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Bats have been portrayed as important consumers of mosquitoes, but evidence supporting this claim is surprisingly scant. We collected the fecal material of 2 common North American bats at 22 sites in Wisconsin, United States and screened samples for mosquitoes using a recently improved molecular method for detecting arthropod DNA. Overall, we detected 17 discrete operational taxonomic units assigned to the mosquito family (Diptera: Culicidae), 15 of which were assigned at the species level. We detected mosquitoes in 71.9% of samples and at all sampling sites for little brown bats (Myotis lucifugus). By comparison, we detected mosquitoes in 33.3% of samples and one-half of the sampling sites for big brown bats (Eptesicus fuscus). Our results suggest that the incidence and taxonomic richness of mosquito prey consumed by bats is considerably higher than has been previously shown. In light of globally declining bat populations, we propose that future studies reassess the importance of trophic interactions between bats and mosquitoes.

Invasive insect pests pose a significant threat to forest ecosystems. Effective pest management relies on detecting these pests, which can be challenging when populations are sparse, newly introduced, or not easily observable. The spotted lanternfly (Lycorma delicatula White), a recent invader to North America, has caused extensive damage across the eastern United States since its introduction in 2014. Conventional monitoring methods, such as traps or visual inspections, are limited in their spatial coverage and may not reliably attract or capture target species. In this study, we explored the potential of bat guano as an additional tool for invasive insect detection. We collected guano samples from five bat species across three forested sites in New Jersey, USA, between 2018 and 2022 and used species-specific quantitative PCR (qPCR) to detect spotted lanternfly DNA. Spotted lanternfly DNA was detected in guano from two bat species: big brown bats (Eptesicus fuscus) and eastern red bats (Lasiurus borealis). Detection probability was strongly influenced by spotted lanternfly phenology, with higher detection rates occurring during the adult life stage. The detection of spotted lanternfly DNA in bat guano demonstrates the feasibility of using guano analysis as a complementary tool for insect pest surveillance. Integrating guano-based monitoring with traditional methods could enhance insect pest detection efforts across diverse forested and agricultural landscapes.

Most bats are insectivorous, but some species have evolved the ability to prey on fish. Although piscivory has been confirmed in the Rickett's big‐footed myotis (Myotis pilosus), the extent of piscivory of other cohabiting Myotis species is uncertain. This study aims to explore the dietary niches and fish consumption of three Myotis species in a subtropical East Asian region, and specifically the fish diet of M. pilosus. Our findings reveal, for the first time, that M. pilosus consumes marine fishes, in contrast to previous research conducted in inland regions that suggested year‐round consumption of cyprinids in freshwater habitats. We also observed seasonal variation in the diets of M. pilosus. It predominately hunted wide‐banded hardyhead silverside [31% relative read abundance (RRA) of all 12S reads], sailfin flying fish, and shorthead anchovy during the wet season, while mainly preying upon mullets (31%) during the dry months. In more inland areas, M. pilosus was found to primarily feed on invasive freshwater poeciliids (13%). Furthermore, M. pilosus consumed more fish during the dry season, while there was a greater consumption of insects during the wet months. Most notably among our findings is the consumption of fish by two individuals of Horsfield's myotis (M. horsfieldii), indicating that the species is potentially piscivorous. We revealed that both M. horsfieldii and M. pilosus consumed water striders, suggesting that foraging of aquatic insects could be driving the evolution of fishing behavior. Our findings have also shed light on the flexibility of foraging behavior in piscivorous bats. In the context of an important Atlantic salmon restoration program conducted in a large river system, we took advantage of the yearly count of smolt to evaluate the suitability of eDNA as a semi‐quantitative tool to monitor smolt migration. Results show a positive and exponential relationship between eDNA concentration and the number of caught smolts each day.

Artificial lights may be altering interactions between bats and moth prey. According to the allotonic frequency hypothesis (AFH), eared moths are generally unavailable as prey for syntonic bats (i.e., bats that use echolocation frequencies between 20 and 50 kHz within the hearing range of eared moths) due to the moths’ ability to detect syntonic bat echolocation. Syntonic bats therefore feed mainly on beetles, flies, true bugs, and non-eared moths. The AFH is expected to be violated around lights where eared moths are susceptible to exploitation by syntonic bats because moths’ evasive strategies become less effective. The hypothesis has been tested to date almost exclusively in areas with permanent lighting, where the effects of lights on bat diets are confounded with other aspects of human habitat alteration. We undertook diet analysis in areas with short-term, localized artificial lighting to isolate the effects of artificial lighting and determine if syntonic and allotonic bats (i.e., bats that use echolocation frequencies outside the hearing range of eared moths) consumed more moths under conditions of artificial lights than in natural darkness. We found that syntonic bats increased their consumption of moth prey under experimentally lit conditions, likely owing to a reduction in the ability of eared moths to evade the bats. Eared moths may increase in diets of generalist syntonic bats foraging around artificial light sources, as opposed to allotonic species and syntonic species with a more specialized diet.

The extent to which persisting species may fill the functional role of extirpated or declining species has profound implications for the structure of biological communities and ecosystem functioning. In North America, arthropodivorous bats are threatened on a continent‐wide scale by the spread of white‐nose syndrome (WNS), a disease caused by the fungus Pseudogymnoascus destructans. We tested whether bat species that display lower mortality from this disease can partially fill the functional role of other bat species experiencing population declines. Specifically, we performed high‐throughput amplicon sequencing of guano from two generalist predators: the little brown bat (Myotis lucifugus) and big brown bat (Eptesicus fuscus). We then compared changes in prey consumption before versus after population declines related to WNS. Dietary niches contracted for both species after large and abrupt declines in little brown bats and smaller declines in big brown bats, but interspecific dietary overlap did not change. Furthermore, the incidence and taxonomic richness of agricultural pest taxa detected in diet samples decreased following bat population declines. Our results suggest that persisting generalist predators do not necessarily expand their dietary niches following population declines in other predators, providing further evidence that the functional roles of different generalist predators are ecologically distinct. While many bat species are known to function as suppressors of arthropod abundance, including several economically important agricultural pest taxa, the broader ecological consequences of disease‐related bat declines have not been fully assessed in many regions. In our study, we tested whether big brown bats (Eptesicus fuscus), which demonstrate lower mortality from white‐nose syndrome, could potentially fill the ecological role formerly occupied by the more severely affected little brown bat (Myotis lucifugus). Overall, we found that big brown bats did not adopt more of the prey formerly consumed by little brown bats and that the dietary niche overlap between the two bat species did not change over time.

The greater round-eared bat, Tonatia bidens (Spix, 1823), is a medium-sized phyllostomid bat distributed in the north of Argentina, Paraguay and Brazil. The diet and foraging patterns of this species are poorly known. We analyzed the composition of the diet of a population of T. bidens and how the temperature influences the consumption of vertebrates and invertebrates. To describe diet composition, we conducted weekly collections of food scrap from two monospecific night-perches. Data of temperature for the study period were taken from the meteorological station installed 300 m from the collection perches. The influence of temperature was evaluated using generalized linear models (GLMs) with negative binomial distribution. Tonatia bidens consumed 28 taxons (204 records), being at least 17 Artropods and 11 Passeriformes birds. Temperature explained a greater proportion of vertebrate abundance (R 2 = 0.23) than invertebrate (R 2 = 0.16) or to both pooled (R 2 = 0.11). The relation with temperature was positive with invertebrates and negative with the vertebrates. The diet of the population of T. bidens comprised mainly invertebrates, which were the most frequent and diverse taxa. Data suggests that T. bidens has a diverse diet, with proportion of the item’s consumption varying temporally. Environmental factors, such as the temperature presented on this work, seems to be good proxies for the dietary traits of this species.

Insects are the principal food for many animals, including bats (Chiroptera), and all species of bats in the United Kingdom feed over agricultural habitats. Bat populations are declining throughout Europe, probably in part as a result of agricultural intensification. Organic farming prohibits the use of agrochemicals, a major component of agricultural intensification, making it an ideal control for a study of intensive agricultural systems. To evaluate the impact of agricultural intensification on bat foraging, we quantified the availability of bat prey by comparing nocturnal aerial insects captured within habitats on 24 matched pairs of organic and conventional farms. Insects were identified to family and moths to species. We compared the abundance of 18 insect families commonly eaten by bats in the United Kingdom between farm types and tested for correlations of abundance with bat activity. Insect abundance, species richness, and moth species diversity were significantly higher on organic farms than on conventional farms. Insect abundance was significantly higher in pastural and water habitats on organic farms than in the same habitats on conventional farms. Of the 18 insect families that are important components of the bat diet, 5 were significantly more abundant on organic farms overall. Some were also more abundant within organic pastural, woodland, and water habitats than on conventional farmland habitats. The activity of bats that mainly ate lepidoptera was significantly correlated with the abundance of this order. Our observations suggest that agricultural intensification has a profound impact on nocturnal insect communities. Because bats are resource limited, a reduction in prey availability through agricultural intensification will adversely affect bat populations. Less-intensive farming benefits British bat populations by providing and maintaining diverse and structurally varied habitats, which in turn support a wide selection of insect prey for bats, including insect families that are significant components of the diet of a number of rare bat species.

A thousand years old 105 cm deep deposit of bat guano in the Domica Cave (southern Slovakia, Slovak Karst National Park) has been discovered for science, and three samples were analysed for pollen to identify the bats' preferred foraging habitats and for insect remains to identify their diet. The bat species concerned, Rhinolophus euryale, is rare in the area, which lies at the northern margin of its distribution. The pollen record captured alder forests between 897–1024 AD, temperate light broad-leaved oak-hornbeam forests with Quercus cerris, Fraxinus ornus, Cornus mas and Corylus avellana between 1522–1800 AD, and almost recently willow shrubs. This pattern may, however, reflect local changes in the surrounding landscape where the bats hunted. Pollen of anemophilous taxa was underrepresented (e.g. Fagus), while entomophilous taxa were overrepresented (e.g. Fraxinus ornus, Loranthus europaeus, Acer, Agrostemma githago). The phenology of the encountered pollen taxa indicates that the bats used the Domica Cave mainly as spring and summer roosts. The pollen record further indicates that the bats prefer to forage in a forest–steppe landscape with open Pannonian broadleaved forests and humid temperate riparian environments. Today, this kind of landscape does not occur further north, which may explain the northern limit of this bat species at the study site.

We evaluated the structure of a community of frugivorous bats using composition and abundance patterns, niche amplitude and food overlap of these animals in four Atlantic Forest fragments, each one exposed to different conservation realities. For twelve months, we captured six bat species and found the seeds of 13 species of pioneering plants in 158 fecal samples. The most abundant bat species were Artibeus planirostris (25.4%), Artibeus lituratus (24.1%) and Carollia perspicillata (23.9%). Only one fragment (Fazenda Unida), the most conserved area, exhibited a significantly different composition and abundance of species. We found low trophic niche amplitude values (<0.60), associated to high food overlaps. Our results suggest that bats can adjust their foraging strategy to deal with food availability variations. By favoring pioneering plant species, the fragmentation process noted of the studied areas creates an attractive environment for bats more tolerant to this type of disturbance. The sampled areas represent important secondary forest remnants in southern Brazil that require attention to avoid an even greater loss of bat diversity.

Temporal variation of insect communities in urban environments is poorly known and mechanisms driving these changes are unclear, as are the implications for insectivorous predators. We examined the relationships between season and nocturnal aerial insect biomass and biodiversity, and between temperature and insect biomass in the Adelaide zoological gardens from December 2005 to September 2006. We also compared the effectiveness of two insect trap types and used a bat detector to assess bat activity in relation to insect biomass. During the study, 9,939 insects from 13 orders were collected at the Adelaide zoo with a Malaise trap and a light trap. Mass and diversity of insects were highest during warm months, as was bat activity, and bat activity was positively correlated with insect biomass. Winter-active insects consisted predominantly of Diptera and Lepidoptera, which may provide an important winter food resource for insectivorous bats. The Malaise trap attracted fewer insect orders and biomass than did the light trap, and insects congregated within 6 m of artificial lights, so bats that forage at lights may have an advantage in urban areas. A strong need for the inclusion of urban insects to biodiversity inventories exists in the context of bat conservation.