Effects of Isaria (Persoon) isolates on the subterranean termite Coptotermes gestroi (Wasmann) (Isoptera: Rhinotermitidae)

Abstract

Coptotermes gestroi (Wasmann) is considered to be one of the most destructive species of subterranean termites because of the damage caused on edifications, urban trees, and crops. One alternative to control it is the use of biocontrol agents, such as the entomopathogenic fungi. The genus Isaria (Persoon) has been suggested for the control of subterranean termites, including the Coptotermes genus. Therefore, the present work aim was to select isolates of Isaria pathogenic to C. gestroi. The workers were sprayed with fungi suspensions of I. farinosa, I. fumosorosea and I. javanica, and evaluated every day to determine mortality. All isolates were pathogenic towards C. gestroi with mortality rates higher than 70%, and virulent, with mean of survival of 2.0 up to 3.9 days. Among the isolates, the ESALQ-1205 isolate of I. farinosa, the ESALQ-1296 isolate of I. fumosorosea, URM-4995 and URM-4993 isolates of I. javanica showed the highest virulence. The estimated CL50 for the ESALQ-1205 isolate of I. farinosa, URM-4995 isolate of I. javanica and ESALQ-1296 isolate of I. fumosorosea was 3.7 x 105, 1.4 x 106and 2.7 x 106 conidia mL-1, respectively. These results suggest high efficiency of these isolates towards the C. gestroi workers. Nevertheless, further studies are necessary to determine a way of using them as well as their efficacy in field.