First report of native Beauveria bassiana and Trichoderma ghanense as bio-control agents against Spodoptera frugiperda in Ghana

Abstract

Signs of mycosis on mummified Spodoptera frugiperda cadavers were found in maize fields in the Ejura-Sekyedumase and Wa Municipalities in the Ashanti Region and Upper West Region of Ghana, respectively, during the 2019 to 2022 growing seasons. Two major signs were observed on two sets of cadavers that were collected. These were dense white powdery colony encapsulating cadavers, and green powdery growth engulfing cadavers. The causal fungi were confirmed as Beauveria bassiana from white cadaver mummies and Trichoderma ghanense from green cadaver mummies based on morphological and molecular characteristics. The two fungi were assessed for their lethal effect against 3rd instar larvae of S. frugiperda by artificial inoculation. The inoculation was performed with conidia suspension of 1 × 108 conidia/ml for each fungi. B. bassiana caused 55% larval mortality, which was significantly higher (p < 0.05) than the 32.5% caused by T. ghanense. No larval mortality was recorded for the control. Artificially inoculated 3rd instar S. frugriperda larvae exhibited signs similar to those observed on infected larvae collected from the field. The respective pathogens were re-isolated and the morphology matched B. bassiana and T. ghanense, respectively. The findings indicate the potential of the two fungi as bio-control agents for management of S. frugiperda on maize. The obtained result could find application in the formulation of bio-pesticides for S. frugiperda management.