Defensive Behavior Research Articles

Aggression between invasive hymenopterans in Southern California: scutellata-hybrids versus German yellowjackets

Honey bee defensive behaviors are crucial for countering new predators such as invasive German yellowjackets (Vespula germanica). We provide the first data on the ability of scutellata-hybrids (Africanized bees) to defend their colonies against V. germanica wasps, as compared to European honey bees. The scutellata-hybrid colonies recruited twice as many defender bees in defense, and killed yellowjackets three times more often than managed European honey bee colonies. The defensive ability of such hybrids against new threats is intriguing and suggests that more research should be conducted into how defensive traits in the wide variety of honey bee subspecies may help against threats such as invasive wasps and hornets.

Role of the rostral dorsomedial column of the periaqueductal gray during social defeat in rats.

Previous studies showed that the dorsal premammillary nucleus of the hypothalamus (PMD) is involved in social passive defensive behaviors likely to be meditated by descending projections to the periaqueductal gray (PAG). We focused on the rostral dorsomedial PAG (rPAGdm) to reveal its putative neural mechanisms involved in mediating social defensive responses. By combining retrograde tracing and FOS expression analysis, we showed that in addition to the PMD, the rPAGdm is influenced by several brain sites active during social defeat. Next, we found that cytotoxic lesions of the rPAGdm drastically reduced passive defense and did not affect active defensive responses. We then examined the rPAGdm's projection pattern and found that the PAGdm projections are mostly restricted to midbrain sites, including the precommissural nucleus, different columns of the PAG, and the cuneiform nucleus (CUN). Also, we found decreased FOS expression in the caudal PAGdm, CUN, and PMD after the rPAGdm was lesioned. The results support that the rPAGdm mediates passive social defensive responses through ascending paths to prosencephalic circuits likely mediated by the CUN. This study provides further support for the role of the PAG in the modulation of behavioral responses by working as a unique hub for influencing prosencephalic sites during the mediation of aversive responses.

Incidental learning of faces during threat: No evidence for enhanced physiological responses to former threat identities

Remembering an unfamiliar person and the contextual conditions of that encounter is important for adaptive future behavior, especially in a potentially dangerous situation. Initiating defensive behavior in the presence of former dangerous circumstances can be crucial. Recent studies showed selective electrocortical processing of faces that were previously seen in a threat context compared to a safety context, however, this was not reflected in conscious recognition performance. Here, we investigated whether previously seen threat-faces, that could not be remembered, were capable to activate defensive psychophysiological response systems. During an encoding phase, 50 participants with low to moderate levels of anxiety viewed 40 face pictures with neutral expressions (6 s each), without an explicit learning instruction (incidental learning task). Each half of the faces were presented with contextual background colors that signaled either threat-of-shock or safety. In the recognition phase, all old and additional new faces (total of 60) were presented intermixed without context information. Participants had to decide whether a face was new or had been presented previously in a threatening or a safe context. Results show moderate face recognition independent of context conditions. Startle reflex and skin conductance responses (SCR) were more pronounced for threat compared to safety during encoding. For SCR, this differentiation was enhanced with higher levels of depression and anxiety. There were no differential startle reflex or SCR effects during recognition. From a clinical perspective, these findings do not support the notion that perceptual biases and physiological arousal directly relate to threat-associated identity recognition deficits in healthy and clinical participants with anxiety and trauma-related disorders.

Influence of Immune System Activation in Early Ontogenesis on Aggressiveness and Sexual Motivationi Adult Wistar Rats

Stresses in early ontogenesis can influence anxiety-depressive, defensive and social behavior, as well as the immune and hormonal reactivity of adult animals. The model of early proinflammatory stress assumes activation of the immune system by the introduction of bacterial lipopolysaccharide (LPS) in early ontogenesis. Whether neonatal LPS stress impacts aggressive behavior or sexual motivation is still unknown. Pathological aggressiveness and disorders in sexual behavior are characteristic of many neuropsychiatric diseases, therefore, the study of the prerequisites for their occurrence is highly relevant. On the 3rd and 5th day after birth, the rats were injected with either LPS at a dose of 50 mcg/kg (LPS group) or saline solution (SAL group, control). The aggressive behavior of adult rats in the resident-intruder test after a week of social isolation was analyzed, as well as the sexual preference of males or females in a three-chamber test. The behavior of rats was compared with baseline levels of corticosterone and interleukin-1beta in blood serum. The males of the LPS group compared with the control had more attacks on the intruder in the resident-intruder test, and the number of attacks did not decrease by the end of the experiment. The males of the LPS group had an increased interaction time with the female at the diestrus stage in the social preference test of males and females. There were no changes in aggressive behavior in females after the administration of LPS in early ontogenesis. The baseline level of interleukin-1beta was higher in males, and corticosterone was higher in females, there were no differences between the LPS and PHYS groups in biochemical parameters. The results obtained indicate an increase in aggressiveness provoked by social isolation, as well as sexual motivation in adult males after early pro-inflammatory stress, i.e., a change in the motivational and emotional component in social behavior.

Advances in neural circuits of innate fear defense behavior.

Fear, a negative emotion triggered by dangerous stimuli, can lead to psychiatric disorders such as phobias, anxiety disorders, and depression. Investigating the neural circuitry underlying congenital fear can offer insights into the pathophysiological mechanisms of related psychiatric conditions. Research on innate fear primarily centers on the response mechanisms to various sensory signals, including olfactory, visual, and auditory stimuli. Different types of fear signal inputs are regulated by distinct neural circuits. The neural circuits of the main and accessory olfactory systems receive and process olfactory stimuli, mediating defensive responses like freezing. Escape behaviors elicited by visual stimuli are primarily regulated through the superior colliculus and hypothalamic projection circuits. And auditory stimuli-induced responses, including escape, are mainly mediated through auditory cortex projection circuits. As for auditory stimuli, they are mainly triggered by the auditory cortical projection circuits, leading to escape and other responses. In this article, we review the research progress on the neural circuits of innate fear defensive behaviors in animals from different sensory systems, especially the projection circuits of olfactory, visual, and auditory systems, to provide references for the mechanistic study of related mental disorders.

Manchester City’s Start of the Offensive Phase: A Lag-Sequential Analysis

Research on the playing patterns of Manchester City, particularly under Pep Guardiola's guidance, is limited. Existing studies do not investigate the associations between the offensive phase's initial actions (interceptions, tackles, defensive behavior followed by a pass) and other elements of the attacking phase, such as pitch space positions (zones) and goals. This study goes beyond subjective observation and applies lag-sequential analysis on Manchester City's 2019-2020 UEFA Champions League group stage matches. Behaviors were recorded using the SoccerEye Observational Instrument and software. The data was analyzed using the Sequential Data Interchange Standard-Generalized Sequential Querier (SDIS-GSEQ) and Microsoft Excel. Of the 417 offensive phase starts, 30.7% began with an interception, 8.2% with a tackle, and 29.5% with defensive behavior followed by a pass. Zone 5 (central mid-defensive sector) had a positive association (z=4.1) with interceptions, while zone 8 (central mid-offensive sector) had a positive association (z=2.67) with defensive behavior followed by a pass. Zones 3 (right defensive sector) and 12 (right offensive sector) showed a positive association with tackles (z=2.96 and z=3.36, respectively). Interceptions (z=-2.61) and defensive behavior followed by a pass (z=-4.46) were inhibited in zone 2. Starting an attack with a tackle may also result in a goal in Lags 7 and 8 (z=2.15, z=2.54, respectively).

The bigger the threat, the longer the gaze? A cross-cultural study of Somalis and Czechs.

High fear reaction, preferential attention, or fast detection are only a few of the specific responses which snakes evoke in humans. Previous research has shown that these responses are shared amongst several distinct cultures suggesting the evolutionary origin of the response. However, populations from sub-Saharan Africa have been largely missing in experimental research focused on this issue. In this paper, we focus on the effect of snake threat display on human spontaneous attention. We performed an eye-tracking experiment with participants from Somaliland and the Czechia and investigated whether human attention is swayed towards snakes in a threatening posture. Seventy-one Somalis and 71 Czechs were tested; the samples were matched for gender and comparable in age structure and education level. We also investigated the effect of snake morphotype as snakes differ in their threat display. We found that snakes in a threatening posture were indeed gazed upon more than snakes in a relaxed (non-threatening) posture. Further, we found a large effect of snake morphotype as this was especially prominent in cobras, less in vipers, and mostly non-significant in other morphotypes. Finally, despite highly different cultural and environmental backgrounds, the overall pattern of reaction towards snakes was similar in Somalis and Czechs supporting the evolutionary origin of the phenomenon. We concluded that human attention is preferentially directed towards snakes, especially cobras and vipers, in threatening postures.

Golden mimics use multiple defenses to counter generalist and specialist predators

Abstract Many prey species employ multiple defenses during interactions with predators. Multiple defenses can provide a selective advantage against a single predator at different stages of the interaction or attack, as well as against multiple predator types. However, the efficacy of multiple defenses both during different sequences of an attack and against multiple predator types, remains poorly understood. We measured and classified defensive traits used by five mimics (Müllerian and Batesian) of the myrmecomorphic golden mimicry complex and one non-mimetic species. We then performed predatory trials using two different predators that differed markedly in their body size, trophic specialization, and how they handle prey—one being an ant specialist (spider) and the other a generalist which avoided ants (skink). We identified 12 defensive traits and classified them into four groups (primary, chemical, mechanical, and behavioral), which were strongly correlated. Skinks were much less likely to attack and capture mimics than the ant-eating spider predators. Our results show that multiple defenses (five or six) were used against each predator. The defensive behaviors and features that were most effective against skinks included appendage waving and large body size, whereas the golden “shine” warning signal, large body size, cuticle thickness, and defensive gland size were most effective against spiders. Most defenses appeared to be predator-specific. We conclude that potential prey in the golden mimicry complex have been selected for multiple defenses because of their vulnerability to different predator types and consequently, the efficacy of some of these defenses likely represents a trade-off.

Does patient behaviour drive physicians to practice defensive medicine? Evidence from a video experiment

ObjectiveBy manipulating patients’ critical attitude in a video experiment, we examined whether physicians are more intended to perform defensive acts because of a higher perceived liability risk in Belgium.MethodsWe assigned 85 practicing gynaecologists/obstetricians and orthopaedists randomly to four hypothetical video consultations, in which the patients show either a critical attitude (i.e., getting ahead of the facts, showing distrust) or a non-critical attitude (i.e., displaying more neutral questions and expressions). We asked the physicians about the care they would administer in the presented cases and the expected likelihood that the patient would sue the physician in case of a medical incident.ResultsBy manipulating patients’ verbal critical attitude (which indicates patients’ intention to take further steps), while keeping constant physician’s communication, patients’ clinical situation, preferences, and non-verbal behaviour in the videos, we were able to discover differential treatment styles driven by physicians’ perceived liability risk among patients with a different critical attitude. We found that physicians perform 17 percentage points more defensive acts (e.g., surgeries and diagnostic tests that are not medically necessary) when experiencing a high liability risk.ConclusionsOur results show that patients’ critical attitude drives physicians’ perceived liability risk and consequent defensive behaviour among obstetricians/gynaecologists and orthopaedists.

Observations on neurophysiological pattern and behavioural traits as death-feigning mechanism in Eucryptorrhynchus scrobiculatus (Coleoptera: Curculionidae).

In adaptation to surrounding environmental stimuli, most insects exhibit defense behaviour (death feigning) to improve survival rates in the wild. However, the underlying mechanism of death feigning remains largely unknown. Here, we tested the neurophysiological pattern and behavioural traits of the death-feigning mechanism in the forestry pest Eucryptorrhynchus scrobiculatus. Using neuroanatomy, LC-MS/MS target metabolomics detection technology and qRT-PCR, we investigated the effects of neurochemicals and metabolic pathways in experimental weevils. Excision and drug tests were conducted to verify the key regulatory body parts involved in regulating the central nervous system in death feigning. Our results reconstructed the death-feigning mechanism of E. scrobiculatus: when the effective stimuli point of arousal weevils received mechanical stimulation, the thoracoabdominal ganglion transmitted signals into the brain through the ventral nerve cord, and then the brain regulated dopamine (DA) and serotonin (5-HT) metabolic pathways, reducing the expression of dopamine (dar2) and octopamine (oar1, oab2) receptor genes, finally inducing death feigning. Our study suggests that the variation of neurotransmitters in the brain is an important indicator of the physiological response of death feigning, and the results provide ecological and theoretical information for future investigations to reveal key behaviour and target genes for pest control.

Automated virtual reality cognitive therapy versus virtual reality mental relaxation therapy for the treatment of persistent persecutory delusions in patients with psychosis (THRIVE): a parallel-group, single-blind, randomised controlled trial in England with mediation analyses

Persecutory delusions are a major psychiatric problem that often do not respond sufficiently to standard pharmacological or psychological treatments. We developed a new brief automated virtual reality (VR) cognitive treatment that has the potential to be used easily in clinical services. We aimed to compare VR cognitive therapy with an alternative VR therapy (mental relaxation), with an emphasis on understanding potential mechanisms of action. THRIVE was a parallel-group, single-blind, randomised controlled trial across four UK National Health Service trusts in England. Participants were included if they were aged 16 years or older, had a persistent (at least 3 months) persecutory delusion held with at least 50% conviction, reported feeling threatened when outside with other people, and had a primary diagnosis from the referring clinical team of a non-affective psychotic disorder. We randomly assigned (1:1) patients to either THRIVE VR cognitive therapy or VR mental relaxation, using a permuted blocks algorithm with randomly varying block size, stratified by severity of delusion. Usual care continued for all participants. Each VR therapy was provided in four sessions over approximately 4 weeks, supported by an assistant psychologist or clinical psychologist. Trial assessors were masked to group allocation. Outcomes were assessed at 0, 2 (therapy mid-point), 4 (primary endpoint, end of treatment), 8, 16, and 24 weeks. The primary outcome was persecutory delusion conviction, assessed by the Psychotic Symptoms Rating Scale (PSYRATS; rated 0-100%). Outcome analyses were done in the intention-to-treat population. We assessed the treatment credibility and expectancy of the interventions and the two mechanisms (defence behaviours and safety beliefs) that the cognitive intervention was designed to target. This trial is prospectively registered with the ISRCTN registry, ISRCTN12497310. From Sept 21, 2018, to May 13, 2021 (with a pause due to COVID-19 pandemic restrictions from March 16, 2020, to Sept 14, 2020), we recruited 80 participants with persistent persecutory delusions (49 [61%] men, 31 [39%] women, with a mean age of 40 years [SD 13, range 18-73], 64 [80%] White, six [8%] Black, one [1%] Indian, three [4%] Pakistani, and six [8%] other race or ethnicity). We randomly assigned 39 (49%) participants assigned to VR cognitive therapy and 41 (51%) participants to VR mental relaxation. 33 (85%) participants who were assigned to VR cognitive therapy attended all four sessions, and 35 (85%) participants assigned to VR mental relaxation attended all four sessions. We found no significant differences between the two VR interventions in participant ratings of treatment credibility (adjusted mean difference -1·55 [95% CI -3·68 to 0·58]; p=0·15) and outcome expectancy (-0·91 [-3·42 to 1·61]; p=0·47). 77 (96%) participants provided follow-up data at the primary timepoint. Compared with VR mental relaxation, VR cognitive therapy did not lead to a greater improvement in persecutory delusions (adjusted mean difference -2·16 [-12·77 to 8·44]; p=0·69). Compared with VR mental relaxation, VR cognitive therapy did not lead to a greater reduction in use of defence behaviours (adjusted mean difference -0·71 [-4·21 to 2·79]; p=0·69) or a greater increase in belief in safety (-5·89 [-16·83 to 5·05]; p=0·29). There were 17 serious adverse events unrelated to the trial (ten events in seven participants in the VR cognitive therapy group and seven events in five participants in the VR mental relaxation group). The two VR interventions performed similarly, despite the fact that they had been designed to affect different mechanisms. Both interventions had high uptake rates and were associated with large improvements in persecutory delusions but it cannot be determined that the treatments accounted for the change. Immersive technologies hold promise for the treatment of severe mental health problems. However, their use will likely benefit from experimental research on the application of different therapeutic techniques and the effects on a range of potential mechanisms of action. Medical Research Council Developmental Pathway Funding Scheme and National Institute for Health and Care Research Oxford Health Biomedical Research Centre.

Defensive responses: behaviour, the brain and the body.

Most animals live under constant threat from predators, and predation has been a major selective force inshaping animal behaviour. Nevertheless, defence responses against predatory threats need to be balanced against other adaptive behaviours such as foraging, mating and recovering from infection. This behavioural balance in ethologically relevant contexts requires adequate integration of internal and external signals in a complex interplay between the brain and the body. Despite this complexity, research has often considered defensive behaviour as entirely mediated by the brain processing threat-related information obtained via perception of the external environment. However, accumulating evidence suggests that theendocrine, immune, gastrointestinal and reproductive systems have important roles in modulating behavioural responses to threat. In this Review, we focus on how predatory threat defence responses are shaped by threat imminence and review the circuitry between subcortical brain regions involved in mediating defensive behaviours. Then, we discuss the intersection of peripheral systems involved in internal states related to infection, hunger and mating with the neurocircuits that underlie defence responses against predatory threat. Through this process, we aim to elucidate the interconnections between the brain and body as an integrated network that facilitates appropriate defensive responses to threat and todiscuss the implications for future behavioural research.

Behavioural Patterns and Interactions of Daphnia magna and Echinuriauncinata: Insights from Controlled Observations in Freshwater Habitats

Within freshwater ecosystems, the ecological influence of keystone primary consumers cannot be overstated. Daphnia magna emerges as a particularly prominent player among such species, significantly impacting a biotic community's higher trophic interactions and nutrient dynamics. Therefore, the Daphnia magna’s presence within these habitats and its intricate interrelationships with other organisms are of critical importance in maintaining homeostasis and fostering functional, biodiverse environments. Despite the importance of studying such interspecies interactions, the coexistence of Daphnia with its endoparasite Echinuriauncinata remains enigmatic and largely unexplored in scientific literature.
 In this study, a series of controlled observation setups were designed to facilitate a comprehensive exploration of the behavioural patterns and interactions between Daphnia and Echinuria. Such observational platforms incorporated concave slide glasses, test tubes, Fresh squared bottles, and digital imaging analysis, enabling precise and detailed descriptions of the organisms' behaviours under varying culturing conditions. Our findings reveal a shared affinity for the benthic habitat, driven by the presence of sinking food particles. Despite the absence of overt competitive interactions for food resources, Daphnia displayed pronounced defensive behaviours, adeptly evading potential attacks from Echinuria. Temperature exerted discernible effects on their initial activities, with transient heightened responsiveness observed at elevated thermal conditions. Our investigations ultimately led to a hypothesis proposing an unintentional infestation scenario, wherein Daphia may unwittingly harbour Echinuria eggs or larvae, likely due to their size resemblance to floating food particles. These empirical insights contribute to understanding predator-prey relationships and inadvertent infestations, augmenting our comprehension of freshwater ecosystem dynamics and preserving these vital aquatic environments.

Larval competition analysis and its effect on growth of Ostrinia furnacalis (Lepidoptera: Crambidae) at natural conditions in Northeast China.

The Asian corn borer (Ostrinia furnacalis, Lepidoptera, Crambidae) and Oriental armyworm (Mythimna separata, Lepidoptera, Noctuidae) are 2 major lepidopteran pests of the maize plant, especially the whorls and tassels. The aim of this study was to investigate competition between 2 lepidopteran pests of maize. Intraspecific and interspecific competition occurs when O. furnacalis and M. separata larvae interact with various stages of the maize plant. Therefore, determining whether this competition can decrease larval damage by causing adverse effects on larval growth is crucial. During the maize growing season of 2022, the interaction of these species was assessed in the experimental field of Jilin Agricultural University, China. Interspecific and intraspecific competition of larvae in different maize tissues and the influence of competition on larval development was determined in the fields. The results showed that first, probing behavior was significantly frequent in O. furnacalis larvae; intraspecific and interspecific attack was significant at 4th instar (with leaf, silk, and kernel). Interspecific defense behavior was significant at 3rd instar (without food). O. furnacalis larvae showed attack behavior toward M. separata larvae frequently. Second, competition increased the mortality rate of O. furnacalis larvae (intraspecific, 67%; interspecific, 33%) and decreased pupation emergence rate. Thus, intraspecific and interspecific competition might affect the competitive displacement of pest species sharing the same ecological niche, as well as the prevalence and population dynamics of pests, and help to develop integrated pest management strategies.

Behavioural implications of risk–return associations based on the adjusted thermal optimal path method: Large versus small banks

AbstractThis article investigates the impact of bank size and business model on bank risk‐taking within the framework of the prospect theory. To fulfil this objective, we use the adjusted thermal optimal path model. The results suggest that conventional banks adopt the same risk‐taking behaviour for performance measures, regardless of their size. However, the size mainly influences the attitudes of managers towards Islamic banks. On the other hand, small Islamic banks, whether under‐ or over‐performing, take excessive risks. This behaviour is mainly explained by loss aversion. However, large Islamic banks that situated above the target are risk‐averse, since they adopt defensive behaviour. The results reveal that for risk measures and for both small and large banks, a bank's business model does not affect managers' attitude to risk. Therefore, small (large) banks adopt excessive risk‐taking (risk‐averse) behaviour and an offensive (defensive) strategy. The study has important implications for GCC banking regulators, supervisors, and market participants. Thus, our findings imply that understanding the impact of the bank size and business model on the risk‐taking behaviour of Islamic and conventional banks can help them reduce their risk and mitigate moral hazard and regulatory arbitrage behaviour.

Diazepam effects on anxiety-related defensive behavior of male and female high and low open‐field activity inbred mouse strains

Open-field activity is a commonly used measure of anxiety-related behavior in rodents. The inbred High and Low Activity strains of mice, selected for extreme differences in open-field activity, have been used as a genetic model of anxiety-related behaviors. These selected strains have been thoroughly studied through extensive behavioral testing, quantitative trait locus (QTL) mapping, whole-genome sequencing, and RNA sequencing, to uncover phenotypic and genotypic differences related to anxiety-related behavior. However, the effects of anxiolytic drugs on anxiety-related behavior in these strains have not been studied previously. This study allowed us to expand on previous findings to further characterize the anxiety-related behavior of these unique strains, using an anxiolytic drug. The goal of this study was to determine whether the treatment of adult male and female High Activity (low anxiety) and Low Activity (high anxiety) mice with diazepam, an agonist at the benzodiazepine allosteric site on the GABAA receptor and a drug commonly prescribed to treat anxiety disorders in humans, led to decreases in anxiety-like defensive behavioral responses as assessed in the open-field test (OFT) and elevated plus-maze (EPM). We tested the effects of three doses of diazepam (0, 0.5, 1.0, 3.0 mg/kg, i.p.), given 30 min before behavioral testing to one High Activity strain (H2) and two Low Activity strains (L1 and L2). There was an anxiolytic effect of diazepam observed in the High Activity strain, with more entries into the open arms of the elevated plus-maze, an effect similar to that seen in common mouse strains. However, the only anxiolytic effect of diazepam seen in the Low Activity strains was a reduction in stretch attend posture (SAP). Low Activity strains also displayed freezing behavior in both the OFT and EPM. The combination of the observed freezing behavior, that was not reduced by diazepam, and the reduction in SAP seen with diazepam, suggests a more complex phenotype that includes a component of innate fear in addition to anxiety-related risk assessment behaviors. Since fear and anxiety are distinguishable traits, and both contribute to human anxiety disorders, these results provide novel insight about interpretation of previous genetic and phenotypic differences observed between the High and Low Activity strains.

Dynamic switching of neural oscillations in the prefrontal–amygdala circuit for naturalistic freeze-or-flight

The medial prefrontal cortex (mPFC) and basolateral amygdala (BLA) are involved in the regulation of defensive behavior under threat, but their engagement in flexible behavior shifts remains unclear. Here, we report the oscillatory activities of mPFC-BLA circuit in reaction to a naturalistic threat, created by a predatory robot in mice. Specifically, we found dynamic frequency tuning among two different theta rhythms (~5 or ~10 Hz) was accompanied by agile changes of two different defensive behaviors (freeze-or-flight). By analyzing flight trajectories, we also found that high beta (~30 Hz) is engaged in the top-down process for goal-directed flights and accompanied by a reduction in fast gamma (60 to 120 Hz, peak near 70 Hz). The elevated beta nested the fast gamma activity by its phase more strongly. Our results suggest that the mPFC-BLA circuit has a potential role in oscillatory gear shifting allowing flexible information routing for behavior switches.

Shock or jump: deimatic behaviour is repeatable and polymorphic in the Apennine yellow-bellied toad, Bombina pachypus

Abstract Inter-individual variation in antipredatory behaviour has long attracted curiosity among scientists. Deimatism is a complex, multi-component antipredatory strategy consisting of prey suddenly unleashing unexpected defences to startle predators and stop their attack. Deimatic species provide an appealing system to investigate the trade-offs between alternative behavioural phenotypes when faced with a threat. Yet, inter-individual variation in deimatic behaviour is almost unexplored. Here, we simulated a predator attack on 71 yellow-bellied toads, Bombina pachypus, to investigate the extent and pattern of inter-individual variation in the unken reflex behaviour, a deimatic display performed by some amphibians. Results show that deimatic displays consistently differ among B. pachypus individuals. Only about half of the individuals reacted to the simulated predation stimuli by exhibiting the display, which varied in responsiveness, duration and intensity. All the behavioural descriptors were highly repeatable. Finally, we found significant correlations between the measured parameters, defining two prevalent behavioural profiles: individuals quickly doing the unken reflex, with high intensity and long duration of the display, and individuals avoiding the unken reflex but instead escaping. This dichotomy resembles the proactive and reactive patterns in coping styles, and raises intriguing questions on the evolutionary processes shaping multiple adaptive responses to predation within populations.

Phenotypic and genetic characterization of Africanized Apis mellifera colonies with natural tolerance to Varroa destructor and contrasting defensive behavior.

Africanized Apis mellifera colonies with promising characteristics for beekeeping have been detected in northern Argentina (subtropical climate) and are considered of interest for breeding programs. Integral evaluation of this feral material revealed high colony strength and resistance/tolerance to brood diseases. However, these Africanized honeybees (AHB) also showed variable negative behavioral traits for beekeeping, such as defensiveness, tendency to swarm and avoidance behavior. We developed a protocol for the selection of AHB stocks based on defensive behavior and characterized contrasting colonies for this trait using NGS technologies. For this purpose, population and behavioral parameters were surveyed throughout a beekeeping season in nine daughter colonies obtained from a mother colony (A1 mitochondrial haplotype) with valuable characteristics (tolerance to the mite Varroa destructor, high colony strength and low defensiveness). A Defensive Behavior Index was developed and tested in the colonies under study. Mother and two daughter colonies displaying contrasting defensive behavior were analyzed by ddRADseq. High-quality DNA samples were obtained from 16 workers of each colony. Six pooled samples, including two replicates of each of the three colonies, were processed. A total of 12,971 SNPs were detected against the reference genome of A. mellifera, 142 of which showed significant differences between colonies. We detected SNPs in coding regions, lncRNA, miRNA, rRNA, tRNA, among others. From the original data set, we also identified 647 SNPs located in protein-coding regions, 128 of which are related to 21 genes previously associated with defensive behavior, such as dop3 and dopR2, CaMKII and ADAR, obp9 and obp10, and members of the 5-HT family. We discuss the obtained results by considering the influence of polyandry and paternal lineages on the defensive behavior in AHB and provide baseline information to use this innovative molecular approach, ddRADseq, to assist in the selection and evaluation of honey bee stocks showing low defensive behavior for commercial uses.

Distinct circuits in anterior cingulate cortex encode safety assessment and mediate flexibility of fear reactions

Safety assessment and threat evaluation are crucial for animals to live and survive in the wilderness. However, neural circuits underlying safety assessment and their transformation to mediate flexibility of fear-induced defensive behaviors remain largely unknown. Here, we report that distinct neuronal populations in mouse anterior cingulate cortex (ACC) encode safety status by selectively responding under different contexts of auditory threats, with one preferably activated when an animal staysing in a self-deemed safe zone and another specifically activated in more dangerous environmental settings that led to escape behavior. The safety-responding neurons preferentially target the zona incerta (ZI), which suppresses the superior colliculus (SC) via its GABAergic projection, while the danger-responding neurons preferentially target and excite SC. These distinct corticofugal pathways antagonistically modulate SC responses to threat, resulting in context-dependent expression of fear reactions. Thus, ACC serves as a critical node to encode safety/danger assessment and mediate behavioral flexibility through differential top-down circuits.