Search Results (173)

Females of predaceous ladybirds use sensing chemicals in larval tracks as an oviposition-deterring pheromone to avoid cannibalism of eggs. We hypothesized that larvae would also respond to the presence of conspecific tracks by slowing their developmental rate and delaying pupation, thereby reducing the time spent as a defenseless pupa in the presence of feeding conspecifics. We reared larvae of the harlequin ladybird Harmonia axyridis in dishes that were replaced daily by a clean one (C) or continuously in a dish with larval tracks accumulated (P). We used three larval densities (1, 4, 8 larvae per dish) for both regimes (C1, C4, C8, P1, P4, P8). We measured the developmental time of the fourth larval instar, pupae, and fresh adult body mass. Developmental time increased at the highest density in the combination C8 but remained unchanged across densities in the dishes with pheromone (P1–P8). Body mass was significantly lower at the highest density in both regimes (C8, P8) and was slightly higher in the presence of pheromone (P). Ladybird larvae respond independently of their density and of the presence of pheromones. The compounds present in the tracks, previously known as oviposition-deterring pheromone, may be associated with a buffering effect on density-related developmental delays. Full article

The traditional mantis search algorithm (MSA) suffers from limitations such as slow convergence and a high likelihood of converging to local optima in complex optimization scenarios. This paper proposes an improved mantis search algorithm (IMSA) to overcome these issues. An adaptive probability conversion factor is designed, which adaptively controls the proportion of individuals entering the search phase and the attack phase so that the algorithm can smoothly transition from large-scale global exploration to local fine search. In the search phase, a probability update strategy based on both subspace and full space is designed, significantly improving the adaptability of the algorithm to complex problems by dynamically adjusting the search range. The elite population screening mechanism, based on Euclidean distance and fitness double criteria, is introduced to provide dual guidance for the evolution direction of the algorithm. In the attack stage, the base vector adaptive probability selection mechanism is designed, and the algorithm’s pertinence in different optimization stages is enhanced by dynamically adjusting the base vector selection strategy. Finally, in the stage of sexual cannibalism, the directed random disturbance update method of inferior individuals is adopted, and the population is directly introduced through the non-greedy replacement strategy, which effectively overcomes the loss of population diversity. The experimental results of 29 test functions on the CEC2017 test set demonstrate that the IMSA exhibits significant advantages in convergence speed, calculation accuracy, and stability compared to the original MSA and the five best meta-heuristic algorithms. Full article

This study presents the first successful laboratory rearing of Eremobelba eharai, with the establishment of a sustainable multigenerational breeding system. We document for the first time its complete morphological ontogeny across all developmental stages (from larva to adult) and characterize its life cycle. We supplement the original adult description with detailed morphological characterization and illustrations of the gnathosomatic structures, including the subcapitulum, palps, and chelicerae. Scanning electron microscopy showed that its surface is covered with a granular cerotegument. Under isolated rearing conditions, this species can complete the entire egg-to-egg developmental cycle. In addition, preliminary behavioral observations during rearing revealed preferences for dark environments, characteristic leg-shaking movements, and gregarious oviposition on active dry yeast particles, with no evidence of cannibalism. Full article

In the fiercely competitive sharing market, manufacturers have launched product sharing/leasing services through business-to-customer (B2C) and peer-to-peer (P2P) platforms. To reduce the channel conflicts caused by product sharing, manufacturers expand product lines by renting products of different quality on their B2C platform. In this paper, we investigate the product lines in a vertically differentiated duopoly. We examine competing manufacturers’ three product line strategies: the no-product line strategy, the high-end product line strategy, and the low-end product line strategy. We characterize the equilibrium outcomes under these strategies and investigate the manufacturers’ preferences regarding these strategies. Our findings reveal a unique equilibrium: the high-quality manufacturer prefers offering a high-end product line, while the low-quality manufacturer opts for a low-end product line. This configuration leverages each firm’s comparative advantage, mitigates channel conflict, reduces cannibalization, and supports effective market segmentation. The equilibrium leads to a Pareto improvement and enhances operational efficiency for both firms. These results suggest that aligning product line design with intrinsic product quality can balance profitability and market efficiency in shared markets. Full article

Cannibalism in Black-necked pheasants is a problem in aviary rearing, and an effective solution is still lacking. We performed the present study to investigate the potential of using tryptophan or silymarin to suppress cannibalism. The following types of investigations were performed: evaluation of the pheasants’ harmful behavior manifestations, and evaluation of the clinical forms, severity and localization of injuries of feathers and tissues, and neurohormonal manifestations. Additionally, the potential of cannibalism control in pheasants by supplementing tryptophan and silymarin to the birds’ diet was investigated. Ethological studies have shown a low intensity of feather pecking in pheasants without cannibalism manifestations. In pheasants with pronounced cannibalism, severe forms of feather and tissue pecking were observed in the head, back, wings, and rump areas, as well as specific forms affecting the tail feathers and the cloaca. Tryptophan and silymarin significantly reduced the levels of injurious pecking in the studied game birds and improved the healing of the lesions. The blood serotonin and dopamine levels in pheasants manifesting cannibalism were significantly lower than those in birds which did not show such behavior. The addition of tryptophan or silymarin to the diet of birds exhibiting cannibalism resulted in significantly increased plasma concentrations of serotonin or dopamine. Full article

CIFA-GI Scampi^® is a genetically improved, fast-growing strain of giant river prawn (Macrobrachium rosenbergii) developed by ICAR-Central Institute of Freshwater Aquaculture. Each year, selected broodstock are reared family-wise in nylon hapas for 3–4 months before use as parents for the next generation. However, this group rearing phase (GR) results in loss of quality broodstock due to aggression and cannibalism. This study evaluated individual rearing (IR) as an alternative to group rearing (GR). GR involved rearing of males or females in separate hapas, while IR placed males and females in separate hard plastic mesh boxes in ponds (18 boxes each). Results showed significantly higher average daily weight gain in GR, but IR achieved 100% survival for both sexes, compared to 50% (males) and 77.8% (females) in GR. No significant differences were observed in female maturity or male morphotypes (small male and no claw morphotypes). Given the markedly higher survival in IR, it is a viable alternative for post-selection rearing to minimize loss of valuable broodstock in the selective breeding program. Full article

In marketing science, product categorization using cannibalization relationship data is an emerging but still underdeveloped area, where clustering using price effect information is a novel direction that is worth further exploration. In this study, by assuming a realistic modeling of the cross-price effect, we developed and experimentally validated with simulations an agglomerative clustering algorithm that outputs clustering results closer to the ground truth compared with other agglomerative algorithms based on traditional cluster linkages. Full article

In this study, the seeking behaviour and food acceptance of larvae of Plodia interpunctella Hübner (Lepidoptera: Pyralidae) were analysed under laboratory conditions. Larval orientation and feeding preferences were assessed using a selection arena for neonate larvae and a four-way olfactometer for third-instar larvae. Stimulants included amaranth bars with additives (honey and chocolate) and natural amaranth (toasted grain only). The results showed that amaranth volatiles influence the orientation and feeding behaviour of this polyphagous insect. A marked preference for sugar-rich foods was observed, with amaranth with honey and amaranth with chocolate being the food sources most frequently chosen by the neonate larvae. These individuals exhibited a gregarious feeding behaviour and did not engage in cannibalism. The third-instar larvae also showed a preference for sweet food but were more attracted to the amaranth–additive combination. In the four-way olfactometer bioassays, chocolate was the most frequently chosen stimulus, while cellophane did not differ significantly from air. An analysis of volatile compounds by gas chromatography mass spectrometry (GC-MS) revealed that amaranth with chocolate releases more volatile compounds (16) compared with honey (12) and natural amaranth (6), suggesting that these volatiles could possibly influence the larvae’s choice of food source. Full article

Background: The relationship between genetic diversity and fitness is well understood, but few studies have investigated how behavior influences genetic diversity, or vice versa. We investigated the relationship between feeding behavior (on a pelleted diet) and genetic diversity in pikeperch, a piscivorous species. Methods: A total of 135 juvenile pikeperch from the same stock were grouped into three behavioral groups: pellet consuming, pellet refusing, and cannibalistic. Eighteen microsatellite markers were used to characterize the genetic diversity and structure of individuals. Results: The juveniles were classified into two genetic clusters: one dominated by pellet-consuming individuals and the other by pellet-refusing individuals containing equal proportions of cannibal individuals. Three of the microsatellite markers were under selection, but only one showed significant genetic segregation between the groups. For this marker, the pellet consumption was associated with low fragment length. Individual multilocus heterozygosity was significantly higher in the pellet-refusing group. Conclusions: These results suggest that pellet consumption acts as an uncontrolled selective force during domestication, influencing the genetic variability of domesticated populations. The ability to habituate to pellets has a significant genetic basis. Cannibalism does not affect genetic variability, and the emergence of the trait is independent of the propensity to consume pellets. Full article

Spiders and other arthropods can sometimes consume others of their kind, and this is most often associated with mating activity, whereby females cannibalize males during or after mating, or during mating attempts. Nonsexual cannibalism is less common but may be associated with food availability or territorial aggression. In the Southeastern United States, a non-native orb-weaving spider, Trichonephila clavata (the “jorō spider”), is expanding its range. Prior lab experiments indicated this species to be “shy” compared to other native spiders, based on behavioral reactions to stimuli. Here, we report descriptive observations and photo-documentation of nonsexual cannibalism by this species, including from anecdotal observations, plus findings from controlled pairings of spiders, both in the lab and in natural webs in the field. In the cases where cannibalism was witnessed, it involved one female biting and killing another, typically after a short fight. When two females of a similar size were placed together in a container (n = 25 trials), fights ensued 40% of the time. When females of different sizes were paired (n = 27 trials), fights happened 18% of the time, and the larger females were not always the aggressor. Across all the lab trials (n = 52), six bouts (9%) led to the direct killing of one female. In field trials where two females were placed on an empty web (n = 14 trials), we observed one fight (7%) where the aggressor ended up killing and wrapping the other spider in silk. Given that some of these instances happened away from any web, these observations imply that the aggression is not necessarily an act of territoriality. The intraspecific aggression could arise when females are provoked or stressed, which deserves more study. Full article

Nucleopolyhedroviruses of lepidopteran larvae (Alphabaculovirus, Baculoviridae) form the basis for effective and highly selective biological insecticides for the control of caterpillar pests of greenhouse and field crops and forests. Horizontal transmission is usually achieved following the release of large quantities of viral occlusion bodies (OBs) from virus-killed insects. In the present review, I examine the evidence for productive midgut infection in different host species and the resulting transmission through the release of OBs in the feces (frass) of the host. This has been a neglected aspect of virus transmission since it was initially studied over six decades ago. The different host–virus pathosystems vary markedly in the quantity of OBs released in feces and in their ability to contaminate the host’s food plant. The release of fecal OBs tends to increase over time as the infection progresses. Although based on a small number of studies, the prevalence of transmission of fecal inoculum is comparable with that of recognized alternative routes for transmission and dissemination, such as cannibalism and interactions with predators and parasitoids. Finally, I outline a series of predictions that would affect the importance of OBs in feces as a source of inoculum in the environment and which could form the basis for future lines of research. Full article

Filial cannibalism is the consumption of one’s own viable progeny. It occurs in a range of taxa but is particularly well-documented in fish species. Since parental care in fishes is typically male-biased, it is usually assumed that filial cannibalism is predominantly performed by the parental male while he is providing care to offspring. Filial cannibalism by females is less studied in fish. Video-recorded observations of ten pairs of adults housed in captivity revealed the first documentation of female filial cannibalism in the redhead goby (Elacatinus puncticulatus). Females were observed consuming both their own eggs and larvae. We discuss non-adaptive and adaptive explanations for female filial cannibalism in the redhead goby, including confinement due to captivity, nutritional or energetic need, and a possible lack of kin recognition. Understanding the evolutionary significance of filial cannibalism exhibited by females is an important biological inquiry. Since the redhead goby is a species used in the aquarium trade, understanding the conditions that influence female filial cannibalism in captivity may yield practical implications. Full article

This paper examines how the slope of the merit-order curve and the share of non-zero-dollar dispatched energy affect photovoltaic (PV) price cannibalization and the declining market value of all generation types. Using historical merit-order data from Alberta, Canada—during its coal-to-gas transition—we simulated the introduction of zero-marginal-cost PV offers. The increased PV penetration rapidly suppresses midday electricity prices, forming a “duck curve” that challenges solar project economics. Emission reductions improve with rising carbon prices, indicating environmental benefits despite declining market revenues. Years with steeper merit-order slopes and lower non-zero-dollar dispatch shares show intensified price cannibalization and a reduced PV market value. The integration of battery storage alongside PV significantly flattened daily price profiles—raising the trough prices during charging and lowering the highest prices during discharging. While this reduces price volatility, it also diminishes the market value of all generation types, as batteries discharge at zero marginal cost during high-price hours. Battery arbitrage remains limited in low- and moderate-price regimes but becomes more profitable under high-price regimes. Overall, these dynamics underscore the challenges of integrating large-scale PV in energy-only markets, where price cannibalization erodes long-term investment signals for clean energy technologies. These insights inform sustainable energy policy design aimed at supporting decarbonization, and investment viability in liberalized electricity markets. 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 diet of the invasive ctenophore Mnemiopsis leidyi in the Gulf of Trieste was examined during its peak occurrence in the summer and early-autumn months (July to October) from 2017 to 2019, through the analysis of stomach contents. Altogether 506 specimens were individually caught for the analysis. A total of 3215 prey items were isolated and identified. Copepods emerged as the primary prey (relative abundance 66.7%), followed by cladocerans (7.7%), and bivalve larvae (6%). Notably, specimens of M. leidyi constituted a significant portion of the diet (5.4.%), providing further evidence of cannibalism within this species. Copepods were also the most commonly occurring prey items in the diet of M. leidyi. Most of them were represented by calanoid and cyclopoid nauplii (48.2%), followed by a harpacticoid M. norvegica (28.3%), and calanoids (26.8%). Other frequently occurring taxa were bivalve larvae (19.3%), M. leidyi (18.7%), and cladoceran Penilia avirostris (16.1%). The rate of cannibalism peaked in July, coinciding with a period of limited food availability. Additionally, the study revealed that fish eggs and larvae were infrequently found in the stomachs of M. leidyi. However, the presence of massive aggregations of M. leidyi may impact microzooplankton populations in late summer or autumn, potentially leading to competition with small pelagic fish. Full article