Abstract
The potato tuber moth, Phthorimaea operculella, is the most damaging potato pest in the world and is difficult to control as the larvae are internal feeders in the foliage or tubers. Entomopathogenic fungi (EPF) which colonize plants as endophytes, have lethal and sublethal pathological effects on insect pests. Experiments showed that Beauveria bassiana colonized the aerial parts of potato plants endophytically after inoculation through soil drenching. The colonization rate reached 100% for both upper and lower foliage parts one day after inoculation, and endophytic B. bassiana remained present for more than 21-day post inoculation. Mortality experiments indicated that B. bassiana and B. bassiana-inoculated potato plants were pathogenic against 2nd instar larvae of P. operculella. Development experiments showed that the weight of P. operculella pupae reared on B. bassiana-colonized potato leaves (4.25 mg) was significantly lighter than of those reared on uninoculated control plants (8.89 mg). Sublethal experiments indicated that B. bassiana negatively affected the growth, development and reproduction of P. operculella. Compared to newly eclosed larvae fed on control plants, those fed on B. bassiana-inoculated plants had significantly lower survival, with only 17.8% developing to the adult stage. Oviposition of P. operculella females reared on B. bassiana endophytically-colonized plants was significantly lower (35 eggs/per female) than of those reared on uninoculated plants (115 eggs/per female). This study demonstrates that endophytic B. bassiana can be a potential biological agent for the control and management of P. operculella.
Field Evaluation of Attracticides in Managing Potato Tuber Moth, Phthorimaea operculella Zeller (Lepidoptera: Gelechidae) in Bhutan
