy circles” (FCs). One of the most frequently discussed hypotheses regards the bare patches to be the result of localised herbivory by sand termites of the genus Psammotermes (family Rhinotermitidae).
TL;DR: The impact of reciprocal gut microbiome transplants between two ecologically very similar, sympatric, and syntopic dung beetle sister species is examined.
Abstract: 1. Microbial symbionts play a crucial role in the development, health, and homeostasis of their hosts. However, the eco‐evolutionary conditions shaping these relationships and the evolutionary scale at which host–microbiome interactions may diverge warrant further investigation, especially in non‐model systems. This study examines the impact of reciprocal gut microbiome transplants between two ecologically very similar, sympatric, and syntopic dung beetle sister species.
TL;DR: Seed dispersal by ants, i.e. myrmecochory, is important in drylands because ants may contribute to overcoming the typical resource limitation imposed on plants in these environments.
Abstract: 1. Seed dispersal by ants, i.e. myrmecochory, is important in drylands because ants may contribute to overcoming the typical resource limitation imposed on plants in these environments. Dispersal distance and directed dispersal of seeds to nutrient‐enriched ant nests benefit plants by reducing parent or sibling competition and improving growth, survival, and reproduction.
TL;DR: This work tested whether foragers can guide nestmates in the direction and the distance of artificial feeders placed in the vicinity of the colony, and whether newcomers use chemical and visual cues originating from nestmates foraging at the food source, but found no evidence for the use of these social cues provided by conspecifics.
Abstract: The tropical stingless bees have evolved intricate communication systems to recruit nestmates to food locations. Some species are able to accurately communicate the location of food, whereas others simply announce the presence of food in the environment. Plebeia droryana is a tiny Neotropical stingless bee that, until recently, was thought to use a solitary foraging strategy, that is without the use of a recruitment communication system. However, recent research has indicated that P. droryana might be able to recruit nestmates to specific food source locations. We tested this by studying whether foragers can guide nestmates in the direction and the distance of artificial feeders placed in the vicinity of the colony. We trained bees to a scented sucrose solution feeder at 10 m and placed different feeders either in different directions (experiment 1) or in different distances (experiment 2). We found that P. droryana directs newcomers in the right direction, but distance information does not seem to be communicated. Moreover, we then tested whether newcomers use chemical and visual cues originating from nestmates foraging at the food source, but found no evidence for the use of these social cues provided by conspecifics. The potential mechanism that P. droryana may use to orient recruits toward the food source, however, remains unknown and requires further study.
TL;DR: Gomez Gomez et al. as mentioned in this paper proposed the Instituto de Biologia Subtropical (IBS) as a sub-tropical branch of the IBS and used it to study the sub-tropical environment.
Abstract: Fil: Gimenez Gomez, Victoria Carolina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Nordeste. Instituto de Biologia Subtropical. Instituto de Biologia Subtropical - Nodo Puerto Iguazu | Universidad Nacional de Misiones. Instituto de Biologia Subtropical. Instituto de Biologia Subtropical - Nodo Puerto Iguazu; Argentina
TL;DR: This study demonstrates a strong trophic cascade initiated by an invasive predator, the recent arrival of the invasive paper wasp Polistes dominula Christ, associated with substantial declines in local butterfly abundance in New Zealand.
Abstract: The direct and indirect impacts that invasive predators have on communities within their invaded range are poorly understood, particularly in the early stages of invasion. Through top‐down control of their prey, predators have the capacity to trigger cascading effects on lower trophic levels. We found the recent arrival of the invasive paper wasp Polistes dominula Christ has been associated with substantial declines in local butterfly abundance in New Zealand. One of the butterfly species we observed to be affected is the monarch, Danaus plexippus Linnaeus with densities reduced by 66% at the study site. Field experiments were conducted to examine the strength of the predation pressure exerted by P. dominula on monarch caterpillars and the cascading effects on milkweed (Gomphocarpus physocarpus E. Mey.) fitness. A survival study of monarch caterpillars was conducted across three habitat types (coastal, forest, and suburban). Caterpillar survival in suburban areas was lowest, with only 45% of caterpillars remaining after just 6 h of exposure to wasp foraging. Predation by P. dominula explained 85% of caterpillar deaths within the trial period. The cascading effects of P. dominula presence were quantified through changes in the height, foliage, and reproductive output of milkweed plants. Monarch caterpillar predation by P. dominula was found to have a positive effect on milkweed fitness. This study demonstrates a strong trophic cascade initiated by an invasive predator. These findings highlight the impacts an invasive species can have on local communities beyond their direct predatory effects.
TL;DR: Functional trait descriptions of communities, including decomposer communities, may provide more comprehensive evaluations of restoration activities and management than taxonomic community metrics alone.
Abstract: 1. Ecosystem restoration often focuses on re‐establishing species richness and diversity of native organisms. However, effective restoration requires re‐establishment of ecosystem functions and processes by all trophic levels. Functional trait descriptions of communities, including decomposer communities, may provide more comprehensive evaluations of restoration activities and management than taxonomic community metrics alone.
TL;DR: This study investigated how the initial size of the population released affects the probability of establishment and population growth in the first season after introduction at isolated sites in New Zealand and concluded that extinction probability in the experimental populations of N. ogloblini was influenced by both a demographic Allee effect and stochasticity.
Abstract: 1. Although most populations of non-native species arriving in new environments fail to establish, mechanisms behind failed biological invasions are still poorly understood. 2. Propagule pressure has been found to be a dominant driver of establishment success, underpinned by processes such as stochasticity and Allee effects. While studies have revealed the presence of a component Allee effect in field populations, empirical support for demographic Allee effects has been limited. 3. We used the leaf-feeding beetle Neolema ogloblini, a biological control agent against the plant Tradescantiafluminensis, as a proxy invasive species to experimentally study the process of establishment. We investigated how the initial size of the population released affects the probability of establishment and population growth in the first season after introduction at isolated sites in New Zealand. 4. The probability of establishment was found to increase with numbers of individuals released. A significant quadratic relationship was found between population size released and per capita population growth rate; that is per capita population growth rate initially increased as population size released increased but decreased at higher population levels. 5. These results support the presence of a demographic Allee effect. However, as the influence of stochasticity (environmental and demographic) could not be completely separated from that of a demographic Allee effect, we conclude that extinction probability in the experimental populations of N. ogloblini was influenced by both a demographic Allee effect and stochasticity. 6. Our study demonstrates and supports the concept that experimental biocontrol agent releases can be used for testing hypotheses regarding invasion biology.
TL;DR: This work applied a Markov random fields/conditional random fields (MRF/CRF) modelling to understand whether and how species associations in ectoparasite infracommunities of small mammals vary along environmental gradients across space and time.
Abstract: 1. We applied a Markov random fields/conditional random fields (MRF/CRF) modelling to understand whether and how species associations in ectoparasite infracommunities of small mammals vary along environmental gradients across space and time.
TL;DR: Parasites are one of the main actors in host–parasite interactions and their role as a prey and the related consequences for such interactions and in other respects, such as food webs, are frequently overlooked.
Abstract: Francisco Valera received financial support from the project PGC2018-097426-B-C22 (MCIU/AEI/FEDER, UE) Jesus Veiga was funded by a pre-doctoral grant (BES-2015-075951) of the Spanish Ministry of Economy, Industry, and Competitiveness