Foraging behaviour by an intraguild predator blowfly, Chrysomya albiceps (Diptera : Calliphoridae)

Optimal foraging theory assumes that predators use different prey types to maximize their rate of energetic gain. Studies focusing on prey preference are important sources of information to understand the foraging dynamics of Chrysomya albiceps. The purpose of this investigation is to determine the influence of larval starvation in C. albiceps on the predation rate of different prey blowfly species and instars under laboratory conditions. Our results suggest that C. albiceps prefers Cochliomyia macellaria larvae to Chrysomya megacephala under non-starvation and starvation conditions. Nevertheless, predators gained more weight consuming C. macellaria. This result suggests that C. albiceps profit more in consuming C. macellaria rather than C. megacephala. The foraging behaviour displayed by C. abiceps on their prey and the consequences for the blowfly community are also discussed.

Feeding habits of the spider crab Libinia spinosa H. Milne Edwards, 1834 (Decapoda, Brachyura) in Ubatuba Bay, São Paulo, Brazil

The main goal of this study was the identification of the items of the diet of the L. spinosa, based on the stomach contents analysis. The crabs were obtained from Ubatuba region north-eastern shore of São Paulo State. In the laboratory, all the individuals were dissected, the stomach was retreated and fixed in 10% formaline. The alimentary items were identified under stereomicroscope and analysed by the method of Frequency of Occurrence. A total of 194 stomachs was analysed and nine alimentary items were obtained. Unindentified material was found in 98% of analysed stomach and poriferan were present in less then 1% of stomachs. These results pointed a diversified diet explored by this crab, as well as the employment of some different methods for food intake. This suggested that these crabs could occupy different position in the trophic chain.

Foraging by the omnivorous crab Pachygrapsus transversus affects the structure of assemblages on sub-tropical rocky shores

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Reproductive biology and feeding habits of Stenocercus caducus (Iguanidae) in semideciduous forest in central Brazil.

Sexual dimorphism, reproduction and diet are described for Stenocercus caducus from semideciduous forest, in Mato Grosso do Sul state, Central Brazil. Lizards are collected in pitfall traps from December 2000, to December 2001. Sexual dimorphism in S. caducus is apparent, mainly in coloration; although females reach a larger SVL than males. A wide variety of arthropods are fed by S. caducus, with ants and termites numerically, and orthopterans and beetles volumetrically the most common prey items. Ontogenetic differences in diet were noted for S. caducus, with juveniles feeding on lesser prey types and smaller sized prey than adults. The reproduction was seasonal, concentrated in the rainy season, with deposition of more than one clutch per season.

Food habits of bats of subfamily vampyrinae in Brazil

We describe and compare diets of 3 species of vampyrine bats based on analysis of food remains found in gastrointestinal tracts of preserved museum specimens. We also examined possible ontogenetic, intersexual, geographic, and seasonal variations in feeding habits of each species. Trachops cirrhosus fed mainly on insects (79% of prey items), whereas Chrotopterus auritus and Vampyrum spectrum primarily ate small vertebrates (61-73% of prey items for both species). Vertebrate prey most frequently eaten by C. auritus were murid rodents whereas V. spectrum consumed primarily passerine birds. The frequency of occurrence of food items did not differ significantly with age or sex, at least for T. cirrhosus and C. auritus. Significant seasonal variations in diet were observed only for C. auritus, which consumed more insects during the wet season. Our findings confirm the importance of insects in the diet of T. cirrhosus and present new information on a diversified diet for V. spectrum and opportunistic feeding for C. auritus.

Influence of physical and chemical factors during foraging and culture of the symbiont fungus in Atta sexdens rubropilosa (Hymenoptera : Formicidae)

The aim of this paper is to investigate the influence of physical and chemical factors on transport and use of substrate for Atta sexdens rubropilosa workers. Three types of rectangular fragments were used to study the physical influence factors: filter paper with paraffin, filter paper without paraffin and polyester film. To study the chemical factors, some fragments were impregnated with organic extract of orange albedo, others were soaked with soybean oil and for the remaining ones nothing was applied. The following parameters were evaluated: (i) attractiveness of substrate for transport and number of loading workers per treatment; (ii) foraged material incorporation; (iii) rejection by numbers of fragments deposited in the garbage or beside the fungus garden. All the polyester film fragments carried out to the fungus garden were subsequently rejected. We verified that chemical factors of the substrate were more quickly detected by the workers, whereas physical factors were used as a criterion in the decision-making to reject or accept the substrate collected.

The more stirring the better: cichlid fishes associate with foraging potamotrygonid rays

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Preliminary data on the feeding habits of the freshwater stingrays Potamotrygon falkneri and Potamotrygon motoro (Potamotrygonidae) from the Upper Paraná River basin, Brazil

As raias da família Potamotrygonidae representam um grupo singular da ictiofauna Neotropical. Apesar de serem antigos os relatos sobre o grupo, ainda são muitas as questões que permanecem sem resposta, sobretudo no que diz respeito à biologia das espécies que ocorrem na Bacia do Paraná-Paraguai. No presente trabalho foi analisada a dieta de Potamotrygon falkneri e Potamotrygon motoro, capturadas no Alto Rio Paraná, a jusante da Usina Hidrelétrica Engenheiro Souza Dias (UHE Jupiá). As duas espécies de raias apresentaram dieta diversificada, ingerindo 14 itens, entre moluscos, crustáceos, insetos e peixes, porém com predominância de insetos aquáticos em diversidade e abundância. Somente um indivíduo de cada espécie ingeriu peixe. Potamotrygon motoro consumiu principalmente Ephemeroptera, enquanto P. falkneri, principalmente Mollusca, Hemiptera e Trichoptera. Os dados aparentemente indicam uma dieta mais especializada de P. motoro, com maior consumo de Ephemeroptera (Baetidae), e uma dieta mais generalizada de P. falkneri. A análise dos indivíduos capturados em três micro-hábitats, que diferem quanto ao tipo de substrato e presença de vegetação marginal, sugere diferenças nos tipos de alimentos consumidos.

Tunnelling behaviour of the Asian subterranean termite in heterogeneous soils: presence of cues in the foraging area

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Soldiers initiate foraging activities in the subterranean termite, Heterotermes tenuis

Caste polyethism has been recorded in some termite species, however the foraging behavior of subterranean termites remains poorly known. Heterotermes tenuis Hagen (Isoptera: Rhinotermitidae) is a subterranean termite that is native to Brazil and is an agricultural and urban pest. The aim of this study was to investigate which caste acts as scouts when searching for food sources and determinate the percentages of each caste present in the foraging territories of field colonies of H. tenuis. Our results showed no significant differences among the caste proportions present in the foraging territories of the three colonies studied in the field. Laboratory experiments showed that minor soldiers were the most frequent initiators of foraging activities. This result suggests that the exploratory phase of the foraging behavior may be regulated by the number of soldiers present in the foraging territories of each colony.

Foraging Behavior and Mortality of Ectatomma brunneum (Hymenoptera, Formicidae) in Simultaneous Exposure to Ant Baits and Conventional Diet in Laboratory

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Foraging Behavior of the Swarm-Founding Wasp, Polybia (Trichothorax) sericea (Hymenoptera, Vespidae): Prey Capture and Load Capacity

The main component of the protein diet of P. sericea was larvae of Lepidoptera (75.38%), with predominance of the following Families: Noctuidae (30.99%), Hesperiidae (19.01%); Pyralidae (19.01%) and Nymphalidae (11.98%). The average weight of the prey captured was 14.2 mg, a value equivalent to 24.7% of the average wasp weight. The average glucidic food load was 28.61 mg, corresponding to approximately half the wasp weight (49.64%). The weight of the load transported in the crop varied according to the food density, which, in turn, influenced the time spent in its collection (Pearson: n=64; r=0.64;p<0.05). Polybia sericea showed predatory interactions against Lepidopteran caterpillars, who are known to be agricultural pests. P. sericea has potential to be used in Integrated Pest Management.

Foraging Behavior of the Swarm-founding Wasp Polybia (Trichothorax) sericea (Hymenoptera, Vespidae): Daily Resource Collection Activity and Flight Capacity

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The goatfish Pseudupeneus maculatus and its follower fishes at an oceanic island in the tropical west Atlantic

The influence of a substratum-disturbing forager, the spotted goatfish Pseudupeneus maculatus on the assemblage of its escorting, opportunistic-feeding fishes was examined at Fernando de Noronha Archipelago (tropical west Atlantic). Followers attracted to spotted goatfish foraging singly differed from followers of spotted goatfish foraging in groups in several characteristics. The larger the nuclear fish group, the greater the species richness and number of individuals of followers. Moreover, groups of foraging spotted goatfish attracted herbivores, not recorded for spotted goatfish foraging singly. The size of follower individuals increased with the size and the number of foraging spotted goatfish. The zoobenthivorous habits of the spotted goatfish and its ability to disturb a variety of soft substrata render it an important nuclear fish for several follower species of the reef fish assemblage at Fernando de Noronha. (c) 2006 the Authors Journal compilation (c) 2006 the Fisheries Society of the British Isles.

Foraging activity and resource use by three parrotfish species at Fernando de Noronha Archipelago, tropical West Atlantic

Parrotfishes are important components of the herbivore and detritivore guilds of tropical and subtropical reefs. Most of parrotfish species are protogynous hermaphrodites that change colour and sex, from initial phase females or males (IP) to terminal phase males (TP). We studied the foraging behaviour of Sparisoma amplum, S. axillare and S. frondosum, three syntopic scarids on the rocky reefs of Fernando de Noronha Archipelago, Tropical West Atlantic. The three parrotfish species differed in food selection and preference, but IP and TP individuals of the same species preferred the same food types, except for S. amplum. Feeding rates of IP individuals were higher than those of TP individuals, but the distribution of feeding frequencies throughout the day of IP and TP individuals of the same species was similar. IP individuals had higher feeding rates than TP ones, which seems related to the fact that TP individuals spend a large amount of time patrolling their territories and chasing away conspecific individuals at the study site. The general foraging pattern we found for S. amplum, S. axillare and S. frondosum is similar to patterns found for other parrotfish species in the Western Atlantic.