Evaluation of entomopathogenic fungi for locust control in the Republic of Georgia

Orthoptera, esp. Caliptamus italicus and Dociostaurus maroccanus, represent frequent, severe sources of crop loss in the Caucuses, esp. Georgia. Thus there is need to identify indigenous entomopathogenic fungi for locust control as alternatives to chemical pesticides. As part of a program to build insect pathology infrastructure within in Georgia, a program was conducted to identify potentially useful fungi for locust control. Five isolates of Beauveria bassiana and eight isolates of Metarhizium anisopliae were made from Georgian Orthoptera. These isolates were evaluated in terms of conidial production in a pilot-scale, solid-substrate fermentation system; vegetative growth under constant temperatures of 10, 15, 20, 25, 30 35 and 37^° C. and also transient 39 and 41^° C., mimicking periods of behavioral fever in host insects; and bioassay efficacy against Melanoplus sanguinipes and/or Schistocerca americana. Six of eight Metarhizium isolates produced >40 g conidia/kg substrate. All B. bassiana isolates were very poor conidia producers, tending towards extensive mycelial growth. There was considerable variability among the isolates in their tolerance to temperatures <15° C. and >30° C., as measured by radial growth on agar media, as well as to 3-9 hr transient exposure to 39 or 41° C. Many showed a 1-2 day lag before resuming normal growth upon return to 28° C. All of the isolates were highly virulent for either of the two acridids. Several of the M. anisopliae isolates have potential for operational use as mycoinsecticides against Georgian Orthoptera. This research was funded by US Agency for International Development grant TA-MOU-03-CA23-022.