Egg Cannibalism Research Articles

Ant queens cannibalise infected brood to contain disease spread and recycle nutrients

Filial cannibalism, where parents eat their own offspring, is a taxonomically widespread behaviour with a multitude of potential adaptive explanations1. Of these, the impact of pathogens on the expression of filial cannibalism is, in particular, poorly understood. Cannibalising young with low survival probability may enable parents to reinvest valuable resources into future reproduction1. However, cannibalising offspring that harbour pathogens may be potentially harmful to parents, and such risk may therefore select against this behaviour. Although disease-induced cannibalism of eggs has been reported in fish2, the benefits of consuming infected brood to contain infections - as an explanation for the evolution of filial cannibalism - remain largely unexplored. Here, we demonstrate that solitarily founding ant queens cannibalise sick larvae in their nests before they become contagious, showing that filial cannibalism both contains an otherwise lethal infection without any long-term consequences on queen survival and also enables the reinvestment of recouped energy into additional egg production.

Glacial Meltwater Increases the Dependence on Marine Subsidies of Fish in Freshwater Ecosystems

In a warming world, the input of glacier meltwater to inland water ecosystems is predicted to change, potentially affecting their productivity. Meta-ecosystem theory, which posits that the nutrient availability in the recipient ecosystem can determine the extent of cross-ecosystem boundary utilization, can be useful for studying landscape-scale influences of glacier meltwater on inland waters. Here, we investigate how the input of glacier meltwater in a river system in Southern Greenland influences the utilization of marine subsidies in freshwater fish. Our study system comprised four sites, with controls for glacial meltwater and marine subsidies, harboring a partially migrating population of arctic char, meaning that some individuals migrate to the ocean and others remain in freshwaters, and two fully resident populations as a freshwater reference. We assessed the incorporation of marine carbon in freshwater resident char using both bulk and amino acid stable isotope analysis of muscle tissue. In the population with partial migration, marine subsidies were a significant resource for resident char individuals, and estimates of trophic position suggest that egg cannibalism is an important mechanism underlying the assimilation of these marine subsidies. In proglacial streams, namely those with high glacial meltwater, the total dependence on marine subsidies increased and reached 83% because char become cannibals at smaller sizes. In the configuration of our focal meta-ecosystem, our results suggest that the importance of marine subsidies to freshwater fish strengthens within increasing meltwater flux from upstream glaciers.

Egg cannibalism by larvae of the weed biological control agent, Neogalerucella calmariensis

ABSTRACT The host-specific beetle Neogalerucella calmariensis was introduced to North America to control Lythrum salicaria, and in some areas has persisted in high population densities despite decimation of target plants. We hypothesised that egg predation might contribute to the survival of the beetles. In small-scale laboratory experiments, we investigated the likelihood of egg cannibalism at different N. calmariensis life stages. Neither neonates nor adults cannibalised eggs, however late instar larvae readily preyed on eggs of conspecifics. Pupal weights of larvae that cannibalised eggs were larger than those fed only leaf material suggesting that egg cannibalism may be associated with a fitness benefit.

Diverse strategies that animals use to deter intraspecific predation.

Intraspecific predation is a special case of prey-predator system that is taxonomically widespread. While a heterospecific predator's main goal is to achieve nutrition, intraspecific predation provides conspecifics with other benefits including elimination of competitors for resources and mates. Traditionally intraspecific predation is termed based on the context they occur within, for example egg cannibalism, infanticide and sexual cannibalism. These diverse forms of intraspecific predation and the strategies by which animals are known to deter them are summarized categorically in this review. The diversity of defence strategies animals deploy against conspecific predators is appreciable and raises interesting questions on their evolution for future research.

Cannibalistic behavior of biological control agent Oenopia conglobata (Linnaeus, 1758) (Coleoptera: Coccinellidae) under laboratory conditions

BackgroundOenopia conglobata (Linnaeus) (Coleoptera: Coccinellidae) is a generalist predator feeding on several insect pests and utilized as a biological control agent in Türkiye. However, significant cannibalism has been observed among its different life stages under low food/prey availability. This study determined adult-egg, adult-larva, larva-egg, and larva-larva cannibalism of O. conglobata under laboratory conditions.ResultsCannibalism among different life stages was observed under no supplemental diet (treatment group) or sufficient (100 Ephestia kuehniella eggs per individual) supplemental diet (control group). Fifty eggs per adult were provided to the 24 h-starved male and female adults for determining adult-egg cannibalism. Similarly, male, and female adults received 30 and 20 1st and 2nd instars, respectively to observe adult-larval cannibalism. Likewise, 10, 20, 30 and 40 eggs to 24-h starved 1st, 2nd, 3rd, and 4th instars, respectively were provided to record larval–egg cannibalism. By the same way, 12-h starved 4th instar was provided 1st instar (20 per individual) to determine larval–larval cannibalism. The experiments for males, females, and instars were conducted separately and cannibalism was assessed by prey consumption in treatment group relevant to the control group. Cannibalism significantly differed among sexes and instars (for larva-egg cannibalism). Overall, males and females consumed higher number of eggs in treatment group compared to their relevant controls. Female and male adults in treatment group exhibited 8.27- and 7.16-fold cannibalism on eggs. Likewise, females exhibited the highest cannibalism (2.84-folds) on 1st instar. The 4th instar consumed the highest number of eggs; however, the highest cannibalism rate was recorded for the 3rd instar. The 3rd instar exhibited 4.63-fold cannibalism on eggs. Nevertheless, the 4th instar exhibited 3.56-folds cannibalism on 1st instar.ConclusionsStarved O. conglobata individuals exhibited significant cannibalism among different life stages. Therefore, during mass rearing they shouldn’t be starved. Furthermore, the cannibalistic behavior should be considered during the mass release of O. conglobata.

Effect of victim relatedness on cannibalistic behaviour of ladybird beetle, Cheilomenes sexmaculata Fabricius (Coleoptera: Coccinellidae)

Cannibalism is taxonomically widespread and has a large impact on the individuals’ fitness and population dynamics. Thus, identifying how the rates of cannibalism are affected by different ecological cues is crucial for predicting species evolution and population dynamics. In current experiment, we investigated how victim relatedness affects the cannibalistic tendencies of different life stages of ladybird, Cheilomenes sexmaculata, which is highly cannibalistic. We provided larval instars and newly emerged adults of C. sexmaculata with a choice of sibling, half-sibling and non-sibling conspecific eggs as victim of cannibalism. First victim cannibalised and latency to cannibalise were observed along with total number of victims cannibalised after 24 h. First preference of victim did not differ with life stages of the cannibals though the number of victims cannibalized did increase with advancement in stage. Percent egg cannibalism also varied significantly with life stage and victim relatedness. First and second instars tend to cannibalise more percentage of sibling and non-sibling eggs while third instars cannibalised more percentage of non-sibling eggs; fourth instars and adults on the other hand cannibalised highest percentage of eggs irrespective of their relatedness. Insignificant effect of victim relatedness was observed on latency to cannibalise eggs, though it varied significantly with the cannibal’s life stage. Shortest latency to cannibalise was recorded for first instars and longest for adults and second instars. In conclusion, kin recognition and avoidance of cannibalism is stage-specific, with fourth instar and newly emerged adults being less discriminatory as compared to early stages owing to increased evolutionary survival pressure.

Effect of diet composition and temperature on the gastric evacuation rate of European sardine: implication for egg predation estimates

Cannibalism and intraguild predation of fish eggs are frequently observed for small and medium pelagic fish and can be an important cause of natural mortality. The European sardine Sardina pilchardus is the major predator of pelagic fish eggs in Atlantic Iberian waters. Estimates of egg mortality due to predation rely on a number of parameters that are frequently unknown for most species, such as gastric evacuation rate (GER) and feeding periodicity, and rates obtained for other fish species are generally used. These assumptions can severely affect egg mortality estimates. We conducted laboratory experiments to estimate the GER of European sardine that were fed diets composed of different proportions of fish eggs and other food types, such as Artemia franciscana nauplii, Brachionus plicatilis and microalgae, at different temperatures experienced by sardine in the wild (15, 17 and 21°C). Temperature, predator size and sex did not influence the gastric rates. Prey type significantly affected the GER of sardines, with slower evacuation when offered diets containing a higher concentration of fish eggs rather than microalgae, rotifers and Artemia nauplii. Fish eggs are more nutritionally rich compared to microalgae, rotifers and Artemia nauplii, and therefore more difficult to digest. GERs obtained here for S. pilchardus were similar to those obtained for Sardinops sagax in South Africa. This study provides important information that allows for improving estimates of daily feeding rates and egg mortality by predation, thus increasing our understanding of small pelagic fish population dynamics.

The Effects of Alternative Foods on Life History and Cannibalism of Amblyseius herbicolus (Acari: Phytoseiidae).

The development, survivorship, fecundity, and cannibalism of the predatory phytoseiid mite, Amblyseius herbicolus (Chant), fed six different alternative foods (Oulenziella bakeri, Tyrophagus putrescentiae, Aleuroglyphus ovatus, almond pollen (Prunus armeniaca), apple pollen (Malus pumila), maize pollen (Zea mays)), and natural prey (Tetranychus urticae) were determined in the laboratory. Our findings indicated that A. herbicolus that fed on all six alternative foods could normally complete its developmental and reproductive cycles. The shortest pre-adult developmental duration was observed when A. herbicolus fed on almond pollen (4.91 d) as well as T. urticae (4.90 d), and the longest when it fed on maize pollen (6.24 d). Pre-adult survival rates were higher when the predator fed on almond pollen (0.99), maize pollen (0.96), and O. bakeri (0.93). The highest fecundity was observed when A. herbicolus fed on apple pollen (28.55 eggs/female), almond pollen (26.06 eggs/female), and O. bakeri (26.02 eggs/female) in addition to T. urticae (48.95 eggs/female), and the lowest when it fed on maize pollen (7.84 eggs/female). The highest value of the intrinsic rate of increase (r) was obtained when A. herbicolus fed on O. bakeri (0.202 d-1) in addition to T. urticae (0.210 d-1), followed by almond pollen (0.163 d-1), and the lowest was when it fed on maize pollen (0.064 d-1). Cannibalism of conspecific eggs by adults of A. herbicolus did not occur when O. bakeri and T. urticae were provided. The cannibalism rate of the predatory mite was the lowest when fed on almond pollen, T. putrescentiae, and A. ovatus and the highest on apple pollen. Above all, when fed on O. bakeri and almond pollen, and with no or low cannibalism rate, A. herbicolus had the best development, survivorship, fecundity, and population parameters. Therefore, O. bakeri and almond pollen could be potential alternative foods for mass rearing programs of A. herbicolus or to support its population in the fields.

Post-spawning defence by male brook charr is linked to perceived paternity

Salmonine fishes are generally thought not to exhibit male parental care, although brief post-spawning mate-guarding by males is known for a number of species, often for populations where eggs are subjected to intense predation (egg cannibalism). Here, detailed in situ data on the spawning behaviour of male brook charr, Salvelinus fontinalis, from a naturally reproducing lake population is used to test whether post-spawning mate guarding (i.e. paternal care) is related to perceived paternity. From video records of spawning events (n = 20), we documented a novel behaviour whereby the dominant male curtails spawning ahead of the female (by ~ 3 s) and immediately inspects the nest. Afterwards, the dominant male significantly reduces courtship behaviour (quivers) but aggressively defends the female with the same intensity as prior to spawning. The duration of mate guarding (range: 3–48 min), however, declined with increasing numbers of peripheral males that had rushed into the nest at spawning. Neither the number of active females present on the spawning grounds nor male body size influenced the amount of time dominant males spent mate guarding. Extensive revisitation (80% of visits) by males to spawning sites and to females during focal sampling bouts highlights the importance of a male’s ability to predict female readiness to spawn as a significant component of reproductive success. Thus, dominant males appear to guard females at a cost of acquiring other mating opportunities and adjust the time spent guarding depending upon their perceived paternity.

Delayed early life effects in the threespine stickleback.

Early life conditions can have a decisive influence on viability later in life. However, the influence of embryo density within a nest or body cavity on subsequent viability has received little attention within an ecological setting. This is surprising given that embryos often compete for limited resources, such as nutrients and oxygen, and this could influence their viability later in life through carry-over and compensatory effects. We show that the density of fertilized eggs within the nests of threespine stickleback males (Gasterosteus aculeatus) influences their viability after hatching. Embryos from larger broods hatch earlier and at a smaller size than those from smaller broods, which reduces their survival until the age of four weeks. This indicates a trade-off between the number and viability of offspring that males can raise to the hatching stage, which could explain the high incidence of partial egg cannibalism in nest-brooding fishes-as a strategy to improve the survival of remaining offspring. These results highlight the importance of considering conditions at the embryonic stage when evaluating the impact of early life conditions on viability and the adaptive value of reproductive decisions.

Egg cannibalism as a foraging tactic by less fit Glaucous-winged Gulls (Larus glaucescens)

Cannibalism, the killing and eating of conspecifics of any life stage, leads to a variety of behavioral and ecological consequences and is influenced by a range of environmental circumstances among numerous taxa. In birds, cannibalism is particularly well known among gulls. Although multiple studies have linked cannibalism to egg and chick failure in gull populations, gull cannibal behavior is poorly understood. During the 2014 and 2015 breeding seasons, we observed the behavior of Glaucous-winged Gulls (Larus glaucescens) that used conspecific egg predation, a form of cannibalism, as a feeding tactic on Protection Island, Washington, USA. Most egg stealing by egg cannibals occurred during colony disturbances, especially by Bald Eagles (Haliaeetus leucocephalus), but egg stealing often occurred without concurrent disturbances. Among other findings, our data showed that egg cannibals were always males, the number of eggs stolen each day correlated with the daily number of eggs laid, egg cannibals ate fewer fish than non-cannibals, and the reproductive success of egg cannibals was lower than that of non-cannibals. This study provides the most comprehensive evaluation to date of how larid cannibals find, capture, and eat conspecific eggs, and it includes the first assessment of reproductive success of egg cannibals in comparison with non-cannibals.

Stationary distribution and extinction of a stochastic two-stage model of social insects with egg cannibalism

Considering the cannibalism behavior of many groups of animals in nature, a two-stage model of social insects with egg cannibalism and nonlinear perturbations is constructed and investigated in this paper. First, we establish sufficient conditions for the existence and uniqueness of an ergodic stationary distribution ψ(⋅) of the stochastic model. In a biological implication, the existence of the distribution ψ(⋅) implies the long-term persistence of social insects. Moreover, sufficient conditions for exponential extinction of social insects are obtained. Finally, our theoretical results are further discussed by several numerical simulations.

Parental Sex and Not Kinship Determines Egg Cannibalism in Arma custos Fallou (Hemiptera: Pentatomidae: Asopinae)

BackgroundArma custosFallou (Hemiptera: Asopinae) is an important predatory insect native to China, South Korea, and Mongolia. It is important to understand the evolution of egg cannibalism inA. custosto evaluate the biocontrol potential of this species. However, few reports have suggested egg cannibalism inA. custos, and whether hungry adultA. custosmales and females prey on their eggs remains unknown. Here, we investigated the effects of the parental sex ofA. custosadults on egg cannibalism of parental and non-parental eggs (kinship) under no-choice and free-choice conditions, along with the effects of predator and egg density on egg cannibalism under starvation conditions.ResultsFemales frequently visited and cannibalized a higher proportion of eggs, whereas males almost did not participate in egg cannibalism (less than 17% males showed egg cannibalism behavior). Moreover, regardless of their relationship with the egg, neither male nor female adults consumed all available eggs even in the absence of an alternative food source, and >70% of eggs remained unconsumed. In contrast, cannibalistic males and females did not discriminate between parental and non-parental egg types. Meanwhile, cannibalism rates were similar when adults were offered 30 eggs or more. However, when offered fewer than 30 eggs, cannibalism rates declined disproportionally, suggesting that limited egg availability reduced cannibalism. Additionally, the lifespan ofA. custosadult females increased significantly with increasing number of consumed eggs (p< 0.05).ConclusionArma custosfemales exhibit a higher tendency for egg cannibalism than males. Neither male or femaleA. custosdiscriminated between parental and non-parental egg types. Cannibalism enhances survival in that a starved individual who predates on eggs survives similarly to a well-fed individual. These findings provide a model to study the evolution and biological significance of egg cannibalism inA. custosand also contribute to the efficient mass rearing and realization ofA. custosfor biological control.

How do gulls synchronize every-other-day egg laying?

Increased sea-surface temperatures lead to increased egg cannibalism in Glaucous-winged Gulls (Larus glaucescens). Under these conditions, female gulls, which lay an egg approximately every 2 d, can synchronize egg laying with other females on an every-other-day schedule. Eggs that are laid synchronously are less likely to be cannibalized. The mechanism for synchronization has remained unknown. We studied the relationship between egg laying and mounting in a colony of Glaucous-winged Gulls on Protection Island, Washington, for clues to a synchronizing mechanism. We found that for an individual female an oviposition event reduced the likelihood of mounts for that day as compared to the day before, and that for sampled areas of the colony, total numbers of mounts and eggs laid occurred in an out-of-phase rhythm. These findings support the following conceptual model: early in the breeding season, individual females that have begun laying exhibit a daily alternation of higher and lower mounting activity caused by their natural 2 d oviposition oscillation. By social facilitation, these mounting oscillations of early layers synchronize mounting across the colony, including mounting events involving females that are not yet laying. Mount synchronization eventually leads to every-other-day egg laying synchronization.

Conspecific neighbors and kinship influence egg cannibalism in the green lacewing, Chrysoperla carnea (Stephens)

BackgroundChrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) is an illustrious predator that performs cannibalism upon facing small and defenseless conspecifics. Eating preference of C. carnea larvae was investigated between conspecific and host (Sitotroga cerealella) eggs. Early instars of C. carnea express significant preference toward conspecific eggs over host eggs. Experiments were carried out to examine the role of conspecific neighbors in execution of cannibalistic decision. These cannibalistic behaviors of larvae were also investigated through locomotion bioassays using the video tracking software ANY-maze®.ResultsLarvae commit low egg cannibalism when alone but express higher cannibalism in the presence of conspecific larvae in the neighborhood. The role of relatedness in egg cannibalism was investigated when larvae were offered a choice between conspecific eggs from related and unrelated parents. Larvae did a discrimination between eggs of their own parents and those of other parents.ConclusionBehavioral bioassays showed attraction toward conspecific eggs and the eggs of unrelated parents. This study emphasizes the significance of informational and descriptive cues that modulate the cannibalistic expression in C. carnea.

Cannibalism and protective behavior of eggs in Arctic charr (Salvelinus alpinus).

From video recordings of spawning events, we quantified protective and cannibalistic behavior of Arctic charr occurring immediately after spawning. The number of fish cannibalizing on stray eggs was examined regarding (a) whether more than one male shed milt during the spawning event, that is, whether sperm competition occurred, (b) whether the sperm competition included few or many males, that is, the intensity of sperm competition, and (c) the density of fish at the spawning site. Response behavior toward egg cannibalism was also examined among females and dominant males in order to determine any parental investment toward protecting the eggs after spawning. Cannibalistic behavior was seen in almost 50% of the spawnings, and the multiple spawning events showed the highest numbers of fish cannibalizing on eggs. Both the number of males releasing milt and the number of fish approaching the spawning site were positively correlated with egg cannibalism. Sperm competition was, however, not a prerequisite for egg cannibalism. Although we also observed partial filial cannibalism, protective behavior of eggs was seen both among dominant males and females, suggesting that charr actually conduct parental care.

Egg Cannibalism Varies With Sex, Reproductive Status, and Egg and Nymph Ages in Arma custos (Hemiptera: Asopinae)

Background: Egg cannibalism is common in nature. In China, Arma custos (Hemiptera: Asopinae) has been widely used as a natural enemy to control agricultural and forestry pests. A previous study showed that adult A. custos devour their eggs. However, no research has investigated the interaction between A. custos cannibalism and egg development. Clarifying the mechanisms involved in egg cannibalism by A. custos improves our understanding of the evolutionary relationships to enable more efficient mass rearing and biological control systems.Results: Virgin females showed a lower egg cannibalism inclination than gravid females. Both virgin and mated females showed a higher egg cannibalism inclination than virgin and mated males. The first and second instar nymphs did not devour eggs. The third, fourth, and fifth instar nymphs devoured eggs. Younger eggs were more readily eaten than older eggs. Neither A. custos nymphs nor female adults consumed all the available eggs, allowing an emergence ratio of >70%.Conclusion:Arma custos females exhibit a higher tendency for egg cannibalism than males. Egg cannibalism varies not only with the developmental stage of the eggs and nymphs but also with sex and reproductive status of A. custos females. These findings help us to better understand the evolutionary relationships in egg cannibalism by A. custos and contribute to the efficient mass rearing and realization of A. custos in biological control systems.

Cannibalism and synchrony in seabird egg‐laying behavior

AbstractDuring years of high sea surface temperature, food resources for glaucous‐winged gulls (Larus glaucescens) are scarce. In response, male gulls cannibalize the eggs of neighbors. When this occurs, female gulls in dense areas of the colony adopt a tactic of egg‐laying synchrony, in which they lay eggs synchronously on an every‐other‐day schedule. Field observations show that the first‐laid egg of each clutch is the most likely to be cannibalized. In this paper, we analyzed a discrete‐time model of egg‐laying behavior that tracks egg order in the nest. Using Jury conditions, we found that the equilibrium destabilizes into a two‐cycle as colony density (nests per unit area) increases through a critical value, and that the two‐cycle becomes increasingly synchronous as density increases further. We demonstrated that more eggs survive cannibalism in synchronous colonies than in nonsynchronous colonies.Recommendations for Resource ManagersIn colonial gulls, increased egg cannibalism and every‐other‐day egg‐laying synchrony are two behavioral consequences of rising sea surface temperature.As nest density (nests per unit area) increases, equilibrium egg laying destabilizes into increasingly synchronous two‐cycles.More eggs survive cannibalism in synchronous colonies than in nonsynchronous colonies.

Every-other-day clutch-initiation synchrony as an adaptive response to egg cannibalism in Glaucous-winged Gulls (Larus glaucescens)

Sea surface temperatures (SST) in the Pacific Northwest of North America rose 1 °C during the last half of the twentieth century. Cannibalism, a behavior observed in diverse taxa, is often associated with low food supplies, which for marine animals can be precipitated by high SSTs. In an 8 year study, we found that in years of higher sea surface temperatures, Glaucous-winged Gulls (Larus glaucescens) breeding in a colony in Washington State, Salish Sea, USA, tended to exhibit higher rates of egg cannibalism by males, higher levels of every-other-day clutch-initiation synchrony by females, and longer egg-laying seasons than in years of lower SST. Clutch-initiation synchrony increased the odds that an egg survived cannibalism and may serve as an adaptive response to egg cannibalism. Short-term climate and resource fluctuations associated with El Niño Southern Oscillation (ENSO) events may select for behavioral plasticity in marine organisms, allowing long-lived individuals such as marine birds to switch between alternative life history tactics. The implications for long-term SST warming, however, remain unknown.

Effect of egg cannibalism on mating preferences and reproductive fitness of Menochilus sexmaculatus Fabricius (Coleoptera: Coccinellidae)

• Mate preferences are plastic in nature and changes with changing environment and mates’ internal conditions. • Non-cannibalistic adults were preferred over cannibalistic adults as mates. • Time to commence mating lasted less for homogeneous diet pairs than heterogeneous diet pairs. • Longer copulation duration and higher fecundity were recorded for non-cannibal pairs. • Egg viability and total developmental durations of offspring were similar for all mating pairs. Cannibalism has been reported in a large proportion of coccinellids in fields as well as in laboratories but studies involving mate preferences and potential benefits of cannibalism on reproduction in Menochilus sexmaculatus Fabricius (Coleoptera: Coccinellidae) have yet not been done. Thus, we assessed the effect of conspecific egg cannibalism on mate preferences and reproductive outputs including offspring development. Higher mate preferences were recorded for non-cannibalistic mates (fed on A. craccivora ) than cannibalistic ones (fed on conspecific eggs). Mating parameters were significantly influenced by cannibalism. Time to commence mating lasted less for homogeneous diet pairs than heterogeneous diet pairs. Longer copulation duration and higher fecundity were recorded when one of the individuals in mating pair or both was a non-cannibal. Egg viability did not differ significantly in all the reciprocal crosses. In addition, the total developmental durations of offspring were similar for all mating pairs.