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Biological control is an environmentally safe alternative in the management of nematodes. The selection of new biocontrol agents has focused on the potential of Bacillus species in in vitro and in vivo studies. In this study, twenty-three local Bacillus isolates were characterised and evaluated for metabolisable carbon source, secondary metabolite production and nematicidal action. The in vitro antagonism studies were evaluated after direct confrontation between infecting juveniles of M. enterolobii and bacterial isolates. In a greenhouse, nematicidal activity was evaluated 51 days after nematode inoculation in melon plants previously inoculated with the bacteria and cultivated in pots. The numbers of egg masses, galls, J2 and eggs in the root, J2 in the soil, the reproduction factor and the biomass yield of the plants were evaluated. From the results obtained in the laboratory experiments, it was observed that five carbon sources (D-glucose, N-acetyl-glucosamine, D-maltose, malic acid and trisodium citrate) were common to all isolates, with variation in the production of secondary metabolites. The sum of nematostatic and nematicidal effects was above 90%. In the pot experiment, a significant reduction in the number of galls was observed with the treatments LCB 03, LCB 40, LCB 45, LCB 47, LCB 51, LCB 56 and LCB 5(3) and there was no increase in plant biomass. Root protection may be associated with effective colonisation through biofilm formation and the action of metabolites with nematicide and disorientation action. However, it is necessary to carry out further studies. Made available in DSpace on 2022-05-11T11:13:33Z (GMT). No. of bitstreams: 1 Melao-Fungo-para-controle-biologico-2022.pdf: 5957977 bytes, checksum: 3573acb8639845fa39fede25201f01fb (MD5) Previous issue date: 2022

Although it is usual, using constant temperature to select thermo-tolerant entomopathogen (EF) strains could discard potentially efficient biocontrol agents (BCA). The objectives of this work were to select virulent EF against C. capitata and evaluate the effect of continual and fluctuating temperature on fungal development and virulence. Initial experiments compared the effect of constant temperatures (CT) (20, 25, 30, 35, and 38 ?C) and simulated intraday temperature variation (SIV) (20?38 ?C) over conidial germination, mycelial growth, and insect mortality. Temperatures ? 35 ?C in the CT experiments significantly reduced conidial germination, and the strains of Beauveria bassiana BbLCB81 and BbLCB289 showed the highest conidial germination and mycelial growth. SIV also caused a significant effect, and M. anisopliae MaLCB62 showed the highest conidial germination and mycelial growth. Applying EF strains as toxic baits in CT showed that the highest mortality occurred at 30 ?C, and BbLCB62 and BbLCB289 showed the largest insect mortality at 38 ?C. Survival analysis showed a slight increase in the average survival time (ST50) at 30 ?C. In SIV conditions, MaLCB56 and BbLCB289 were highly virulent. In a field cage experiment at a warmer temperature, BbLCB62 was the most virulent strain according to the M-C test comparing survival curves. However, confirmed accumulated mortality on the 10th day was similar to the moderately tolerant BbLCB289 (Tukey, p < 0.05). During winter, all EF strains showed similar mortality on 10th day (Tukey, p < 0.05), but a significant difference in the survival analysis. EF strains with mild temperature tolerance can be applied in seasons with high temperatures, and BbLCB62 and BbLCB289 were selected as potential biocontrol agents against C. capitata. Made available in DSpace on 2022-10-03T17:06:21Z (GMT). No. of bitstreams: 1 Selecting-thermal-tolerant-strains-of-entomopathogenic-fungi-to-control-2022.pdf: 992654 bytes, checksum: 48abceab5db586424f82819bf08858d6 (MD5) Previous issue date: 2022