CHARACTERIZATION OF NEW BIOTYPES OF P157 STRAIN OF Metarhizium anisopliae var. anisopliae, GOT BY TREATMENT WITH GAMMA RADIATION

Conidios de la cepa silvestre P 157 de Metarhizium anisopliae var.  anisopliae (Metsch.) Sorokin, fueron expuestas a la radiación gama para la obtención de nuevos biotipos. En la dosis de 390Gy se obtuvo 36 colonias (MaP). Cinco colonias (MaP 03, MaP 17, MaP 25, MaP 27), expresaron alteración morfológica para el color en el Medio Completo. En este, 21 colonias presentaron crecimiento micelial significativamente distinto del testigo silvestre, después de 12 días de la inoculación. La colonia MaP 25, presentó mayor valor de crecimiento micelial y la colonia MaP 11, el menor valor. Entre las colonias obtenidas, solamente la colonia MaP 28 presentó auxotrofia, identificada como una deficiencia en la síntesis del ácido paraminobenzóico. Los conidios de 29 colonias, presentaron un promedio de porcentaje de germinación significativamente distinto del respectivo aislamiento silvestre, después de 12 horas de incubación en Medio Mínimo, a 25°C. Las colonias MaP 02, MaP 21 y MaP 36, presentaron precocidad en la germinación de los conidios en relación al patrón silvestre

Pathogenic activity of Isaria spp. for control of Dactylopius opuntiae (Hemiptera: Dactylopiideae) and the effects of selected insecticides

We analyzed the activity of the entomopathogenic fungi Isaria farinosa, I. fumosorosea and I. javanica against the cochineal Dactylopius opuntiae, as well as the effects of the insecticides clorpirifos, acetamiprid, thiamethoxam and lambda-cyhalothrin on the conidia germination, mycelium growth and a sporulation of the fungi. These fungi were not pathogenic to cochineal. This the first report of the efficiency of Isaria spp. against this the insect. The bioassays of the compatibility of the insecticides acetamiprid and thiametoxam with species of Isaria indicate the possibility of the joint use of these products in studies on the control of D. opuntiae.El trabajo analizó las acciones de los hongos entomopatógenos Isaria farinosa, I. fumosorosea y I. javanica contra la cochonilla Dactylopius opuntiae, así como el efecto de los insecticidas clorpirifos, acetamiprid, tiametoxam y lambda-cialotrina sobre la germinación, el crecimiento micelial y esporulación del mismo. Los hongos no fueron patógenos a D. opuntiae, siendo éste el primer reporte de la eficiencia de Isaria spp., sobre este insecto. Los bioensayos de la compatibilidad de los insecticidas acetamiprid y thiametoxam con especies de Isaria indican la posibilidad de uso conjunto de estos productos en estudios para el control de D. opuntiae

Pathogenicity of Beauveria bassiana and production of cuticle-degrading enzymes in the presence of Diatraea saccharalis cuticle

The sugarcane borer, Diatraea saccharalis, is one of the worst pests in Brazilian sugarcane crop, causing high levels of financial losses every year. Beauveria bassiana is an entomopathogenic fungus widely used in the biological control of several agricultural pests. The aims of this study were to: (1) evaluate the pathogenicity of B. bassiana strains against D. saccharalis (2) investigate the production of proteases and chitinase by B. bassiana in the presence of the cuticle of sugarcane borer; and, (3) evaluate the relation between the production of enzymes and pathogenicity of the strains. All isolates tested were pathogenic to D. saccharalis and the mortality ranged from 36 to 88%. The production of enzymes was higher in the medium containing cuticle, showing that the process is stimulated by specific components found in the cuticle of the host. Pr1 activity was higher than Pr2 and both were produced at 24 h. The highest production of chitinase was obtained at 96 h of culture for all strains tested. Levels of specific cuticle-degrading enzymes such as proteases correlated positively with specific virulence parameters. B. bassiana URM2915 showed promising features to be used in a biological control program of D. saccharalis.Key words: Biological control, sugarcane, subtilisin-like protease, trypsin-like protease, chitinase

Biological insect control using Metarhizium anisopliae: morphological, molecular, and ecological aspects

Microbial control of insects is based on the rational use of pathogens to maintain environmentally balanced pest population levels, and Metarhizium anisopliae has been the most studied and most utilized fungal species for that purpose. The natural genetic variability of entomopathogenic fungi is considered one of the principal advantages of microbial insect control. The inter- and intraspecific variability and the genetic diversity and population structures of Metarhizium and other entomopathogenic fungi have been examined using ITS-RFLP, ISSR, and ISSP molecular markers. The persistence of M. anisopliae in the soil and its possible effects on the structures of resident microbial communities must be considered when selecting isolates for biological insect control

Horizontal transmission and effect of the temperature in pathogenicity of Beauveria bassiana against Diatraea saccharalis (Lepidoptera: Crambidae)

The aim of this work was to evaluate the effect of temperature on the pathogenicity of Beauveria bassiana against Diatraea saccharalis and evaluate the horizontal transmission capacity among the sugarcane borer larvae. The strains were most pathogenic at 26ºC, followed by 32ºC than at 20ºC, with respective mortalities of 100, 50 and 30.3%. The lethal time was also affected by the temperature, with the shortest LT 50 observed at 26ºC (2.2 days) and the longest at 20ºC (16.2 days). The URM2915 strain appeared most effective in all the experiments as having potential for deployment in biological control programs for the sugarcane borer. Results in horizontal transmission of B. bassiana showed that this procedure could also be adopted as control strategy for the sugarcane borer

PERSISTÊNCIA DE Metarhizium anisopliae spp NO SOLO SOB DIFERENTES CONDIÇÕES DE TEMPERATURA E UMIDADE

The fungi entomopathogenic are actually objects of works according to their importance in the ecological system. This work analysed the persistence of Metarhizium anisopliae var. anisopliae and M. anisopliae var. acridum, under different conditions of temperature and humidity, in the period of September to December. After inoculation on soil the fungi were submitted to four different treatments: environment temperature and 25% of humidity; environment temperature and 75% of humidity; 28º C and 25% of humidity; 28º C and 75% of humidity, during 120 days. The results show that M. anisiopliac var. anisopliae presented the most recuperation in the treatment at 28º C and 75% of humidity (P > 0,05) in 30 days and maintained a positive conditions on soil for 120 days of experiment. The same did not happen to M. anisopliae var. acridum that, during the whole process of observation and controll the colonies recuperation avoiding its persistence on soil, during the 120 days of experiment

Genetic variability in regenerated Metarhizium flavoviride protoplasts

Protoplast isolation and regeneration were evaluated in two wild-type and two colour mutant strains of Metarhizium flavoviride. Cultivation in liquid medium, followed by mycelium treatment with Novozym 234 in the presence of KCl 0.7M as osmotic stabilizer, produced 5.05 x 10(6) to 1.15 x 10(7)x mL-1 protoplasts. The percentage of regeneration ranged from 6.65 to 27.92%. Following protoplast regeneration, one strain produced spontaneously stable morphological variant colonies. Although colonies with altered morphology have been reported in bacteria following protoplast regeneration, this is the first time that the same is described in a filamentous fungus. The original strain and one derived variant were tested for sensitivity to the fungicides benomyl and captan.<br>A formação e regeneração de protoplastos foram avaliadas em duas linhagens selvagens e duas linhagens mutantes para coloração de conídios em Metarhizium flavoviride. O cultivo em meio líquido seguido do tratamento do micélio com Novozym 234 na presença de KCl 0,7 M como estabilizador osmótico, resultou na produção de 5,05´10(6) a 1,15´10(7) protoplastos´mL-1. A porcentagem de regeneração das diferentes linhagens variou de 6,65 a 27,92%. Após a regeneração, uma das linhagens selvagens produziu espontaneamente variantes estáveis, com morfologia alterada. Embora variantes morfológicos já tenham sido observados após regeneração de protoplastos em bactérias, esta parece ser a primeira vez que tal ocorrência é descrita em fungos filamentosos. Um desses variantes, além da linhagem selvagem da qual ele foi originado, foi testado para sensibilidade aos fungicidas benomil e captano

BEHAVIOR AND CYTOLOGICAL ASPECTS OF Metarhizium anisopliae and Metarhizium flavoviride AFTER PASSAGE IN Chrysomya albiceps

Metarhizium anisopliae var. anisopliae and Metarhizium flavoviride var. flavoviride are entomopathogenic fungi with proved action against several species of insects. In this work, the behavior and cytology of the M. anisopliae var. anisopliae (PL43) and M. flavoviride var. flavoviride (CG291) were evaluated after the passage in eggs, larvae and adults Chrysomya albiceps, an important causer of secondary myiais. The experiment was carried out under an acclimatized environment's humidity and temperature of 60 ± 10% and 28 ± 1oC. The most expressive results of the biological parameters studied (percentage of germination, quantity of conidia, quantity and diameter of colonies) were reached from re-isolated fungi of larvae. No significant differences were observed in the cytological aspects of the life cycle of the fungi post-passage in eggs, larvae and adults. These results suggest the possibility of the use of the fungi in the control of C. albiceps fly