Selection of Entomopathogenic Fungi to Control Varroa destructor (Acari: Varroidae)

Marta Rodríguez1*, Marcos Gerding1, and Andrés France1

The aim of this work was select entomopathogenic fungi tolerant to temperatures inside the brood area of honey bees (Apis mellifera) for to control Varroa destructor. For this purpose, 50 Beauveria bassiana (Balsamo) Vuillemin and 48 Metarhizium anisopliae (Metschn.) Sorokin isolates were evaluated at 30 and 35 ºC. For each isolate, colony discs of 5 mm with mycelium were placed in the center of a Petri dish with Sabouraud dextrose agar (SDA) medium. The dishes were incubated at 30 and 35 °C, without light. Radial growth of each colony was measured daily. All the B. bassiana and M. anisopliae isolates presented a lineal growth rate at a temperature of 30 ºC. However, at 35 ºC, most of the isolates did not grow, except three B. bassiana and 14 M. anisopliae isolates (P < 0.001). These isolates were selected to evaluate the pathogenicity on V. destructor by applying a suspension of 107 conidia mL-1. The most effective isolate was M. anisopliae Qu-M845 (P = 0.0033) which produced 85% mortality. The pathogenic capacity of this isolate on V. destructor and its tolerance to hive conditions allows us to consider this strain as an alternative to control this pest.

Keywords: biological control, entomopathogenic fungi, Varroa destructor, varroasis, entomopathology
1Instituto de Investigaciones Agropecuarias INIA, Av. Vicente Méndez 515, Chillán, Chile. *Corresponding author (mrodrigu@inia.cl)