Efeito de pós vegetais sobre sitophilus zeamais (mots., 1855) (coleoptera: curculionidae) / Effect of plant powders on Sitophilus zeamais (mots., 1855) (Coleoptera: Curculionidae)

Objetivou-se testar a atividade inseticida de pós vegetais em Sitophilus zeamais. Foram testados os pós de Anadenanthera colubrina (folhas); Annona muricata (sementes); Azadirachta inidica (folhas e flores); Caesalpinia pyramidalis (folhas), Chenopodium ambrosioides (folhas e flores); Cymbopogon sp.(folhas); Cymbopogon citratus (folhas); Momordica charantia (folhas e frutos); Piper nigrum (sementes); e Ricinus communis (folhas). Além disso, avaliou-se o potencial inseticida de folhas e flores de C. ambrosioides em diferentes dosagens. Na avaliação de repelência foi estabelecido um índice de preferência, e utilizado o teste t para comparação das médias das espécies vegetais. Também foi realizada a comparação das médias das plantas que foram classificadas como repelentes. Para avaliação da mortalidade, procedeu-se a análise de variância e a comparação das médias pelo teste de Tukey e também o teste t para comparação das médias dos tratamentos C. ambrosioides e P. nigrum. Os dados de emergência foram analisados pelo teste de Tukey. Para avaliar os dados de mortalidade, ocasionados por C. ambrosioides, determinou-se a CL50 utilizando a análise de Probit. Os dados de emergência foram verificados pela análise de regressão. As plantas que provocaram repelência foram Cymbopogon sp., C. citratus e C. ambrosioides. A planta que mais afetou a sobrevivência da praga foi C. ambrosioides, que provocou mortalidade total dos insetos infestantes e nenhuma emergência. Adultos de S. zeamais são mais suscetíveis a concentração de 0,125 g do pó de C. ambrosioides.

Effect of plant powders on Sitophilus zeamais (Mots., 1855) (Coleoptera: Curculionidae). The objective of the present study was to test the insecticidal activity of vegetable powders on Sitophilus zeamais. Powders of Anadenanthera colubrina (leaves); Annona muricata (seed); Azadirachta inidica(leaves and flowers);Caesalpinia pyramidalis(leaves);Chenopodium ambrosioides (leaves and flowers);Cymbopogon sp. (leaves);Cymbopogon citratus (leaves); Momordica charantia (leaves and fruits);Piper nigrum (seed); andRicinus communis (leaves) were evaluated. In addition, we evaluated the insecticidal potential of leaves and flowers of C. ambrosioidesat different dosages. In the evaluation of repellency a preference index was established, and the t test was used to compare the means of plant species. The means of plants that were classified as repellent were also compared. To assess mortality, we proceeded with the analysis of variance and comparison of means by Tukey test and also the t test for comparing the means of the C. ambrosioides and P. nigrum treatments. The emergence data were analyzed by Tukey test. To evaluate the data on mortality caused by C. ambrosioides, the CL50 was determined using Probit analysis. The emergence data were verified by regression analysis. Plants that caused repellency were Cymbopogon sp., C. citratusand C. ambrosioides. The plant that most affected the survival of the pest wasC. ambrosioides, which caused total mortality of insect infestations and no adult emergence. Adults of S. zeamaisare most susceptible to the concentration of 0.125 g ofC. ambrosioides powder.

Ecological correlates of polyphenism and gregarious roosting in the grass yellow butterfly Eurema elathea (Pieridae)

Adultos de Eurema elathea foram estudados semanalmente (1992-1994) em seis locais (dormitórios), ao redor de um fragmento de mata em uma fazenda e em dois locais na área urbana de Uberlândia, MG. Os machos foram classificados em seis categorias fenotípicas, as quais variam desde a presença de uma grande e conspícua barra preta na margem interna dorsal da asa anterior (forma escura da estação úmida) até a ausência da barra (forma clara da estação seca). A massa corporal e a área da asa foram comparadas: formas diferentes mostraram médias similares. A abundância das borboletas e a freqüência das formas variaram conforme a umidade (chuvas). Na estação úmida, os indivíduos foram menos freqüentes e monomorficamente escuros, enquanto na seca, a população aumenta e as formas claras predominam. As taxas de recaptura e recrutamento são comparadas com outras borboletas que se agregam durante a noite. O potencial de dispersão foi similar entre os sexos e variou sazonalmente, sendo que a população é mais sedentária no período seco. O máximo tempo de residência registrado foi de 91 dias para uma fêmea e de 84 dias para um macho. A fração de indivíduos que se moveram de um sítio de descanso para outro foi similar em ambos os sexos e formas de machos, mas foi significativamente maior na fazenda em relação à área urbana. Da mesma forma, foi recapturada uma fração significativamente maior (21,3) de borboletas marcadas na área urbana do que na fazenda (15,6), sugerindo modificação comportamental para o sedentarismo nos indivíduos urbanos. São discutidas as forças seletivas que moldam o hábito de descanso gregário em E. elathea e em outras borboletas, e propõe-se uma estratégia protocooperativa de economia de energia.

Genetic variability and social structure of colonies in Acromyrmex heyeri and A. striatus (Hymenoptera: Formicidae)

The breeding structure of both colony and population of social insects can be examined by genetic analysis. Colonies of the leaf-cutting ants Acromyrmex heyeri and A. striatus (Myrmicinae, Attini) were thus analyzed for isoenzyme systems MDH, a-GPDH, and AMY to describe genotype variability and social structure. A total of five loci were investigated (three for amylase and one for each other system). Ninety-seven colonies of A. heyeri and 103 of A. striatus were sampled in different localities in Southern Brazil (State of Rio Grande do Sul). The genotypes found show the occurrence of monogyny and polygyny associated or not with polyandry, which indicates that the social organization is colony-specific. The polygyny and polyandry observed are likely to be responsible for the great genotypic diversity of the colonies. The average inbreeding coefficient per colony was higher in A. striatus than in A. heyeri, which may reflect the different patterns of production of sexual individuals and nuptial flight of those two species

The use of filter paper plasticized with polyvinyl alcohol-glutaraldehyde in ELISA

F1-antigen purified from Yersinia pestis was covalently linked to 5-mm diameter filter paper discs plasticized with polyvinyl alcohol-glutaraldehyde. These discs were used both for ELISA and dot-ELISA for the detection of anti-F1 IgG in rabbits. The best conditions were achieved using 1.25 µg of F1 antigen/disc, 3 percent w/v skim milk in PBS as blocking agent, anti-IgG peroxidase conjugate diluted 12,000 times, and serum from rabbits immunized or not against Y. pestis, diluted 6,400 times. The absorbance values obtained from the comparative study between this procedure and conventional ELISA were not significantly different but the low cost of the reagents employed in ELISA using the filter paper discs plasticized with polyvinyl alcohol-glutaraldehyde makes this method economically attractive.

Cellulose acetate as solid phase in ELISA for plague

Antigen from Yersinia pestis was adsorbed on cellulose acetate discs (0.5 cm of diameter) which were obtained from dialysis membrane by using a paper punch. ELISA for human plague diagnosis was carried out employing this matrix and was capable to detect amount of 1.3 µg of antigen, 3,200 times diluted positive serum using human anti-IgG conjugate diluted 1:4,000. No relevant antigen lixiviation from the cellulose acetate was observed even after washing the discs 15 times. The discs were impregnated by the coloured products from the ELISA development allowing its use in dot-ELISA. Furthermore, cellulose acetate showed a better performance than the conventional PVC plates.

Fatores que interferem no conteúdo celular do leite de cabra / Factors affecting milk cell content in dairy goats

The effects of stage of lactation, parity and breed on the somatic cell count were studied in 68 female Saanen, Anglo-Nubian and Pardo Alpine goats. The animals were assisted during seven months and bacteriologically negative milk samples were submitted to somatic cell count (SCC). Significant effects (P<0.05) of stage of lactation, parity and breed on SCC were observed, with higher values being obtained in late lactation and in goats with four or more parturations. The SCC mean was 0.95x10 elevada a sexta potência cel/ml. The mean values of cell count observed indicate that physiological factors interfere in cell count of the udder

Selection, recombination and history in a parasitic flatworm (Echinococcus) inferred from nucleotide sequences

Three species of flatworms from the genus Echinococcus (E. granulosus, E. multilocularis and E. vogeli) and four strains of E. granulosus (cattle, horse, pig and sheep strains) were analysed by the PCR-SSCP method followed by sequencing, using as targets two non-coding and two coding (one nuclear and one mitochondrial) genomic regions. The sequencing data was used to evaluate hypothesis about the parasite breeding system and the causes of genetic diversification. The calculated recombination parameters suggested that cross-fertilisation was rare in the history of the group. However, the relative rates of substitution in the coding sequences showed that positive selection (instead of purifying selection) drove the evolution of an elastase and neutrophil chemotaxis inhibitor gene (AgB/1). The phylogenetic analysis revealed several ambiguities, indicationg that the taxonomic status of the E. granulosus horse strain should be revised.