The role of habitat complexity in the survival rates of migratory (native) and sedentary (non-native) species of fish larvae

The increasing losses of original features of many riverine environments and the consequent decline of native aquatic species are now a widely recognized problem. The main river basins of South America have been undergoing constant changes in their communities of fish, with native migratory species disappearing and the rising of sedentary exotic ones. However, few studies report experiments that qualify and/or quantify this correlation. Three experiments were conducted to evaluate the predation mortality of two species of fish larvae (native and non-native) regarding their habitat features. The hypothesis that natural features of habitat (aquatic vegetation and water turbidity) controls the survival rates of fish larvae was tested. The experiments highlight the importance of community structure on population dynamics. The native fish larvae showed to be more adapted than the non-native to using the aquatic plants for refuge. The habitat complexity can be closely related to the persistence of native migratory fish species.(AU)

Volatile compounds from soybeans under multiple on herbivores infestations attract the predatory mite Neoseiulus californicus (Acari: Phytoseiidae) / Compostos voláteis da soja sob infestação múltipla de herbívoros atraem o ácaro predador Neoseiulus californicus (Acari: Phytoseiidae)

Plant-induced resistance can be an important component of soybean mites biological control programs. This work evaluates the preference of predatory mite Neoseiulus californicus (Acari: Phytoseiidae) to soybean plants under single and multiple herbivory conditions by two-spotted spider mite Tetranychus urticae (Acari: Tetranychidae), and velvetbean caterpillar Anticarsia gemmatalis (Lepidoptera: Noctuidae). Using a Y olfactometer, the following scenarios were evaluated: soybean with no infestation and soybean infested with A. gemmatalis; soybean infested with T. urticae and A. gemmatalis, and soybean infested with T. urticae and with both T. urticae and A. gemmatalis. Volatile compounds released by plants were analyzed and identified by a Trace GC Ultra gas chromatograph coupled to a mass spectrometer with a solid phase micro-extraction ion-trap. The predatory mite N. californicus preferred soybean plants infested with T. urticae compared to those infested with A. gemmatalis. Multiple infestation did not interfere with its preference to T. urticae. Multiple herbivory of T. urticae and A. gemmatalis modified the chemical profile of volatile compounds emitted by soybean plants. However, it did not interfere with the search behavior of N. californicus. Out of the 29 identified compounds only five promoted predatory mite response. Thus, regardless of single or multiple herbivory by T. urticae with or without A. gemmatalis, the indirect induced resistance mechanisms operate similarly. As such, this mechanism contributes to an increase in the encounter rate between predator and prey for N. Californicus and T. urticae, and the efficacy of biological control of mites on soybean.

A resistência induzida por plantas pode ser um importante componente dos programas de controle biológico de ácaros da soja. Este trabalho avalia a preferência do ácaro predador Neoseiulus californicus (Acari: Phytoseiidae) às plantas de soja sob condições de herbivoria simples e múltipla pelo ácaro-rajado Tetranychus urticae (Acari: Tetranychidae) e pela lagarta-da-soja Anticarsia gemmatalis (Lepidoptera: Noctuidae). Utilizando o olfatômetro Y, foram avaliados os seguintes cenários: soja sem infestação e soja infestada com A. gemmatalis; soja infestada com T. urticae e A. gemmatalis, e soja infestada com T. urticae e com T. urticae e A. gemmatalis. Os compostos voláteis liberados pelas plantas foram analisados ​​e identificados por um cromatógrafo gasoso Trace GC Ultra acoplado a um espectrômetro de massas com uma armadilha de íons de microextração em fase sólida. O ácaro predador N. californicus preferiu plantas de soja infestadas com T. urticae em relação àquelas infestadas com A. gemmatalis. A infestação múltipla não interferiu na preferência por T. urticae. A herbivoria múltipla de T. urticae e A. gemmatalis modificou o perfil químico de compostos voláteis emitidos por plantas de soja. No entanto, não interferiu no comportamento de busca de N. californicus. Dos 29 compostos identificados apenas cinco promoveram resposta de ácaros predadores. Assim, independentemente da herbivoria simples ou múltipla por T. urticae com ou sem A. gemmatalis, os mecanismos de resistência induzida indiretamente operam de forma semelhante. Assim, esse mecanismo biológico contribui para o aumento da taxa de encontro entre predador e presa para N. Californicus e T. urticae, e para a eficácia do controle de ácaros em soja.

Linking toxicity and predation in a venomous arthropod: the case of Tityus fuhrmanni (Scorpiones: Buthidae), a generalist predator scorpion

Abstract Background: Scorpions are arachnids that have a generalist diet, which use venom to subdue their prey. The study of their trophic ecology and capture behavior is still limited compared to other organisms, and aspects such as trophic specialization in this group have been little explored. Methods: In order to determine the relationship between feeding behavior and venom toxicity in the scorpion species Tityus fuhrmanni, 33 specimens were offered prey with different morphologies and defense mechanisms: spiders, cockroaches and crickets. In each of the experiments we recorded the following aspects: acceptance rate, immobilization time and the number of capture attempts. The median lethal dose of T. fuhrmanni venom against the three different types of prey was also evaluated. Results: We found that this species does not have a marked difference in acceptance for any of the evaluated prey, but the number of capture attempts of spiders is higher when compared to the other types of prey. The immobilization time is shorter in spiders compared to other prey and the LD50 was higher for cockroaches. Conclusions: These results indicate that T. fuhrmanni is a scorpion with a generalist diet, has a venom with a different potency among prey and is capable of discriminating between prey types and employing distinct strategies to subdue them.

Linking toxicity and predation in a venomous arthropod: the case of Tityus fuhrmanni (Scorpiones: Buthidae), a generalist predator scorpion

Background: Scorpions are arachnids that have a generalist diet, which use venom to subdue their prey. The study of their trophic ecology and capture behavior is still limited compared to other organisms, and aspects such as trophic specialization in this group have been little explored. Methods: In order to determine the relationship between feeding behavior and venom toxicity in the scorpion species Tityus fuhrmanni, 33 specimens were offered prey with different morphologies and defense mechanisms: spiders, cockroaches and crickets. In each of the experiments we recorded the following aspects: acceptance rate, immobilization time and the number of capture attempts. The median lethal dose of T. fuhrmanni venom against the three different types of prey was also evaluated. Results: We found that this species does not have a marked difference in acceptance for any of the evaluated prey, but the number of capture attempts of spiders is higher when compared to the other types of prey. The immobilization time is shorter in spiders compared to other prey and the LD50 was higher for cockroaches. Conclusions: These results indicate that T. fuhrmanni is a scorpion with a generalist diet, has a venom with a different potency among prey and is capable of discriminating between prey types and employing distinct strategies to subdue them.(AU)

Once a prey, now a predator: an unusual record of a scorpion (Scorpiones: Chactidae) predated by a katydid (Orthoptera: Tettigoniidae) in the western Brazilian Amazon / Antes presa, agora predador: um registro incomum de predação de um escorpião (Scorpiones: Chactidae) por uma esperança (Orthoptera: Tettigoniidae) no oeste da Amazônia brasileira

Orthopterans are an important component of the food chain. The species belonging to the order Orthoptera are herbivores or predators, and several behave as opportunistic predators. However, their predatory habits are not well understood. Here we report the predation of a Chactopsis sp. scorpion by a Hyperomerus sp. katydid in a fragment of terra firme forest in the western Brazilian Amazon. The specimens were found on a 60-cm tall bush. The scorpion showed spasmodic motions of the metasoma while it was being devoured by the katydid. This is the first report of a predator­prey interaction between an orthopteran and a scorpion in the Amazon biome. We believe that records of this type are important to allow a better understanding of predator-prey interactions in tropical invertebrate communities.(AU)

Os ortópteros são um componente importante da cadeia alimentar. As espécies pertencentes a ordem Orthoptera são herbívoras ou predadoras, e muitas se comportam como predadores oportunistas. No entanto, seus hábitos predatórios não são bem compreendidos. Aqui nós relatamos a predação de um escorpião Chactopsis sp. por uma esperança Hyperomerus sp. em um fragmento de floresta de terra firme no oeste da Amazônia brasileira. Os espécimes foram encontrados em um arbusto de 60 cm de altura. O escorpião apresentou movimentos espasmódicos do metassoma enquanto era devorado pela esperança. Este é o primeiro relato de interação predador-presa entre um ortóptero e um escorpião no bioma Amazônia. Nós acreditamos que registros deste tipo são importantes por permitir um melhor entendimento das interações predador-presa em comunidades de invertebrados tropicais.(AU)

Prey selectivity of the invasive largemouth bass towards native and non-native prey: an experimental approach

Non-native predators are known to cause ecological impacts through heightened consumption of resources and decimation of native species. One such species is Micropterus salmoides. Often introduced for sport fishing worldwide; it has been listed by International Union for Conservation of Nature and Natural Resources as one of the 100 of the world's worst invasive species. Whilst impacts conferred towards native prey are well known, its relationship with other non-native species has received much less attention. Therefore, the aim of this study was to experimentally investigate the feeding preference of M. salmoides towards native prey (Geophagus iporangensis) compared to non-native prey (Oreochromis niloticus and Coptodon rendalli) using comparative consumption and the Manly-Chesson selectivity index. We found a higher consumption by M. salmoides towards the non-native prey and a tendency for this non-native preference to increase when prey availability increased. Our results are in line with the hypothesis that the invasion of the non-native predator can be facilitated by the high abundance and reproductive rate of the non-native prey. This is relevant considering the interaction of multiple invaders in an ecosystem, in particular environments modified by humans. Interspecific relationships are complex and their understanding is necessary for environmental management decision-making.(AU)

Predadores não-nativos são conhecidos por causar impactos ecológicos com o aumento do consumo de recursos e do declínio das espécies nativas. Uma dessas espécies é Micropterus salmoides. Frequentemente introduzida ao redor do mundo para pesca esportiva; essa espécie foi listada pela União Internacional para a Conservação da Natureza como uma das 100 piores espécies invasoras do mundo. Embora os impactos nas presas nativas sejam bem conhecidos, sua relação com outras espécies não-nativas tem recebido muito menos atenção. Portanto, o objetivo deste estudo foi pesquisar experimentalmente a preferência alimentar de M. salmoides por presas nativas (Geophagus iporangensis) em comparação com presas não-nativas (Oreochromis niloticus e Coptodon rendalli) comparando o consumo e o índice de seletividade de Manly-Chesson. Encontramos que M. salmoides tem um maior consumo de presas não-nativas e uma tendência de aumento de preferência pela presa não-nativa com o aumento da disponibilidade de presas. Nossos resultados são consistentes com a hipótese de que a invasão do predador não-nativo pode ser facilitada pela grande abundância e capacidade reprodutiva de presas não-nativas. Isso é relevante considerando a interação de múltiplos invasores em um ecossistema, particularmente em ambientes modificados pelo homem. Relações interespecíficas são complexas e seu entendimento é necessário para a tomada de decisões de gestão ambiental.(AU)

South American Sea Lions Otaria flavescens, a good indicator of relative spatial and temporal changes in the distribution and abundance of marine resources? / Lobos marinos de un pelo sudamericanos Otaria flavescens ¿buenos indicadores de cambios espaciales y temporales relativos en la distribución y abundancia de los recursos marinos?

Oceanographic fluctuations and changes in ocean productivity directly affect the abundance and distribution of prey species, which in turn, affect the population status of their predators. In order to have a better understanding of this predator-prey relationship, the aim of the present study was to analyze the diet of the South American Sea Lion Otaria flavescens (Shaw, 1800) in two rookeries of the San Matias Gulf, in northern Patagonia (Argentina). A total of 52 scat samples of O. flavescens were collected in the Promontorio Belén colony and 35 in Caleta de los Loros during the late spring of 2011. The analysis of the samples indicated that at both localities fish occurred in 100% of scats with prey remains, followed by cephalopods (32.3%) and crustaceans (21.4%). The fish Raneya brasiliensis (Kaup, 1856) constituted the main prey taxon, both in terms of occurrence and numerical abundance. The octopod Octopus tehuelchus (d' Orbigny, 1834) and squids of the genus Doryteuthis constituted the dominant cephalopod prey. It is concluded that sea lions focused their foraging activity on those species of demersal and benthic habits, associated with coastal and shelf waters. Furthermore, this study reports for the first time the feeding habits of the South American Sea Lion colony of Promontorio Belén, second in population size of Río Negro province.

Las fluctuaciones oceanográficas y los cambios en la productividad del océano afectan directamente a la abundancia y distribución de las especies presa, que a su vez afectan al estado de la población de sus predadores. Con el fin de tener una mejor comprensión de esta relación predador-presa, el objetivo del presente trabajo fue analizar la dieta del lobo marino de un pelo sudamericano Otaria flavescens (Shaw, 1800) en dos apostaderos del Golfo San Matias, en Patagonia norte (Argentina). Se colectaron un total de 52 muestras de fecas de O. flavescens en el apostadero de Promontorio Belén y 35 en Caleta de los Loros durante la primavera tardía de 2011. El análisis de las muestras indicó que en ambas localidades los peces ocurrieron en el 100% de las muestras con remanentes alimentarios, seguidos por cefalópodos (32.3%) y crustáceos (21.4%). El pez Raneya brasiliensis (Kaup, 1856) constituyó el principal taxón presa, tanto en términos de ocurrencia como de abundancia numérica. El octópodo Octopus tehuelchus (d' Orbigny, 1834) y los calamares del género Doryteuthis constituyeron los cefalópodos presa dominantes. Se concluye que los lobos marinos centraron su actividad forrajera en aquellas especies de hábitos demersales y bentónicos, asociado a aguas costeras y de plataforma. Además, este estudio analiza por primera vez los hábitos alimenticios de la colonia de lobos marinos de un pelo sudamericanos en el apostadero de Promontorio Belén, segunda en tamaño poblacional de la provincia de Río Negro.

Water column use by reef fishes of different color patterns

Color in animals responds to selective pressures and mediates the relationship between organism and environment. Reef fishes have the amplest variety of pigment cell types. This color patterns' variety may function as camouflage and be related to spatial use. We tested the hypothesis that the coloration of reef fish relates to water column stratum occupation. We predicted that sedentary animals connected to the background take advantage of background matching or disruptive patterns; more mobile demersal species apply disruptive coloration or motion-dazzle; and that pelagic species tend to have silvery bodies. We classified color patterns and categorized the water column stratum use for the Brazilian reef fishes in FishBase. Our analyses confirmed that irregular contrasting contour breaks, suggestive of disruptive coloration, occurs in benthic species and that silvering color was more prevalent in the pelagic stratum. Our raw data suggested a higher frequency of contrasting regular stripes, typical of motion-dazzle, in demersal species. However, the considerable uncertainty around estimates did not confirm this pattern. Reef fishes coloration is correlated to occupation of different strata in the water column. This can be interpreted as fishes being adapted to these habitats and partially explaining the richness of color patterns among them.(AU)

A cor nos animais responde a pressões seletivas e media a relação entre organismo e ambiente. Peixes recifais têm a maior variedade de tipos de células de pigmento. Essa variedade de padrões de coloração pode funcionar como camuflagem e estar relacionada ao uso espacial. Nós testamos a hipótese de que a coloração dos peixes recifais está relacionada à ocupação do estrato da coluna d'água. Previmos que animais sedentários conectados ao fundo aproveitam a semelhança ao fundo ou padrões disruptivos; espécies demersais mais móveis aplicam coloração disruptiva ou deslumbramento de movimento; e que espécies pelágicas tendem a apresentar corpos prateados. Classificamos os padrões de coloração e categorizamos o uso do estrato da coluna d'água para os peixes recifais brasileiros no FishBase. Nossas análises confirmaram que quebras de contorno irregulares, sugerindo coloração disruptiva, ocorrem em espécies bentônicas e que a cor prateada prevaleceu no estrato pelágico. Nossos dados brutos sugeriram uma maior frequência de listras contrastantes, típicas do deslumbramento de movimento, em espécies demersais. Mas a considerável incerteza dessas estimativas não confirmou esse padrão. A coloração dos peixes recifais está correlacionada com a ocupação de diferentes estratos da coluna d'água. Isso pode ser interpretado como peixes sendo adaptados a estes habitats, explicando em parte a riqueza de padrões de coloração entre eles.(AU)

Voracity, reaction to stings, and survival of domestic hens when feeding on the yellow scorpion (Tityus serrulatus)

Abstract Background: Scorpionism is a worldwide problem that has already made thousands of victims, and multi-disciplinary approaches for controlling their populations are to be more successful. Hens are often mentioned as tools for controlling scorpions; however, systematic/experimental behavioral studies are not available. Moreover, there is no systematic information on the effect of scorpion venoms on hens. Using the venomous yellow scorpion Tityus serrulatus, the present study aimed to clarify the following aspects: (1) voracity of hens, (2) how hens react when stung, (3) the effect of scorpion stings on hen behavior during attacks, and (4) hen survivorship after feeding on scorpions. Methods: We attracted hens with corn powder, offered them scorpions and then recorded the hen-scorpion interaction. To test the effects of the sting we manually removed the scorpions telson. Results: We found that some hens ate up to six scorpions within minutes. By means of an ethogram and drawings, we showed that they exhibited several aversive behaviors when capturing scorpions. Removal of the scorpion telson stopped the aversive reactions, which was not observed in the control group. Finally, hens did not exhibit atypical behaviors after 1, 7 and 30 days and were all alive after 30 days. Conclusion: This is the first empirical and video recorded study providing evidence that hens are clearly affected by scorpion venom but do not die. Therefore, they may have potential to be used in biological control of these arthropods.

Filling gaps in the ecological knowledge on Auchenipteridae catfishes (Ostariophysi: Siluriformes): first data for Trachelyichthys exilis / Preenchendo lacunas no conhecimento ecológico de bagres Auchenipteridae (Ostariophysi: Siluriformes): primeiros dados para Trachelyichthys exilis

The feeding habit of Trachelyichthys exilis is described for the first time, with additional comments on its growth type and size at sexual maturity. We analyzed 42 specimens from the Amanã Reserve (Amazonas state, Brazil) collected with a seine net amidst stands of floating herbaceous vegetation during the dry season of 2002. Stomach contents revealed a predominantly carnivorous habit (tending to piscivorous), an isometric growth type, and size at maturity around 5.5 cm standard length. Based on the biological characteristics of the consumed prey, we presume that T. exilis forage actively during the twilight/night around and among the root tangle of herbaceous vegetation, preying upon nocturnally active animals such as small fishes and aquatic invertebrates, and/or close to the water surface, where diurnally active prey usually rests. Our findings provide essential information to fill knowledge gaps on the natural history of auchenipterid catfishes, especially on trophic ecology.(AU)

O hábito alimentar de Trachelyichthys exilis é descrito pela primeira vez, com comentários adicionais sobre seu tipo de crescimento e tamanho de maturação sexual. Nós analisamos 42 espécimes da Reserva Amanã (Amazonas, Brasil) coletados com rede de cerco em bancos flutuantes de herbáceas durante a estação seca de 2002. Conteúdos estomacais revelaram um hábito predominantemente carnívoro (tendendo a piscívoro), um tipo de crescimento isométrico e tamanho de maturação sexual em torno de 5,5 cm de comprimento padrão. Com base nas características biológicas das presas consumidas, presumimos que T. exilis forrageia ativamente durante o crepúsculo/noite ao redor e entre as raízes dos bancos flutuantes, onde captura presas noturnas como pequenos peixes e invertebrados aquáticos, e/ou próximo à superfície da água, onde geralmente repousam as presas diurnas. Nossos resultados fornecem informações essenciais para preencher lacunas de conhecimento sobre a história natural de bagres auchenipterídeos, especialmente sobre a ecologia trófica.(AU)

Coexistence of endemic peacock basses (Cichla) in a Neotropical reservoir (Cichlidae: Cichliformes)

Peacock basses (genus Cichla) are predatory fish widely distributed across the Amazon, where two or more species normally coexist in a same drainage. The mechanisms that allow coexistence remain poorly understood, although these species share a number of functional traits and behavioral aspects. To advance on this question, the present study compared population and functional traits of Cichla kelberi and C. piquiti, based on data collected between 2010 and 2020 in the upper section of the Lajeado Reservoir, Tocantins River. Both species were captured in all sampling sites, frequently in a same sample, but C. piquiti was far more frequent and abundant. The species used the same habitats, and co-occurred more often than expected by chance. Species had a similar diet (small-sized fish), reproductive effort, fecundity and fat accumulation, but C. piquiti showed larger body sizes, shoaling behavior, a longer reproductive period, and morphology associated with greater swimming potential. Overall, results revealed that these species coexist in the impoundment, with significant overlap in the use of habitats and food resources. Differences in other functional traits may favor their coexistence, possibly involving niche partitioning, which seem to explain the dominance of C. piquiti in the impoundment.(AU)

Tucunarés (gênero Cichla) são peixes predadores amplamente distribuídos pela Amazônia, sendo comum que duas ou mais espécies coexistam em uma mesma drenagem. Os mecanismos que permitem sua coexistência permanecem pouco compreendidos, embora essas espécies compartilhem uma série de traços funcionais e comportamentais. Para avançar nessa questão, o presente estudo comparou uma série de características populacionais e funcionais de Cichla kelberi e C. piquiti, com base em dados coletados entre 2010 e 2020 no reservatório de Lajeado, rio Tocantins. Ambas as espécies foram capturadas em todos os locais de amostragem, frequentemente em uma mesma amostra, mas C. piquiti foi muito mais frequente e abundante que C. kelberi. As espécies ocuparam os mesmos habitats, e co-ocorreram mais vezes do que o esperado ao acaso. As espécies apresentaram dieta (composta por peixes de pequeno porte), esforço reprodutivo, fecundidade e acúmulo de gordura semelhantes, mas C. piquiti apresentou tamanho corporal maior, comportamento de formar cardumes, período reprodutivo mais longo, e morfologia associada com maior poder de natação. No geral, os resultados revelaram que essas espécies coexistem no represamento, com sobreposição significativa no uso de habitats e recursos alimentares. Diferenças em outros traços funcionais devem favorecer sua coexistência, possivelmente envolvendo partição de nicho, o que parece explicar a dominância de C. piquiti no represamento.(AU)

Mini DNA barcodes reveal the details of the foraging ecology of the largehead hairtail, Trichiurus lepturus (Scombriformes: Trichiuridae), from São Paulo, Brazil

The largehead hairtail, Trichiurus lepturus, is an opportunistic, voracious, and piscivorous predator. Studies of fish feeding behavior based on the analysis of stomach contents are limited by the potential for the visual identification of the ingesta. However, molecular tools, in particular DNA barcoding, have been used successfully to identify stomach contents. When morphological analyses are not possible, molecular tools can precisely identify the components of the diet of a fish based on its stomach contents. This study used mini barcoding to identify food items ingested by T. lepturus off the northern coast of São Paulo State, Brazil. Forty-six sequences were obtained and were diagnosed as belonging to six different fish species: Pimelodus maculatus, Paralonchurus brasiliensis, Isopisthus parvipinnis, Opisthonema oglinum, Harengula clupeola, and Pellona harroweri or as belonging to the genera Lycengraulis and Sardinella. Trichiurus lepturus is an opportunistic predator that will exploit an available prey of an appropriate size. The results indicate that these fish migrate to warmer waters, such as those found in estuarine environments, at certain times of the year, where they exploit prey species that reproduce in this environment. One example was Pimelodus maculatus, which was the prey species most exploited based on the analysis of the material collected.(AU)

O peixe-espada, Trichiurus lepturus, é um predador oportunista, voraz e piscívoro. Os estudos do comportamento alimentar dos peixes com base na análise do conteúdo estomacal são limitados pelo potencial de identificação visual do material ingerido. No entanto, ferramentas moleculares, em particular o DNA barcode, têm sido utilizadas com sucesso para identificar o conteúdo do estômago. Quando as análises morfológicas não são possíveis, essas ferramentas moleculares podem identificar com precisão os componentes da dieta de um peixe com base em seu conteúdo estomacal. Este estudo utilizou o mini barcode (uma sequencia parcial do gene COI do DNA mitocondrial) para identificar alimentos ingeridos por T. lepturus no litoral Norte do estado de São Paulo, Brasil. Quarenta e seis sequências foram obtidas e combinadas com seis espécies diferentes de peixes: Pimelodus maculatus, Paralonchurus brasiliensis, Isopisthus parvipinnis, Opisthonema oglinum, Harengula clupeola e Pellona harroweri ou como pertencente aos gêneros Lycengraulis e Sardinella. Trichiurus lepturus é um predador oportunista que explora qualquer presa disponível que possua tamanho apropriado. Os resultados indicam que esses peixes migram para águas mais quentes em determinadas épocas do ano, como as encontradas em ambientes estuarinos, onde exploram espécies que se reproduzem neste ambiente. Um exemplo foi Pimelodus maculatus, sendo a espécie mais explorada por T. lepturus, a partir da análise do material coletado.(AU)

Spodoptera frugiperda (Noctuidae) fed on transgenic maize can transfer Bt proteins to Podisus nigrispinus (Pentatomidae)

An important concern with the use of genetically modified (GM) plants expressing Bacillus thuringiensis (Bt) insecticidal toxins is the deleterious effect on non-target organisms. The predatory stink bug Podisus nigrispinus (Dallas) (Hemiptera: Pentatomidae) is used in biological control programs and may be exposed to Bt toxins. This study evaluated the indirect effects of different Cry proteins on P. nigrispinus with the prey Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae), fed on simple or pyramided Bt maize genotypes. The experiment was carried out in a completely randomized design with three treatments: i) Isohybrid (not Bt), ii) Herculex® (transgenic maize encoding Cry1F protein) and iii) PowerCore® (pyramidal transgenic maize encoding the Cry1F, Cry1A.105, and Cry2Ab2 proteins), which were used to feed S. frugiperda for 48 h. The caterpillars were used as prey by P. nigrispinus females. We evaluated the presence of Cry proteins, consumed prey biomass (predation), oviposition period, number of postures, number of eggs, number of eggs per posture, number of nymphs, egg viability, embryonic period, female longevity and development, and survival rates of immature. The results show that different Cry proteins move through the food chain of P. nigrispinus and provide evidence that the ingestion of three different proteins does not lead to unexpected synergistic effects. However, Cry toxins promoted histopathological changes in midgut cells of P. nigrispinus.

Voracity, reaction to stings, and survival of domestic hens when feeding on the yellow scorpion (Tityus serrulatus)

Scorpionism is a worldwide problem that has already made thousands of victims, and multi-disciplinary approaches for controlling their populations are to be more successful. Hens are often mentioned as tools for controlling scorpions; however, systematic/experimental behavioral studies are not available. Moreover, there is no systematic information on the effect of scorpion venoms on hens. Using the venomous yellow scorpion Tityus serrulatus, the present study aimed to clarify the following aspects: (1) voracity of hens, (2) how hens react when stung, (3) the effect of scorpion stings on hen behavior during attacks, and (4) hen survivorship after feeding on scorpions. Methods: We attracted hens with corn powder, offered them scorpions and then recorded the hen-scorpion interaction. To test the effects of the sting we manually removed the scorpion's telson. Results: We found that some hens ate up to six scorpions within minutes. By means of an ethogram and drawings, we showed that they exhibited several aversive behaviors when capturing scorpions. Removal of the scorpion telson stopped the aversive reactions, which was not observed in the control group. Finally, hens did not exhibit atypical behaviors after 1, 7 and 30 days and were all alive after 30 days. Conclusion: This is the first empirical and video recorded study providing evidence that hens are clearly affected by scorpion venom but do not die. Therefore, they may have potential to be used in biological control of these arthropods.(AU)

Effects of parasites and predators on nociception: decreases analgesia reduces overwinter survival in root voles (Rodentia: Cricetidae)

ABSTRACT Growing evidence suggests that parasite-infected prey is more vulnerable to predation. However, the mechanism underlying this phenomenon is obscure. In small mammals, analgesia induced by environmental stressors is a fundamental component of the defensive repertoire, promoting defensive responses. Thus, the reduced analgesia may impair the defensive ability of prey and increase their predation risk. This study aimed to determine whether coccidia infection increases the vulnerability to predation in root voles, Microtus oeconomus (Pallas, 1776), by decreased analgesia. Herein, a predator stimulus and parasitic infection were simulated in the laboratory via a two-level factorial experiment, then, the vole nociceptive responses to an aversive thermal stimulus were evaluated. Further, a field experiment was performed to determine the overwinter survival of voles with different nociceptive responses via repeated live trapping. The coccidia-infected voles demonstrated reduced predator-induced analgesia following exposure to predator odor. Meanwhile, pain-sensitive voles had lower overwinter survival than pain-inhibited voles in enclosed populations throughout the duration of the experiment. Our findings suggest that coccidia infection attenuates predator-induced analgesia, resulting in an increased vulnerability to predation.

First records of Brazilian three-banded armadillo (Tolypeutes tricinctus, Mammalia, Cingulata, Chlamyphoridae) predation by jaguar (Panthera onca, Mammalia, Carnivora, Felidae)

Abstract The jaguar Panthera onca and the Brazilian three-banded armadillo Tolypeutes tricinctus are two threatened mammals that coexist in the Caatinga dry forests and the Cerrado savannas of Brazil. Yet, to the best of our knowledge, interactions between these species have not been reported in the literature. Here, we present the first records of P. onca predation on T. tricinctus from two different areas in the Caatinga in northeastern Brazil. We showed that P. onca can pierce the hard carapace of T. tricinctus, which may be possible due to its distinctly strong bite and associated predation behavior. We argue that P. onca may be the most adapted non-human predator to feed on T. tricinctus, and that the smaller body sizes of P. onca individuals in the Caatinga may increase their likelihood to feed on smaller prey, including T. tricinctus. Thus, the originality of our records is probably more related to insufficient research in the areas where these species coexist than to the rarity of this interaction.

First records of Brazilian three-banded armadillo (Tolypeutes tricinctus, Mammalia, Cingulata, Chlamyphoridae) predation by jaguar (Panthera onca, Mammalia, Carnivora, Felidae)

Abstract The jaguar Panthera onca and the Brazilian three-banded armadillo Tolypeutes tricinctus are two threatened mammals that coexist in the Caatinga dry forests and the Cerrado savannas of Brazil. Yet, to the best of our knowledge, interactions between these species have not been reported in the literature. Here, we present the first records of P. onca predation on T. tricinctus from two different areas in the Caatinga in northeastern Brazil. We showed that P. onca can pierce the hard carapace of T. tricinctus, which may be possible due to its distinctly strong bite and associated predation behavior. We argue that P. onca may be the most adapted non-human predator to feed on T. tricinctus, and that the smaller body sizes of P. onca individuals in the Caatinga may increase their likelihood to feed on smaller prey, including T. tricinctus. Thus, the originality of our records is probably more related to insufficient research in the areas where these species coexist than to the rarity of this interaction.

A new species of the micro snail genus Heleobia (Caenogastropoda, Cochliopidae) from Bahia, Brazil

Abstract The prey of a recent described characid fish, so far endemic of the small lake Pratinha (Iraquara, Bahia, Brazil), a small (~2.5 mm) lentic gastropod, revealed to be a new (possible endemic) species. It is herein formally described as Heleobia brucutu sp. nov. The description includes anatomical features, revealing interesting idiosyncrasies such as egg laying attached to shell, and penis lacking glands, but with terminal papilla. The new species appears to be endemic of that small lake as much as its fish predator. As the species is now formally described and named, protective efforts must be implemented.

A new species of the micro snail genus Heleobia (Caenogastropoda, Cochliopidae) from Bahia, Brazil

Abstract The prey of a recent described characid fish, so far endemic of the small lake Pratinha (Iraquara, Bahia, Brazil), a small (~2.5 mm) lentic gastropod, revealed to be a new (possible endemic) species. It is herein formally described as Heleobia brucutu sp. nov. The description includes anatomical features, revealing interesting idiosyncrasies such as egg laying attached to shell, and penis lacking glands, but with terminal papilla. The new species appears to be endemic of that small lake as much as its fish predator. As the species is now formally described and named, protective efforts must be implemented.

Stable isotope analysis reveals partitioning in prey use by Kajikia audax (Istiophoridae), Thunnus albacares, Katsuwonus pelamis, and Auxis spp. (Scombridae) in the Eastern Tropical Pacific of Ecuador

Kajikia audax, Thunnus albacares, Katsuwonus pelamis, and Auxis spp. occupy high and middle-level trophic positions in the food web. They represent important sources for fisheries in Ecuador. Despite their ecological and economic importance, studies on pelagic species in Ecuador are scarce. This study uses stable isotope analysis to assess the trophic ecology of these species, and to determine the contribution of prey to the predator tissue. Isotope data was used to test the hypothesis that medium-sized pelagic fish species have higher δ15N values than those of the prey they consumed, and that there is no overlap between their δ13C and δ15N values. Results showed higher δ15N values for K. audax, followed by T. albacares, Auxis spp. and K. pelamis, which indicates that the highest position in this food web is occupied by K. audax. The stable isotope Bayesian ellipses demonstrated that on a long time-scale, these species do not compete for food sources. Moreover, δ15N values were different between species and they decreased with a decrease in predator size.(AU)

Kajikia audax, Thunnus albacares, Katsuwonus pelamis e Auxis spp. ocupam posições tróficas intermedias e/ou elevadas nas cadeias alimentares. Estas espécies representam um importante recurso pesqueiro no Ecuador. Apesar da sua importância económica e ecológica, estudos nestas espécies pelágicas no Ecuador são raras. Este estudo usa isótopos estáveis para avaliar o seu nível trófico de modo a determinar a contribuição das suas presas para os tecidos destes predadores. Dados dos isótopos foram usados para testar a hipótese de que estas espécies de peixes pelágicos possuem valores mais elevados de δ15N do que daqueles das presas consumidas, e que não existe uma sobreposição entre os valores de δ13C e δ15N. Resultados mostram que valores mais elevados de δ15N para K. audax, seguidos por T. albacares, Auxis spp. e K. pelamis, indicam que a posição mais elevada na cadeia alimentar é ocupada por K. audax. Elipses Bayesianas de isótopos estáveis demonstram que, a uma escala de longo-termo, estas espécies de peixes não competem pelos recursos. Adicionalmente, os valores de δ15N são diferentes entre espécies de peixe estudadas e estes valores decrescem com a diminuição do tamanho do predador.(AU)