Prey Preference Research Articles

DNA metabarcoding to assess prey overlap between tuna and seabirds in the Eastern tropical Atlantic: Implications for an ecosystem-based management

Overfishing has been drastically changing food webs in marine ecosystems, and it is pivotal to quantify these changes at the ecosystem level. This is especially important for ecosystems with a high diversity of top predators such as the Eastern Atlantic marine region. In this work we used high-throughput sequencing methods to describe the diet of the two most abundant tuna species, the Skipjack tuna (Katsuwonus pelamis) and the Yellowfin tuna (Thunnus albacares), highly targeted by fisheries off west Africa. We also explored prey diversity overlap between these tuna species and the seabird species breeding in Cabo Verde that are most likely to share prey preferences and suffer from bycatch, the Brown booby (Sula leucogaster) and Cape Verde shearwater (Calonectris edwardsii). Overall, the diet of both tuna species was more diverse than that of seabirds. Skipjack tuna diet was dominated by prey from lower trophic levels, such as krill, anchovies, and siphonophores, while the Yellowfin tuna diet was mainly based on epipelagic fish such as flying and halfbeak fishes. Some of the most abundant prey families detected in the Yellowfin tuna diet were shared with both seabird species, resulting in a high prey diversity overlap between this tuna species and seabirds These results have implications for the management of tuna fisheries in the Eastern Tropical Atlantic, because a large decrease of both tuna species might have cascading effects on both primary and secondary consumer levels, and the decrease of these underwater predators may have implications on the viability of tropical seabird populations.

Brace yourselves, winter is coming: the winter activity, natural diet, and prey preference of winter-active spiders on pear trees

Brace yourselves, winter is coming: the winter activity, natural diet, and prey preference of winter-active spiders on pear trees

Can smaller predators expand their prey base through killing juveniles? The influence of prey demography and season on prey selection for cheetahs and lions

Smaller predators may overcome body size restrictions on their prey base by selecting for juveniles of larger prey species. However, traditional prey selection models ignore demographic classes within prey species. We refined these models for two predators with contrasting body sizes and hunting strategies, by including seasonal consumption and availability of prey demographic classes. We predicted that cheetahs would select for smaller neonate and juvenile prey especially of larger species, while lions would select for larger, adult prey. We further predicted seasonal diet shifts in cheetah, but not lion. We recorded species-specific demographic class prey use (kills) via direct observation and GPS cluster of cheetahs and lions fitted with GPS collars. Species-specific demographic class prey availability was estimated from monthly driven transects, and species-specific demographic class prey preferences were estimated. The availability of prey demographic classes varied seasonally. Cheetahs preferred neonates, juveniles, and sub-adults during the wet season, but adults and juveniles during the dry season. Lions preferred adult prey irrespective of season, with sub-adults, juveniles, and neonates killed relative to their abundance. This confirms that traditional prey preference models do not adequately account for demographic-specific prey preference. This is particularly important for smaller predators, like cheetahs, that focus on smaller prey but can expand their prey base by killing juveniles of larger species. For these smaller predators, prey availability will vary strongly seasonally, making them more vulnerable to processes that influence prey reproduction, like global change.

Molecular Identification of Asian Hornet Vespa velutina nigrithorax Prey from Larval Gut Contents: A Promising Method to Study the Diet of an Invasive Pest.

The Asian hornet, Vespa velutina nigrithorax (Hymenoptera: Vespidae), is an invasive hornet that was accidentally introduced into Europe in 2004. It mainly preys on other invertebrates and arthropod species, and often targets honey bee (Apis mellifera) colonies. The introduction of these hornets may damage indigenous fauna and apiculture. Knowledge of V. velutina prey preference and the species composition of their diet is relatively limited. In this study, we assessed methodologies for the molecular identification of prey using dissected larvae from destroyed nests. Ten larval samples were taken from five nests in areas where the hornets had not yet established: two from the Channel Islands and three in the mainland UK. DNA was extracted from the gut contents and sequenced and analysed by metabarcoding with Oxford Nanopore Technologies' Flongle and MinION devices. Numerous taxa were detected in each larval sample with the species composition varying by individual and by nest. Between 15 and 26 species were found per nest, with wasps (Vespula spp.), spiders, honey bees and blow flies being the most abundant taxa. These results demonstrate that metabarcoding larval gut contents can be used to study the Asian hornet diet and give a first snapshot of the prey items captured by V. v. nigrithorax in the UK. This method could be used for future large-scale testing of the gut contents of hornet nests, in order to provide a greater insight into the foraging behaviour of this predator across Europe and elsewhere.

Are shark teeth proxies for functional traits? A framework to infer ecology from the fossil record.

Modern sharks have an evolutionary history of at least 250 million years and are known to play key roles in marine systems, from controlling prey populations to connecting habitats across oceans. These ecological roles can be quantified based on their functional traits, which are typically morphological (e.g., body size) or behavioural (e.g., feeding and diet). Nonetheless, the understanding of such roles of extinct sharks is limited due to the inherent incompleteness of their fossil record, which consists mainly of isolated teeth. As such, establishing links between tooth morphology and ecological traits in living sharks could provide a useful framework to infer sharks' ecology from the fossil record. Here, based on extant sharks from which morphological and behavioural characteristics are known, the authors assess the extent to which isolated teeth can serve as proxies for functional traits. To do so, they first review the scientific literature on extant species to evaluate the use of shark dental characters as proxies for ecology to then perform validation analyses based on an independent data set collected from museum collections. Their results reveal that 12 dental characters have been used in shark literature as proxies for three functional traits: body size, prey preference and feeding mechanism. From all dental characters identified, tooth size and cutting edge are the most widely used. Validation analyses suggest that seven dental characters - crown height, crown width, cutting edge, lateral cusplets, curvature, longitudinal outline and cross-section outline - are the best proxies for the three functional traits. In particular, tooth size (crown height and width) was found to be a reliable proxy of all three traits; the presence of serrations on the cutting edge was one of the best proxies for prey preference; and tooth shape (longitudinal outline) and the presence of lateral cusplets were among the best indicators of feeding mechanism. Overall, the authors' results suggest that in the absence of directly measurable traits in the fossil record, these seven dental characters (and different combinations of them) can be used to quantify the ecological roles of extinct sharks. This information has the potential to provide key insights into how shark functional diversity has changed through time, including their ecological responses to extinction events.

Seasonal variation in prey preference, diet partitioning and niche breadth in a rich large carnivore guild

AbstractLarge carnivore community structure is affected by direct and indirect interactions between intra‐guild members. Co‐existence between different species within a carnivore guild may occur through diet, habitat or temporal partitioning. Since carnivore species are highly dependent on availability and accessibility of prey, diet partitioning is potentially one of the most important mechanisms in allowing carnivores to co‐exist. Intra‐guild interactions may vary over time as carnivore prey preference and diet overlap can change due to seasonal changes in resource availability. We conducted scat analysis to compare the seasonal changes in prey preference, diet partitioning and niche breadth of four large carnivore species, namely leopard Panthera pardus, spotted hyena Crocuta crocuta, brown hyena Parahyaena brunnea and wild dog Lycaon pictus in central Tuli, Botswana. Large carnivores in central Tuli display a high dietary overlap, with spotted hyena and brown hyena displaying almost complete dietary overlap and the other carnivore species displaying slightly lower but still significant dietary overlap. Dietary niche breadth for both hyena species was high possibly due to their flexible foraging strategies, including scavenging, while leopard and wild dog showed a relatively low niche breadth, suggesting a more specialised diet. High dietary overlap in central Tuli is possibly explained by the high abundance of prey species in the area thereby reducing competition pressure between carnivore species. Our research highlights the need to assess the influence of diet partitioning in structuring large carnivore communities across multiple study sites, by demonstrating that in prey rich environments, the need for diet partitioning by carnivores to avoid competition may be limited.

Relating marine mammal distribution to water column prey structure derived from echosounding

Managing human impacts on marine mammal populations depends on understanding their distributions in space and time. Knowledge of these distributions is becoming increasingly important due to offshore energy development and climate-induced shifts in oceanic habitat. Most models assessing pelagic marine mammal abundance and distribution primarily use ocean surface or ocean floor variables as proxies for water column habitat. Here, we used a ship-based marine mammal sighting survey to test the utility of echosounder-based predictive variables for modeling marine mammal distribution and abundance. We assessed the distribution of 7 marine mammal taxa and 3 feeding guilds along the shelf break off the northeast USA relative to prey structure derived from acoustic data. We classified prey into 4 categories: (1) fish with swimbladders; (2) small resonant bubbles as phytoplankton, fish larvae, and gelatinous zooplankton; (3) fluid-like scatterers such as krill and copepods; and (4) fish with no swimbladder. We quantified the spatial structure of prey by calculating backscattering strength, location, dispersion, occupied areas, evenness, and aggregation. Spatial resolution along the survey track line was set to bins 1000 m in distance and either 50 or 200 m in depth. We then built generalized additive models (GAMs) using these acoustically derived variables to explain marine mammal distribution. The resulting GAMs explained between 9 and 38% of deviance, with model fit often reflecting aspects of foraging depth and prey preference. This approach could contribute to improved management through more accurate species distribution models that employ direct measurements of prey.

Stomach content and stable isotopes illustrate large spatial similarity in the Wadden Sea fish food-web structure

Spatial variability in the Wadden Sea fish food-web structure was studied by comparing stomach content and bulk stable isotopes of fish species caught simultaneously in the Ems and Marsdiep basins during 2012-2014. Almost all 31 fish species caught were generalist feeders. In both basins, similar predator-prey relationships were found in which a few key prey species fuelled the fish food web. Copepods and brown shrimp were the most important prey species in both basins, mysid shrimp were more important as prey in the Ems basin, while shore crab and herring were more important prey species in the Marsdiep basin. The observed spatial variability in prey preferences was most likely the result of local differences in predator and prey abundances. Published absolute trophic positions based on compound-specific stable isotopes were available for some fish species and indicated low variability between the basins. Estimated absolute trophic positions based on stomach content and on bulk stable isotopes could not be used for the analysis of spatial variability due to sensitivity to sampling procedure (stomach content) and sampling size and baseline (bulk stable isotopes). Although estimates based on bulk stable isotopes underestimated absolute trophic levels in both basins, they can be used for the analysis of relative trophic positions of fish species. Relative trophic positions showed a significant correlation for most fish between the Ems and Marsdiep basins, also indicating a large spatial similarity in trophic structure.

Synchronisation of gut enzymes with differential foraging spectrum of two species of firefly (Coleoptera: Lampyridae: Luciolinae) from India with special reference on prey preferences of their larvae

Synchronisation of gut enzymes with differential foraging spectrum of two species of firefly (Coleoptera: Lampyridae: Luciolinae) from India with special reference on prey preferences of their larvae

Hydrology and small pelagic fish drive the spatio–temporal dynamics of springtime zooplankton assemblages over the Bay of Biscay continental shelf

As mesozooplankton is the preferential prey of small pelagic fish (SPF), environmentally–driven mesozooplankton dynamics can have critical effects on SPF population dynamics. Despite previous studies on SPF habitats’ dynamics, hydrological landscapes and mesozooplankton dynamics in the Bay of Biscay (BoB), knowledge gaps persist at the BoB regional–scale pelagic ecology and in particular about the mesozooplankton assemblages and their long–term space–time patterns. Here, we present 16 years of spring mesozooplankton assemblage interannual spatial dynamics over the BoB continental shelf and we describe the correlations between the mesozooplankton space–time patterns and those in hydrology, primary producers and SPF. We gathered data originating from the PELGAS surveys (2004–2019) and remote sensing products. Mesozooplankton samples were collected with a 200–µm mesh size WP2 net vertically towed from 100 m depth (or 5 m above the sea floor) to the surface. They were analysed with imaging and deep-learning tools and the biomass in 24 coarse taxonomic groups was calculated. Automated procedures for spatial gridding and missing data imputation enable the generation of yearly maps time series with the same spatial resolution across the pelagic ecosystem components and years. These comprehensive multivariate datasets were analysed with a multi–table method known as Multiple Factor Analyses to depict time–consistent spatial patterns in each ecosystem component and the temporal variability around them. Finally, the main time–consistent spatial patterns in the hydrology, primary producers and SPF ecosystem components were used as predictors in generalized linear models, to explain those in the mesozooplankton. Mesoscale coastal-offshore and north–south gradients were the main patterns observed in each of the pelagic ecosystem components studied. The spatial patterns in the mesozooplankton assemblage were stable, without any significant changes detected in the taxonomic composition nor its spatial structure over the studied period. Small copepods, gelatinous and meroplanktonic organisms characterised coastal areas. Euchaetidae and meroplanktonic crustaceans’ larvae displayed higher biomass in the northern part of the BoB while Metridinidae, Cladocera, Appendicularia and Echinodermata had higher biomass in the southern part. Surface and bottom water temperature, salinity–related parameters, water column stratification and SPF biomasses were the variables that best explained the observed space–time patterns in the mesozooplankton communities.

Effect of the entomopathogenic fungus, Lecanicillium lecanii, on the biology and predation rate of the anthocorid predatory bug, Blaptostethus pallescens, feeding on the flower thrips, Frankliniella schultzei Trybom (Thysanoptera: Thripidae)

BackgroundThe flower thrips, Frankliniella schultzei Trybom (Thysanoptera: Thripidae) is a notorious pest that attacks the plants of economic importance. The anthocorid bug Blaptostethus pallescens Poppius (Heteroptera: Anthocoridae) is a predator of thrips in field crops and greenhouses. Another biocontrol agent, the entomopathogenic fungi (EPF) Lecanicillium lecanii (Zimm.) (Hypocreales: Cordycipitaceae), has been effectively used in management of various insect pests. With the aim to develop an effective combination of biocontrol agents like microbial and insect predator for the management of the serious pest F. schultzei, the present studies were carried out on development, predation rate and prey preferences of the predator B. pallescens provided with the EPF (ICAR-NBAIR Vl-8)-treated thrips under laboratory conditions.ResultsThe predator, B. pallescens, could complete its life cycle on treated thrips. The nymphal duration of bugs fed on treated thrips was higher (25.25 ± 0.13 days). The Vl-8 strain did not show any negative effect on hatchability of eggs (83% hatchability in treatment; 86% in control). However, the longevity was comparatively less in bugs fed on treated thrips than that of control group The fecundity of the treated group was found to be reduced to one half of the control group. The rate of daily feeding potential of bugs on treated thrips was less (7.29 ± 0.15) than the untreated thrips (12.54 ± 0.1) throughout their lifetime. Moreover, when the F1 generation from both parents line fed on treated and untreated thrips allowed to feed on Corcyra cephalonica eggs, it did not show any difference in terms of nymphal duration which revealed that the fungi did not affect the F1 generation. When choice was given between treated and untreated thrips to different instars of this predatory bug, all the instars including adult significantly preferred the untreated thrips. However, nymphs and adult bugs were found to encounter both the treated and untreated thrips. No mortality was observed in any stage of the predator.ConclusionThis study shows that the effect of L. lecanii (ICAR-NBAIR Vl-8) on B. pallescens is not harmful. However, further field studies are required to evaluate their combined effect against this pest.

Direct and indirect effects of banker plants on population establishment of Harmonia axyridis and aphid control on pepper crop.

Banker plant systems increase biological pest control by supporting populations of natural enemies, i.e., using non-pest arthropod species as alternative prey. However, the presence of alternative prey does not always result in improved control of the target pest species owing to the complexity of biotic interactions. To increase the effectiveness of banker plants in IPM programs, a fine understanding of the indirect interactions between target aphid and alternative prey mediated by biocontrol agents is necessary. In this study, we first established a banker plant system, banker plant (Vicia faba)-alternative prey (Megoura japonica)-predator (Harmonia axyridis), to control the target pest (Myzus persicae) on pepper. We found that M. japonica strongly preferred faba bean as a host plant and posed no risk to Solanaceous crops. Harmonia axyridis adults had no significant predation preference for the alternative prey. In the short term, the interaction direction of the two aphid species depended on the relative initial density and the timescale. Harmonia axyridis showed a stronger negative effect on M. persicae than that on M. japonica. In the long term, the presence of alternative prey, M. japonica, enhanced the control effect of H. axyridis to M. persicae with initial density of 100-500 aphids per plant. The presence of the alternative prey could proliferate the population of H. axyridis, with from 0.2- to 2.1-fold increase of H. axyridis eggs. Overall, we put forward a strategy for setting the initial density of alternative prey of the banker plant system to target the high and low density of aphids, which highlighted the importance of indirect interactions in designing a proper banker plant system.

Maternal cannibalistic preferences affect offspring preferences and development in Menochilus sexmaculatus Fabricius (Coleoptera: Coccinellidae): A transgenerational investigation

AbstractCannibalism has been widely reported across taxa. However, the heritability and expression of cannibalistic traits have been least explored. The variation in the expression of cannibalism is likely to exist amongst the population affecting the propensity of cannibalism. Thus, to know whether the mother has any role in the transgenerational transmission of this trait in a ladybird beetle, Menochilus sexmaculatus, we studied the interaction between maternal and offspring prey preferences and its effect on, development duration and body weight of offspring over generations. An insignificant effect of maternal dietary history on offspring prey preference was observed across generations except for the non‐cannibalistic adults who significantly preferred aphids over eggs. The long‐term detrimental effect of cannibalism was found in cannibals with increased developmental duration and decreased body weight of offspring over generations. In conclusion, the results show that maternal diet did not affect the offspring preferences in M. sexmaculatus but cannibalism had a profound generational effect on the cannibalistic propensity, development and body weight of offspring across generations shows that larval dietary history and nutritional composition of prey contribute to the expression of cannibalistic behaviour across generations.

Nest Ecology and Prey Preference of the Mud Dauber Wasp Sceliphron formosum (Hymenoptera: Sphecidae).

(1) Background: Sceliphron is a genus of sphecid wasps that build mud nests for reproduction. These wasps prey exclusively on spiders, and commonly inhabit human constructions. The nesting behaviour and prey selection of many Sceliphron species are well studied, but despite being a common insect in urban areas, Sceliphron formosum has never been comprehensively studied. (2) Methods: In this study, over 650 mud nests of S. formosum were collected, analysed and examined to establish prey preference, nest ecology and interspecific interactions. Prey preference was evaluated in terms of abundance, diversity and morphology. Preference in terms of morphology was estimated using body length to leg span ratio (BLR). (3) Results: S. formosum largely preys on ground-hunting spiders, among which Salticidae represented the most collected prey. In terms of prey size, S. formosum captures prey with a large BLR. Moreover, an unexpected discovery showed that the enclosed mud nests provide a micro niche that supports a wide variety of insects. Sixteen families and 23 species of insects were found associated with the use of mud nests, comprising the insect orders Hymenoptera, Diptera and Coleoptera. These included important pollinators, new species and native species not recorded in the past 20 years of mud dauber wasp research. We propose the potential of S. formosum as a keystone species, due to its ability to provide a micro niche for native species in urban areas. We also discuss how these results contribute to our knowledge on the role of insects in urban ecosystems and their significance in relation to conservation, ecology and biodiversity studies.

Poison frog dietary preference depends on prey type and alkaloid load.

The ability to acquire chemical defenses through the diet has evolved across several major taxa. Chemically defended organisms may need to balance chemical defense acquisition and nutritional quality of prey items. However, these dietary preferences and potential trade-offs are rarely considered in the framework of diet-derived defenses. Poison frogs (Family Dendrobatidae) acquire defensive alkaloids from their arthropod diet of ants and mites, although their dietary preferences have never been investigated. We conducted prey preference assays with the Dyeing Poison frog (Dendrobates tinctorius) to test the hypothesis that alkaloid load and prey traits influence frog dietary preferences. We tested size preferences (big versus small) within each of four prey groups (ants, beetles, flies, and fly larvae) and found that frogs preferred interacting with smaller prey items of the fly and beetle groups. Frog taxonomic prey preferences were also tested as we experimentally increased their chemical defense load by feeding frogs decahydroquinoline, an alkaloid compound similar to those naturally found in their diet. Contrary to our expectations, overall preferences did not change during alkaloid consumption, as frogs across groups preferred fly larvae over other prey. Finally, we assessed the protein and lipid content of prey items and found that small ants have the highest lipid content while large fly larvae have the highest protein content. Our results suggest that consideration of toxicity and prey nutritional value are important factors in understanding the evolution of acquired chemical defenses and niche partitioning.

Learning behavior of Neoseiulus californicus from astigmatid to spider mites

Oulenziella bakeri is often used as an alternative prey for the mass rearing of Neoseiulus californicus in China. Long-term alternative prey feeding experience may cause a decline in the predatory capacity of phytoseiid mites toward their target prey. Learning behavior of predatory mites can help them adapt to the changes from preying on thrips to preying on spider mites (Rahmani et al., 2010), but there are few studies on the learning behavior of predatory mites from astigmatid mites to spider mites. Here, we compared the attack latency, prey preference, and functional response of N. californicus toward Tetranychus urticae among the “natural prey strains” (feeding only on T. urticae), “alternative prey strains” (feeding only on O. bakeri), and “learning behavior treatment” (alternative prey strains experienced in attacking but not feeding on T. urticae). The results showed that the attack latency of “alternative prey strain” of N. californicus on T. urticae was significantly longer than that of “natural prey strain” and “learning behavior treatment”. The “alternative prey strain” showed no obvious predatory preference between the protonymphs of T. urticae and O. baker. There were no significant differences in the capture rate and handling time among the three treatments. Our results indicated that the long-term rearing on alternative prey mainly prolonged the attack latency of N. californicus to the target prey and changed its prey preference, while learning behavior could help alternative prey strain of N. californicus to shorten the attack latency and restore its prey preference toward target prey (Zhu et al., 2022).

Predation ability of Stratiolaelaps scimitus (Acari: Laelapidae) to Tyrophagus putrescentiae (Acari: Acaridae) on edible fungi

Tyrophagus putrescentiae is one of the major pests of many edible fungi, whereas Stratiolaelaps scimitus is one of its main natural predators, which can be used to control T. putrescentiae on edible fungi. In our study, the prey preference and predation ability of S. scimitus to T. putrescentiae were determined in the laboratory. The results showed that both female and male adults of S. scimitus preferred adults to larvae of T. putrescentiae. The daily consumption of female adults of S. scimitus was higher than that of male adult mites. The consumption and predation rates of female and male adult mites reached the maximum within the first hour, then gradually decreased. This research provided a theoretical basis for the mass breeding of S. scimitus and field control of T. putrescentiae for edible fungi.

Nematocyst sequestration within the family Fionidae (Gastropoda: Nudibranchia) considering ecological properties and evolution

Aeolid nudibranchs are well-known for their ability to incorporate cnidarian nematocysts and use them for defense; this process is tightly linked with the feeding preferences of molluscs. As many nudibranch groups show signs of ecology-based adaptive radiation, studies of prey-based defensive mechanisms can provide valuable insight into details of nudibranch evolutionary history. The main goal of this study is to test the correlation of ecological traits, feeding mechanisms, and prey preferences with cnidosac fine morphology and to pinpoint the phylogenetic value of these traits. We study the cnidosac morphology in thirteen species—representatives of the main lineages within the family Fionidae s.l. The morphological analysis includes histological sections, transmission electron microscopy, confocal laser scanning microscopy, and scanning electron microscopy. For phylogenetic study, available molecular data from public repositories were used, and phylogenetic trees were produced based on Bayesian Inference and Maximum likelihood analysis for a concatenated dataset of three molecular markers (COI, 16S, H3). In general, fionid cnidosacs fit the common aeolid pattern, but among different species we detected a high variation in type of obtained nematocysts, their arrangement within cnidophages, and in number of cell types within cnidosacs. We report on presence of cellules speciale in the haemocoel of all studied species, and for the first time, we report on cells with chitinous spindles in the haemocoel of all fionids except Eubranchus. The function of both these cell types remains unknown. The loss of functional cnidosacs occurred at least three times within Fionidae, and in case of the genera Phestilla, Calma, and Fiona, this loss is linked to their non-cnidarian diet. The diversity of cnidosac fine structure within Fionidae s.l. correlates with that of the radular morphology and feeding preferences of each species. Prey shifts between cnidarian and non-cnidarian prey (both through evolutionary shifts and individual variation) rarely occur within Fionidae s.l.; however, microevolutionary shifts between different hydrozoan species within a single genus are more common. Cnidosac morphology demonstrates considerable resulting changes even when switching between similar hydrozoan species, or changing the feeding site on same prey species. These data indicate that cnidosac morphology likely follows microevolutionary prey shifts—in other words, it is affected by switches in prey species and changes in feeding sites with a single prey species. Thus, the cnidosac morphology may be a useful indicator when studying ecological features of particular species.

Predation potential of the earwig Euborellia annulipes on fruit fly larvae and trophic interactions with the parasitoid Diachasmimorpha longicaudata

AbstractThe earwig Euborellia annulipes (Lucas) (Dermaptera: Anisolabididae), a generalist predator, has been observed in fruits infested with fruit fly larvae, which are frequently parasitized by parasitoid wasps. Neither the capacity of earwigs to predate on fruit flies nor intraguild interactions between earwigs and fruit fly parasitoids have been investigated. Here, we studied in laboratory conditions the predation on the fruit fly Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) by the earwig E. annulipes, and whether parasitism of fruit fly larvae by the parasitoid wasp Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae) influences predation by the earwig. We evaluated the predation capacity, functional response and prey preference of E. annulipes for parasitized and non‐parasitized fruit fly larvae in choice and no‐choice tests. We found that earwigs prey on second‐ and third‐instar larvae and pupae of C. capitata and consumed larger numbers of second‐instar larvae, followed by third‐instar larvae and pupae. Females prey on larger numbers of fruit flies than did males, regardless of the prey developmental stage, but both sexes exhibited a type II functional response. Interestingly, males killed but did not consume fruit fly larvae more than did females. In no‐choice tests, earwig females consumed equal numbers of parasitized and non‐parasitized fruit fly larvae. However, in choice tests, the females avoided feeding on parasitized larvae. Subsequent tests with hexane‐washed parasitized and non‐parasitized larvae showed that putative chemical markings left on fruit flies by parasitoids did not drive the earwig preference towards non‐parasitized larvae. These findings suggest that E. annulipes is a potential biological control agent for C. capitata, and that, because the earwig avoids consuming larvae parasitized by D. longicaudata, a combination of the two natural enemies could have an additive effect on pest mortality.

Sexual segregation in the foraging distribution, behaviour, and trophic niche of the endemic Boyd’s shearwater (Puffinus lherminieri boydi)

Studies on sex-specific segregation in foraging behaviour and trophic niche have been focussed on large and dimorphic seabirds, with less information on small monomorphic species. Here, we used mini-GPS loggers, habitat suitability models, and stable isotopes to assess sex differences in the foraging movements, spatial distribution, and trophic ecology of Boyd’s shearwaters Puffinus lherminieri boydi in Raso Islet (16°36’ N, 24°35’ W), Cabo Verde, during the chick-rearing periods of 2018–2019. The existence of sexual foraging segregation was tested in short (< 1 day) and in long trips (≥ 1 day). Females engaged in slightly longer and more distant foraging trips, reaching northerly regions when compared to males, although sex differences were more pronounced during short trips. Spatial overlap within and between sexes was low, indicating a sex-specific pattern, albeit slight, in the foraging behaviour and spatial distribution of adult breeders. Habitat suitability models revealed a higher contribution of sea surface temperature and height for short and long trips, respectively, and regardless of sex. Stable isotope analysis revealed that both sexes occupied similar isotopic niches and the mixing model revealed no diet differences. In the absence of sexual size dimorphism, these findings may indicate that differential energetic demands may not manifest in strong differences in foraging behaviour or prey preferences, however, may be perceptible in differences in provisioning behaviour. Thus, it is possible that other factors involving distinct parental investment in chick-provisioning, such as the sensitivity to chick begging, could help explain the occurrence of sexual segregation in Boyd’s shearwater.