2016-11-16T20:15:18

The control of Acromyrmex leaf-cutting ants is necessary due to the severe damage they cause to diverse crops. A possibility was to control them using the bacterium Bacillus thuringiensis (Bt) that characteristically produces insecticidal crystal proteins (ICPs). The ICPs have been effective in controlling lepidopterans, dipterans, and coleopterans, but their action against hymenopterans is unknown. This paper describes an attempt to isolate Bt from ants of two Acromyrmex species, to evaluate its pathogenicity towards these ants, and to test isolates by PCR. Bacterial isolates of Bt obtained from A. crassispinus and A. lundi have been assayed against A. lundi in the laboratory. The bioassays were carried out in BOD at 25°C, with a 12-hour photoperiod, until the seventh day after treatment. The Bt isolates obtained were submitted to total DNA extraction and tested by PCR with primers specific to cry genes. The results showed Bt presence in 40% of the assessed samples. The data from the in vivo assays showed a mortality rate higher than 50% in the target population, with the Bt HA48 isolate causing 100% of corrected mortality. The PCR results of Bt isolates showed a magnification of DNA fragments relative to cry1 genes in 22% of the isolates, and cry9 in 67%. Cry2, cry3, cry7, and cry8 genes were not detected in the tested samples, and 22% had no magnified DNA fragments corresponding to the assessed cry genes. The results are promising not only regarding allele identification in new isolates, but also fort the assays aimed at determining the Bt HA48 LC 50 's, which can eventually be applied in controlling of Acromyrmex leaf-cutting ants.Key words: bioassay, leaf-cutting ants, Bacillus thuringiensis. RESUMO Patogenicidade de Bacillus thuringiensis isolados de duas espécies deAcromyrmex (Hymenoptera, Formicidae)O controle das formigas-cortadeiras do gênero Acromyrmex é necessário em razão dos severos danos que causam a diversas culturas. Uma alternativa é a utilização da bactéria Bacillus thuringiensis (Bt), caracterizada pela produção de proteínas inseticidas eficazes para lepidópteros, dípteros e coleópteros, mas cuja ação é ainda desconhecida para himenópteros. O presente trabalho teve por objetivo isolar Bt a partir de formigas de duas espécies de Acromyrmex, avaliar sua patogenicidade a formigas-cortadeiras e testar por PCR.

Oryzophagus oryzae (Costa Lima 1936) (Coleoptera: Curculionidae)

Environmental legislation has driven the reduction of sulfur levels in automotive fuels worldwide (≤10 ppm). We evaluate the behavior of microbial biomass in terms of community composition, metabolite production, and degradation of the Brazilian blend B10, made with ultra-low-sulfur diesel (ULSD, 6.3 ppm), high-sulfur diesel (HSD, 327 ppm), and ultra-high-sulfur diesel (UHSD, 861 ppm) during simulated storage. The microcosm was assembled in glass flasks containing an aqueous phase (mineral medium) and an oil phase (fuels) at two conditions of microbial contamination: natural (∼103 colony-forming units (CFU) per liter ) and inoculated (∼106 bacterial cells and fungal spores per milliliter), evaluated each 10 days for 40 days. The results showed that biomass production was more pronounced in inoculated treatment and could be described at T 40 as UHSD < ULSD < HSD B10. The higher degradation of terminal methyl ester fraction (50 ± 1%), and aromatic compounds (46 ± 2%) was in HSD B10, and ULSD B10 suffered the lowest degradation (23 ± 3%; 26 ± 7%, respectively) (p < 0.05). Pseudomonas (Proteobacteria) was the predominant bacterial genus at the interface (∼91%), but in the water phase, changes in relative abundance and development of Pandoraea (Proteobacteria) and Propionispora (Firmicutes) were observed (p < 0.05). Ascomycota and Basidiomycota were the most abundant fungal phyla (∼78%). Putative fatty acids myristic, palmitic, stearic, oleic, linoleic, and α-linolenic acid were detected in the water phase with high relative abundance at all sulfur levels compared to controls (p < 0.05), indicating the degradation products of the fatty acid methyl esters present in soybean biodiesel. The data set suggests that the reduction of sulfur content may have favored microbial growth; however, the addition of fatty acid methyl ester (FAME), additives, and the origin of petroleum-based fuels may be a more-relevant factor in the B10-blend aerobic biodegradation.

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