The use of artificial light at night (ALAN) has increased drastically worldwide over the last decades. ALAN can have major effects on nocturnal communities, including insects and bats. Insects are attracted to street lights and few bat species take advantage of this by foraging on the attracted insects. ALAN potentially affects the temporal patterns of insect abundance and thereby bat foraging behaviour. In a natural dark environment, these patterns are usually bimodal, with an activity peak in the early evening and the morning. Little is known about how ALAN affects insect presence throughout the night, and whether the light spectrum plays a role. This is important, as these temporal changes may be a key driver of disturbances in bat-insect interactions. Here, we studied how white and red light affect insects\' and bats\' nightly activity patterns. The activity of insects and bats (Pipistrellus spp.) was recorded throughout the night at seven experimentally illuminated sites in a forest-edge ecosystem. ALAN disrupted activity patterns, with both insects and bats being more active throughout the night. ALAN facilitated all-night foraging in bats especially near white light, but these effects were attenuated near red light. The ability to forage throughout the night may be a key advantage causing synanthropic bats to dominate in illuminated environments, but this could also prove detrimental in the long term. As red light reduced disturbing effects of ALAN on insects and bats diel activity pattern, it opens the possibility of using spectral composition as a mitigation measure.

Prey-predator interactions play a pivotal role in elucidating the evolution and adaptation of various organism\'s traits. Numerous approaches have been employed to study the dynamics of prey-predator interaction systems, with agent-based methodologies gaining popularity. However, existing agent-based models are limited in their ability to handle multi-modal interactions, which are believed to be crucial for understanding living organisms. Conversely, prevailing prey-predator integration studies often rely on mathematical models and computer simulations, neglecting real-world constraints and noise. These elusive attributes, challenging to model, can lead to emergent behaviors and embodied intelligence. To bridge these gaps, our study designs and implements a prey-predator interaction scenario that incorporates visual and olfactory sensory cues not only in computer simulations but also in a real multi-robot system. Observed emergent spatial-temporal dynamics demonstrate successful transitioning of investigating prey-predator interactions from virtual simulations to the tangible world. It highlights the potential of multi-robotics approaches for studying prey-predator interactions and lays the groundwork for future investigations involving multi-modal sensory processing while considering real-world constraints.

Nematode-trapping fungi (NTF) and nematodes are common and sympatric in nature. The molecular basis that underlies this interkingdom predator-prey interaction remains largely uncharacterized. Both NTF and nematodes can be easily isolated from soil samples. NTF do not form traps in nutrient-rich environments, yet trap morphogenesis can be observed under nutrient-poor conditions and upon simultaneous sensing of the nematode cues. Here, we present protocols for laboratory maintenance and culturing of the model NTF Arthrobotrys oligospora. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Growth of nematode-trapping fungi on solid medium Basic Protocol 2: Growth of nematode-trapping fungi in liquid medium Basic Protocol 3: Collection of conidia from solid medium Support Protocol 1: Preparation of Miracloth filter funnel Basic Protocol 4: Induction of trap morphogenesis Alternate Protocol: Quantitative measurement of trap induction Support Protocol 2: Preparation of synchronized C. elegans L4 Basic Protocol 5: Establishing C. elegans survival rate upon exposure to A. oligospora Basic Protocol 6: Storage of nematode-trapping fungi strains.

Predators ingest microplastics directly from the environment and indirectly via trophic transfer, yet studies have not investigated the contribution of each pathway to microplastic ingestion in fish. We assessed the relative importance of the two exposure routes using mysids (Neomysis spp.) and a benthic fish (Myoxocephalus brandti) as a model prey-predator system. We first exposed the mysids to fluorescent polyethylene beads (27-32 μm) at concentrations of 200 and 2000 μg/L. We then exposed the fish to water containing the same concentrations of polyethylene beads or to nine mysids pre-exposed to polyethylene beads. We quantified the size and overall mass of polyethylene beads in mysids and in fish to assess polyethylene beads fragmentation by the mysids. Mysids ingested 2-3 more polyethylene beads from water containing the higher concentration, and fish ingested 3-11 times more polyethylene beads via trophic transfer than from the water column. The percentage of fragmented particles was higher in mysids and in fish fed bead-exposed mysids, suggesting that the mysids can fragment polyethylene beads. Our experiments demonstrate that trophic transfer is a major route of microplastic ingestion by fish and that prey such as mysids can fragment microplastics. Small particles can translocate from the digestive system into tissues and exert adverse physiological effects. Trophic transfer of microplastics may therefore pose more serious threats to organisms at higher trophic levels.

The use of physical barriers is a common defensive strategy in small-sized endophagous arthropods, but this feeding mode often results in tracks being left on host organisms, thus increasing predation risk. Mechanisms of escape from tracking predators are thus particularly important for endophagous arthropods. Leaf miners are herbivorous insects that inhabit the interiors of leaves and produce various forms of tracks on their host plants. Such tracks are called \"mines,\" and parasitoid wasps, which are the primary enemy of leaf miners, use mines as cues to find host larvae. In the present study, we use the leaf-mining moth Acrocercops transecta (Insecta: Lepidoptera: Gracillariidae), which changes mine forms during larval growth, and its primary parasitoid Aneurobracon philippinensis (Hymenoptera: Braconidae). Larvae of A. transecta make narrow linear mines in the first and second instars, the third instars expand the mines to flat blotch mines, and the fourth and fifth instars construct three-dimensional tentiform blotch mines. A laboratory parasitization experiment showed that successful oviposition rates were significantly lower on tentiform blotch mines than on other mine types. In contrast, all fifth instars that were transplanted into flat blotch mines were oviposited, suggesting that older instars did not deter ovipositing parasitoids and that the lower rates of successful oviposition on tentiform blotch mines were attributable to refuges inside such mines provided by their three-dimensional structure. Field data demonstrated a plateau in parasitism rates in fourth instar larvae, confirming the results of the laboratory experiment. These results indicate that different mine forms affect the viability of endophagous larvae.

A guild of cellular slime molds (CSM) consisting of two isolates from each of five species, representing two genera, and obtained from the same square meter of forest soil exhibited extensive growth rate variation when tested on a suite of 18 bacteria isolated from the same soil. Significant growth rate differences were found at each taxonomic level examined: among species of different genera, between genera, among species within genera, and between isolates (=clones) within species. The type of bacteria used as prey determined the relative rank of the growth rates in different CSM isolates, as well as the taxonomic level at which significant differences were found. We suggest a possible reconciliation between a previous hypothesis, based on competition, and contradictory experimental work on resource partitioning in this guild of bacterial predators. Our results raise a question about the efficacy of using single genotypes to represent a species when ecological ideas are developed through laboratory investigations.

Research into the biodegradation of soil contaminants has rarely addressed the consequences of predator-prey interactions. Here, we investigated the joint effect of predation and dispersal networks on contaminant degradation by linking spatial abundances of degrader (Pseudomonas fluorescens LP6a) and predator (Bdellovibrio bacteriovorus) bacteria to the degradation of the major soil contaminant phenanthrene (PHE). We used a laboratory microcosm with a PHE passive dosing system and a glass fiber network to facilitate bacterial dispersal. Different predator-to-prey ratios and spatial arrangements of prey and predator inoculation were used to study predation pressure effects on PHE degradation. We observed that predation resulted in (i) enhanced PHE-degradation at low predator counts (PC) compared to controls lacking predation, (ii) reduced PHE-degradation at elevated PC relative to low PC, and (iii) significant effects of the spatial arrangement of prey and predator inoculation on PHE degradation. Our data suggest that predation facilitated by dispersal networks (such as fungal mycelia) may support the build-up of an effective bacterial biomass and, hence, contaminant biodegradation in heterogeneous systems such as soil.

Predicting the effects of pollution at the community level is difficult because of the complex impacts of ecosystem dynamics and properties. To predict the effects of copper on a plant-herbivore interaction in a freshwater ecosystem, we built a model that focuses on the interaction between an alga, Scenedesmus sp., and a herbivore, Daphnia sp. The model assumes logistic growth for Scenedesmus and a type II functional response for Daphnia. Internal copper concentrations in Scenedesmus and Daphnia are calculated using a biodynamic model. We include two types of direct effects of copper on Scenedesmus and Daphnia that results from hormesis: a deficiency effect at low concentration and a toxic effect at high concentration. We perform a numerical analysis to predict the combined effects of copper and nutrient enrichment on the Scenedesmus-Daphnia interaction. Results show three types of outcomes depending on copper concentration. First, low (4 μg L(-1)) and high (50 μg L(-1)) copper concentrations cause deficiency and toxicity, respectively, leading to the extinction of all populations; for less extreme concentrations (between 4 and 5 μg L(-1) and between 16.5 and 50 μg L(-1)), only the consumer population becomes extinct. The two populations survive with intermediate concentrations. Second, when population dynamics present oscillations, copper has a stabilizing effect and reduces or suppresses oscillations. Third, copper, on account of its stabilizing effect, opposes the destabilizing effect of nutrient enrichment. Our model shows that (1) Daphnia is affected by copper at lower concentrations when community interactions are taken into account than when analyzed alone, and (2) counterintuitive effects may arise from the interaction between copper pollution and nutrient enrichment. Our model also suggests that single-value parameters such as NOEC and LOEC, which do not take community interactions into account to characterize pollutants effects, are unable to determine pollutant effects in complex ecosystems. More generally, our model underscores the importance of ecosystem-scale studies to predict the effects of pollutants.

Predation is a strong selective force that promotes the evolution of antipredator behaviors and camouflage in prey animals. However, the independent evolution of single traits cannot explain how observed phenotypic variations of these traits are maintained within populations. We studied genetic and phenotypic correlations between antipredator behaviors (shoaling and risk-taking) and morphology traits (pigmentation and size) in juvenile three-spined sticklebacks by using pedigree-based quantitative genetic analysis to test phenotypic integration (or complex phenotype) as an evolutionary response to predation risk. Individuals with strongly melanized (i.e., camouflaged) phenotype and genotype were less sociable to conspecifics, but bolder during foraging under predation risk. Individuals with faster growing phenotype and genotype were bolder, and those with lager eyes were more fearful. These phenotypic integrations were not confounded with correlated plastic responses to predation risk because the phenotypes were measured in naïve fish born in the laboratory, but originated from a natural population with predation pressure. Consistent selection for particular combinations of traits under predation pressure or pleiotropic genes might influence the maintenance of the genetic (co)variations and polymorphism in melanin color, growth trajectory, and behavior patterns.