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The green lacewing, Mallada basalis (Walker) (Neuroptera: Chrysopidae), is one of the most important natural enemies used in biological control programs for forestry and agricultural pests. However, it is difficult to mass rear M. basalis instars because they are voracious cannibals. This study was conducted to determine the effect of cannibalism on the development and fecundity of M. basalis. We analyzed the developmental parameters of 3rd instars that cannibalized M. basalis eggs and 1st instars, and the relationship between the proportion of each of the 3rd instars cannibalized and the number of folded paper barriers provided in an arena to minimize the frequencies of encounters. In all treatments the green lacewing instars were provided eggs of the pyralid, Corcyra cephalonica (Stainton). In Treatment I the pyralid eggs were supplemented with M. basalis eggs and in Treatment II, the pyralid eggs were supplemented with M. basalis 1st instars. The developmental times of the 3rd instars and pupae of Treatment I and Treatment II were significantly shorter than in the control. The pupal weights, fecundities and egg hatch rates of Treatments I and II were significantly larger than in the control. When 3rd instars cannibalized M. basalis eggs or 1st instars, the pupal weights significantly increased from 10.3 (control) to 11.0 and 10.9 mg, respectively, fecundities significantly increased from 91 (control) to 141 and 121 eggs, respectively, and the egg hatch rates significantly increased from 62% (control) to 70% and 68%, respectively. Moreover, as the number of folded paper barriers per arena increased, the proportions of 3rd instars cannibalized at first tended to decrease but then increased. When the different instars were studied separately, the proportion of 3rd instars cannibalized was larger than the corresponding proportions of 1st and 2nd instars. The research indicated that cannibalism enhances both development and fecundity of M. basalis. The use of paper barriers to frequent encounters reduced cannibalism somewhat, but this method was not adequately effective for the 3rd instars. Our findings may contribute to the mass production of this economically important predatory green lacewing.

Every year, billions of egg layer chicks around the world are hatched under highly stressful, industrial circumstances. Here, it is investigated how the stressful procedure in the commercial hatchery, including incubation, hatching, processing, and transport affects the chicks with regards to traits relevant for the egg production industry. These traits were compared to those of a control group hatched in a small incubator and handled gently och quietly in a quiet room without any processing and transport. The chicks were weighed at hatch and at eight additional time points: 4 days, 1 week (w), 2 w, 3 w, 5 w, 8 w, 20 w and 25 w of age. Feather pecking was studied at 15 w of age and damages to the feathers and injuries on the comb and wattle were assessed at 25 w of age. From 19 w of age, eggs were collected on three days per week, counted and weighed. Chicks from a commercial hatchery had a lower hatch weight than control chicks (p<0.001). At 20 w of age, the weight of the commercial hatched chicks was still numerically lower, although this did not reach statistical significance. Commercially hatched chicks tended to show more feather pecking behaviour at 15 w of age compared to control chicks (p<0.1), although feather condition at 25 w of age showed the opposite pattern. Regarding production, commercially hatched chickens laid fewer (p<0.05) and smaller (p<0.05) eggs than chicks hatched and handled under calm circumstances. From this experiment, it is concluded that the stressful experience in the commercial hatchery has an overall negative effect on traits relevant for the industry.

The propensity to kill and consume conspecifics (cannibalism) varies greatly between and within species, but the underlying mechanisms behind this variation remain poorly understood. A rich literature has documented that consistent behavioural variation is ubiquitous across the animal kingdom. Such inter-individual behavioural differences, sometimes referred to as personality traits, may have far-reaching ecological consequences. However, the link between predator personality traits and the propensity to engage in cannibalistic interactions remains understudied. Here, we first quantified personality in Eurasian perch ( Perca fluviatilis ), measured as activity (time spent moving) and sociability (time spent near conspecifics). We then gave perch of contrasting behavioural types the option to consume either conspecific or heterospecific (roach, Rutilus rutilus ) prey. Individual perch characterized by a social-active behavioural phenotype (n = 5) selected roach before being cannibalistic, while asocial-inactive perch (n = 17) consumed conspecific and heterospecific prey evenly. Thus, asocial-inactive perch expressed significantly higher rates of cannibalism as compared to social-active individuals. Individual variation in cannibalism, linked to behavioural type, adds important mechanistic understanding to complex population and community dynamics, and also provides insight into the diversity and maintenance of animal personality.

The range of limnological conditions that support Atlantic cod populations in meromictic Arctic lakes is known to be relatively restricted. The degree to which differences in these features, particularly in the availability of allochthonous and autochthonous prey, affect the condition and growth of cod in these populations is unknown. We compared measures of condition among three Atlantic cod populations on Baffin Island, Nunavut, to assess their relationship to differences in potentially important habitat parameters. We also compared data spanning two decades (Ogac Lake) to five decades (Qasigialiminiq) to assess the degree to which natural and anthropogenic factors may have affected these populations. In general, growth rate and asymptotic length tend to be high under situations of intense cannibalism and when alternative prey species are relatively abundant. Biotic and abiotic habitat features in Ogac Lake appear to have been relatively stable since the 1950s, although the abundance of sea urchins appears to have decreased, which may explain the observation that the incidence of cannibalism has doubled. The mean size of angled cod in Qasigialiminiq has decreased by about 10 cm over the past 20 years. L'étendue des conditions limnologiques qui soutiennent les populations de morue franche dans les lacs méromictiques de l'Arctique est reconnue pour être relativement restreinte. La mesure dans laquelle les différences caractérisant ces conditions a une incidence sur l'état et la croissance des morues n'est pas connue, particulièrement en ce qui a trait à la disponibilité de proies allochtones et autochtones. Nous avons comparé les mesures des conditions de trois populations de morues de l'île de Baffin, au Nunavut, dans le but d'évaluer leur relation avec les différences caractérisant des paramètres d'habitat susceptibles d'être importants. Nous avons également comparé des données s'étendant sur deux décennies (lac Ogac) à cinq décennies (lac Qasigialiminiq) pour évaluer la mesure dans laquelle les facteurs naturels et anthropogéniques pourraient avoir une incidence sur ces populations. En général, le taux de croissance et la longueur asymptotique ont tendance à être élevés dans les situations de cannibalisme intense de même que lorsque les espèces de proies de rechange sont relativement abondantes. Les caractéristiques des habitats biotiques et abiotiques au lac Ogac semblent relativement stables depuis les années 1950, bien que l'abondance d'oursins semble avoir diminué, ce qui pourrait expliquer l'observation selon laquelle le cannibalisme a doublé. La grosseur moyenne de la morue prise à la ligne au lac Qasigialiminiq a diminué d'environ 10 centimètres ces 20 dernières années.

The red-bellied black snake (Pseudechis porphyriacus) is a member of the Elapidae family and is distributed on the east coast of Australia. The species is known to feed on a variety of ectothermic prey, including frogs and lizards. It is also known to be ophiophagous (snake-feeding), and stomach-content analyses suggest that P. porphyriacus also exhibits cannibalistic behavior, yet this extreme case of ophiophagy has rarely been documented. Here, a case of cannibalism in P. porphyriacus, which was observed in Lamington (Queensland, Australia), has been photographically documented and is described.

Honey bees balance colony populations against available food resources by adjusting brood rearing during nutritionally-stressed periods. Workers limit colony populations primarily through brood cannibalism of eggs and young larvae but often resume brood rearing when conditions improve. However, extended brood cannibalism reduces brood and removes brood signals that mediate brood rearing, such as E-β-ocimene, a volatile pheromone produced by eggs, young larvae, prepupae and ovipositing queens. We examined the effects of pollen supplementation on ocimene signaling in nutritionally-stressed colonies. Pollen-deprived colonies showed declines in ocimene emissions that coincided with sustained brood cannibalism of pheromone-producing brood. In contrast, pollen-supplemented colonies reared more brood and released more ocimene. Twelve day old workers that completed adult development in pollen-deprived colonies had less well developed hypopharyngeal glands and fat bodies than workers that matured in pollen-supplemented colonies. Given that ocimene emissions increased once brood rearing resumed, we considered the possibility that ocimene may help suppress brood cannibalism and support egg retention in nutritionally stressed nuc colonies. Broodless nucleus frames were treated with synthetic ocimene releases equivalent to 3,744 L2-L3 larvae. All ocimene-supplemented nucs retained large numbers of eggs and young larvae four days after initial treatment. By contrast, half of the unsupplemented nucs cannibalized all of their eggs and L1 larvae. Most of the remaining unsupplemented nuc colonies retained fewer eggs and L1 larvae than ocimene supplemented nuc colonies. E-B-ocimene may prime nutritionally stressed workers to increase brood rearing during dearth periods by projecting the presence of healthy eggs and young larvae.

Oviparous animals across many taxa have evolved diverse strategies that deter egg predation, providing valuable tests of how natural selection mitigates direct fitness loss. Communal egg laying in nonsocial species minimizes egg predation. However, in cannibalistic species, this very behavior facilitates egg predation by conspecifics (cannibalism). Similarly, toxins and aposematic signaling that deter egg predators are often inefficient against resistant conspecifics. Egg cannibalism can be adaptive, wherein cannibals may benefit through reduced competition and added nutrition, but since it reduces Darwinian fitness, the evolution of anticannibalistic strategies is rife. However, such strategies are likely to be nontoxic because deploying toxins against related individuals would reduce inclusive fitness. Here, we report how D. melanogaster use specific hydrocarbons to chemically mask their eggs from cannibal larvae. Using an integrative approach combining behavioral, sensory, and mass spectrometry methods, we demonstrate that maternally provisioned pheromone 7,11-heptacosadiene (7,11-HD) in the eggshell's wax layer deters egg cannibalism. Furthermore, we show that 7,11-HD is nontoxic, can mask underlying substrates (for example, yeast) when coated upon them, and its detection requires pickpocket 23 (ppk23) gene function. Finally, using light and electron microscopy, we demonstrate how maternal pheromones leak-proof the egg, consequently concealing it from conspecific larvae. Our data suggest that semiochemicals possibly subserve in deceptive functions across taxa, especially when predators rely on chemical cues to forage, and stimulate further research on deceptive strategies mediated through nonvisual sensory modules. This study thus highlights how integrative approaches can illuminate our understanding on the adaptive significance of deceptive defenses and the mechanisms through which they operate.

Cannibalism is a commonly observed phenomenon in arthropod species having relevant consequences for population dynamics and individual fitness. It is a context-dependent behaviour and an understanding of the factors affecting cannibalism rate is crucial to highlight its ecological relevance. In mosquitoes, cannibalism between larval stages has been widely documented, and the role of density, food availability and length of contact between individuals also ascertained. However, although mosquitoes can develop in temporary water habitats with very heterogeneous topologies, the role of the site shape where cannibals and victims co-occur has been instead overlooked. In this paper, we investigated this issue by using a simulation approach and laboratory cannibalism experiments between old (third- and fourth-instars) and young (first-instar) larvae of the tiger mosquito Aedes albopictus. Three virtual spaces with different shapes were simulated and the number of larval encounters was estimated in each one to assess whether the spatial shape affected the number of encounters between cannibal and victims. Then, experimental trials in containers with similar shapes to those used in the simulations were performed, and the cannibalism rate was estimated at 24 and 48h. Our results showed that the spatial shape plays a role on cannibalism interactions, affecting the number of encounters between individuals. Indeed, in the experimental trials performed, we observed the highest cannibalism rate in the container with the highest number of encounters predicted by the simulations. Interestingly, we found also that spatial shape can affect cannibalism not only by affecting the number of encounters, but also the number of encounters \"favorable\" for cannibalistic events. Temporary waters are inhabited by several species other than mosquitoes. Our results, showing an influence of the spatial shape on cannibalism in Ae. albopictus larvae, add a new critical factor to those affecting ecological interactions in these habitats.

Swarming and mass migration are spectacular and sometimes devastating features of the biology of various animal species. These phenomena are typically associated with actual or anticipated depletion of food resources after an increase in population density, but the mechanisms driving such collective movements are poorly understood. Here we reveal that insects in large, coordinated migratory bands consisting of millions of Mormon crickets in western North America were deprived of two essential nutritional resources: protein and salt. The insects themselves provided a major source of these nutrients, and cannibalism was rife. We show that protein and salt satiation reduced cannibalism and that protein satiation inhibited walking. Additionally, experimentally reducing the motility or mobility of crickets substantially increased their risk of being cannibalized by other band members. As a result, the availability of protein and salt in the habitat will influence the extent to which bands march, both through the direct effect of nutrient state on locomotion and indirectly through the threat of cannibalism by resource-deprived crickets approaching from the rear. The crickets are, in effect, on a forced march. Migratory band formation and subsequent mass movement, therefore, are manifestations of specific tradeoffs between the costs and benefits of group living. Bands afford antipredator benefits to individual group members. Group movement then mitigates the resulting costs of intraspecific competition, namely local depletion of nutritional resources and the associated increased risk of cannibalism.

Pfennig reviews both the theory of how kinship should affect prey choices and the evidence bearing on those predictions, and he explores the behavioral mechanisms used by animals to identify kin.