In vitro Screening of Natural Metarhizium spp. Isolates for Bioinsecticidal and Biofungicidal Activity

Aims: To increase conidia production of local Metarhizium spp—strains by selecting the low-cost media to test obtained bioformulation against the sucking pests and fungal plant pathogens.

Study Design: The phytophages like black bean aphid (Aphis fabae), a scale insect (Aspidiotus nerii) and spider mite (Tetranychus urticae) are economically essential pests in Kyrgyzstan. The current requirement is to use environmentally friendly protection to reduce the number of these pests. The entomopathogenic fungus from the Metarhizium genus was used to reduce harmful pests in vitro and in vivo experiments.

Place and Duration of Study: Department of Plant Protection, Kyrgyz-Turkish Manas University between May 2021 and May 2023.

Methodology: Natural Metarhizium spp. strains were isolated from dead insect bodies of the Lepidoptera and Apidae families. A laboratory bioassay was conducted to evaluate isolated Metarhizium spp.strains against nymphal stages and adults of sucking pests like A. fabae ((Blackfly), A.nerii (Scale insect) and T.urticae (Spider mite). The inhibitory effect of Metarhizium spp.against Fusarium oxysporum, Alternaria spp. and Rhizoctonia solani was detected using a dual culture technique.

Results: The results of in vitro bioassay tests against sucking pests have revealed the LC50 and LT50 values of TLK-1 isolate. The LC50 of this isolate for A. fabae adults was 1 × 106 conidia\ mL-1; for A.nerii, it was lower - 7 × 105 conidia\ ml-1; while for adults T.urticae it was higher- 13 × 106 conidia \ ml-1. Such mortality occurred after 49.63 hours in adults of A. fabae (LT50), after 46.30 hours in A.nerii (LT50), and after 75.87 hours in deutonymph and adults of T. urticae (LT50). Three isolates, TLK-1, TLA-2 and BZТК1, have exhibited biofingicide activity in pathogen fungi like Fusarium oxysporum and Alternaria spp.

Conclusion: The found isolates can be simultaneously used against pathogenic fungi, essential for developing inexpensive biological formulas based on these fungi.