Potential of Metarhizium anisopliae (Metsch.) Sorokin (Ascomycetes, hypocreales) in the control of Bonagota salubricola (Meyrick) (Lepidoptera, Tortricidae) and its compatibility with chemical insecticides

Several insects are harmful to apples grown in Brazil, especially the leafroller Bonagota salubricola (Lepidoptera, Tortricidae), usually controlled with chemical insecticides. The purpose of the present study was to investigate the use of Metarhizium anisopliae strains in the control of the apple leafroller, by assessing their virulence to B. salubricola larvae in bioassays with suspensions of 2 x 10(5) to 2 x 10(9) conidia/mL as well as their relationship with protease expression. The most effective strain underwent a compatibility test with chemical insecticides. The M. anisopliae E6 strain showed a good performance, with up to 88% mortality and a LT50 of 1.66 days. The virulence was positively correlated with a higher enzymatic activity. The E6 strain was compatible with tebufenozide, evidencing its potential to control B. salubricola

Genetic variability in the endophytic fungus Guignardia citricarpa isolated from citrus plants

During some phases of of their life-cycle endophytic fungi colonize plants asymptomatically being found most frequently inside the aerial part of plant tissues. After surface disinfection of apparently healthy leaves from three varieties of mandarin orange and one tangor, and after incubation on appropriate culture medium, 407 fungal isolates were obtained, giving a total infection frequency of 81%. No fungal growth was observed from disinfected seeds, indicating that fungi are probably not transmitted via seeds. Of the fungal isolates, 27% belonged to the genus Guignardia, with 12 isolates being identified as Guignardia citricarpa Kiely, which is described as a citrus pathogen. The isolates were variable in respect to the presence of sexual structures and growth rates. Most of the isolates produces mature asci, supporting the hypothesis that they are nonpathogenic endophytes, which recently were identified as G. mangiferae. High intraspecific genetic variability (an average similarity coefficient of 0.6) was detected using random amplified polymorphic DNA (RAPD) markers generated by seven different primers. The highest similarity coefficient (0.9) was between isolates P15 and M86 and the smallest (0.22) between isolates P15 and C145. These results did not allow us to establish an association between genetic similarity of the fungal isolates and the citrus varieties from which they were obtained