Thermotolerance of Fungal Conidia

N. PEDRINI; E.K.K. FERNANDES; F.R.S. DA PAIXAO

Microbes for Sustainable lnsect Pest Management, Sustainability in Plant and Crop Protection

Springer Nature

Año: 2019; p. 185 - 196

Conidia of entomopathogenic fungi (EF) are the propagules most frequentlyused in arthropod biocontrol programs. This anamorphic form is essentialfor the infection process, including spore germination, penetration, vegetativegrowth, conidiogenesis and dissemination. Most EF are mesophilic and can developbetween 10 and 40 °C, but optimal growth is between 25 and 35 °C. Abiotic factors,especially temperature (high or low) can determine their viability, virulence andsuccess or failure of infection process. Temperature has the highest impact onconidial stress inhibiting metabolic processes, such as decreased morphogenesisduring germination, protein denaturation and membrane disorganization. Severalstudies show that some strains of Beauveria spp., Metarhizium spp., and Isaria spp.exhibit conidial survival even when grown at high temperatures, indicating a relationshipbetween conidial thermotolerance and their geographical isolation origin.Moreover, the high variability in fungal thermotolerance is also dependent of theculture media composition and growth condition. EF that grow at high temperaturesdo not grow at low temperatures and vice versa. Moreover, when growth conditionsare not set at optimal temperatures, EF development is affected and their effectivenessin biological control programs of arthropods is reduced. Thermal stress directlyimpacts on fungal strains ability to target arthropods and their environmental activityperformance. The screening for fungal strains with a higher thermotolerance andthe improvement on conidial formulations may aid in optimizing the conditions for biocontrol agent application.