Effect of different concentrations of Metarhizium anisopliae (Metsch.) (Ascomycota: Hypocreales) and Beauveria bassiana (Bals.) (Ascomycota: Hypocreales), in nymphs of Oebalus insularis Stal (Heteroptera: Pentatomidae), under controlled abiotic conditions

The potential of two strains of entomopathogenic fungi was evaluated, as biological control agents in nymphs of third and fifth instar of Oebalus insularis, in abiotics conditions. Beauveria bassiana and Metharhizium anisopliae, collected and isolated in another species. For this purpose, a trial was established under controlled abiotic conditions, in wich they were evaluated in B. bassiana and M. anisopliae, in five concentrations of conidia / ml; 1x10⁵, 1x10⁶, 1x10⁷, 1x10⁸ , 1x10⁹. Each trial consisted of 50 third and fifth instar nymphs of O. insularis, applying the entomopathogenic fungi by means of the spraying method. Subsequently, the mortality of nymphs was recorded after 24 hours, from the inoculation in different concentrations of the entomopathogenic fungi evaluated. Mortality was corrected using Abbott´s formula and Analysis of Variance (ANOVA) was performed to compare the mortality between treatments. The DL₅₀  and DL₉₀, was obtained by the Probit Test. The experimental design was completely randomized with five treatments considering four repetitions per treatment. The mortality reported at concentrations of 1.18x10⁹ and 1.20x10⁹, B. bassiana and M. anisopliae applied in third instar nymphs was 38.0 and 47.0%, respectively. Mortality in fifth instar nymphs of O. insularis, with the higest concentrations, was 54.0% of B. bassiana and 40.0% for M. anisopliae. The most virulent strain was B. bassiana by LD ₅₀ (9.86x10⁸  conidiums/ml) and  LD₉₀  (2.22x10⁹ conidium /ml), in nymphs of O. insularis.