Efficacy of entomopathogenic fungi against adult Diaphorina citri from laboratory to field applications

Abstract

The Asian citrus psyllid, Diaphorina citri, is the most serious threat to citrus crops worldwide, and its management relies exclusively on frequent applications of chemical insecticides. Entomopathogenic fungi may play an important role for regulating this citrus pest. Two virulent fungal strains, Isaria fumosorosea ESALQ-1296 and Beauveria bassiana ESALQ-PL63, were selected among 17 fungal isolates under laboratory conditions and caused 77.8 and 78.4% adult mortality, respectively, while in semifield trials the adult mortality reached up to 83.5% with B. bassiana and 80.6% with I. fumosorosea. The bioefficacy of these two fungi on D. citri adults was assessed through monthly applications during 1 year in a commercial citrus grove located in Itapetininga, São Paulo, Brazil. The application of I. fumosorosea ESALQ-1296 and B. bassiana ESALQ-PL63 was as effective as the chemical insecticides in most trials. The fungal-induced mortality of D. citri adults ranged from 96.1% in December 2011 to 57.8% in October 2012. This mortality level tended to build up with the increase in the maximum relative humidity; the percentage of sporulated cadavers was positively correlated with both higher relative humidity and rainfall but negatively associated with maximum temperatures. These results support the use of I. fumosorosea or B. bassiana as an eco-friendly biopesticide for the integrated management of D. citri.