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ABSTRACT Larvae of Hydrotaea species are facultative predators of larvae of other fly species on poultry farms, chicken feces, pig, and decaying carcasses. The Neotropical species H. albuquerquei occurs together with M. domestica in these environments and might be useful in the biological control of the latter. To verify the predatory capacity of H. albuquerquei larvae on the larvae of M. domestica, we varied the size of the larvae and the densities of the predators and prey under controlled laboratory conditions. Adults were collected from a poultry farm for the experiment, and the larvae they produced were reared in the laboratory. The second and third instar larvae of H. albuquerquei, when at higher densities, suppressed populations of house fly larvae when the latter were smaller than the former. This means that the functional response increases gradually with an increase in prey population density and predator size. In these conditions, one H. albuquerquei larva consumes up to 29 M. domestica larvae at high prey densities and could reduce 100% of the house fly population under a 50% prey density. This study confirmed a pattern previously observed in other predatory larvae and our results have implications for the biological control and integrated pest management programs of M. domestica in poultry and swine farms.

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Predator diversity in a system can have different results on the biological control of pests. Positive results can arise if natural enemies have niche complementarity, whereas negative effects can occur when one enemy interferes with heterospecifics-e.g., via intraguild predation-resulting in weaker pest suppression. Nevertheless, a coexistence is possible if enemies use the resource differentially leading to resource partitioning, and/or if the intraguild prey has some competitive advantage over the intraguild predator-i.e., is better at exploiting the shared resource or exhibits avoidance behavior. In this study, we conducted a series of field-sampling and semifield experiments to elucidate the spatiotemporal association patterns of the coccinellids Eriopis connexa (Germar) and Cycloneda sanguinea L. (Coleoptera: Coccinellidae) and determine how the trophic interactions between them could affect the biological control of aphids. We found that both coccinellid species coexist in sweet-pepper crops over time, and this coexistence could be explained by a temporal niche complementarity. Despite cooccurring spatially, they were segregated at the leaf level, which segregation can be explained by an avoidance behavior to prevent negative trophic interactions, such as cannibalism and intraguild predation. Under semifield conditions, the possible negative trophic interactions did not affect the control of aphids when both species were present, but the density of C. sanguinea was reduced at the end of the experiment. These results suggest that biological control strategies that include both species would be positive for the control of aphids on the basis of these considerations.

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Biological control of the Mexican fruit fly, Anastrepha ludens, is mainly carried out by releasing parasitoids, such as Diachasmimorpha longicaudata, and by applying entomopathogenic fungi (EPF), such as Metarhizium anisopliae, Beauveria bassiana, or Isaria fumosorosea, which can be applied to the soil or dispersed using infective devices. The combined use of two or more biocontrol agents could improve A. ludens control, but IGP between natural enemies, if it occurs, may have negative effects. We evaluated the effects of EPF on D. longicaudata. First, we determined the susceptibility of adults of D. longicaudata to strains of EPF (Metarhizium robertsii strain V3-160 and M. anisopliae strain MAAP1). We also evaluated the infection of these two fungi on A. ludens larvae parasitized by D. longicaudata. Finally, we determined sub-lethal effects on adults of D. longicaudata that emerged from larvae that had been exposed to low concentrations of M. robertsii. Both fungi caused moderate mortality to D. longicaudata adults. There were no adverse effects on the longevity of parasitoids that emerged from parasitized larvae exposed to M. robertsii. Based on these results, we argue that M. robertsii has the potential to be used for biocontrol of A. ludens, with limited risk to D. longicaudata adults.

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Entomopathogenic nematodes (EPNs) and predatory mirids are among the most effective natural enemies for the control of Tuta absoluta, a key pest of tomato worldwide. In the case of South America, the native EPN Heterorhabditis amazonensis and the predator Macrolophus basicornis (Stal) coexist in tomato. The intraguild interactions of two ENPs, H. amazonensis JPM4 and the widely used Steinernema carpocapsae, with the predator M. basicornis, were studied in laboratory setups with the objective of evaluating the potential interactions between them. We hypothesized that the two natural enemies do not interact negatively. The first nymphal stage of the predator was not affected when exposed to tomato leaves directly sprayed with both EPNs, which we attributed to the small size of its stylet. Individuals treated with H. amazonensis JPM4 had low mortality rates in all developmental stages with a maximum of 1.3%. Mortality was higher when the predator was exposed to S. carpocapsae (28% for adults) and correlated positively with increasing developmental stages. In prey choice tests between larvae infected with H. amazonensis and uninfected larvae, M. basicornis fed indistinctively showing no clear preference. When presented with choice larvae infected with S. carpocapsae, the consumption of healthy larvae was higher. In a no-choice prey acceptance experiment, M. basicornis preyed on both healthy and infected larvae with no difference in larvae consumed. Predators that had fed from infected larvae did not exhibit signs of nematode infection and survived. Our results indicate that the South American native H. amazonensis JPM4 and M. basicornis do not show a negative interaction and are promising candidates for combined use in T. absoluta biological control.

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Abstract The jaguarundi (Puma yagouaroundi) is the second most widespread carnivore of the Americas, and considered a threatened species in Brazil. However, most of its ecology is unknown, and few information is available about species that may act as its predator. In this study we present evidence of the predation of a jaguarundi by puma (Puma concolor) in a protected area (Carlos Botelho State Park) in the state of São Paulo, southeastern Brazil. We collected fecal samples in trails and dirt roads in the study area, and by using hair cuticle imprints and medullar patterns, we identified a puma scat containing hair and claws of a jaguarundi. Pumas usually consume carnivores, but the presence of felids is uncommon, especially in Brazil. This could be considered an antagonist interaction, but pumas and jaguarundis do not compete for territory or prey in large protected areas, since pumas have a high intake of larger prey (> 1 kg). Thus, we conclude that this an episode of intraguild predation for feeding purposes, not a kill in response to competition for prey or territory. This is an important record that helps to understand a bit more of the complex trophic relationships in tropical forests.

Resumo O gato-mourisco (Puma yagouaroundi) é o segundo carnívoro com maior distribuição nas Américas, e considerado vulnerável a extinção no Brasil. No entanto, grande parte de sua ecologia é desconhecida, e há pouca informação disponível sobre espécies que poderiam atuar como seu predador. Nesse estudo, apresentamos evidências da predação do gato-mourisco por onça-parda (Puma concolor) em uma unidade de conservação (Parque Estadual Carlos Botelho) no estado de São Paulo. Coletamos amostras fecais de onça-parda em trilhas e estradas de terra na área estudada, e por meio da análise de microestrutura dos pelos, identificamos pelos e garras de um gato-mourisco em uma das amostras fecais. As onças-pardas normalmente consomem carnívoros, mas a predação de outros felinos é incomum, especialmente no Brasil. Essa poderia ser considerada uma interação antagonista, mas a onça-parda e o gato-mourisco não competem por território ou presas em grandes áreas protegidas, uma vez que as onças-pardas consomem preferencialmente presas maiores (> 1 kg). Portanto, concluímos que esse é um episódio de predação intraguilda com propósito alimentar da onça-parda, e não uma predação por conta de competição por território ou presas. Esse registro é importante e ajuda a compreender um pouco mais sobre as complexas relações tróficas em florestas tropicais.

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The decline of the North American native lady beetle, Coccinella novemnotata Herbst, is strongly correlated with the introduction of Coccinella septempunctata L., and C. novemnotata are locally extirpated across much of the United States. Since C. novemnotata's decline, the invasive Harmonia axyridis Pallas has become dominant in North America. This study investigated whether H. axyridis has the potential to impede the recovery of C. novemnotata populations. To determine how H. axyridis interacts with C. novemnotata via intraguild predation and competition for prey, we paired first-instar C. novemnotata with first-instar H. axyridis at low and high densities of pea aphid. Coccinella novemnotata survival when paired interspecifically was significantly lower than H. axyridis survival at both aphid densities. Both species had similar weights at eclosion across aphid densities; however, H. axyridis developed faster than C. novemnotata. To examine the effect of larval size on intraguild interactions, we conducted a second experiment where we varied the C. novemnotata and H. axyridis instar in our pairings. Coccinella novemnotata survival and final weight increased when paired with younger H. axyridis larvae. The percentage survival of C. novemnotata in interspecific treatments, at the low aphid density, was lower than for same-aged C. novemnotata reared conspecifically, except for pairs initiated with C. novemnotata larvae that were two instars more advanced than H. axyridis larvae. These results suggest that intraguild predation and competition for prey by H. axyridis have the potential to affect the recovery of C. novemnotata populations negatively.

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Identification of the mechanisms enabling stable coexistence of species with similar resource requirements is a central challenge in ecology. Such coexistence can be facilitated by species at higher trophic levels through complex multi-trophic interactions, a mechanism that could be compromised by ongoing defaunation. We investigated cascading effects of defaunation on Pachymerus cardo and Speciomerus giganteus, the specialized insect seed predators of the Neotropical palm Attalea butyracea, testing the hypothesis that vertebrate frugivores and granivores facilitate their coexistence. Laboratory experiments showed that the two seed parasitoid species differed strongly in their reproductive ecology. Pachymerus produced many small eggs that it deposited exclusively on the fruit exocarp (exterior). Speciomerus produced few large eggs that it deposited exclusively on the endocarp, which is normally exposed only after a vertebrate handles the fruit. When eggs of the two species were deposited on the same fruit, Pachymerus triumphed only when it had a long head start, and the loser always succumbed to intraguild predation. We collected field data on the fates of 6569 Attalea seeds across sites in central Panama with contrasting degrees of defaunation and wide variation in the abundance of vertebrate frugivores and granivores. Speciomerus dominated where vertebrate communities were intact, whereas Pachymerus dominated in defaunated sites. Variation in the relative abundance of Speciomerus across all 84 sampling sites was strongly positively related to the proportion of seeds attacked by rodents, an indicator of local vertebrate abundance. SYNTHESIS: We show that two species of insect seed predators relying on the same host plant species are niche differentiated in their reproductive strategies such that one species has the advantage when fruits are handled promptly by vertebrates and the other when they are not. Defaunation disrupts this mediating influence of vertebrates and strongly favours one species at the expense of the other, providing a case study of the cascading effects of defaunation and its potential to disrupt coexistence of non-target species, including the hyperdiverse phytophagous insects of tropical forests.

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BACKGROUND: Geocoris punctipes (Hemiptera: Lygaeidae) and Eretmocerus eremicus (Hymenoptera: Aphelinidae) are whitefly natural enemies. Previously, under laboratory conditions, we showed that G. punctipes engages in intraguild predation (IGP), the attack of one natural enemy by another, on E. eremicus. However, it is unknown whether this IGP interaction takes place under more complex scenarios, such as semi-field conditions. Even more importantly, the effect of this interaction on the density of the prey population requires investigation. Therefore, the present study aimed to establish whether this IGP takes place under semi-field conditions and to determine whether the predation rate of G. punctipes on the whitefly decreases when IGP takes place. RESULTS: Molecular analysis showed that, under semi-field conditions, G. punctipes performed IGP on E. eremicus. However, although IGP did take place, the predation rate by G. punctipes on the whitefly was nevertheless higher when both natural enemies were present together than when the predator was present alone. CONCLUSION: While IGP of G. punctipes on E. eremicus does occur under semi-field conditions, it does not adversely affect whitefly control. The concomitant use of these two natural enemies seems a valid option for inundative biological control programmes of T. vaporariorum in tomato. © 2015 Society of Chemical Industry.

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Interaction between Musca domestica L. and its predator Muscina stabulans (Fallén) (Diptera, Muscidae): Effects of prey density and food source abundance. The objective of this work was to evaluate the influence of prey density and food source abundance on the predatory behavior of Muscina stabulans over M. domestica. Three predator/prey proportions were evaluated (1:1, 1:3 and 1:6), using 100 third instar predator larvae against second instar prey larvae. Each proportion was maintained using three different levels of food substrate (25, 50 and 100 g). The experiments were carried out in triplicate in BOD incubators (25ºC, UR 70% ± 10% and 12 h photoperiod). The mortality of the M. domestica larvae was 100% under all conditions, except in the 1:6 predator/prey proportion, at the 50g and 100g food substrate levels, where it was 99.99% and 99.22%, respectively. There was a significant increase in the development period of M. stabulans in relation to the increase in prey density and decrease in quantity of food substrate. An increase in the proportion of individuals and a reduction in the amount of resource slowed down larval development. Muscina stabulans pupal weight was proportional to the increase in prey density and the amount of food substrate. The proportion or the density influenced the survival of M. stabulans, with no difference in relation to the amount of food source and consequently in the interaction of the factors. There was no difference between the 1:1 and 1:3 predator-prey densities, with both differing from the 1:6 density.

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Harmonia axyridis (Pallas) (Coleoptera, Coccinellidae) is a polyphagous Asian species, well-known as a classical biological control agent of aphids around the world, introduced probably accidentally in Brazil, sampled for the first time in 2002. It is an important intraguild predator, competing for food with native coccinellids. It was studied H. axyridis alimentary sources and host plants, its abundance compared with native and established species, the influence of abiotic factors and the seasons over the abundance of H. axyridis throughout one year, and discussed the mechanisms which influence the displacement of species. Harmonia axyridis was found in 38 plant species, among them 20 were new records, feeding on 20 aphid species, eight of them new alimentary records. Between 2006/2007, eight Coccinellidae species were collected and H. axyridis was the most abundant (91.23 percent). Harmonia axyridis peak of abundance occurred in August and September 2007, probably influenced by the temperature and food availability. From 1999 to 2007 a reduction and variation in the diversity of collected species of Coccinellidae were observed with the predominance of H. axyridis, which may indicate their displacement.

Harmonia axyridis (Pallas) (Coleoptera, Coccinellidae) é uma espécie asiática, polífaga e reconhecida como agente de controle biológico de afídeos pelo mundo, provavelmente introduzida acidentalmente no Brasil, coletada pela primeira vez em 2002. É um importante predador intraguilda, pois compete por alimento com as espécies nativas de coccinelídeos. Foram estudadas as fontes alimentares de H. axyridis e suas plantas hospedeiras, sua abundância em relação às espécies nativas e estabelecidas, a influência dos fatores abióticos e as estações do ano sobre sua abundância durante um ano e discutidos os mecanismos que influenciam no deslocamento das espécies nativas de Coccinellidae. Além disso, foi testada a influência dos fatores abióticos e as estações do ano sobre sua abundância durante um ano. Harmonia axyridis foi encontrada em 38 espécies de plantas, sendo 20 delas novos registros, alimentando-se de 20 espécies de afídeos, oito novos registros alimentares. Entre os anos de 2006/2007, oito espécies de Coccinellidae foram coletadas e H. axyridis foi a mais abundante (91,23 por cento). O pico de abundância de H. axyridis ocorreu em agosto e setembro de 2007, provavelmente influenciado pela temperatura e disponibilidade de alimento. Entre 1999 e 2007, foram observadas a redução e variação na diversidade de espécies de Coccinellidae coletadas, com a predominância de H. axyridis, o que pode indicar o desalojamento destas espécies.

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Objetivou-se no presente trabalho estudar aspectos da predação entre larvas de Chrysoperla externa e Ceraeochrysa cubana, sob condições de laboratório, verificando a sobrevivência desses predadores nos diferentes ínstares, quando mantidos nas proporções de 1:1, 2:2 e 3:3. De modo geral, C. externa apresentou maior sobrevivência, independente do ínstar e da proporção de adensamento entre indivíduos. Ao contrário, C. cubana foi fortemente afetada pela interação com C. externa, tendo sua capacidade de sobrevivência reduzida com o aumento da proporção de adensamento e com o desenvolvimento larval. No final da fase larval, verificou-se uma taxa de sobrevivência próxima a 96, 90 e 95 por cento, e 56, 23 e 9 por cento para C. externa e C. cubana nas proporções de 1:1, 2:2 e 3:3 indivíduos, respectivamente.

This work aimed to study aspects of predation among Chrysoperla externa and Ceraeochrysa cubana larvae under laboratory conditions. The survival of those predators in different larval stages was studied, maintaining the larvae grouped in proportions of 1:1, 2:2 and 3:3 individuals. C. externa presented higher survival rates, independently of larval ínstar and density proportion among individuals. On the other hand, C. cubana was strongly affected by interaction with C. externa, and had its survival capacity reduced with the increase of grouping proportion and larval development. At the end of larval phase, a survival rate around 96, 90, and 95 and 56, 23 and 9 percent for C. externa and C. cubana in proportions of 1:1, 2:2 and 3:3 individuals, respectively, was verified.

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Studies on interactions among plants, herbivores and natural enemies are important for understanding population dynamics of species in food webs, but they are also important for the practice of pest control with natural enemies. Biological control programs heavily rely on the occurrence of trophic cascades, where the addition of one natural enemy causes a decrease of pest densities and an increase of plant biomass. However, when more that one natural enemy is used to control various pests in the same system, artificial food webs are created and simple tritrophic interactions change to more complicated ones. The occurrence of complex interactions and omnivory in these food webs may modify the sign and the strength of direct effects of natural enemies on pests. In this paper, we show and discuss the experimental results on interactions mediated by predators in an artificial food web that occurs on cucumber plants in greenhouses where biological control is applied. The two pests in this food web are the two-spotted spider mite Tetranychus urticae Koch, and the western flower thrips Frankliniella occidentalis (Pergande). The predatory mites Phytoseiulus persimilis Athias-Henriot and Neoseiulus californicus (McGregor) are used to control spider mites, and the generalist predatory bug Orius laevigatus (Fieber) and a specialist predatory mite Neoseiulus cucumeris (Oudemans) are predators of thrips. Results from behavioural studies showed that some of these species are attracted to the same patch and do not avoid each other's presence. We show some complex interactions arising from the meeting of these species: (a) the intraguild predation by O. laevigatus on P. persimilis, (b) the use of spider-mite web as a refuge by thrips larvae against their predators. The consequences of such interactions for population dynamics of predators and prey and their implications for success of biological control are discussed.

Estudos sobre interações entre plantas, herbívoros e inimigos naturais são importantes para o entendimento da dinâmica populacional das espécies em teias alimentares, bem como para o sucesso do controle de pragas por inimigos naturais. Os programas de controle biológico fundamentam-se na ocorrência de sucessões tróficas, onde a adição de um inimigo natural causa o decréscimo na densidade da presa/hospedeiro e o aumento da biomassa da planta. Entretanto, quando mais de uma espécie de inimigo natural é usada para controlar várias pragas no mesmo sistema, teias alimentares artificiais são criadas e as interações tritróficas simples transformam-se em outras mais complicadas. A ocorrência de interações complexas e de onivoria nestas teias alimentares pode modificar a direção e a intensidade dos efeitos diretos dos inimigos naturais sobre as pragas. Neste artigo, são apresentados e discutidos os resultados experimentais sobre interações mediadas por predadores em uma teia alimentar artificial. Esta teia é formada em plantas de pepino em casa de vegetação onde o controle biológico é aplicado. A teia constitui-se de duas pragas, o ácaro rajado Tetranychus urticae Koch e o tripes Frankliniella occidentalis (Pergande). Para o controle dos ácaros rajados são liberados os ácaros predadores Phytoseiulus persimilis Athias-Henriot e Neoseiulus californicus (McGregor). O controle dos tripes é feito através de liberações do percevejo generalista Orius laevigatus (Fieber) e do ácaro predador especialista Neoseiulus cucumeris (Oudemans). Resultados de estudos comportamentais mostraram que algumas destas espécies são atraídas para o mesma planta e não evitam plantas ocupados por outras espécies. Quando estas espécies são encontradas na mesma planta, interações complexas ocorrem: (a) predação intraguilda de O. laevigatus sobre P. persimilis, (b) uso da teia produzida pelo ácaro rajado pelas larvas de tripes como refúgio contra seus predadores. As conseqüências ...

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The relative importance of intraspecific, interspecific, and seasonal causes of larval mortality were investigated for aquatic larvae of the giant damselfly Megaloprepus coerulatus in Panama. These larvae live in water-filled holes in fallen and living trees, where they and three other common odonate species are the top predators. By mid wet season, M. coerulatus larvae were found in nearly half of all tree holes that harbored odonates. Although M. coerulatus were typically, but not always, eliminated from holes inhabited by larger hetero-specifics, M. coerulatus were more likely to encounter conspecifics than other odonate species. Hole with less than 11 of water rarely contained more than a single larva. In large holes where M. coerulatus was the only odonate species present, multiple larvae coexisted at a density of one larva per 1-21 of water. There the absence of 2-4 of the 5 larval size classes, despite a continuous input of eggs, suggested that cannibalism was a common cause of mortality. The size of the final instar, which determined adult body size, was correlated positively with tree hole volume for male, but not female, larvae. Experiments showed that when two larvae were placed together in 0.4-1 holes with abundant tadpole prey, the larger larva killed the smaller one. Often the larva that was killed was not eaten. Small larvae were more tolerant of each other than were pairs of medium or large larvae. Before killing occurred, the presence of larger larvae reduced the growth of smaller individuals, relative to controls. 'Obligate' killing was density-dependent. In 3.0-1 holes with ad libitum prey, conspecific killing occurred until the larval density stabilized at one larva per 1-1.5 I, similar to the density found in large holes under field conditions, For M. coerulatus, cannibalism functions to reduce the number of potential competitors for food in addition to providing nutrition. When interactions between paired larvae in small holes were experimentally prevented, competition for food reduced the growth of one or both larvae relative to controls. Holes that were watered during the dry season supported larval densities similar to those in the wet season. Thus, dry season mortality could not be attributed to a decrease in available prey. Rather, M. coerulatus larvae could not survive more than 1 month of complete drying. Because the dry season typically lasts more than 6 weeks, habitat drying is a secondary source of mortality, affecting second- or third-generation larvae that fail to emerge before tree holes dry out completely.