Metarhizium anisopliae isolates as biological control agents of the tomato leafminer, Tuta absoluta (Lepidoptera: Gelechiidae) and compatibility with Tuta pheromone

Tomato, Solanum lycopersicum is an important economic vegetable in the tropics and a major component of diet. However, the production and productivity of tomato are highly hampered by the invasive tomato leafminer Tuta absoluta, that causes yield loss of up to 100%. As a quarantine pest, it also leads to loss of lucrative export markets. Currently, the commonly used management strategy is synthetic insecticides with hazardous effects on human and environment. Use of entomopathogenic fungal biopesticides is a promising alternative to synthetic insecticides. Pathogenicity of dry conidia of 12 fungal Metarhizium anisopliae isolates was evaluated against adult T. absoluta, the effects of the most potent isolates on the pupation, adult emergence and compatibility with Tuta pheromone were assessed in the laboratory. All the fungal isolates were found pathogenic to T. absoluta, with M. anisopliae ICIPE 18, ICIPE 20 and ICIPE 665 outperforming the others causing mortality of 95.0, 87.5 and 86.25% respectively. The lethal time to 50% mortality (LT₅₀) was 5.13, 3.17 and 2.38 days for ICIPE 18, ICIPE 20 and ICIPE 665, respectively. ICIPE 18, ICIPE 20 and ICIPE 665 significantly reduced pupal formation and adult emergence. The three potent isolates were also found to be compatible with the Tuta pheromone (TUA-Optima®) with 90.25, 90.00 and 89.5% conidial germination for ICIPE 18, ICIPE 20 and ICIPE 665, respectively. The three potent isolates are good biocontrol candidates for use in combination with Tuta pheromone within an IPM context for Tuta management.