Efficacy of the entomopathogenic fungi Beauveria bassiana and Lecanicillium muscarium in the control of the tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)

Abstract Background Among the phytosanitary problems, affecting tomato crops in greenhouses heated by geothermal water in southern Tunisia, the tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is gaining prominence from year to year. Results This study determined the susceptibility of eggs, second-instar larvae of T. absoluta to commercial formulations of the entomopathogenic fungi (EPF) Beauveria bassiana and Lecanicillium muscarium at different doses (10 10 , 10 9 , 10 8 , 10 7 and 10 6 spores/ml). Pathogenicity tests were carried out under controlled laboratory conditions at 27 ± 1 °C, and RH of 75 ± 5%, showed that the three commercial formulations of B. bassiana R444 (Bb-Protec ® ), B. bassiana ATCC 74,040 (Naturalis ® ) and L. muscarium Ve6 (Mycotal ® ) were effective against eggs and second instar larvae of T. absoluta . Mortality rates of eggs and larvae were high with increasing the concentrations of the fungi . B. bassiana ATCC 74,040 was the most effective one, with an egg mortality rate of (71.42%) and larval mortality was greater than (80%), at the highest concentration of 10 10 spores/ml. The lethal concentration required to kill 50% of eggs was 1.56 × 10 8 , 1.73 × 10 9 and 1.09 × 10 10 conidia/ml for B. bassiana ATCC, B. bassiana R444, and L. muscarium , respectively. After 7 days, the median lethal concentration (LC 50 ) values against larvae were the lowest for B. bassiana ATCC with 2.63 × 10 7 and 4.76 × 10 6 conidia/ml by way 1 and way 2 treatments, respectively. Thus, these three formulations affected the emergence of pest’s adults. The fungi significantly reduced pupation and adult emergence. Only 50.25, 60.15 and 69.16% of T. absoluta adults emerged in the treatments with B. bassiana ATCC, B. bassiana R444, and L. muscarium , respectively. Conclusions Biological performances of the EPF showed the role of a biological control agent that can be played against T. absoluta within the framework of an Integrated Pest Management program.