Female-committed infanticide followed by juvenile-enacted cannibalism in wild white-faced capuchins.

On 5 February 2021, we observed the first instance of female-committed infanticide followed by cannibalism in a long-studied (> 35 years) population of wild white-faced capuchins (Cebus imitator) in the Santa Rosa Sector of the Área de Conservación Guanacaste, Costa Rica. The events leading up to and including the infanticide and cannibalism were observed and documented ad libitum, with segments digitally recorded, and a post-mortem necropsy performed. Here we detail our observations and evaluate the events within the framework of leading adaptive explanations. The infanticide may have been proximately motivated by resource competition or group instability. The circumstances of the observed infanticide provided support for the resource competition, adoption avoidance, and social status hypotheses of infanticide, but not for the exploitation hypothesis, as neither the perpetrator nor her kin consumed the deceased infant. The subsequent cannibalism was performed by juveniles who observed the infanticide and may have been stimulated by social facilitation and their prior experience of meat consumption as omnivores. To our knowledge, cannibalism has been documented only once before in C. imitator, in an adjacent study group, with the two cases sharing key similarities in the context of occurrence and manner of consumption. These observations add to our growing knowledge of the evolutionary significance of infanticide and its importance as a reproductive strategy in nonhuman primates.

Factors Influencing Mating Behavior and Success in the Red Palm Weevil, Rhynchophorus ferrugineus Olivier (Coleoptera: Dryophthoridae).

The effects of body size, age, feeding and mating status, conspecific volatiles from live adults, synthetic aggregation pheromone, and a pheromone synergist, ethyl acetate, on the mating behavior of red palm weevil, Rhynchophorus ferrugineus Olivier, were investigated. To evaluate these factors, variables such as mating latency, frequency and duration, and refractory period were assessed. While both, body size and age, influenced the mating behavior, the latter showed a stronger effect. The large males recorded frequent and longer matings, whereas the young males outperformed the old weevils in all the studied variables. The difference in body size or age of females showed a limited effect. After 72 h without food, the males showed a significant decline in mating frequency and duration, and refractory period. Mating status showed comparatively stronger effects on mating variables. In the case of females, mating status emerged as the most important factor affecting four out of five variables. The volatiles from the males, grouped males and females, and synthetic aggregation pheromone both alone and in combination with ethyl acetate triggered mating initiation, propelled mating frequency, prolonged total mating duration, and reduced the refractory period. However, the presence of females or ethyl acetate alone was a weak mating stimulator.

Oviposition Deterrents in Larval Frass of Potato Tuberworm Moth, Phthorimaea operculella (Lepidoptera: Gelechiidae).

The potato tuberworm moth (PTM) Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae) is one of the most damaging pests of potato Solanum tuberosum L. in warm temperate and subtropical areas. Our previous experiment showed that extracts of larval frass of PTM deterred oviposition of conspecific females. In this study, we investigated the identification of chemicals in larval frass that were influencing the oviposition of PTM by behavioral bioassays and electroantennography analysis in the laboratory. Frass was collected from third and fourth instar larvae and combined analysis of gas chromatography coupled with electroantennography (GC-EAD) of dichloromethane extracts showed that eight compounds from larval frass extracts elicited repeatable antennal responses from mated females. Seven EAD-active compounds in frass volatile extract were identified by gas chromatography-mass spectrometry (GC-MS) as linoleic acid, octadecanoic acid, tricosane, pentacosane, heptacosane, nonacosane, and cholesterol. Oviposition bioassays indicated that frass extracts had a deterrent effect on egg laying, the deterrent activity increased with the concentration of frass extracts, and the threshold value for statistical significance in oviposition deterrence was in the range of 20-200 mg frass per cage. Linoleic acid, pentacosane, heptacosane, nonacosane, and cholesterol in larval frass volatiles were found to play a key role in repelling oviposition in a dose-dependent manner. We suggest that the bioactive compounds in larval frass are responsible for repelling oviposition of PTM, and n-alkanes, especially pentacosane, strongly deter oviposition and may be considered as a potential oviposition deterrent for potential applications.

Resolving the paradox of clumped seed dispersal: positive density and distance dependence in a bat-dispersed species.

One of the hypothesized benefits of seed dispersal is to escape density- and distance-responsive, host-specific, natural enemies near maternal plants where conspecific seed and seedling densities are high. Such high conspecific neighbor densities typically result in lower offspring growth and survival (i.e., negative density-dependent effects), yet many dispersal modes result in clumped seed distributions. New World leaf-nosed bats transport fruits to their feeding roosts and deposit seeds, thereby creating high-density seed/seedling patches beneath feeding roosts in heterospecific trees away from maternal trees, which seemingly nullifies a key benefit of seed dispersal. Such dispersal may still be adaptive if negative density-dependent effects are reduced under feeding roosts or if the benefit of being dispersed away from maternal trees outweighs negative effects of conspecific seed/seedling density below roosts. We mapped the entire post-germination population of a bat-dispersed tree species Calophyllum longifolium (Calophyllaceae) in a 50-ha plot on Barro Colorado Island, Panama in each of three successive years. We tested two hypotheses: (1) distance-dependent effects are stronger than density-dependent effects on seedling performance because seedlings far from conspecific adults are more likely to escape natural enemies even when at high densities and (2) negative density-dependent effects will be reduced far from vs. near conspecific adults. Density and distance were naturally decoupled, as expected. However, in contrast to our expectation, we found positive density effects on seedling survival and density-dependent effects did not differ with distance from conspecific adults. Both density and distance had positive effects on seedling survival when considered together, while only year had a significant effect on seedling growth. Thus, both being dispersed under bat feeding roosts and escaping the vicinity of conspecific adults were beneficial for C. longifolium seedling survival, supporting the directed dispersal and escape hypotheses, respectively. Despite resulting in high densities of conspecific seedlings, favorable habitat under bat feeding roosts and lack of negative density-dependent effects appear to provide evolutionary advantages in C. longifolium.

Interspecific variation in conspecific negative density dependence can make species less likely to coexist.

Conspecific negative density dependence (CNDD) is thought to promote plant species diversity. Theoretical studies showing the importance of CNDD often assumed that all species are equally susceptible to CNDD; however, recent empirical studies have shown species can differ greatly in their susceptibility to CNDD. Using a theoretical model, we show that interspecific variation in CNDD can dramatically alter its impact on diversity. First, if the most common species are the least regulated by CNDD, then the stabilising benefit of CNDD is reduced. Second, when seed dispersal is limited, seedlings that are susceptible to CNDD are at a competitive disadvantage. When parameterised with estimates of CNDD from a tropical tree community in Panama, our model suggests that the competitive inequalities caused by interspecific variation in CNDD may undermine many species' ability to persist. Thus, our model suggests that variable CNDD may make communities less stable, rather than more stable.

The role of singing style in song adjustments to fluctuating sound conditions: A comparative study on Mexican birds.

Many bird species adjust their songs to noisy urban conditions by which they reduce masking and counteract the detrimental impact on signal efficiency. Different species vary in their response to level fluctuations of ambient noise, but it remains unclear why they vary. Here, we investigated whether noise-dependent flexibility may relate to singing style and signal function of the flexible acoustic trait. Species with highly variable songs may generally be more flexible and strongly repetitive singers may be more limited to stray from their stringent patterns. We exposed males of four passerine species with contrasting singing styles (repertoire size, immediate or eventual variety singing and syllable diversity) to three experimental sound conditions: 1) continuous urban noise; 2) intermittent white noise and 3) conspecific song playback. We found no spectral or temporal changes in response to experimental noise exposure in any of the four species, but significant temporal adjustment to conspecific playback in one of them. We argue that the consistency in song frequency and timing may have signal value, independent of singing style, and therefore be an explanation for the general lack of noise-dependent flexibility in the four species of the current study.

Beta-Adrenergic Blockade Decreases the Neuroimmune Changes in Mice Induced by Cohabitation with an Ehrlich Tumor-Bearing Cage Mate.

OBJECTIVES: Cohabitation with Ehrlich tumor-bearing (ETB) mice induced behavioral, neurochemical, hormonal, and immune effects in the conspecifics as a consequence of stress-induced activation of the sympathetic nervous system (SNS) with catecholamine release. In the current study, the nonspecific ß-AR blocker d,l-propranolol and the specific ß2-AR blocker ICI-118.551 were employed as pharmacological tools to assess the extent to which catecholamines participated in the effects induced by cohabitation with ETB mice. METHODS: Two experiments were performed, 1 with d,l-propranolol treatment and the other with ICI-118.551. One mouse in the experimental group was called the "companion of the sick partner" (CSP) since it was forced to live in the same cage with 2 (experiment 1) or 1 (experiment 2) cage mate that had been i.p. injected with 5 × 106 Ehrlich tumor cells. RESULTS: The d,l-propranolol treatment, but not the ICI-118.551 treatment, attenuated the effects of cohabitation with 2 ETB mice on both open-field behavior and the hypothalamic levels and turnover rate of norepinephrine. The 2 ß-AR blockers were unable to change the serum corticosterone levels and adrenal weights of the CSP mice; however, these drugs abrogated the effects of cohabitation on neutrophil oxidative burst and phagocytosis. Finally, an increase in the 5-HT turnover rate was observed in the olfactory bulb of CSP mice compared to their respective controls, an effect that was not modified by ß-AR blockade. CONCLUSION: These results confirm and strengthen our hypothesis that the SNS is involved in the effects induced by cohabitation with ETB mice and point towards ß2-AR participation in the immune effects analyzed.

Species with greater seed mass are more tolerant of conspecific neighbours: a key driver of early survival and future abundances in a tropical forest.

Multiple niche-based processes including conspecific negative density dependence (CNDD) determine plant regeneration and community structure. We ask how interspecific and intraspecific density-dependent interactions relate to plant life histories and associated functional traits. Using hierarchical models, we analysed how such interactions affected first-year survival of seedling recruits of 175 species in a tropical forest, and how species abundances and functional traits are related to interspecific variation in density-dependent effects. Conspecific seedling neighbour effects prevailed over the effects of larger conspecific and all heterospecific neighbours. Tolerance of seedling CNDD enhanced recruit survival and subsequent abundance, all of which were greater among larger seeded, slow-growing and well-defended species. Niche differentiation along the growth-survival trade-off and tolerance of seedling CNDD strongly correlated with regeneration success, with manifest consequences for community structure. The ability of larger seeded species to better tolerate CNDD suggests a novel mechanism for CNDD to contribute to seed-size variation and promote species coexistence through a tolerance-fecundity trade-off.

Effect of floor space on the behavior of laying hens in commercial cages / Area de piso y su efecto sobre la conducta de gallinas alojadas en jaulas comerciales / Área de piso e seu efeito sobre o comportamento de galinhas alojadas em gaiolas comerciais

Background: the size of commercial cages has been raised as the major component in the welfare of laying hens. Objectives: to describe the effect of floor space on the behavior of laying hens housed in commercial cages. Methods: one hundred and thirty-five Hy-Line Brown laying hens (aged 25 ~ 50 weeks) were housed in different sized commercial cages and monitored using video technology during 10 h per day at 2-week intervals. Results: total time spent standing, dozing, and sleeping were significantly higher in small cages than in medium and large cages. Total time spent walking was higher in large cages. Cage-pecking frequency was higher in small cages while stretching frequency was higher in large cages. Moreover, preening frequency was lower in small cages. Conspecific pecking was higher in small cages. Conclusions: cage size is a critical factor affecting the behavior of laying hens. This study can help managers to understand spatial relations in caged hens.

Antecedentes: el tamaño de la jaula para gallinas en explotaciones comerciales es el principal problema de bienestar animal en esa especie. Objetivo: describir el efecto del espacio de piso sobre el comportamiento de las gallinas ponedoras alojadas en jaulas comerciales. Métodos: ciento treinta y cinco ponedoras Hy - Line Brown (25 ~ 50 semanas de edad) fueron alojadas en jaulas comerciales de diferentes tamaños y se monitorearon utilizando tecnología de vídeo durante 10 horas diarias en intervalos de 2 semanas. Resultados: la duración total de permanencia en pie, yaciendo y durmiendo fue significativamente mayor en jaulas pequeñas que en las medianas y grandes. El tiempo gastado caminando fue mayor en las jaulas grandes. La frecuencia de picoteo a la jaula fue mayor en las jaulas pequeñas y la frecuencia del estiramiento de alas fue mayor en las grandes. Por otra parte, la frecuencia de acicalamiento fue menor en las jaulas pequeñas. El picoteo entre gallinas fue mayor en las jaulas pequeñas. Conclusiones: se encontró que el tamaño de la jaula es un factor crítico que afecta el comportamiento de las gallinas ponedoras. Este estudio podría ayudar en el manejo de la gallina ponedora enjaulada al mejorar la comprensión sobre las relaciones espaciales en dicha especie.

Antecedentes: o tamanho da gaiola para galinhas de granjas comerciais é a principal questão do bem-estar animal nesta espécie. Objetivo: descrever o efeito do espaço sobre o comportamento de galinhas poedeiras alojadas em gaiolas comerciais. Métodos: 135 Hy-Line Brown (25-50 semanas de idade) foram alojadas em gaiolas comerciais de diferentes tamanhos e foram monitoradas utilizando a tecnologia de vídeo durante 10 horas por dia, em intervalos de duas semanas. Resultados: o tempo total gasto em pé, deitado e dormindo foi significativamente maior em gaiolas pequenas do que em gaiolas de porte mediano e grande. O tempo gasto caminhando foi maior em gaiolas grandes. A frequência de bicar a gaiola foi maior nas gaiolas pequenas e a frequência de alongamento das asas foi maior em gaiolas grandes. Além disso, a frequência de limpeza por elas mesmas foi menor em gaiolas pequenas. A bicagem entre as galinhas foi maior em gaiolas pequenas. Conclusões: Verificou-se que o tamanho da gaiola é um fator crítico que afeta o comportamento das galinhas poedeiras. Este estudo pode ajudar no manejo de galinhas poedeiras para melhorar a compreensão das relações espaciais nesta espécie.

Intraspecific non-sexual interactions of Grammostola schulzei (Araneae: Theraphosidae) under laboratory conditions

Intraspecific interactions of araneomorph spiders have received considerable attention, but there are few detailed studies on intraspecific interactions of mygalomorph spiders. Moreover, a thorough understanding of theraphosid biology and ecology is necessary from a conservation standpoint because natural populations may be threatened by habitat disturbances and captures for pet commerce. We described the behavior of conspecific individuals of Grammostola schulzei during non-sexual interactions, under laboratory conditions. Pairs of individuals involving adult males, adult females and juveniles were confronted and observed in resident and intruder conditions, totalizing 115 trials. When confronted two adult females, they retreated or grappled, and performed gaping display with bite attempts, usually resulted in severe injury of the intruder spiders. When confronted females with large juveniles, we frequently observed cannibalism on juveniles. Juveniles exposed to females or to other juveniles retreated or made leg tapping with forelegs and palpal drumming, which are common displays of courting adult males. Adult males courted and clasped some juveniles, but juveniles avoided or reject clasping. The behaviors observed during intraspecific interactions could play an important role determining spatial distribution and could lead to behavioral adaptations of territoriality. Rev. Biol. Trop. 59 (3): 1173-1182. Epub 2011 September 01.

Hay pocos estudios detallados sobre las interacciones intraespecíficas de arañas migalomorfas. Por lo tanto, se describe el comportamiento de individuos conspecíficos de Grammostola schulzei durante interacciones nosexuales en condiciones de laboratorio. Se confrontaron y observaron pares de individuos involucrando machos adultos, hembras adultas y juveniles en condiciones de locatarios y visitantes, totalizando 115 encuentros. Cuando dos hembras adultas se enfrentaron, retrocedieron o lucharon adoptando elevaciones anteriores e intentos de mordeduras que usualmente resultaron en arañas visitantes heridas. Cuando se enfrentaron hembras con juveniles, frecuentemente se observó canibalismo sobre los juveniles. Los juveniles expuestos a otros juveniles o hembras retrocedieron o realizaron golpes con patas delanteras y tamborileos de palpos, los cuales constituyen unidades de comportamiento comunes durante el cortejo de los machos. Los machos adultos cortejaron y trabaron a algunos juveniles, mientras que los juveniles los evitaron o rechazaron el enganche. Los comportamientos observados durante las interacciones intraespecíficas podrían jugar un papel importante en la distribución espacial y podrían generar adaptaciones al territorialismo.

Influence of natural settlement cues on the metamorphosis of fiddler crab megalopae, Uca vocator (Decapoda: Ocypodidae)

Megalopae of many decapod crab species accelerate their development time to metamorphosis (TTM) when exposed to natural physical and/or chemical cues characteristic of the parental habitat. In the present study, the influence of natural settlement cues on the moulting rates and development TTM in megalopae of the fiddler crab Uca vocator was investigated. The effects of mud from different habitats (including well-preserved and degraded-polluted mangrove habitats) and conspecific adult 'odours' (seawater conditioned with crabs) on the induction of metamorphosis were compared with filtered pure seawater (control). 95 to 100 percent of the megalopae successfully metamorphosed to first juvenile crab stage in all treatments, including the control. However, the development TTM differed significantly among treatments. Settlement cues significantly shortened development, while moulting was delayed in their absence. The fact that megalopae responded to metamorphosis-stimulating cues originating from both adult and non-adult benthic habitats demonstrates that settlement in this species may occur in a wider range of habitats within the mangrove ecosystem, including impacted areas.

Megalopas de muitas espécies de caranguejos decápodes aceleram seu período de desenvolvimento até a metamorfose (TOM) quando são expostas a estímulos naturais físicos e/ou químicos característicos do habitat parental. No presente estudo, a influência de estímulos naturais sobre as taxas de muda e sobre o PDM foi investigada nas megalopas do caranguejo violinista Uca vocator. Os efeitos da (i) lama de diferentes habitats (incluindo habitats de um manguezal bem preservado e de um degradado e poluído) e (ii) 'odores' dos adultos conspecíficos (água do mar acondicionada com caranguejos) sobre a indução da metamorfose foram comparados com (iii) água do mar pura e filtrada (controle). 95 a 100 por cento das megalopas realizaram a metamorfose com sucesso para o primeiro estágio de caranguejo juvenil em todos os tratamentos, incluindo o controle. No entanto, o PDM diferiu significativamente entre os tratamentos. Os estímulos encurtaram significativamente o desenvolvimento, enquanto que a muda foi retardada na ausência deles. O fato de que as megalopas responderam aos estímulos indutores da metamorfose oriundos de ambos os habitats bentônicos dos adultos e de habitats onde eles são ausentes, demonstra que o assentamento nesta espécie pode ocorrer em uma grande variedade de habitats dentro do ecossistema de manguezal, incluindo áreas impactadas.