INSECTICIDAL ACTIVITY AND PERSISTENCE OF A FORMULATION BASED ON Beauveria bassiana FOR Diatraea saccharalis CONTROL

Abstract

The development and use of microbial pesticides for the control of agricultural pests has intensified
in recent years due to the increasing need for reductions in the use of highly toxic agrochemicals. To
fill this growing need for biopesticides it is necessary to develop suitable formulations that stabilize
microorganisms against environmental stress factors that reduce their efficacy and persistence in
the field. In this context, the objective of the present work was to determine the insecticidal activity
and persistence on sugarcane plants, of an emulsifiable concentrate (EC) containing Beauveria
bassiana for the control of sugarcane borer, Diatraea sp. Photostability of the formulation under
UV radiation type B and the mean and ninety lethal concentrations were also determined under
laboratory conditions. The EC reached more than 80% efficacy against D. saccharalis larvae under
semi-controlled field conditions. The EC efficiently photostabilized the conidia, maintaining 68.9%
germination after nine minutes of irradiation while unformulated conidia completely lost the ability
to germinate. This effect was also observed for the insecticidal activity, with unformulated conidia
losing 30% more efficacy than formulated conidia after nine minutes of irradiation. The insecticidal
activity and conidia count on sugarcane plants under field conditions decreased one and two weeks
post application, respectively. Although the EC containing on B. bassiana demonstrated effective
insecticidal activity against D. saccharalis, it is necessary to carry out field trials to optimize the