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 (1010, 109, 108, 107 and 106 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 1010 spores/ml. The lethal concentration required to kill 50% of eggs was 1.56 × 108, 1.73 × 109 and 1.09 × 1010 conidia/ml for B. bassiana ATCC, B. bassiana R444, and L. muscarium, respectively. After 7 days, the median lethal concentration (LC50) values against larvae were the lowest for B. bassiana ATCC with 2.63 × 107 and 4.76 × 106 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.

Background The geothermal greenhouses in Southern Tunisia are an important axis of agricultural development. This sector faces many abiotic and biotic constraints that could threat its sustainability. Thus, the heated greenhouses encounter destructive pests such as the whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) and the two-spotted spider mite Tetranychus urticae (Koch) (Acari: Tetranychidae). Results This study aimed to assess the effect of the entomopathogenic fungi (EPF) Beauveria bassiana (strain ATCC and strain R444) and Lecanicillium muscarium strain Ve6 on simultaneous existence of T. urticae and B. tabaci in the host plants. The EPF had a significant effect on eggs and larvae of B. tabaci and on eggs and mobile forms of T. urticae in particular. The use of B. bassiana ATCC, B. bassiana R444 and L. muscarium strains Ve6 showed significant efficacies against B. tabaci larvae and eggs compared to untreated control. Indeed, the reduction percent of B. tabaci eggs varied between 42.65 and 58.52%. Thus, the efficacy against the number of B. tabaci larvae was in order to 65.04, 60.26 and 55.52% of B. bassiana strain ATCC, B. bassiana strain R444 and L. muscarium strain Ve6, respectively. In addition, these EPF were very effective on T. urticae eggs with a percentage reduction greater than 92.86%, whereas the percentage reduction in the T. urticae mobile forms varied between 95.11 and 98.52%. Conclusions Use of EPF will be an imperative to develop directed interventions at the integrated management of these two pests in protected and geothermal crops.

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