RESUMEN
The slow action of fungi is one of the biggest challenges in using entomopathogenic fungi. A promising alternative to reduce the time of action is to combine conidia with extracellular enzymes. This study aimed to characterize the production of Pr1 subtilisin protease and lipases by Beauveria bassiana and Metarhizium anisopliae in different culture media and to evaluate the efficiency of the enzymatic treatment against Aphis gossypii and Spodoptera frugiperda. The isolates were cultivated in five different liquid cultures, and, after 7 days, the culture was filtered and centrifuged, and the activity of the Pr1 and lipases was measured. The fungi cultured in a Luria-Bertani broth medium had the highest activity of proteases and lipases. The mortality of A. gossypii nymphs treated with conidia 7 days after the treatment was 39% (JEF-410), 76.5% (JEF-492), 74.8% (ERL-836), and 70.9% (JEF-214). The B. bassiana JEF-410 supernatant combined with conidia increased the fungal virulence at day 5 and day 6 after treatment. When S. frugiperda larvae were treated with B. bassiana JEF-492 conidia combined with its supernatant, the time of infection was shorter compared to the larvae treated with conidia only. Once the supernatant was incubated at 37 °C, the relative activity decreased from 100% to 80% after 2 h and to 45% after 24 h. The results suggest that the supernatant of entomopathogenic fungi may be formulated and used as a biopesticide in an efficient strategy for the biological control of pests.
RESUMEN
BACKGROUND: Duddingtonia flagrans and Monacrosporium thaumasium are promising fungus species in veterinary biological control of gastrointestinal nematodes because of their production capacity of fungal structures (conidia and/or chlamydospores), growth efficiency in laboratory solid media and especially their predatory capacity. However, their large-scale production remains a challenge. This work aimed at evaluating the mycelial mass production of D. flagrans (AC001 and CG722) and M. thaumasium (NF34A) nematophagous fungi under different culture conditions. RESULTS: The results did not present significant differences (p > 0.05) in mycelia mass production between the isolates cultured under pH 4.0. Furthermore, after 168 hrs., the isolate CG722 presented a lower production of mycelial mass in medium CM (corn meal) (p < 0.05). CONCLUSION: We therefore concluded the use of culture media SD (soy dextrose) and CG (corn grits) at pH values between 6.0 and 7.0 is suitable for high mycelial mass production of D. flagrans and M. thaumasium.
