Exotic snakes in São Paulo City, southeastern Brazil: Why xenophobia ?

Introduced exotic species cause environmental changes and threat public health in target sites. Illegal trade has enhanced this problem. To first report these risks in Brazil, exotic snakes found in São Paulo City (SPC) (23degrees32' S, 46degrees38' W), southeastern Brazil, and sent to Instituto Butantan between 1995 and 2000, were listed and characterized by their biological attributes. Seventy-six individuals of sixteen alien species were collected. Euriecians snakes, mainly booids, were predominant. Using multivariate techniques, their ecological niches were compared to those of 26 native species, as a way to point out the resource's availability. To evaluate the potential of successful implantation, two species absent in SPC and considered as problem snakes are included in these analyses: the brown treesnake Boiga irregularis and the habu Trimeresurus flavoviridis. There were niche similarities between these pest snakes, exotic booids and native viperids largely due to the similarities in the chosen prey (mammals), diel activity (nocturnal), color pattern (variegated) and body size (medium to large). To avoid predictable undesirable effects of implanted pest snakes, traffic control and punishment should be improved, as well as parallel environmental education programs.

Effects of nutrients on feeding activities of the pest termite Heterotermes tenuis (Isoptera : Rhinotermitidae)

Heterotermes tenuis is a native termite of large negative impact on the Brazilian economy. Many studies have focused on optimizing the baiting method for termite control by improving its use and its efficacy. In order to maximize termite bait consumption, this study aimed to select nutrient solutions which are able to enhance termite feeding. The effects of some sugars and urea on feeding preference of the subterranean termite H. tenuis were determined by double choice feeding tests, and the consumption was evaluated by variation in dry mass of filter paper after 28 days of termite feeding. Most of the solutions tested did not significantly influence feeding of H. tenuis. Termites fed preferentially on filter paper treated with 0.03 g/ml trehalose and 0.015 g/ml urea solutions. The data indicate that trehalose and urea solutions are phagostimulants to H. tenuis, and their future use in bait matrices may increase consumption of baits and improve this control technique.

Occurrence of Three Haplotypes of Linepithema micans (Forel) (Hymenoptera: Formicidae) in Southern Brazil

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

Reproduction of Cichla kelberi Kullander and Ferreira, 2006 introduced into an artificial lake in southeastern Brazil

O objetivo do estudo foi caracterizar a reprodução de Cichla kelberi em um lago artificial no município de Leme, Estado de São Paulo, Brasil. A época reprodutiva ocorreu na primavera e verão. O L50 e o L100 desta espécie foram de 192 e 235 mm (L50) para machos e fêmeas, respectivamente e 290 mm (L100) para ambos os sexos. A desova foi do tipo parcelado. O tamanho dos ovócitos maduros foi de 428,4 µm, atingindo o máximo em 2.203,2 µm. A média da fecundidade foi de 12.129,2 ovócitos com média de cada desova de 4.897,7 ovócitos. Esta espécie adequou-se à definição de peixes com fecundação externa, não migradoras e com cuidado parental da prole. Os atributos para a introdução dos tucunarés podem ser tentadores. Porém, suas características reprodutivas e alimentares fazem com que não existam competidores ou predadores naturais e, assim, a sua expansão populacional seja de difícil controle e erradicação.

Growth and mortality of Cichla spp. (Perciformes, Cichlidae) introduced in Volta Grande Reservoir (Grande River) and in a small artificial lake in Southeastern Brazil

Os parâmetros de crescimento e mortalidade foram estimados indiretamente pelas distribuições das frequências de comprimento para espécies de Cichla spp. introduzidas em um lago em Leme (SP) e no reservatório de Volta Grande (SP-MG). em Leme, Cichla kelberi apresentou maior frequência nas classes de comprimentos inferiores, maior taxa instantânea de mortalidade natural e menor número de coortes do que C. kelberi e C. piquiti em Volta Grande. Os valores de performance de crescimento obtidos para as espécies foram próximos, corroborando a validade dos parâmetros estimados de crescimento e de mortalidade. A pressão em crescer rapidamente, devido à predação, aumenta quanto menor e menos diverso for o ambiente. O gênero Cichla adapta-se bem nos locais em que é introduzido, entretanto essa adaptação mostra-se fortemente ajustada a cada ambiente em particular, determinando com isso grande plasticidade e capacidade de estabelecimento.

Seasonal and ontogenetic variations in the diet of Cichla kelberi Kullander and Ferreira, 2006 introduced in an artificial lake in southeastern Brazil

A dieta de Cichla kelberi introduzido em um lago artificial em Leme-SP foi composta predominantemente pelas espécies de peixes mais comuns nesse lago (Oreochromis niloticus e o próprio C. kelberi). Na primavera e no verão, o item mais consumido foi O. niloticus. Porém, o canibalismo foi muito comum para esta espécie. As altas frequências de O. niloticus e de C. kelberi revelam que a espécie apresenta um ciclo sazonal, se alimentando das presas mais comuns em cada período do ano, com uma redução da sua atividade alimentar durante o inverno. As dietas foram diferentes entre os exemplares imaturos e maduros, sugerindo que existem diferenças ontogenéticas, principalmente relacionadas ao tipo de presa, como: Ephemeroptera, consumidos pelos tucunarés imaturos e peixes, pelos maduros, além do tamanho das presas.

Feeding of introduced species of Cichla (Perciformes, Cichlidae) in Volta Grande reservoir, River Grande (MG/SP)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Cannibalism as the main feeding behaviour of tucunares introduced in Southeast Brazil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Feeding dynamics of Cichla kelberi Kullander & Ferreira, 2006 introduced into an artificial lake in southeastern Brazil

O objetivo desse estudo foi caracterizar sazonalmente a dieta de Cichla kelberi em um lago artificial em Leme-SP, determinando os itens alimentares e as relações com os sexos e com a maturação gonadal dos exemplares amostrados. A dieta de C. kelberi apresenta uma dinâmica em três diferentes períodos: os meses de inverno foram caracterizados por baixa atividade alimentar e alta concentração de peixes indeterminados, durante a primavera ocorreu um aumento na atividade alimentar, sendo Tilapia sp. o item alimentar dominante e durante o verão e início do outono foi evidenciada alta taxa de canibalismo. A plasticidade na composição da dieta foi marcada pela quantidade de presas disponíveis durante os períodos do ano e pelo período reprodutivo.

Optimal pest control problem in population dynamics

One of the main goals of the pest control is to maintain the density of the pest population in the equilibrium level below economic damages. For reaching this goal, the optimal pest control problem was divided in two parts. In the first part, the two optimal control functions were considered. These functions move the ecosystem pest-natural enemy at an equilibrium state below the economic injury level. In the second part, the one optimal control function stabilizes the ecosystem in this level, minimizing the functional that characterizes quadratic deviations of this level. The first problem was resolved through the application of the Maximum Principle of Pontryagin. The Dynamic Programming was used for the resolution of the second optimal pest control problem.

Mathematical modeling and control of population systems: Applications in biological pest control

The aim of this paper is to apply methods from optimal control theory, and from the theory of dynamic systems to the mathematical modeling of biological pest control. The linear feedback control problem for nonlinear systems has been formulated in order to obtain the optimal pest control strategy only through the introduction of natural enemies. Asymptotic stability of the closed-loop nonlinear Kolmogorov system is guaranteed by means of a Lyapunov function which can clearly be seen to be the solution of the Hamilton-Jacobi-Bellman equation, thus guaranteeing both stability and optimality. Numerical simulations for three possible scenarios of biological pest control based on the Lotka-Volterra models are provided to show the effectiveness of this method. (c) 2007 Elsevier B.V. All rights reserved.

Azteca barbifex Forel (Hymenoptera: Formicidae): potential pest of citrus crops in eastern Amazon

Damage caused by the ant Azteca barbifex (Forel) was identified in orange trees (Citrus sinensis), in Capitão Poço County, Guamá microregion, Pará State. The damage caused by the scraping of stems and branches lead to reduction in yield with subsequent death of the plant. These characteristics indicate A. barbifex as a potential pest of citrus crops in the eastern region of Amazon.

SEASONAL SPACE USAGE BY THE INTRODUCED PHARAOHS ANT, MONOMORIUM-PHARAONIS (L) (HYM, FORMICIDAE), IN INSTITUTIONAL SETTINGS IN BRAZIL AND ITS RELATION TO OTHER STRUCTURAL ANT SPECIES

In an institutional setting in Brazil, the pharaoh's ant, Monomorium pharaonis was found to be the dominant and most abundant ant present throughout the year. The only other regularly collected ant was the exotic Tapinoma melanocephalum. However, M. pharaonis dominated bait station visitations, although locally concentrated, with other species restricted to regions in which M. pharaonis was not found.

Density and population size of mammals introduced on a land-bridge island in southeastern Brazil

The introduction of alien species is one of the main threats to the conservation of native species, especially in island ecosystems. Here, we report on the population growth of 15 species of mammals introduced in 1983 on the island of Anchieta, an 828 ha land-bridge island in southeastern Brazil. We estimated the density of mammals through 296 km of line transect census. Five species introduced became extinct (coypu, brocket deer, six-banded armadillo, nine-banded armadillo, maned three-toed sloth); six became over-abundant (marmoset, coati, agouti, seven-banded armadillo, and capybara); one has a stable population (capuchin monkey). Anchieta Island has the highest density of mammals in the entire Atlantic forest (486.77 ind/km(2)), especially nest predators (232.83 ind/km(2)) and herbivores (253.58 ind/km(2)). Agoutis (Dasyprocta spp.) and marmosets (Callithrix penicillata) were, by far, the species with the highest population growth. The high density of mammals in this island may have strong consequences for plant recruitment and bird diversity.

Expressed sequence tags from Atta laevigata and identification of candidate genes for the control of pest leaf-cutting ants.

Leafcutters are the highest evolved within Neotropical ants in the tribe Attini and model systems for studying caste formation, labor division and symbiosis with microorganisms. Some species of leafcutters are agricultural pests controlled by chemicals which affect other animals and accumulate in the environment. Aiming to provide genetic basis for the study of leafcutters and for the development of more specific and environmentally friendly methods for the control of pest leafcutters, we generated expressed sequence tag data from Atta laevigata, one of the pest ants with broad geographic distribution in South America. Results: The analysis of the expressed sequence tags allowed us to characterize 2,006 unique sequences in Atta laevigata. Sixteen of these genes had a high number of transcripts and are likely positively selected for high level of gene expression, being responsible for three basic biological functions: energy conservation through redox reactions in mitochondria; cytoskeleton and muscle structuring; regulation of gene expression and metabolism. Based on leafcutters lifestyle and reports of genes involved in key processes of other social insects, we identified 146 sequences potential targets for controlling pest leafcutters. The targets are responsible for antixenobiosis, development and longevity, immunity, resistance to pathogens, pheromone function, cell signaling, behavior, polysaccharide metabolism and arginine kynase activity. Conclusion: The generation and analysis of expressed sequence tags from Atta laevigata have provided important genetic basis for future studies on the biology of leaf-cutting ants and may contribute to the development of a more specific and environmentally friendly method for the control of agricultural pest leafcutters.