Defensive Behavior Research Articles

Predators drive selection for adaptive plasticity in prey defense behavior.

Plasticity to reduce activity is a common way prey evade predators. However, by reducing activity prey often experience lower individual growth rates because they encounter their own prey less often. To overcome this cost, natural selection should not simply favor individuals generating stronger plasticity to reduce activity rates, but also selection to resume activity once the threat of predation subsides. If such plasticity is adaptive, it should vary under environmental conditions that generate stronger selection for greater plasticity, such as predator density. Using a mesocosm experiment and observational study with a damselfly-prey/fish-predator system we show that fish predation exerts selection for greater plasticity in activity rates of damselflies. Such selection allows damselfly activity levels to initially decrease and then rebound when the threat of predation dissipates, potentially helping to ameliorate a hypothesized growth penalty from activity reductions. We also find that the extent of plasticity in activity to the threat of fish predation increases, albeit slightly (r2 = 0.04-0.063%), as fish densities increase across natural lakes, consistent with the idea that the magnitude of plasticity is shaped by environmental conditions underlying selection. Collectively, these results demonstrate how selection acts to drive adaptive plasticity in a common predator avoidance strategy.

The ability of lacewing larvae to predate two pest caterpillars in relation to the prey defensive behaviour and body size

The ability of lacewing larvae to predate two pest caterpillars in relation to the prey defensive behaviour and body size

Parabrachial CGRP neurons modulate active defensive behavior under a naturalistic threat.

Recent studies suggest that calcitonin gene-related peptide (CGRP) neurons in the parabrachial nucleus (PBN) represent aversive information and signal a general alarm to the forebrain. If CGRP neurons serve as a true general alarm, their activation would modulate both passive nad active defensive behaviors depending on the magnitude and context of the threat. However, most prior research has focused on the role of CGRP neurons in passive freezing responses, with limited exploration of their involvement in active defensive behaviors. To address this, we examined the role of CGRP neurons in active defensive behavior using a predator-like robot programmed to chase mice. Our electrophysiological results revealed that CGRP neurons encode the intensity of aversive stimuli through variations in firing durations and amplitudes. Optogenetic activation of CGRP neuron during robot chasing elevated flight responses in both conditioning and retention tests, presumably by amyplifying the perception of the threat as more imminent and dangerous. In contrast, animals with inactivated CGRP neurons exhibited reduced flight responses, even when the robot was programmed to appear highly threatening during conditioning. These findings expand the understanding of CGRP neurons in the PBN as a critical alarm system, capable of dynamically regulating active defensive behaviors by amplifying threat perception, ensuring adaptive responses to varying levels of danger.

Similar host instar preferences by three sympatric parasitoids of Chielomenes sexmaculata (Coleoptera: Coccinellidae): potential host niche overlapping.

Parasitoids employ diverse oviposition strategies to enhance offspring survival and maximise fitness gains from hosts. Ladybird parasitoids, significant natural enemies of ladybirds, have the potential to disrupt biocontrol efforts, yet their biology and ecology remain poorly understood. This study investigated the host-parasitoid interaction among three sympatric larval endoparasitoids of Cheilomenes sexmaculata (Coleoptera: Coccinellidae): Homalotylus hemipterinus (Hymenoptera: Encyrtidae), Nothoserphus mirabilis (Hymenoptera: Proctotrupidae) and Oomyzus scaposus (Hymenoptera: Eulophidae). Our objective was to understand host instar preferences from five perspectives related to host profitability, handling difficulty or parasitism decision-making, and to examine the occupation rates of each parasitoid in different host instars. Host profitability was determined by development time, adult offspring dry mass, sex ratio, brood size, parasitism success rate and host handling time. Host handling difficulty was evaluated through host defensive behaviour and handling time. Parasitism decision-making was evaluated through acceptance rate and preference score that considered the first reaction of female wasp to the host. Results showed that each parasitoid responded differently to the host from various perspectives. However, the first two suitable hosts of these parasitoids overlap on the third instar host, with first to third instar hosts being ideal for H. hemipterinus, and third to fourth instar hosts being ideal for N. mirabilis and O. scaposus. In the field, the occupation rate of each parasitoid in third instar host was influenced by the population of N. mirabilis, implying its superior competitiveness. This study reveals the host instar preferences of ladybird parasitoids and highlights the potential for interspecific competition.

Individual capture history affects site use and defensive behavior of foraging eastern copperheads at a recreational site

To maximize energy available for foraging or reproduction, optimality theory suggests individuals allocate energy toward defensive behaviors equivalent to risk of predation. In this framework, repeat encounters with humans by wildlife that do not reduce individual fitness could result in a decreased defensive response toward humans in subsequent encounters. We investigated whether individual experience influenced the defensive behaviors and frequency of site use of foraging eastern copperheads (Agkistrodon contortrix) at Koomer Ridge Campground in the Daniel Boone National Forest, Kentucky. Beginning in 2015, this site has been used for annual mark-recapture studies of copperhead foraging ecology as they predate emerging annual cicadas (Neotibicen tibicen). Using a standardized behavioral trial, we tested how copperhead defensive behavior toward humans was influenced by capture history, body size, and soil temperature. Model averaging results indicated that the overall intensity of copperhead defensive response to humans increased with capture history length, and soil temperature was positively associated with likelihood to respond when touched. Number of years recaptured was a significant, positive predictor of foraging frequency in 2022. Therefore, copperheads with longer capture histories visit the site to forage more frequently and are more willing to defend their opportunity to forage, suggesting a degree of acquired tolerance absent from naïve snakes that fled readily. Collectively, these results provide evidence that eastern copperheads at our site modulate their foraging and defensive behavior based on previous capture experience to more efficiently predate a seasonally abundant prey item.

Thermo-TRP regulation by endogenous factors and its physiological function at core body temperature.

Transient receptor potential (TRP) channels with temperature sensitivities (thermo-TRPs) are involved in various physiological processes. Thermo-TRPs that detect temperature changes in peripheral sensory neurons possess indispensable functions in thermosensation, eliciting defensive behavior against noxious temperatures and driving autonomic/behavioral thermoregulatory responses to maintain body temperature in mammals. Moreover, most thermo-TRPs are functionally expressed in cells and tissues where the temperature is maintained at a constant core body temperature. To perform physiological functions, the activity of each thermo-TRP channel must be regulated by endogenous mechanisms at body temperature. Dysregulation of this process can lead to various diseases. This review highlights the endogenous factors regulating thermo-TRP activity and physiological functions at constant core body temperature.

No evidence of quantitative honest signaling in aposematic traits of the green and black dendrobatid frog Dendrobates auratus in Costa Rica

Abstract Aposematism is an antipredator strategy in which conspicuous coloration acts as a warning of chemical defenses to potential predators. Evidence suggests that aposematism largely functions under positive frequency-dependent selection, which is thought to maintain uniformity of aposematic signals. Many studies of aposematic organisms have found evidence that color signals and defenses are positively correlated, indicating a quantitatively honest aposematic signal. Dendrobatid poison frogs represent a well-studied group of aposematic organisms that in addition to exhibiting a diversity of color signals also display unique defensive behaviors. Few studies have examined if both behavior and coloration act as quantitative honest signals of alkaloid defenses in poison frogs. We aimed to determine if coloration and behavior are quantitatively honest signals in the green and black poison frog (Dendrobates auratus) among six populations from Costa Rica. We (1) evaluated antipredator displays by using behavioral assays in the field, (2) assessed frog conspicuousness and pattern using digital images, and (3) quantified alkaloid profiles from frog skin secretions. We found that Pacific populations are less conspicuous in coloration, had greater quantities of alkaloids, and more frequently performed body-raising defensive behaviors when compared to Caribbean populations. Our results do not support the hypothesis that aposematic traits in D. auratus are quantitatively honest. Rather, our results suggest that phenotypic differences among populations may represent different phenotypic optima for advertising unprofitability to predators based on local environmental conditions, leading to the diversification of aposematic signals in this species.

Perilaku Defensif Lebah Apis cerana Terhadap Stimulus Isopentil Asetat (IPA)

Honey bee workers perform colony defense behavior to maintain colony integrity against predators. The aim of this research was to explore the response of A. cerana defensive behavior by using Isopentyl Acetate (IPA) as the stimulus which is the main volatile compound in the venom. Five concentrations of IPA volume i.e. 10, 20, 30, 40, and 50 µL IPA were used as the stimulus and each volume was pipetted to a cotton ball. The cotton ball was placed 10 cm in front of the hive entrance in oscillatory motion for five minutes. Natural defensive behavior of A. cerana (balling behavior), balling temperature and A. cerana predator were observed. Observation of defensive behavior was conducted by using colonies A. cerana obtained from Parung Panjang, Bogor and Nyalidung, Sukabumi; and using colonies A. cerana obtained from Sumedang and Banjarsari, Lebak. Based on the research, five A. cerana defensive behavior responses were observed, i.e.: guarding in front of bee hive entrance, recruitment at the hive entrance, fly toward the cotton ball, balling around the hive entrance, and balling on cotton ball. A. cerana showed defensive behavior due to IPA stimulus, however, there was no significant difference (P>0.05) with the variety IPA stimulus volume. We found the temperature of 44°C inside the natural balling of A. cerana defense behavior, as the colony defense mechanism in response to the natural predator Vespa sp. wasp.

Defensive Behaviour in Intertidal Crabs

ABSTRACTDespite a long roster of prey defences against predators now documented by biologists, any given species utilises only some of them, and we have few a priori predictions as to if, when or where they will be employed. In order to uncover general trends in the way in which crabs avoid predation attempts after they have been detected, we examined the antipredator behaviour of nine intertidal decapod species on three continents. We studied five different types of defensive behaviour and seven morphological and environmental factors which might affect such behaviours at different stages of the predatory sequence. In combination with other studies, we suggest that although intertidal crabs invest a great deal in crypticity to avoid detection, once discovered, they remain immobile, raise their chelae or flee but the extent to which these and other defences are exhibited differ markedly across species. We found that luminance contrast with the background, body size, chelae size and immediate habitat in which crabs were found affected antipredator behaviour whereas neither sex, nor chromatic contrast with the background were important. Our findings broaden understanding of defensive behaviour in several decapod species and highlight how species tailor the use of the same defences in different ways according to threat, morphology and local environment.

How do Kuwaiti teachers and headteachers practice their voice behavior? Influential factors in a centralized school structure

PurposeThe study investigates the voice behavior of teachers and headteachers in Kuwaiti schools, along with organizational factors associated with teachers’ voice behavior.Design/methodology/approachThe study employed a convergent mixed-method approach. Questionnaires were administered to a sample of 815 teachers and headteachers, with 28 of them participating in open-ended interviews.FindingsIn quantitative findings, high levels of prosocial voices were observed, while interviews revealed significant occurrences of defensive and acquiescent voice behaviors. Teachers practice prosocial voice behavior to protect students' interests, but various factors, such as individual characteristics, school leadership, hierarchy and governmental decisions at the district levels, influence their voices.Originality/valueThe findings enhance our understanding of voice behavior among teachers and headteachers, shedding light on the factors influencing voice behavior in Kuwait and centralized systems worldwide.

Monitoring active osprey nests with drones is more time efficient and less disturbing than conventional methods

Drones are used to monitor bird nesting sites at less accessible locations, such as on cliffs, human infrastructure, or within the tree canopy. While there are a growing number of studies documenting avian behavioral responses to various drones, there is a continued need to monitor taxa‐specific responses to different drone models. We explored both the time efficiency and impact of different nest survey methods (drones, nest climbing, and observations from a bucket truck) and different drone model sizes (small, medium, large) on the nest defense behavior of breeding ospreys. We conducted 166 surveys (126 drone, 25 climbing, 15 bucket truck) at 85 active nests across three nesting stages. We found variation in four of six pre‐defined behavioral categories, namely for calling, flying, at nest, and perching behaviors with survey method, sex, and nest stage. Females were more responsive to all survey methods compared to males and engaged in nest‐protection behaviors most frequently during incubation. Ospreys spent greater time at their nests during drone surveys compared to other methods. Agitated calling and flying were also less frequent during drone surveys. We recorded defensive behaviors across all survey types and there were no strikes on drones or researchers. Drone size appeared to influence behavior, with female ospreys spending, on average, 18% of survey time calling when surveyed with medium‐sized drone compared to smaller (8%) or larger (6%) models. Surveys with drones took less time to complete compared to the other methods tested. Based on our findings, drones appear to be the best choice for monitoring osprey nests as they are adaptable, time efficient, and result in less apparent disturbance to nesting ospreys than other methods tested. Our research aids in setting best practices, optimizing drone size, and developing evidence‐driven approaches for monitoring avian nests across a variety of landscapes and contexts.

Contributions of associative and non-associative learning to the dynamics of defensive ethograms

Defensive behavior changes based on threat intensity, proximity, and context of exposure, and learning about danger-predicting stimuli is critical for survival. However, most Pavlovian fear conditioning paradigms focus only on freezing behavior, obscuring the contributions of associative and non-associative mechanisms to dynamic defensive responses. To thoroughly investigate defensive ethograms, we subjected male and female adult C57BL/6 J mice to a Pavlovian conditioning paradigm that paired footshock with a serial compound stimulus (SCS) consisting of distinct tone and white noise (WN) stimulus periods. To investigate how associative and non-associative mechanisms affect defensive responses, we compared this paired SCS-footshock group with four control groups that were conditioned with either pseudorandom unpaired presentations of SCS and footshock, shock only, or reversed SCS presentations with inverted tone-WN order, with paired or unpaired presentations. On day 2 of conditioning, the paired group exhibited robust freezing during the tone period with switching to explosive jumping and darting behaviors during the WN period. Comparatively, the unpaired and both reverse SCS groups expressed less tone-induced freezing and rarely showed jumping or darting during WN. Following the second day of conditioning, we observed how defensive behavior changed over two extinction sessions. During extinction, the tone-induced freezing decreased in the paired group, and mice rapidly shifted from escape jumping during WN to a combination of freezing and darting. The unpaired, unpaired reverse, and shock-only groups displayed defensive tail rattling and darting during the SCS, with minimal freezing and jumping. Interestingly, the paired reverse group did not jump to WN, and tone-evoked freezing was resistant to extinction. These findings demonstrate that non-associative factors promote some defensive responsiveness, but associative factors are required for robust cue-induced freezing and high-intensity flight expression.

Gregarious, chemically defended pine sawflies as a new model to study cooperative interactions in an ecological context

AbstractOne of the key challenges of evolutionary theory is to determine how cooperation is promoted in different environmental contexts. This is because the costs and benefits of cooperation can be difficult to identify as they have many facets and are often highly context-dependent. To address this challenge, we need new study systems where the costs and benefits of cooperative behaviour can be quantified at an individual level under different environmental conditions. Here, we review the opportunities to study this with the herbivorous, haplodiploid gregarious pine sawflies (genera Neodiprion and Diprion from the family Diprionidae, Hymenoptera). These species are social only during the larval stage, when they feed in groups and perform collective chemical defence against predators by deploying their defensive secretions in synchrony. Defence behaviour is costly for individuals, and the extent to which individuals contribute to defence also depends on environmental conditions. Furthermore, there is both individual and sex-biased variation in the secretion of defence fluid. Our review highlights the possibilities of using the pine sawfly system to manipulate both ecological (e.g., diet quality) and social (e.g., kin structure, sex ratio, or group density) conditions during the larval stage and to experimentally quantify the impact of the environment on cooperative interactions. As a result, pine sawflies can tell us what leads to heterogeneity in the expression of cooperation in collective goods and elucidate the role of ecological interactions in promoting or constraining cooperation.

Involvement of the parabrachial nucleus in emergence from general anesthesia.

The parabrachial nucleus (PBN), located in the dorsolateral pons, is involved in many important biological functions, such as sensory signaling, feeding, defensive behaviors, fear, anxiety, and sleep-wake cycles. General anesthesia shares the classical feature of reversible loss of consciousness with natural sleep, and accumulating evidence has indicated that general anesthesia and sleep-wake behaviors share some common underlying neural mechanism. In recent years, emerging studies have investigated the involvement of PBN in emergence from general anesthesia, but divergence exists in terms of different types of general anesthetics or different durations of treatment with the same group of general anesthetics. Here, we reviewed the current literature and summarized the evidence about the contribution of PBN to general anesthesia.

Neural Circuits of Fear and Anxiety: Insights from a Neuroethological Perspective.

The predatory imminence continuum (PIC) of antipredator defensive behavior has been a helpful strategy for modeling anxiety and fear-related disorders in nonclinical research. The PIC is divided into three different sequential stages that reflect defensive behavioral strategy in response to predatory imminence. However, the PIC was experimentally addressed using a series of shock-based fear conditioning experiments rather than predatory threats. In this study, we will consider the PIC in a more naturalistic behavioral setting, focusing on analyzing the neural systems of animals responding to terrestrial and aerial predators. Of relevance, there is a sequential engagement of the distinct neural circuits along each phase of the PIC. In the preencounter phase, prefrontal cortical networks are particularly involved in planning and organizing behavioral responses to ambiguous threats. As the predatory cues or the real predator is detected, there is an engagement of amygdalar and hippocampal > hypothalamic pathways in conjunction with the periaqueductal gray, which organize fear responses. This dynamic particularly reveals how specific neural circuits are set into action to subserve distinct defensive responses. Moreover, we further explored the neural circuits governing other fearful situations outside the context of the PIC, including agonistic social encounters and interoceptive challenges. This analysis revealed an interesting overlap between the neural systems responding to these threats and those involved in response to predatory threats. The present review clarifies how defensive circuits respond to natural threats and provides a more realistic view of the neural systems underlying anxiety and fear responses.

Impacts of social isolation stress in safety learning and the structure of defensive behavior during a spatial-based learning task involving thermal threat

Safety learning during threat and adversity is critical for behavioral adaptation, resiliency, and survival. Using a novel mouse paradigm involving thermal threat, we recently demonstrated that safety learning is highly susceptible to social isolation stress. Yet, our previous study primarily considered male mice and did not thoroughly scrutinize the relative impacts of stress on potentially distinct defensive mechanisms implemented by males and females during the thermal safety task. The present study assessed these issues while considering a variety of defensive behaviors related to safety-seeking, escape, coping, protection, ambivalence, and risk-taking. After a two-week social isolation stress period, mice were required to explore a box arena that had thermal threat and safety zones (5 vs. 30°C, respectively). Since visuospatial cues clearly differentiated the threat and safety zones, the majority of the no-stress controls (69–75%) in both sexes exhibited optimal memory formation for the safety zone. In contrast, the majority of the stress-exposed mice in both sexes (69–75%) exhibited robust impairment in memory formation for the safety zone. Furthermore, while the control groups exhibited many robust correlations among various defensive behaviors, the stress-exposed mice in both sexes exhibited disorganized behaviors. Thus, stress severely impaired the proper establishment of safety memory and the structure of defensive behavior, effects that primarily occurred in a sex-independent manner.

First record of White-Collared Peccary (Dicotyles Tajacu) with Piebaldism across its entire distribution

Coloration is crucial for mammalian adaptation, influencing predator defense and social behavior. In recent decades, chromatic anomalies have been documented in Neotropical mammals, including albinism, leucism, and piebaldism, affecting several species. Piebaldism is a rare autosomal disorder characterized by asymmetric depigmented patches on the body. This study presents the first record of piebaldism in the collared peccary (Dicotyles tajacu Linnaeus, 1758) throughout its distribution. The record was obtained using camera traps at the Estação Ecológica (ESEC) da Terra do Meio in 2023. Observations showed that the affected peccary coexisted normally with other peccaries and engaged in typical feeding and social behaviors, suggesting that piebaldism does not affect individual social interactions. This finding is consistent with the literature indicating that chemical signals are more important than visual signals in Tayassuidae. This finding highlights the need to understand the frequency and distribution of chromatic anomalies to assess their implications for conservation plans over time.

Dopamine-mediated behavioral alterations following exposure to a social video in socially isolated mice during the developmental period.

Video exposure is known to affect brain function, yet its impact on neurodevelopmental processes remains unclear. This study aimed to investigate whether exposure to a video depicting social behavior induces behavioral and neurological changes in socially isolated mice. On Postnatal Day (PND) 21, male mice were separated from their dams and randomly assigned to three groups: socially grouped mice; socially isolated mice (ISO), where mice were housed without any social stimulation; and social video-exposed mice (SVE), where mice were exposed to a social video played on a tablet from PND21 to PND56 under socially isolated conditions. On PND56, all animals underwent behavioral tests. Compared to the socially grouped mice and ISO group, the SVE group showed an attenuated response to amphetamine treatment. In the social cognition test, the ISO group exhibited decreased affiliative behavior and increased offensive and defensive behavior. However, the SVE group showed a partial improvement in social cognition, including increased affiliative behaviors and decreased defensive behaviors, although no changes in offensive behaviors were observed. Furthermore, the SVE group exhibited elevated levels of tyrosine hydroxylase and dopamine transporter in key social cognition regions-namely the prefrontal cortex, retrosplenial cortex, and hippocampus. This neurochemical shift implies that socially isolated mice can acquire social behaviors through exposure to video-based social interactions. These effects may be related to the compensatory response of the dopamine system, which is implicated in various psychiatric disorders. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

The role of NMDA receptors in fish stress response: Assessments based on physiology of the caudal neurosecretory system and defensive behavior.

Stress strongly influences the physiology and behavior of animals, and leads into a pathological condition and disease. NMDA receptors (NMDARs) play a crucial role in the modulation of neural activity. To understand the role of NMDARs in fish stress response, we used NMDARs agonist aspartate to test the functional role of its input on the Dahlgren cell population in the caudal neurosecretory system (CNSS) of the olive flounder. In addition, the effect of the NMDARs antagonist D-AP5 on the expression of genes of the main secretory products of the CNSS after stress was investigated by using qPCR technology and the effect of the NMDARs antagonist D-AP5 on post-stress behavior was explored by behavioral methods. Ex vivo electrophysiological experiments showed that the NMDARs agonist aspartate enhanced the firing frequency of Dahlgren cells. Additionally, aspartate treatment increased the incidence of cells exhibiting bursting firing pattern, this result is corroborated by the observed upregulation in the expression of ion channels and major hormone genes in the CNSS. Furthermore, the excitatory influence of aspartate was effectively counteracted by NMDARs antagonist D-AP5. Interestingly, NMDARs antagonist D-AP5 treatment also significantly decreased the plasma cortisol levels and the expression of CRH, UI, and UII in CNSS after acute stress. Treatment with D-AP5 effectively attenuated the stress response, as evidenced by alterations in respiratory metabolism, sand-burying behavior, swimming distance, simulated capture, and escape response. In conclusion, modulation of Dahlgren cell excitability in the CNSS by NMDARs contributes to the regulation of the stress response, NMDARs antagonist D-AP5 can effectively suppress stress response in flounder by regulating the stress hormone expression and secretion. CLINICAL TRIAL REGISTRATION: Project code SHOU-DW-2022-032.

Selection for altruistic defense in structured populations.

We model natural selection for or against an anti-parasite (or anti-predator) defense allele in a host (or prey) population that is structured into many demes. The defense behavior has a fitness cost for the actor compared to non defenders ("cheaters") in the same deme and locally reduces parasite growth rates. Hutzenthaler et al. (2022) have analytically derived a criterion for fixation or extinction of defenders in the limit of large populations, many demes, weak selection and slow migration. Here, we use both individual-based and diffusion-based simulation approaches to analyze related models. We find that the criterion still leads to accurate predictions for settings with finitely many demes and with various migration patterns. A key mechanism of providing a benefit of the defense trait is genetic drift due to randomness of reproduction and death events leading to between-deme differences in defense allele frequencies and host population sizes. We discuss an inclusive-fitness interpretation of this mechanism and present in-silico evidence that under these conditions a defense trait can be altruistic and still spread in a structured population.