Search Results (69)

Same-sex sexual behavior in invertebrates includes interactions such as courtship, mounting, copulation, tandem running, and pair formation between individuals of the same sex. We conducted a systematic synthesis of 222 primary studies and 12 reviews and found published evidence of SSB in approximately 207 species spanning arthropods, mollusks, annelids, echinoderms, nematodes, and flatworms. Although most reports involved insects (approximately 89%), standardized reporting rates suggest this bias reflects research effort rather than true biological prevalence. Observations came from field studies, although several taxa, particularly Diptera and Hymenoptera, were disproportionately represented by laboratory work. Copulation-like interactions were the most frequently reported behavior, followed by courtship and mounting. Where authors proposed explanatory frameworks, mistaken identity or indiscriminate mating was the most invoked interpretation, although adaptive functions and socially mediated explanations were also recurrent. Direct measurements of fitness consequences were rare and yielded mixed outcomes, suggesting that the consequences of SSB are context dependent rather than uniformly beneficial or maladaptive. Overall, the available evidence supports the view that SSB in invertebrates is neither anomalous nor reducible to a single mechanism. Instead, it appears as a heterogeneous component of the behavioral repertoire whose expression is shaped by mating system, study type, and taxonomic history. Full article

Male infertility is an increasing global health concern associated with declining population growth. Mancozeb (MZ) exposure may induce reproductive toxicity through endocrine disruption and oxidative stress, impairing spermatogenesis. This study evaluated the effects of White Bualuang extract (WBE) on sexual behavior, testicular histomorphometry, and spermatogenic parameters in rats exposed to MZ. Thirty mature male rats were randomly assigned to the following five groups (n = 6): Control, MZ 500 mg/kg, MZ + 0.55 mg/kg WBE, MZ + 1.10 mg/kg WBE, and MZ + 2.20 mg/kg WBE, for 30 days. Sexual behaviors, relative testis weight, antioxidant properties, and histomorphometry parameters were determined. MZ-exposed rats had significantly decreased courtship behavior, seminiferous tubule diameter, and a tendency toward decreased spermatogenic cell numbers, along with enlarged interstitial spaces. However, pretreatment with WBE, especially at a dose of 0.55 mg/kg, showed improvements in courtship behavior and several histomorphometry parameters and was associated with increased Sertoli cell efficiency and spermatogenic organization compared with the MZ group. WBE showed potential to reduce lipid peroxidation (LPO) and advanced oxidation protein products (AOPP) in MZ-exposed rats, particularly, the 0.55 mg/kg dose improved courtship behavior and reproductive parameters, supporting further investigation of WBE as an antioxidant and potential functional supplement. Full article

Progesterone (P₄) regulates diverse reproductive processes across vertebrates through nuclear receptors; however, its mechanisms in squamate reptiles—particularly in viviparous species—remain poorly understood. In Squamata, P₄ primarily acts through progesterone receptor (PR) isoforms A and B, although relatively few reptilian PR sequences have been characterized to date. Squamate PR exhibits ~50% overall sequence divergence from mammalian homologs yet retains striking conservation in both the ligand and DNA-binding domain across vertebrates. Despite the broadly conserved physiological roles of P₄ (folliculogenesis, ovulation, courtship behavior, pregnancy maintenance, and parturition/oviposition), P₄ dynamics in viviparous squamates remain unresolved due to heterogeneous circulating hormone concentrations and limited PR phylogeny and structure studies. While mammalian models dominate P₄ research due to their biomedical relevance, squamates offer unique evolutionary insights: as the only reptile order exhibiting both oviparity and viviparity within the same clade, squamates represent an ideal model for investigating transitions in parity mode. Elucidating P₄ mechanisms in squamates will help bridge this critical evolutionary gap, with important implications for reproductive biology and conservation. Full article

Mating behavior plays a critical role in the reproductive success and population dynamics of insects. Praon volucre is a widespread, broadly oligophagous aphid parasitoid and an important natural enemy in agricultural and natural ecosystems. The present study provides the first detailed characterization of the courtship and mating sequence of P. volucre, examining the effects of host association and behavioral lateralization on mating performance. Behavioral observations were conducted on virgin P. volucre adults emerging from two aphid hosts, Macrosiphum euphorbiae feeding on Citrus aurantium and Aulacorthum solani feeding on Malva neglecta. Males from both host-derived populations exhibited a left-side mounting bias, which was associated with faster mate detection, reduced courtship duration, and higher mating success. Mating behavior remained largely stable across host origins, indicating a high degree of behavioral stability. This behavioral robustness, combined with enhanced mating efficiency driven by lateralization, underscores the suitability of P. volucre as a biological control agent. The results have practical implications for mass-rearing and release programs, suggesting that a potential host switching during rearing is unlikely to compromise reproductive performance. Full article

Cavity limitations and interspecific competition render large macaws valuable models for elucidating the integration of parental care, pair-bond maintenance, and nest defense across reproductive stages. Through continuous video monitoring of a single artificial polyvinyl chloride nest box in the Tambopata National Reserve, Peru, we quantified the complete breeding cycle of a resident green-winged macaw (Ara chloropterus) pair and the visitation behavior of a sympatric scarlet macaw (Ara macao) pair within the same cavity. We constructed daily time budgets for 17 behaviors, categorized into seven functional groups, from motion-triggered video clips; employed multivariate tests; and generalized additive models with beta error distribution to describe the temporal changes across the five reproductive stages. The resident A. chloropterus exhibited a significant reorganization of parental investment, with early courtship behaviors transitioning to peak nest attendance and sentinel vigilance during incubation and early brooding. In later stages, locomotion increased significantly, associated with chick provisioning, whereas the frequency of allopreening remained relatively constant throughout the cycle. The visiting A. macao displayed a brief, behaviorally rich prospecting phase, characterized by nest inspection and locomotion, followed by a sharp decline in minimal activity. These divergent strategies align with owner–intruder asymmetries and floater dynamics, indicating that artificial cavities can support A. chloropterus breeding, while suggesting that additional cavities may redistribute breeding opportunities among competing macaws, a hypothesis necessitating multi-nest and multi-year evaluation. Full article

The Sakhalin pine sawyer, Monochamus saltuarius Gebler, 1830 (Coleoptera: Cerambycidae), is a newly discovered insect vector of the pine wood nematode (Bursaphelenchus xylophilus) in China. Despite its ecological importance, the detailed morphology of its sensory systems remains largely unexplored. This study presents comprehensive ultrastructural analysis of the compound eyes and stridulatory organs in adult M. saltuarius, with a focus on sexual differences. Our morphometric results revealed pronounced sexual dimorphism: males possessed significantly larger compound eyes in terms of total area and perimeter. Furthermore, all three types of ommatidial facets (hexagonal, pentagonal, and quadrilateral) exhibited significantly greater area, perimeter, and diameter in males. Interestingly, while the total number of ommatidia and the counts within the dorsal and ventral eye regions showed no significant sexual difference, they were strongly positively correlated with body length in both sexes. Regarding the stridulatory organs, key morphological features including the transverse diameter, longitudinal diameter, and width of the lateral sulcus of the stridulatory file were also significantly greater in males. In contrast, no sexual dimorphism was detected in the width or density of the stridulatory teeth. These findings collectively indicate a significant investment in sexually dimorphic sensory organs in M. saltuarius, which we hypothesize is closely linked to sex-specific behavioral roles, particularly in active mate searching, courtship displays, and intrasexual competition. This research provides a crucial morphological foundation for understanding the species’ visual and acoustic communication, supporting future work on its sensory ecology and the development of behavior-based control strategies for pine wilt disease. Full article

The courtship behavior of moths is closely related to the biosynthesis and release of sex pheromones. To understand the mechanisms of the reproductive behavior of the ghost moth Endoclita davidi, a host insect of Cordyceps xuefeng (Ophiocordyceps xuefengensis), this study examined the courtship behavior and the ultrastructure of the sex pheromone gland of E. davidi. Infrared photography was used to analyze the courtship behavior, while SEM, paraffin tissue sectioning, and TEM were employed to examine the sex pheromone glands on the hind tibia. The courtship behavior of E. davidi occurs during the scotophase, during which males vibrate their wings and unfold the hairpencils located on the hind tibiae to lure the female moths. The hairpencil’s surface features regular longitudinal ridges interspersed with multiple circular pits. Multiple small holes were evident on the slightly enlarged areas close to the ends of the hairpencils. These small holes, formed at the base of the circular pits, connect to the internal glandular duct within the hairpencil, which links to the tibia glandular canal. The epidermal layer of the hind tibiae contains numerous glandular canals and dense microvilli. The glandular cells, specialized from dermal cells, contain numerous mitochondria, rough endoplasmic reticulum, clear vesicles of varying sizes, and round lipid droplets. The sex pheromone glands of male E. davidi release pheromones through the hairpencils in the hind tibia. The courtship behavior and ultrastructure of the sex pheromone gland of the male E. davidi provide a basis for further understanding pheromone release and communication mechanisms. Full article

Cerci function as crucial sensory organs in insects, featuring a diverse array of sensilla on their surface, analogous to those found on antennae. Using scanning electron microscopy (SEM), we characterized the ultrastructure and distribution of cercal sensilla in Hierodula patellifera (H. patellifera) and Statilia maculata (S. maculata). Results show that the cerci of H. patellifera and S. maculata are highly similar, with main differences observed in the number of cercal articles and the length of cerci. The cerci of both species and sexes are composed of multiple cylindrical articles, and there is variation in the number of types of sensilla on their surface articles within sex and individuals. Females possess more cercal articles than males, and their cerci are generally longer than those of males. In both sexes of these praying mantises, four types of cercal sensilla were identified: sensilla filiformia (Sf), sensilla chaetica (Sc), sensilla campaniformia (Sca) and cuticular pore (CP), with sensilla chaetica further classified into two subtypes (ScI, ScII). Sc are widely distributed over the entire cerci, while Sf are distributed in a circular pattern on the cercal articles. While the overall distribution patterns of cercal sensilla were conserved between the sexes, significant sexual dimorphism was observed in the morphological parameters of the sensory hairs, including their quantity, length, and basal diameter. Based on distinct sensilla arrangements on the cerci, we propose a novel zoning of the cerci into four parts (I–IV), which reflects a functional gradient specialized for reproductive roles: the proximal region is enriched with robust mechanoreceptors likely involved in mating and oviposition, the central region serves as a multimodal hub for integrating courtship and mating cues, and the distal region is simplified for close-range substrate assessment. These findings highlight the adaptive evolution of cercal sensilla in relation to reproductive behaviors and provide a morphological basis for future studies on mantis phylogeny and sensory ecology. Full article

The pre-courtship behavior of Proholopterus chilensis on Nothofagus obliqua trees was recorded for the first time, documenting a putative female “calling” behavior and the consequent male “oriented search,” enabling the description of behavioral units, sequences, frequencies, and degrees of stereotypy. Post-resting activity in both sexes began with walking and grooming during the first hour of the scotophase, following a period of daytime inactivity. Subsequently, females extended their ovipositor both horizontally and vertically, alternating between contact with the tree substrate and, simultaneously, walking the surface (=putative calling behavior), while males became active, extending their antennae perpendicularly to the longitudinal body axis. In response to the putative call, males exhibited oriented flight and hasty walking that followed the trajectory and direction previously taken by females on the substrate, ultimately leading to their location. Statistical analysis of behavioral sequences and the stereotypy index indicated that both behaviors were non-random and partially stereotyped. These findings are consistent with previous chemical analyses of female aerations and terminalia performed by our research group, which identified semiochemicals likely functioning as long-range sex pheromones guiding males to the vicinity of the female’s tree, as well as potential trail pheromones facilitating close-range localization. This dual signaling system seems necessary to the high mobility displayed by females during calling behavior, characterized by frequent and extended bidirectional vertical walks along the trunk, which may enhance signal dispersal and/or reduce predation risk. If confirmed, this would represent a novel sexual encounter mechanism within Cerambycidae. Full article

The objective of this study was to characterize the sexual behavior and reproductive performance of Colombian Creole bulls from the Romosinuano (ROM) and Costeño con Cuernos (CCC) breeds, to support their strategic use in tropical production systems and sire selection programs. A standardized sexual behavior test, including nine behavioral indicators, was conducted over a 15 min observation period to assess libido and service capacity. Significant differences (p < 0.05) were found between the breeds in terms of the frequency of urination and mounting behaviors. ROM bulls exhibited a more uniform and rapid behavioral response, while CCC bulls showed greater individual variability and a broader behavioral repertoire, with courtship behaviors—such as smelling, the Flehmen reflex, and butting—strongly associated with ejaculation events. Libido scores were high in both breeds, with 80.35% of bulls rated as very good to excellent. CCC bulls also achieved mounts more frequently within the first five minutes of exposure. Additionally, bull age was inversely associated with mounting time (p < 0.05), suggesting that maturity and sexual experience influence behavioral efficiency. These findings represent the first quantitative assessment of sexual behavior in CCC bulls and provide comparative insights with ROM bulls, highlighting the functional reproductive potential of Colombian Creole bulls under low-input tropical conditions. Full article

Beyond its crucial role as a tight barrier to protect the nervous system, the Blood–Brain Barrier (BBB) is increasingly being recognized for its physiological processes that affect brain function and behavior. In Drosophila melanogaster, the BBB expresses sex-specific transcripts, and a change in the sexual identity of adult BBB cells results in a significant reduction in male courtship behavior. The molecular nature of this BBB/brain interaction and the molecules that mediate it are unknown. Here we feminize BBB cells by targeted expression of the Drosophila female-specific master regulator TraF in otherwise normal males. We examined the effect on RNA expression in dissected brains by RNA sequencing. We find that 283 transcripts change in comparison to normal control males. Transcripts representing cell signaling processes and synaptic communication are enriched, as are hormonal mediators. These transcripts provide a valuable resource for addressing questions about BBB and brain interaction. Full article

This review explores sexual aggression in broiler breeder males, aiming to synthesize existing scientific evidence regarding its causes, behavioral manifestations, and consequences, while addressing the genetic, neuroendocrine, and environmental mechanisms involved. Through an extensive analysis of scientific literature, the paper highlights that intensive genetic selection aimed at enhancing growth and productivity has resulted in unintended behavioral dysfunctions. These include the reduction or absence of courtship behavior, the occurrence of forced copulations, and a notable increase in injury rates among hens. Reproductive challenges observed in meat-type breeder flocks, in contrast to those in layer lines, appear to stem from selection practices that have overlooked traits related to mating behavior. Environmental and managerial conditions, including photoperiod manipulation, stocking density, nutritional imbalances, and the use of mixed-sex rearing systems, are also identified as contributing factors to the expression of sexual aggression. Furthermore, recent genetic findings indicate a potential link between inherited neurobehavioral factors and aggressive behavior, with the SORCS2 gene emerging as a relevant candidate. Based on these insights, the review emphasizes the importance of considering behavioral parameters in breeding programs in order to reconcile productivity objectives with animal welfare standards. Future research may benefit from a more integrative approach that combines behavioral, physiological, and genomic data to better understand and address the multifactorial nature of sexual aggression in poultry systems. Full article

Insect mating behaviors are complex, diverse, and primarily regulated by neuropeptides and their receptors. Neuropeptides are peptide signaling molecules mainly secreted by insects’ central nervous system (CNS) to reach target organs. A substantial body of research on the role of neuropeptides in regulating mating behaviors in insects has been undertaken. This review aims to (1) synthesize existing knowledge on insect mating behaviors, (2) elucidate the neuropeptidergic mechanisms governing these behaviors, and (3) identify knowledge gaps and propose future research directions. The mating process, covering mate attraction, courtship rituals, copulation, and post-mating behaviors, was elucidated with appropriate examples. Additionally, specific neuropeptides involved at each stage of the mating process, their functions, and mechanistic aspects were discussed as demonstrated in research. The review highlights that insects display behavioral dimorphism in the mating process driven by a complex underlying neuropeptidergic mechanism. While previous publications have generally addressed the role of neuropeptides in insect behavior, none has intensively and methodically examined their role in mating behaviors. In this review, we synthesized 18 neuropeptides that we found to regulate mating behaviors in insects. We note that some of the neuropeptides are malfunctional in their regulatory roles, while others are specific. We also note that these neuropeptides execute their regulatory functions through the G protein-coupled receptor (GPCR) signaling pathway but may take different routes and messengers downstream to effect behavioral change. Neuropeptides also interact with other regulatory systems, such as the endocrine system, to discharge their functions. Given their significance in mediating mating and reproduction, targeted manipulation of the signaling system of neuropeptides could serve as viable targets in the production of ecologically friendly pest management tools. Tools that could disrupt the mating process would be applied in crop production systems to reduce the population pressure of destructive pests, consequently reducing the urge to use chemical pesticides that are ecologically unfriendly. Our findings not only advance the understanding of neuropeptide-mediated mating regulation but also highlight their potential as eco-friendly pest control targets. Full article

We report a sequence of unusual male behaviors observed in Nephila pilipes (Fabricius, 1793) (Araneae: Nephilidae Simon, 1894), a sexually size dimorphic tropical spider species in Singapore. We documented a male suitor using his mouth parts (chelicerae) rather than his copulatory organs (pedipalps) to repeatedly probe female genitals. The behaviors may have served as a strategy to assess the female’s mating status, functioned as a courtship strategy, or, most plausibly, represented an attempt to remove a genital plug. The documented chrono-sequence culminated in the male’s attempted commensalism, followed by an aggressive attack by the female, resulting in near-fatal injury to the male. Notably, the attack did not escalate into cannibalism, suggesting that the extreme size difference in Nephila may render small males unappealing as prey. Full article

The physical properties of plants affect the transmission of plant-borne vibrational signals, which many herbivorous insects use for communication. Male calling signals (MCaSs, with sections S0, S1, and S2) and courtship signals (MCoSs, with sections S1 and S2) of Empoasca onukii Matsuda (Hemiptera: Cicadellidae), a major pest of tea plant, have a multicomponent structure. The same MCaS was repeatedly played back on different leaves of a tea branch, and parameters of the transmitted signal and female responses were measured on the leaf inhabited by females. We also measured the signal parameters and behaviors of E. onukii on single leaves of different ages. The intensity of MCaSs from other leaves attenuated after they propagated to leaves on which females were located, which decreased the duration of MCaS-S2. Higher leaf thickness, leaf hardness, and leaf area were associated with an increased pulse repetition time (PRT) of MCaSs, number of pulses in MCaS-S2, and duration of MCaS-S2, respectively. MCoS-S1 had a higher dominant frequency (Df) in leaves with a long main vein and high hardness, and the PRT of MCoS-S2 was longer on thicker leaves. In the initial stage of courtship, the signal excitation of males was affected by leaf traits, especially the temporal parameters of MCaS-S2, which was the most significantly affected section after host transmission; it also had an important effect on the response delay of females. In the location stage, the signal excitation of males was not only affected by leaf traits but also interacted with the signal excitation of females. These results facilitate exploration of the interaction between leafhoppers and host plants during courtship communication and have implications for the breeding of E. onukii-resistant varieties. Full article