Fighting Behavior Research Articles

Monkeys fight more in polluted air

Air pollution is a global environmental problem, and its effects on human behavior, psychology, and health have been well studied. However, very few studies were done on if and how air pollution affects animal behavior, for example, social conflict. Many physiological and psychological evidences suggest a possible positive relationship between air pollution and animal social conflict, thus we established a multiple linear regression model using a captive monkey group to explore if monkeys behave more aggressively in polluted air. Our results confirmed that daily social fighting behaviors occurred more when air is polluted. Temperature has a nonlinear effect on monkey social conflict, with a fighting peak at 25–29 °C. To our knowledge, this is the first report that animal social conflict, like humans, is also affected by air pollution and temperature.

Motion Direction Inconsistency‐Based Fight Detection for Multiview Surveillance Videos

Nowadays, with the increasing number of surveillance cameras, human behavior detection is of importance for public security. Detection of fight behavior using video surveillance is an essential and challenging research field. We propose a multiview fight detection method based on statistical characteristics of the optical flow and random forest. Cyberphysical systems for monitoring can obtain timely and accurate information from this method. Two novel descriptors named Motion Direction Inconsistency (MoDI) and Weighted Motion Direction Inconsistency (WMoDI) are defined to improve the performance of existing methods for videos with different shooting views and solve the misjudgment on nonfight, such as running and talking. First, YOLO V3 algorithm is applied to mark the motion areas, and then, the optical flow is computed to extract descriptors. Finally, Random Forest is used for classification based on statistical characteristics of descriptors. The evaluation results on CASIA dataset demonstrate that the proposed method can improve the accuracy and reduce the rate of missing alarm and false alarm for the detection, and it is very robust against videos with different shooting views.

Elevated Proinflammatory Cytokines in Cerebrospinal Fluid of Perpetrators of Domestic Violence

Background: Domestic violence (DV) is a major health problem. To date, the “fight” behavior manifested by perpetrators of domestic violence (PDV) has largely been attributed to psychosocial causes, with little emphasis given to biological antecedents. Since cytokines can modulate brain processing and have been associated with human aggression, we postulated that changes in cytokine levels may have a role in the pathology of DV. Methods: We obtained cerebral spinal fluid (CSF) as well as plasma samples from PVD with and without a diagnosis of alcohol dependence, as well as alcoholics and healthy controls without a history of DV. The presence or absence of violence as well as a lifetime diagnosis of PTSD were analyzed as independent variables and alcohol dependence was a covariate. Findings: Patients with a history of DV had significantly higher CSF concentrations of IL-6 and IL-8 than the non-violent controls. The IL-6 effect was driven by an interaction of perpetrator status and a lifetime diagnosis of PTSD. There were no correlations between the cytokine levels present in the CSF and those in the plasma. Interpretation: Our results, add to a growing literature indicating that cytokines have a role in psychopathology. The interaction between IL-6 and PTSD suggests that trauma may alter the production of cytokines, and thereby modulate the neuropathways that facilitate fight behavior. Fight behavior conveys survival benefit in war but becomes pathological in the home-setting with devastating consequences. Funding Statement: This research was supported by the Intramural NIAAA research program. Declaration of Interests: All authors report no biomedical financial interests or potential conflicts of interest. Ethics Approval Statement: This study was approved by the NIH Institutional Review Board. All participants provided written informed consent before participation.

The interplay of parenting style and family rules about video games on subsequent fighting behavior.

Due to ongoing concerns about adolescent interpersonal aggression and debates surrounding violent media, this study assesses the potential impacts of parental mediation and parenting style on mature video game play and fighting behaviors using a longitudinal, random-digit-dial survey of adolescents (N = 2722). By simultaneously considering fighting, M-rated video game play, parental restrictions on media use, parenting style, and important covariates, we aim to provide further nuance to existing work on risk and protective factors for interpersonal aggression. Our results show that parental restriction has a significant, linear relationship with later fighting, whereby higher restrictions on a child's M-rated video game play predict decreases in reported fighting behavior. Authoritative parenting, high in both warmth and supervisory attention, also relates to decreased levels of fighting compared to other styles. Parenting style also moderated the effects of restriction, such that restriction was not equally predictive of fighting behavior across all parenting styles. However, the association between restriction and fighting was similar for highly demanding parenting styles, suggesting that authoritative parenting is not inherently superior to authoritarian. The effects of restriction were significant despite controlling for multiple covariates. Parental restriction of media use may be an effective strategy for parents concerned about violent games. Given some limitations in our dataset, we call for continued study in this area.

Health and behavioural outcomes of bullying victimisation among Indonesian adolescent students: findings from the 2015 Global School-based Student Health Survey

ABSTRACT Bullying victimisation among adolescents is globally recognised as an important predictor for several adverse health and behavioural outcomes. Due to a paucity of studies in Indonesia, this study aimed to identify the adverse health and behavioural outcomes due to bullying victimisation among school-going adolescents and investigate the possible moderation by age and sex. This was an analysis of the second Global School-based Student Health Survey data of Indonesia conducted in 2015. The eligible samples were 9,601 adolescent students. The main independent variable was bullying victimisation status, while the dependent variables consisted of mental health problems, substance use, and other risk behaviours. Binary logistic regression controlling for some confounders was applied to identify the associations among sex-merged and sex-separated samples. Furthermore, adjusted margin probabilities of having adverse outcomes were calculated by bullying victimisation frequency and age. This study found that nearly 2 out of 10 adolescent students were bullied in the last 30 days. Bullying victimisation was associated with the odds of all adverse health and behavioural outcomes that include loneliness, anxiety, suicidal ideation, smoking cigarettes, alcohol use, truancy, physical fight, and sedentary behaviour. The associations were slightly larger among female than male students for some of the outcomes. The odds of these adverse outcomes increased with the rising frequency of bullying and by age. The findings suggest that bullying victimisation was associated with a number of adverse health and behavioural outcomes among Indonesian adolescent students. Implementation of anti-bullying interventions among students right from a young age is essential to prevent unexpected adverse outcomes and its detrimental consequences.

Numerical study of debris flight in a tornado-like vortex

This paper presents the numerical study on the flight behaviour of spherical compact debris in a tornado-like wind field. The tornado-like vortex corresponding to a swirl ratio of 0.7 was generated using Large-eddy Simulation and the trajectories of 2250 individual debris particles placed in the flow were computed using Lagrangian-particle tracking. The debris corresponded to five groups (A, B1, B2, B3 and C) based on the value of the Tachikawa number (K) which ranged between 0.6 and 2.5. An analysis of the simulated flow field revealed that the tornado-like vortex consisted of two main features - a core at the centre with low velocity (∼0.25 m/s) which was surrounded by thick vortex wall composed of high velocity magnitudes (∼9.4 m/s). Updraft flows were observed around the core of the vortex and as a result, debris positioned around the core radius region were found to be 24% more likely to become wind-borne than debris positioned at the vortex wall region. Three groups of debris (B1, B2 and B3) with varying mass and density were studied for the aerodynamic similarity by retaining the fixed value of K = 1.2; all three debris groups exhibited the propensity to travel with similar flight characteristics. An analysis of the data pertaining to the fight behaviour of the three debris group (A, B1 and C) with varying K revealed that the low mass debris group A (K = 2.5) had the highest propensity to become wind-borne and was more likely to travel for the longest time with considerable variability observed in individual debris trajectories. However, somewhat counterintuitively, the high mass debris group C (K = 0.6) were found to have the furthest impact range despite their short flight duration; this was due the high mass debris being ejected out of the vortex with greater inertia, while debris with a lower mass had a tendency to be trapped in the flow that circulates around the vortex core.

Effects of female body size and age and male mating status on male combat in Anastatus disparis (Hymenoptera: Eupelmidae)

1. Aggressive behaviour is widely exhibited by animals to acquire important resources and usually shows a dangerous or nondangerous pattern. Dangerous fighting patterns are usually characterized by fights ending with contestants being severely injured or killed. Resource value is an important nonstrategic factor influencing fighting behaviour. Studies of many species addressing nondangerous fighting behaviour have shown that when resource values change, organisms usually adjust their fighting behaviour accordingly. Only a few species show dangerous fighting patterns. Thus, few relevant studies have addressed how variation in resource value affects aggression with a dangerous fighting pattern.2. Here, an egg parasitoid wasp, Anastatus disparis, which exhibits a dangerous fighting pattern to acquire mating opportunities, was used as an experimental model to study the adjustment of fighting behaviour resulting from a change in resource value.3. Our results show that the female properties of body size and age affect their objective resource value and that males increased their fighting intensity for relatively large and young females. However, male mating status in A. disparis may not influence the subjective value of mate resources, and fighting intensity did not significantly differ between mated and virgin males. In addition, the number of times a male had previously mated had no significant effect. These results suggest that mating opportunities are important for both virgin and mated males, resulting in neither of them showing any adjustment in fighting for mating opportunities.4. Generally, A. disparis males with extreme fighting patterns adjust their fighting behaviour according to the variation in resource value, which avoids the meaningless costs of injury and death.

Effect of Winning Experience on Aggression Involving Dangerous Fighting Behavior in Anastatus disparis (Hymenoptera: Eupelmidae).

Aggressive behavior is widely observed in animal species for acquiring important resources and usually includes both dangerous and nondangerous fighting patterns. Only a few species show dangerous fighting patterns that are defined by fights ending with contestants being severely injured or killed. Prior experience, an important factor in many species, has been demonstrated to affect a contestant’s subsequent fighting behavior. Few studies have focused on the effect of experience on aggression involving dangerous fighting patterns. Here, an egg parasitoid wasp, Anastatus disparis, which shows extreme and dangerous fighting behavior to acquire mating opportunities, was used as an experimental model. Our results showed that the fighting intensity of the winning males significantly decreased subsequent fighting behavior, which was inconsistent with general predictions. Transcriptomic analyses showed that many genes related to energy metabolism were downregulated in winners, and winners increased their fighting intensity after dietary supplementation. Our study suggested that fighting in A. disparis is a tremendous drain on energy. Thus, although males won at combat, significant reductions in available energy constrained the intensity of subsequent fights and influenced strategic decisions. In addition, winners might improve their fighting skills and abilities from previous contests, and their fighting intensity after dietary supplementation was significantly higher than that of males without any fighting experience. Generally, in A. disparis, although winners increased their fighting ability with previous experience, the available energy in winners was likely to be a crucial factor affecting the intensity and strategic decisions in subsequent fights.

Analysis of the source of aggressiveness in gamecocks

Although the fighting behaviour in gamecocks has evolved because of artificial selection, it is unknown whether the selection for aggressiveness affects neurotransmitter levels in the avian central nervous system. We sought to identify the source and origin of this trait. We collected the brain samples from 6 female Shamo gamecocks and 5 Shaver Brown chickens (control; bred for egg production). The midbrain levels of norepinephrine (NE) were significantly higher in Shamo gamecocks (P = 0.0087) than in the controls. Moreover, alleles encoding adrenergic receptors differed between the breeds in terms of response to NE. Gene mutations specific to Shamo and potentially associated with fighting behaviour were in sites T440N of ADRα1D; V296I of ADRα2A; and T44I, Q232R, and T277M of ADRβ2. The evolutionary analysis indicated that the ADRβ2 (T44I and Q232R) mutations were heritable in all Galliformes, whereas the T440N mutation of ADRα1D and V296I mutations of ADRα2A were unique to Shamo and originated by artificial selection. A high NE level may confer a selective advantage by enabling gamecocks to be aggressive and pain tolerant. Therefore, the strong fighting behaviour of Shamo has resulted from a combination of naturally inherited and mutant genes derived by artificial selection.

Effects of prenatal ethanol exposure on acoustic characteristics of play fighting-induced ultrasonic vocalizations in juvenile rats

Juvenile rats display rough-and-tumble playing with conspecifics (play fighting behavior) and produce 22 and 50 kHz ultrasonic vocalizations (USVs). The 22 kHz USV is considered to reflect negative emotionality such as anxiety, fear, and distress, whereas the 50 kHz USV is considered to reflect positive emotionality such as joy, happiness, and satisfaction. USV is a sensitive tool for measuring emotionality in socially interactive situations. However, effects of prenatal ethanol-exposure on the acoustic characteristics of play fighting-induced USVs have remained unclear. In Experiment I, we recorded USVs produced by prenatally ethanol-exposed rats during play fighting on postnatal days (PNDs) 40–42 and examined the acoustic characteristics of negative and positive emotion-induced USVs. In Experiment II, we examined the anxiety levels through elevated plus maze testing on PNDs 37–39 and frequencies of playful attacks on PNDs 43–45 in ethanol-exposed rats. Ethanol was administered to pregnant rats in three gradually increased concentrations between gestational days (GDs) 8 and 20. From GDs 14 to 20, ethanol-containing tap water at concentrations of 30% and 15% (v/v) was administered to the high- and low-ethanol groups, respectively. Tap water without added ethanol was given to the control group. On PNDs 40–42, three rats from the same sex and same ethanol concentration group but from different litters were placed together into a playing cage for play fighting. The high-ethanol male triads displayed elevations of 20–35 kHz USVs reflecting negative emotionality and reductions of 45–70 kHz USVs reflecting positive emotionality compared with both the low-ethanol and control male triads. The high-ethanol male triads had prominent elevations of 20–35 kHz USVs with durations longer than 200 ms, whereas the control male triads did not produce such 20–35 kHz USVs at all. There was no difference in USV acoustic characteristics among the female triads. In addition, the high-ethanol male rats exhibited greater anxiety levels and less frequencies of play fighting than the control male rats. Altogether, we conclude that prenatal exposure to ethanol enhances negative emotionality such as anxiety and, accordingly, 20–35 kHz USVs reflecting negative emotionality are produced with a marked decrease in play fighting, suggesting difficulties in social interactions with conspecifics.

Physical Fighting among School-Attending Adolescents in El Salvador: An Examination of the 2013 Global School-Based Health Survey.

Background: Violence among school-attending adolescents is an important public health problem worldwide. The present study examined demographic correlates for physical fighting behavior among a nationally representative sample of school-attending adolescents in El Salvador. Methods: Initial cross-tabulations to screen for correlations was then followed by logistic regression to understand the direction and the strength of selected demographic variables for physical fighting behavior, which occurred within a 12 month period of recall. Results: Out of a sample of 1910 school-attending adolescents in El Salvador, 11.5% reported having been involved in two or more physical fights during the recall period. Regression analyses indicated that being male (OR = 3.55; 95% CI = 2.11–6.00); having experienced bullying (OR = 2.16; 95% CI = 1.44–3.24); physical activity (OR 0.61; 95% CI 0.46–0.80); a sedentary lifestyle (OR 1.54; 95% CI 1.05–2.27), suicide planning (OR 2.28; 95% CI 1.46–3.56), and having non-understanding parents (OR = 1.45; 95% CI 1.06–1.98) were significantly associated with physical fighting among the sampled adolescents. Conclusion: Within the limitations of cross-sectional surveys conducted in school settings, the results of the present study suggest that giving attention to preventing bullying behavior among males and involving parents should be components of a multi-pronged strategy to preventing physical fighting in schools in El Salvador.

Psychopathic Sims: Testing the Cheater-Hawk Hypothesis in a Video Game

We investigated the Cheater-Hawk Hypothesis of psychopathy in a sample of 205 undergraduate students. Participants played The Sims 3 video game with four pre-made same-sex roommate characters whose personalities were selected to represent a cheater, a hawk, a cooperator, and a dove. Interactions between game characters were coded for charm, friendliness, and provoked/unprovoked aggression (“mean” and “fight” behaviors). Overall, people with psychopathic traits used more hawk behaviors (mean and fight behaviors), irrespective of character, but they did not use more of the cheater-related behaviors (“friendly,” “funny,” and “complimenting” behaviors). With respect to specific characters, participants with psychopathic traits used primarily hawk behaviors with the cheater and dove and cheater behaviors with the hawk (in keeping with predictions). Overall, there was some support for the Cheater-Hawk Hypothesis. As well, people higher on psychopathic traits appear to engage in different behaviors depending upon the target of their behavior. Overall, the study also lends support to the use of video game paradigms for investigating behavior.

Allometry and Fighting Behaviour of a Dimorphic Stag Beetle Cyclommatus mniszechi (Coleoptera: Lucanidae).

Male stag beetles (Coleoptera: Lucanidae) use their mandibles as weapons to compete for resources and reproduction. Mandible size in stag beetles can be associated with different behaviours and the outcome of male contests. We investigated the allometric relationship between mandible and body size in males of the stag beetle Cyclommatus mniszechi to uncover distinct morphs. The results divided male C. mniszechi into majors and minors with the switch point of mandible length at 14.01 mm. The allometric slope of mandibles was positive for both morphs but was steeper for the minors. We also characterised the fighting behaviour of the different morphs in size-matched contests using sequential analyses. Males matched each other’s behaviour in contests with many physical contacts, no injury and a progression from low towards high aggression and rare de-escalation. Major and minor males employed the same behavioural elements in contests, but major males were more likely to escalate directly into more aggressive phases and minor males tended to stay within phases. This finding suggests that major males may compete more aggressively than minor males in contests.

Involvement in Physical Fights among School Attending Adolescents: A Nationally Representative Sample from Kuwait.

Background: Interpersonal violence in school settings is an important public health problem worldwide. This study investigated the individual and social correlates for being involved in a physical fight amongst a nationally representative sample of school-attending adolescents in Kuwait. Methods: We carried out bivariate and multivariate analyses to determine the strength and direction of associations with adolescent involvement in problematic fighting behavior within a 12-month recall period. Results: Within a total sample of 3637, n = 877 (25.2%) of school-attending adolescents reported being involved in two or more physical fights during the recall period. The multivariate analysis indicated that being male (OR = 2.71; CI = 1.88–3.90), a victim of bullying (OR = 2.77; CI = 2.14–3.58), truancy (OR = 2.52; CI = 1.91–3.32), planning a suicide (OR = 2.04; CI = 1.49–2.78) and food deprivation (OR = 1.91; CI = 1.37–2.65) were associated with an increased risk of involvement in physical fighting. Peer support in the form of having close friends (OR = 0.85; CI = 0.76–0.96) was found to be associated with a reduced involvement in fighting behavior. Conclusion: The results, when taken together, suggest that supportive school environments may represent important settings for violence mitigation and prevention strategies.

The influence of Hermetia illucens larvae as feed on fitness and the agonistk character of Betta fish (Betta sp.)

The behavior of Betta sp. was very much influenced by nutritious food. The method used is descriptive that is measuring weight gain and body length and survival in the control treatment (0%), 25%, 50%, 75% and 100%, then also observed pre fighting behavior which includes opening operculum, tail flix, tail fin and stering and also fighting behavior was observed. The results showed that starting from weight gain, the length of all BSF treatments was higher than the control, then all treatments were also crossed, for Pre fighting operculum opening, tail flixes, tail fin and stering for various treatments BSF was also better than the control so it was also in fights shows all BSF treatment wins against control.

Size Does Not Matter: Same-Sex Sexual Behavior Occurred Regardless of Mandible Size in Male Stag Beetle Aegus chelifer chelifer (Coleoptera: Lucanidae)

Male Aegus chelifer chelifer stag beetles are normally equipped with long mandibles as a weapon to compete with rival males over females, where fighting or aggressive behavior is generally expected during the encounter between two male stag beetles. However, three main patterns were observed between 164 pairings of male stag beetles. Besides the predominant aggressive or fighting behavior (107 pairings), male stag beetles also exhibited disregarding behavior (29 pairings) and same-sex sexual behavior (28 pairings). For sexual interactions, active males exhibited courting and mating behavior as found in male-female interactions, but the insemination process was unsuccessful. Responses of passive males varied from totally passive to resisting and running away. Visual confusion of short-mandible males for females by active males was not likely to be responsible for the same-sex sexual behavior because the correlation between body size and the sexual behavior or sexual role between male-male pairs was not significant. Rather, sexual recognition via chemicals on the cuticle surface might be responsible for the same-sex sexual behavior.

Fighting Assessment Triggers Rapid Changes in Activity of the Brain Social Decision-Making Network of Cichlid Fish.

Social living animals have to adjust their behavior to rapid changes in the social environment. It has been hypothesized that the expression of social behavior is better explained by the activity pattern of a diffuse social decision-making network (SDMN) in the brain than by the activity of a single brain region. In this study, we tested the hypothesis that it is the assessment that individuals make of the outcome of the fights, rather than the expression of aggressive behavior per se, that triggers changes in the pattern of activation of the SDMN which are reflected in socially driven behavioral profiles (e.g., dominant vs. subordinate specific behaviors). For this purpose, we manipulated the perception of the outcome of an agonistic interaction in an African cichlid fish (Oreochromis mossambicus) and assessed if either the perception of outcome or fighting by itself was sufficient to trigger rapid changes in the activity of the SDMN. We have used the expression of immediate early genes (c-fos and egr-1) as a proxy to measure the neuronal activity in the brain. Fish fought their own image on a mirror for 15 min after which they were allocated to one of three conditions for the two last minutes of the trial: (1) they remained fighting the mirror image (no outcome treatment); (2) the mirror was lifted and a dominant male that had just won a fight was presented behind a transparent partition (perception of defeat treatment); and (3) the mirror was lifted and a subordinate male that had just lost a fight was presented behind a transparent partition (perception of victory treatment). Results show that these short-term social interactions elicit distinct patterns in the SDMN and that the perception of the outcome was not a necessary condition to trigger a SDMN response as evidenced in the second treatment (perception of defeat treatment). We suggest that the mutual assessment of relative fighting behavior drives these acute changes in the state of the SDMN.

Pay attention to the ladies: female aggressive behavior and weapon allometry provide clues for sexual selection in freshwater anomurans (Decapoda: Aeglidae)

Contesting scarce resources can trigger the evolution of specialized morphological structures (i.e., animal weapons). While most research focus on male weapons, females might also bear weapons, although generally smaller and less conspicuous than male weapons. Social selection is evoked to explain female weaponry in which females fight for nonsexual resources such as food and shelter. Males might fight for similar resources but are expected to have proportionally larger weapons due to additional inputs from sexual selection. We tested whether males have proportionally larger weapons than females in two species of Aegla crabs. Interestingly, only males of one species had proportionally larger claws than females. Given that these larger weapons typically correlate to increased aggression, we expected males to fight more intensely than females. Thus, we compared intrasexual contests of males and females of the same species. Females fought similarly to males: latency, contest duration, and frequency of highly aggressive acts were similar between the sexes. Therefore, despite males having proportionally larger weapons in one species (as predicted by sexual selection), they fought similarly to females. Our results hint that fighting might not necessarily be the source of selection for sexual dimorphism we typically expect. Other sources, such as the frequency of fighting and predation pressure, might be selecting larger claws in males despite the similar fights, while fecundity costs might downsize female claws. We highlight that comparing female with male weapons and the associated fighting behavior shows that selection on weapons is not as straightforward as we might think. We show that studying the highly neglected female weapon allometry and usage allows us to infer on the selective process acting on animal weapons. We show here that males of one species have proportionally larger weapons, and, despite that, males fight similarly to females in every aspect analyzed. Therefore, fighting per se might not be the sole source of selection to explain sexual dimorphism. Other sources, such as frequency of fighting, and how expensive it is to produce gametes might be additional sources of selection.

An Attachment Theoretical Perspective on Tend-and-Befriend Stress Reactions

This study investigates the “tend-and-befriend” hypothesis proposed in 2000 by Taylor and colleagues, which posits that women utilize an alternative stress response to fight-or-flight, ensuring the survival of themselves and their offspring (tend) through the formation of groups (befriend). In contrast, we propose that, while sexes may differ in the use of tend-and-befriend behaviors, attachment style is a more robust predictor of these behaviors. The relationships among sex, adult attachment anxiety and avoidance, and stress responses were examined in 237 young adults. Participants completed the Experiences in Close Relationships—Revised and the Tend-and-Befriend Questionnaire. Results suggest that women preferred tend/befriend and flight responses over men, while men engaged in more fight responses than women. However, importantly, women and men both endorsed being most likely to engage in tend/befriend behaviors during stress than other responses. Attachment style was an independent and robust predictor of all stress responses, with anxious attachment predicting fight and flight behaviors and increased tend/befriend behavior, and avoidant attachment predicting decreased tend/befriend behavior. One interaction was also identified: Women who were more avoidantly attached were as likely as men to engage in fight behaviors, while less avoidant women reported the lowest fight response. Our findings suggest that while sex differences in self-reported tend-and-befriend behaviors may exist, exploration within sexes (an important oversight of previous research) may indicate different patterns of results. We found evidence of strong effects of attachment style on all forms of stress response, even after accounting for sex, indicating the importance of attachment behavior in stress responsivity.

Effect of variation in objective resource value on extreme male combat in a quasi-gregarious species, Anastatus disparis

BackgroundAggressive behaviour is widely observed in animal kingdom, which compete for resources such as territory, food and mates. Resource value is the most important non-strategic factor influencing fighting behaviour, and may vary among contests and contestants. Usually, contestants adjust their fighting behaviour when the resource value changes, and as potentially damaging and energetically costly, individuals of most species usually avoid conflict escalation. However, in a quasi-gregarious egg parasitoid, Anastatus disparis (Hymenoptera: Eupelmidae), mates are valuable resources and females mate only once; thus, males engage in frequently extreme combat behaviour to acquire mating opportunities, even in the absence of females. In this study, we attempted to test whether males of this species have the ability to adjust their fighting behaviour in response to changes in the objective value of female.ResultsOur results suggested that objective resource value in A. disparis is likely to be influenced by female mating status rather than by fecundity. Consistent with a number of empirical studies, A. disparis males adjusted their fighting behaviour according to the value of the contested resources: males significantly increased their fighting intensity to acquire mating opportunities with virgin females but decreased their fighting intensity for mated females. We also found that rather than chemical cues, visual cues and physical sexual contact appear to play a role in determining males’ ability to detect variation in female mating status.ConclusionsOur study suggested that although in this species, males have evolved extreme fighting behaviour and females are valuable resources, males do not always escalate fighting behaviour in competition for mating with a female. Valuable resources and variation in resource value were detected and estimated by A. disparis males, which then adjusted their fighting behaviour accordingly and to some extent avoided incoming fighting costs.