Abstract
Ghanaian chili pepper exports are subject to stringent regulations on pesticide residues in significant foreign markets. Therefore, safer pest management options are needed to supplement current non-chemical control techniques, especially for controlling Thaumatotibia leucotreta Meyrick (False codling moth, FCM), an important phytosanitary pest. A national survey was initiated in 2023 to identify native entomopathogenic fungi (EPF) from Ghanaian farms. Seven Metarhizium isolates were recovered from soils and induced substantial mortalities of soil-residing final-instar stages of FCM in vitro. To advance the development of a mycoinsecticide targeting FCM and other key insect pests of chili pepper, the present study evaluated the in vitro temperature tolerance of the seven isolates and persistence of two (UGSUHC1 and UGJKCS9) under field conditions. Temperature tolerance assays based on in vitro radial growth (at 6-40 °C) indicated that all isolates could grow between 15 and 35 °C, with optimum development occurring between 25 and 27 °C. No growth occurred at 6, 8, 38, and 40 °C. Two-month semi-field persistence trials using sterile soil inoculated with each respective isolate and buried in chili pepper farms at Adidome, Peki, and the University of Ghana, demonstrated that both isolates remained viable in the soil throughout the trial period and retained their infectivity against FCM. These results highlight the potential of these Ghanaian isolates against subterranean life stages of FCM. The need for further evaluations, particularly field trials, is therefore imperative for the development of an effective and sustainable control option for FCM in chili peppers in Ghana.