RESUMO
INTRODUCTION: This study evaluated whether different strains of Brevibacillus laterosporus could be used to control larvae of the blowfly Chrysomya megacephala, a pest that affects both human and animal health. METHODS: Mortality rates were recorded after 1-mL suspensions of sporulated cells of 14 different strains of B. laterosporus were added to 2.5g of premixed diet consisting of rotting ground beef fed to first instar larvae of C. megacephala. All bioassays were performed using 10 larvae per strain, with a minimum of three replicates for each bioassay. Larval mortality was recorded daily up to seven days. RESULTS: Strains Bon 707, IGM 16-92, and Shi 3 showed the highest toxicity toward the larvae producing 70.5%, 64.5%, and 51.6% of larval mortality, respectively, which was significantly higher than that in the control group (p < 0.05). In contrast, strains NRS 1642, NRS 661, NRS 590 BL 856, NRS 342, ATCC 6457, Bon 712, and NRS 1247 showed limited or no pathogenic activity against the target larvae. CONCLUSIONS: Our preliminary data indicated that B. laterosporus could be used to develop bioinsecticides against C. megacephala.
Assuntos
Brevibacillus/fisiologia , Dípteros/microbiologia , Controle Biológico de Vetores/métodos , Animais , Bioensaio , Dípteros/classificação , Larva/microbiologiaRESUMO
: This study evaluated whether different strains of
Mortality rates were recorded after 1-mL suspensions of sporulated cells of 14 different strains of
Strains Bon 707, IGM 16-92, and Shi 3 showed the highest toxicity toward the larvae producing 70.5%, 64.5%, and 51.6% of larval mortality, respectively, which was significantly higher than that in the control group (p < 0.05). In contrast, strains NRS 1642, NRS 661, NRS 590 BL 856, NRS 342, ATCC 6457, Bon 712, and NRS 1247 showed limited or no pathogenic activity against the target larvae.
Our preliminary data indicated that
Assuntos
Animais , Brevibacillus/fisiologia , Dípteros/microbiologia , Controle Biológico de Vetores/métodos , Bioensaio , Dípteros/classificação , Larva/microbiologiaRESUMO
Mycotoxins including aflatoxins, deoxynivalenol, fumonisins and ochratoxin A are among the main fungal secondary metabolites detected as natural contaminants in South America in different commodities such as peanuts (aflatoxins), cereals (deoxynivalenol and fumonisins) or grapes (ochratoxin A). Different strategies including crop rotation, tillage practices, fungicide application and planting less susceptible cultivars are used in order to reduce the impact of these mycotoxins in both food and feed chains. The development of fungicide resistance in many fungal pathogens as well as rising of public concern on the risks associated with pesticide use led to the search for alternative environmentally friendly methods. Biological control of plant pathogens and toxigenic fungi offers an alternative that can complement chemical control in the frame of an integrated pest management to reduce the impact of mycotoxins in the food and feed chains. The advances made in Argentina on reducing the impact of toxigenic fungi and mycotoxins in peanut, grapes and cereals using the biocontrol strategy are summarised. Native bacteria, yeasts and filamentous fungi have been selected to evaluate them as potential biocontrol agents. Field trials showed that Bacillus subtilis RC 218 and Brevibacillus sp. RC 263 were effective at reducing deoxynivalenol accumulation in wheat. The application of Clonostachys rosea isolates on wheat stubble reduced Fusarium colonisation on the stubble. Bacillus amyloliquefaciens and Microbacterium oleovorans showed good activity to control both Fusarium verticillioides growth and the accumulation of fumonisins at pre-harvest stage in maize. Control of toxigenic Aspergillus flavus and aflatoxin accumulation in peanuts was achieved using a native atoxigenic Aspergillus flavus strain based on competitive exclusion of the toxigenic strains. Kluyveromyces thermotolerans strains were used as biocontrol agents to reduce the impact of Aspergillus section Nigri and ochratoxin A accumulation in grapes.
Assuntos
Arachis/microbiologia , Agentes de Controle Biológico , Grão Comestível/microbiologia , Micotoxinas/análise , Vitis/microbiologia , Aflatoxinas/análise , Argentina , Aspergillus flavus/isolamento & purificação , Bacillus subtilis/fisiologia , Brevibacillus/fisiologia , Contaminação de Alimentos/análise , Microbiologia de Alimentos , Fumonisinas/análise , Fusarium/isolamento & purificação , Ocratoxinas/análise , Zea mays/microbiologiaRESUMO
The aim of this study was to evaluate the larvicidal activity, and sub lethal effects of entomopathogenic bacteria Brevibacillus laterosporus, Bacillus thuringiensis var. israelensis, B. thuringiensis var. kurstaki, and a commercial formulation of Bacillus sphaericus on Musca domestica. Bacterial suspensions were prepared in different concentrations and added to the diet of newly-hatched larvae which were monitored until the adult stage. The larvae were susceptible to the B. laterosporus, B. thuringiensis var. israelensis, and B. thuringiensis var. kurstaki bacteria in varied concentration levels. These bacteria have larvicidal and sub lethal effects on the development of flies, reducing both adult size, and impairing the reproductive performance of the species.