ABSTRACT. Phytophagous mites can cause economic losses in many crops, including grapevines. The changes in their population levels may be associated with changes in the predator-prey relationship. Knowledge of the distribution of mites in plants is important for planning sampling strategies and facilitating control decisions. The aims of this study were to (i) evaluate the abundances of Tetranychus urticae (Tetranychidae) and Neoseiulus californicus (Phytoseiidae), and the correlations between them and environmental factors; (ii) determine their distribution on the top, middle, or base strata of the evaluated grapevines (Vitis vinifera, Chardonnay cultivar) and, additionally, report the first occurrence of damage caused by T. urticae in grapevine leaves in the state of Rio Grande do Sul, Southern Brazil. Sixteen samplings were conducted, divided between the 2018 and 2019 seasons. In each sampling, three leaves from the three strata of the plant (top, middle, and base) were collected from 20 plants, totaling 60 leaves per sampling. The predator-prey relationship and their association with environmental variables were evaluated with multivariate correlation, whereas the number of mites per plant leaf strata was compared using a generalized linear mixed model in R software. It was possible to observe the symptoms of damage caused by T. urticae attacks on grapevines in Southern Brazil, characterized by the presence of yellow spots and general yellowing of the vineyard. Our findings indicate that T. urticae and N. californicus individuals are strongly associated with each other regardless of the environmental variables, and such relationship occurs mainly on the lower strata (middle and base leaves) of grapevines. Thus, by taking into account the damage on the leaves of grapevines and the occurrence of T. urticae and N. californicus majorities on specific strata of these vineyards, we suggest that the lower strata of grapevines should be the priority targets for management strategies to control such mites.

RESUMO 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.

ABSTRACT 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.

Resumen Las infecciones bacterianas provocan respuestas inmunitarias, incluyendo neutrófilos, cuyo reclutamiento es estimulado por la presencia de la bacteria pero que muere después de eliminar esas bacterias. Esta doble interacción entre las concentraciones de bacterias y neutrófilos, más complicada que la simple relación depredador-presa que describe las interacciones entre bacterias y macrófagos, crea un ambiente en el que los neutrófilos tal vez sólo puedan despejar infecciones suficientemente pequeñas. Este estudio describe esta relación utilizando un sistema dinámico no lineal sencillo que exhibe un comportamiento de biestabilidad conocido como una bifurcación hacia atrás. El crecimiento bacteriano se supone limitado por un nutriente clave. En contraste con un estudio anterior que mantuvo los niveles de neutrófilos y nutrientes constantes y requería términos de saturación para producir la biestabilidad, nuestro modelo muestra que los términos bilineales sencillos fomentan la biestabilidad cuando las densidades de nutrientes y neutrófilos pueden variar en respuesta a la densidad bacteriana. Un ejemplo aplicado a la bacteria Borrelia burgdorferi, que se alimenta de manganeso, ilustra por qué la respuesta rápida de los neutrófilos es clave para su capacidad de contener las infecciones bacterianas.

Abstract Bacterial infections elicit immune responses including neutrophils, whose recruitment is stimulated by the bacteria’s presence but which die after eliminating those bacteria. This dual interaction between bacteria and neutrophil concentrations, more complicated than the simple predator-prey relationship that describes macrophage-bacteria interactions, creates an environment in which neutrophils may only be able to clear sufficiently small infections. This study describes this relationship using a simple nonlinear dynamical system which exhibits bistability behavior known as a backward bifurcation. Bacterial growth is assumed limited by a key nutrient. In contrast to a previous study which held neutrophil and nutrient levels constant and required saturation terms to produce bistability, our model shows that simple bilinear terms support bistability when nutrient and neutrophil densities are allowed to vary in response to bacterial density. An example application involving Borrelia burgdorferi, which feeds on manganese, illustrates why neutrophils’ rapid response is key to their ability to contain bacterial infections.

RESUMO A tesourinha Euborellia annulipes vem sendo estudada como inimigo natural de insetos-pragas e potencial predadora da traça-das-crucíferas. A temperatura é um fator importante para mediar o aumento da densidade populacional de pragas, podendo afetar as dinâmicas da relação predador-presa. Objetivou-se avaliar o efeito da temperatura e do estágio de desenvolvimento de indivíduos de Plutella xylostella na preferência alimentar de fêmeas de E. annulipes. Três temperaturas (18 ºC, 25 ºC e 32 ºC), dois estágios de desenvolvimento (lagartas e pupas) e duas condições de alimentação relacionadas à captura das presas (com e sem escolha) foram avaliados. Independentemente da temperatura, fêmeas de tesourinha mostraram preferência alimentar por lagartas, ao invés de pupas. As condições de temperatura e de escolha influenciaram na quantidade de presas consumidas, mas apenas para larvas (não para pupas). O menor consumo de lagartas foi observado sob 18 ºC, em ambas as condições de captura.

ABSTRACT The ring-legged earwig Euborellia annulipes has been studied as a natural enemy of pest-insects and a potential predator of diamondback moth. Temperature is an important factor that mediates the pest population density and may affect the predator-prey relationship dynamics. This study aimed to evaluate the effect of the temperature and development stage of Plutella xylostella individuals on the feeding preference of E. annulipes females. Three temperatures (18 ºC, 25 ºC and 32 ºC), two development stages (larvae and pupae) and two feeding conditions related to the prey capture (with or without choice) were assessed. No matter the temperature, ring-legged earwig females showed a preference for eating larvae, instead of pupae. The temperature and choice conditions influenced the amount of consumed preys, but only for larvae (not for pupae). The lowest larvae consumption was observed at 18 ºC, in both prey capture conditions.

Abstract Tetranychus urticae Koch (Acari: Tetranychidae) is the main pest in rose (Rosa sp.) (Rosales: Rosaceae) by reducing the amount of chlorophyll in plants and at high densities they are overexploited and even killed. One of the most used biological controllers for this pest for its high efficiency is the mite Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae). Our hypothesis was: P. persimilis reduces the populations of T. urticae and therefore chlorophyll is not affected. The objectives were: 1) to determine the susceptibility or resistance of rose varieties to the attack of T. urticae, 2) determine the relationship between the condition of the plant and the population density of T. urticae, 3) know the predation effect of P. persimilis in the control of T. urticae and its efficiency; and 4) determine in which variety of rose P. persimilis performs best. We established the experiment in two parts; the first was one-way and the second consisted of repeated measurements to analyze the effects of T. urticae and the release of P. persimilis through the chlorophyll content variables in SPAD cm-2 units, percentage of damage per cm2 and the number of mites per cm2 in rose varieties. We did three repetitions for each stratum (upper, middle and lower) by variety of rosebush per week, for which we analyzed 72 samples per variety. The varieties of rose evaluated were Virginia and Ojo de Toro. At random we released 100 T. urticae and 12 P. persimilis mites per plant. The data analysis was one-way ANOVA and repeated means, simple linear, multiple and non-linear regressions to determine the dependence between the variables. Prior to the release of P. persimilis there were significant differences between the varieties with respect to the abundance of T. urticae per cm2, but not in the chlorophyll content and percentage of damage. After the release of P. persimilis, the abundance of T. urticae was different in the strata of both varieties. The Ojo de Toro variety had the lowest chlorophyll content. There was no difference in the percentage of damage and the abundance of P. persimilis between both varieties. Phytoseiulus persimilis was more efficient in the Ojo de Toro variety than in the Virginia variety. It also reduced the damage by T. urticae but did not prevent the reduction of chlorophyll content by the phytophagous.

Resumen Tetranychus urticae Koch (Acari: Tetranychidae) es la plaga principal en rosal (Rosa sp.) (Rosales: Rosaceae), al reducir la cantidad de clorofila de la planta y en grandes densidades la sobreexplotan e incluso las matan. Uno de los controladores biológicos más utilizados para esta plaga por su alta eficacia es el ácaro Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae). La hipótesis fue: P. persimilis reduce las poblaciones de T. urticae y por ende la clorofila no es afectada. Los objetivos fueron: 1) determinar la susceptibilidad o resistencia de variedades de rosal al ataque de T. urticae, 2) determinar la relación entre la condición de la planta y la densidad poblacional de T. urticae, 3) conocer el efecto de depredación de P. persimilis en el control de T. urticae y la eficiencia, y 4) determinar en cual variedad de rosal, P. persimilis se desempeña mejor. El experimento se estableció en dos partes, la primera fue de una vía y la segunda de medidas repetidas, para analizar los efectos de T. urticae y la liberación P. persimilis mediante las variables contenido de clorofila en unidades SPAD cm-2, porcentaje de daño por cm2 y el número de ácaros por cm2 en variedades de rosal. Las repeticiones fueron tres por cada estrato (superior, medio e inferior) por variedad de rosal por semana, por lo cual se analizaron 72 muestras por variedad. Las variedades de rosal evaluadas fueron Virginia y Ojo de Toro. Al azar se liberaron 100 T. urticae y 12 ácaros P. persimilis por planta. El análisis de datos fue ANDEVA de una vía y de medias repetidas, regresiones simples lineales, múltiples y no lineales para determinar la dependencia entre las variables. Previo a la liberación de P. persimilis hubo diferencias significativas entre las variedades con respecto a la abundancia de T. urticae por cm2, pero no, en el contenido de clorofila y porcentaje de daño. Después de la liberación de P. persimilis, la abundancia de T. urticae fue diferente en los estratos de ambas variedades. La variedad Ojo de Toro presentó el menor contenido de clorofila. No hubo diferencia en el porcentaje de daño y la abundancia de P. persimilis entre ambas variedades. Phytoseiulus persimilis fue más eficiente en la variedad Ojo de Toro que en la variedad Virginia. Además redujo el daño por T. urticae pero no evitó la reducción del contenido de clorofila por el fitófago.

Existe poco conocimiento sobre el impacto que tienen los jaguares sobre las tortugas marinas que anidan en el Parque Nacional Tortuguero, Costa Rica. Este estudio evaluó el impacto de la depredación de jaguar sobre tres especies de tortugas marinas (Chelonia mydas, Dermo-chelys coriáceay Eretmochelys imbricata)que anidan en Tortuguero. Los reportes de depredación fueron obtenidos empleando dos metodologías, revisión literaria (eventos registrados antes del 2005) y monitoreos semanales a lo largo de la playa (durante el periodo 2005-2013). La depredación del jaguar se ha incrementado de una tortuga en 1981 a 198 tortugas en 2013. Asimismo, los jaguares consumieron anualmente un promedio de 120 (SD= 45) y 2 (SD= 3) tortugas verdes y tortugas baula en Tortugue-ro, respectivamente. Nuestros resultados indican que los jaguares no representan una amenaza para la población de tortugas verdes que anida en Tortuguero, y no son la causa principal de la disminución poblacional de la tortuga baula y carey. No obstante, se recomienda continuar con el monitoreo con el fin de entender cómo esta interacción depredador-presa evolucionará en el futuro.

Little is known about the effects of jaguars on the population of marine turtles nesting in Tortuguero National Park, Costa Rica. This study assessed jaguar predation impact on three species of marine turtles (Chelonia mydas, Dermochelys coriáceaand Eretmochelys imbricata)that nest in Tortuguero beach. Jaguar predation data was obtained by using two methodologies, literature review (historical records prior the year 2005) and weekly surveys along the 29 km stretch of beach during the period 2005-2013. Our results indicated that jaguar predation has increased from one marine turtle in 1981 to 198 in 2013. Jaguars consumed annually an average of 120 (SD= 45) and 2 (SD= 3) green turtles and leatherbacks in Tortuguero beach, respectively. Based on our results we concluded that jaguars do not represent a threat to the population of green turtles that nest in Tortuguero beach, and it is not the main cause for population decline for leatherbacks and hawksbills. Future research should focus on continuing to monitor this predator-prey relationship as well as the factors that influence it so the proper management decisions can be taken.

As lagoas costeiras do Oceano Atlântico Sul abrigam altas densidades de peixes juvenis e são áreas-chave para diversas aves marinhas que dependem dos recursos oferecidos por esses ecossistemas. O objetivo do presente trabalho foi analisar a abundância e a composição de peixes na região estuarina da Lagoa Costeira Mar Chiquita (Argentina), a dieta do talha-mar (Rynchops niger) e as variações interanuais. Os peixes foram coletados com uma rede de praia tipo picaré e a dieta do talha-mar analisada a partir de suas fezes. O peixe-marinhos dependentes do estuário foram a categoria bio-ecológica melhor representada, seguido por peixes de água doce. Foram observadas diferenças intranuais e interanuais significativas na abundância e composição da ictiofauna. A riqueza de espécies foi maior durante o verão e no primeiro ano da amostragem. A ocorrência de peixes de água doce como um grupo importante e diversificado na área estuarina do Mar Chiquita contrasta com resultados de estudos anteriores realizados na área. A dieta do talha-mar incluiu peixes de água doce, estuarinos e marinhos. Apesar dessa ave se alimentar em águas rasas da área estuarina do Mar Chiquita, uma baixa similaridade entre sua dieta e abundância local de peixes foi observada. Esses resultados reforçam a importância da realização de avaliações a fim de proporcionar avanço nos estudos e melhorar as interpretações sobre a ecologia alimentar de predadores de topo.

Lagoons along the western coast of the South Atlantic Ocean shelter high densities of juvenile fish and are key areas for several seabirds that rely on the resources offered by this kind of ecosystem. The objective of this study was to analyze fish composition and abundance in shallow-water areas of the estuarine region of Mar Chiquita Coastal Lagoon (Argentina) and the diet composition of the Black skimmer (Rynchops niger) during its non-breeding season as well as evaluating its inter-annual variations. Fish were sampled with a beach-seine net and the skimmers' diet was analyzed from their pellets. The estuarine-dependent marine fishes were the best represented bio-ecological category followed by freshwater fishes. Significant differences were observed in fish abundance and composition between and within years. Species richness was higher during the summer season and during the first year sampled. The occurrence of freshwater fishes as an important and diverse group of the Mar Chiquita estuarine area contrasted with previous reports. The diet of the Black skimmer included freshwater, estuarine and marine fish species. Skimmers forage in the shallow waters of the estuarine area of the Mar Chiquita Coastal lagoon though little similarity was observed between its diet and local fish abundance. These results emphasize the importance of performing these evaluations in order to improve the quality of studies and the interpretations of top predators foraging ecology.

Cada espécie animal pode apresentar seletividade por micro-habitats priorizando proteção, forrageio ou microclima. Para compreender os padrões de distribuição de pequenos mamíferos ao nível do solo e de sub-bosque, nós analisamos o uso de micro-habitat por pequenos mamíferos em uma floresta estacional no sul do Brasil. Dez estações amostrais com sete pontos de captura foram usadas para amostragem dos seguintes microhabitats: liana, tronco caído, solo apenas coberto por folhiço, solo coberto por samambaias, árvore com tronco simples, árvore com bifurcações e arbustos do gênero Piper sp.. Sete fases de campo foram executadas durante oito dias consecutivos de setembro de 2006 a janeiro de 2008. Quatro espécies de roedores (Akodon montensis, Sooretamys angouya, Oligoryzomys nigripes e Mus musculus) e duas espécies de marsupiais (Didelphis albiventris e Gracilinanus microtarsus) foram capturadas. As espécies capturadas apresentaram diferença significativa quanto ao uso do microhabitat (ANOVA p= 0,003), particularmente entre locais no solo e sub-bosque. Akodon montensis utilizou com maior frequência samambaias terrestres e troncos caídos, S. angouya lianas, D. albiventris troncos caídos e Piper sp. e G. microtarsus árvores e lianas. Nós demonstramos que a comunidade de pequenos mamíferos locais, de fato, apresenta uma seleção de microhabitats, com associações entre a maioria das espécies e habitats. Além disso, há forte indício de seleção de habitat devido à pressão de predação.

Each animal species selects specific microhabitats for protection, foraging, or micro-climate. To understand the distribution patterns of small mammals on the ground and in the understorey, we investigated the use of microhabitats by small mammals in a deciduous forest of southern Brazil. Ten trap stations with seven capture points were used to sample the following microhabitats: liana, fallen log, ground litter, terrestrial ferns, simple-trunk tree, forked tree, and Piper sp. shrubs. Seven field phases were conducted, each for eight consecutive days, from September 2006 through January 2008. Four species of rodents (Akodon montensis, Sooretamys angouya, Oligoryzomys nigripes and Mus musculus) and two species of marsupials (Didelphis albiventris and Gracilinanus microtarsus) were captured. Captured species presented significant differences on their microhabitat use (ANOVA, p = 0.003), particularly between ground and understorey sites. Akodon montensis selected positively terrestrial ferns and trunks, S. angouya selected lianas, D. albiventris selected fallen trunks and Piper sp., and G. microtarsus choose tree trunks and lianas. We demonstrated that the local small-mammal assemblage does select microhabitats, with different types of associations between species and habitats. Besides, there is a strong evidence of habitat selection in order to diminish predation.

The knowledge and body size estimation of a prey item through undigested remains is important for the determination of prey's sizes selectivity by predator and understand these (predator-prey) interactions. Therefore, large size bones are used to perform these estimates, in part due to their resistance to digestion. The aim of this study is to determine the existence of bones with high correlation between them and body size in Eleginops maclovinus in order to estimate those parameters. Most of the measurements showed a highly significant correlation, but we decided only to work with the following bones: quadrate, suboperculum, cleithrum and maxilla because they showed the highest correlation coefficient. The length-weight relationship was: Weight = 0.041 Lt2.597. We proposed that the selected measurements are suitable for morphometric analysis, and will help in a better understanding the predator-prey interactions, and potentially constitutes a good tool for studies of trophic relationship.

El conocimiento y estimación del tamaño de un ítem presa a través de restos no digeridos es importante para la determinación de selectividad de tamaños por depredador y comprender dicha interacción (depredador-presa); es por esto que son utilizados huesos de gran dimensión para realizar dichas estimaciones, en parte por su resistencia a la digestión. El objetivo del presente trabajo fue determinar la existencia de huesos que presenten una alta correlación entre ellos y el tamaño del cuerpo en Eleginops maclovinus para estimar dichos parámetros. La mayoría de las mediciones presentaron una correlación altamente significativa, pero se decidió solo trabajar con los huesos cuadrado, subopércular, cleitro y maxilar ya que presentaron el mayor coeficiente de determinación. La relación longitud-peso fue: Peso = 0,041 Lt2,597. Se propone que las medidas seleccionadas son adecuadas para análisis morfométricos, pudiendo ayudar a entender mejor las interacciones depredador/presa y potencialmente constituye una herramienta útil para estudios de relaciones tróficas.

Seasonal zooplankton biomass (ZB) and ichthyoplankton density (ID) in the water column on the continental shelf of the southern Gulf of Mexico were analyzed to determine their vertical distribution patterns and assess if there is a relationship between both components. Five depth levels were sampled: 0-6, 6-12, 12-18, 45-55 and 95-105 m. The vertical distribution patterns of ZB and ID were similar for all sampling seasons, with the greatest concentration of organisms in the upper levels and the lowest at deeper levels. These results suggest that the water column in the study area may be divided into a surface layer (0-18 m) and a deep layer (45-100 m), and seasonal differences may be attributed to mixing processes. The difference between the surface and the deep layers occurs because, in general, the upper layer is the most productive sector of the water column. The relationship between ZB and ID in the water column was positive and significant (ANCOVA, P<0.05) throughout the sampling seasons for most depths, probably because the production cycle is continuous in the southern Gulf of Mexico, as is common in tropical and subtropical areas, and it maintains the availability of food, and consequently the predator-prey relationships. The relationship between the ZB and the ID in the water column is mainly affected by the seasonal variations in the continental water discharges and the mixing processes.

Se analizó estacionalmente la biomasa zooplanctónica (BZ) y la densidad ictioplanctónica (DI) en la columna de agua sobre la plataforma continental del sur del Golfo de México, para determinar sus patrones de distribución vertical y establecer si existe una relación entre ambos componentes. Se muestrearon cinco niveles de profundidad: 0-6 m, 6-12 m, 12-18 m, 45-55 m y 95-105 m. El patrón de distribución vertical de la BZ y de la DI fue similar en todas las épocas de muestreo, con la mayor concentración de organismos en los niveles superficiales y la más baja en los niveles más profundos. Estos resultados sugieren que la columna de agua en el área de estudio puede estar dividida en una capa superficial (0 a 18 m) y una capa profunda (45 a 100 m) y que las diferencias estacionales pueden ser atribuidas a los procesos de mezcla. Esta diferencia entre las capas superficiales y las profundas ocurre porque, en general, las capas superficiales de la columna de agua son las más productivas. La relación entre la BZ y la DI fue positiva y significativa (ANCOVA, P<0,05) a través de las épocas de muestreo y en la mayoría de las profundidades probablemente porque el ciclo de producción es continuo en el sur del Golfo de México como sucede en áreas tropicales y subtropicales, manteniendo la disponibilidad de alimento y consecuentemente, la relación depredador-presa. La relación BZ y DI en la columna de agua es afectada principalmente por la variación estacional de las descargas de agua continental y el proceso de mezcla.

Data reported here are intended to describe patterns of predation by a solitary hunter, as well as to bring new insights into the predator-prey relationship in the Neotropical region. The goal of this study was to verify if there was small mammal selection in the diet of the maned wolf. Also, we attempt to test for a functional response in relation to the consumption of small mammals. The study was carried out in the Ecological Station of Itirapina (ESI), São Paulo, Brazil. Faeces collection and small mammal abundance survey by pitfall trapping were conducted simultaneously during 2000-2002. The maned wolf was selective in the consumption of small mammals. Calomys tener and Oligoryzomys nigripes (Muridae) were consumed less than expected by chance, whereas Clyomys bishopi (Echimyidae) was preyed on more than expected. We did not detect a clear functional response by this canid in the ESI to overall shifts in abundance of small mammals. However, prey switching was detected by an increase in diet diversity in the wet season when small mammals become less available.

Comensalismo entre Corydalus Latreille, 1802 (Insecta, Megaloptera, Corydalidae) e Corynoneura Winnertz, 1846 (Insecta, Diptera, Chironomidae, Orthocladiinae) foi registrado no córrego Indaiá situado a 1.380 m de altitude no Parque Nacional da Serra do Cipó (19-20ºS, 43-44ºW) e nas nascentes do rio São Francisco a 1.300-1.700 m de altitude no Parque Nacional da Serra da Canastra (20º00'-20º30'S, 46º15'-47º00'W), Minas Gerais, Brasil. Setenta e oito larvas de Corydalus (tamanhos: 22-88 mm) foram coletadas: 61 no córrego Indaiá e 17 em outros córregos. Doze larvas de Corydalus (tamanhos: 22-79 mm) no córrego Indaiá e três encontradas nas nascentes do rio São Francisco (tamanhos: 38-50 mm) apresentaram larvas e pupas de Corynoneura em suas brânquias (3ª a 6ª) e algumas larvas fixadas nos segmentos abdominais de grandes Corydalus (> 25 mm). Sessenta e nove larvas de Corynoneura foram retiradas do material regurgitado por Corydalus. É importante observar que fixados aos predadores de grande tamanho corporal as presas se tornam livres de outros predadores além de serem transportados por eles.

Commensalism between Corydalus Latreille, 1802 (Megaloptera, Corydalidae) and Corynoneura Winnertz, 1846 (Diptera, Chironomidae, Orthocladiinae) larvae was recorded in Indaiá stream, at 1,380 m a.s.l. (Parque Nacional da Serra do Cipó, 19º-20ºS, 43º-44ºW) and in the headwaters of São Francisco river, at 1,300-1,700 m a.s.l. (Parque Nacional da Serra da Canastra, 20º00'-20º30'S, 46º15'-47º00'W), in Minas Gerais state, Brazil. Seventy eight Corydalus larvae (range 22-88 mm) were sampled: 61 in the Indaiá stream and 17 in other two streams. Twelve Corydalus larvae (22-79 mm) in the Indaiá stream and three out of 15 larvae in the headwaters of São Francisco river (38-50 mm) had Corynoneura, larvae and pupae on their gills (3rd to 6th) and a few larvae attached to the abdominal segments of larger Corydalus larvae (> 25 mm). Sixty-nine larvae of Corynoneura were found in the regurgitated material from Corydalus. It is remarkable that by attaching to larger body size predators, prey could become free from predator bouts and could also be transported by them.

As avaliações foram realizadas, semanalmente, durante os estádios vegetativo e de floração/frutificação em quatro quadrantes (N, S, L, O) da planta. Foram coletadas 2.230 espécimes de S. articulatus, sendo 1.224 no estágio vegetativo e 1.006 no florescimento/frutificação, sendo 59,8% adultos. De um total de 965 P. egena, 416 foram imaturos e 549 adultos. As principais conclusões deste trabalho são: (1) M. communis pode ser indicada como planta isca; (2) esta planta pode ser cultivada ou não próxima às culturas de importância econômica, pois funciona como um repositório da praga ou de seu inimigo natural; (3) a relação predador/presa/quadrante da planta/estágio fenológico foi, respectivamente, 1,14:1,0 e 1,0:1,08 nos quadrantes norte e leste; enquanto, à sul e oeste da planta M. communis foi de 1,0:2,26 e 1,0:2,80; (4) a predação de S. articulatus por P. egena ocorreu, em média, de 1,0 a 2,8 ninfas e 1,66 a 4,44 adultos (no estágio vegetativo) e de 1,0-3,76 a 1,0-3,98 (no estágio de florescimento/frutificação), com diferenças significativas em P< 0,0l.

The evaluations were conducted weekly in the vegetative and blooming/fructification phases in four quadrants (N, S, E, W) of the plant. It was collected 2,230 specimens of S. articulatus, 1,224 in the vegetative phase and 1,006 in the blooming/fructification, being 59,8% adults. From the total of 965 of P. egena, 416 were immatures and 549 adults. The main conclusions are: (1) M. communis may be indicated as plant bait; (2) this plant, may be cultivated or not around the crops of economic importance, because it may function as a reservoir of the pest or of its natural enemies; (3) the relation predator/prey/plant quadrant/phenology phases was, respectivelly, 1.14:1.0 and 1.0:1,08 in north and east quadrant; while in south and west quadrant was 1.0:2.26 and 1.0:2.80; and, (4) the predaction of S. articulatus by P. egena was, in average, 1.02.8 nymphs and 1.664.44 adults (in vegetative phases) and 1.03.76 and 1.0-3.98 (in blooming/fructification), with significant differences at P< 0.01.

The predator-prey relationship of Palaemonetes argentinus Nobili, 1901 and Culex pipiens s.l. larvae was studied under laboratory conditions. The prawns were separated in two groups, isolated and grouped ones. Mosquitoe larvae were offered to prawns in two forms, limited and unlimited offer to both groups. In the first analysis, values of predation did not differ significantly between males and females of P. argentinus. Predation in 24 h was 14,9 ± 4,2 larvae/prawn. A reduction of predation was observed with unlimited offer for the same hour, during all the experiment. Predation with unlimited offer was higher on the first day than on the second, but returned to high values on the third day, for both groups. In the grouped experiment, predation with limited offer was total on the first days, decreasing to the last day. As a result, P. argentinus was considered an efficient predator of C. pipiens s.l. larvae under laboratory conditions.