Studies on the potential and safety of emerging entomopathogenic bacteria

The present thesis had the objective of studying some emerging entomopathogenic bacteria determining their potential against invertebrate pests (i.e., insects and nematodes) and evaluating their safety profile for non-targets insects. Accordingly, experiments involved different strains of the spore-former Brevibacillus laterosporus and of the multitalented plant growth promoting species Pseudomonas protegens. More in detail, spores of an insecticidal strain of B. laterosporus (UNISS 18) were assayed on a range of water-dwelling invertebrates including mosquito larvae and some non-target species, revealing a high susceptibility of mosquito larvae, and different degrees of susceptibility of other species, which suggests a careful use of this bacterium in the aquatic environment. A honeybee-borne strain of B. laterosporus (F5) was instead assayed on soil-dwelling nematodes including the pest species Meloidogyne incognita. A protein fraction containing different virulence factors extracted from the culture supernatant of this bacterial strains proved to be effective in causing a significant nematode mortality. The biocidal potential against Culex pipiens and Aedes albopictus of a recently isolated strain of P. protegens (COI) was determined by laboratory bioassays in which this bacterium was found to be active against both species. In addition to biocidal effects, when larvae were exposed to sub-lethal concentrations, also immature development was significantly affected. Comparative experiments including reference strain CHA0 were also conducted, which confirmed for the first time the potential of P. protegens against mosquitoes. To investigate the safety of this bacterial species that has primary importance for the agroecosystem management, investigations were conducted on the lacewing Chrysoperla carnea. This study confirmed the safety of this entomopathogenic bacterium to green lacewing immatures and adults, with no significant effects on development and adult reproductive potential. According to the results of this thesis, both entomopathogenic bacterial species appears promising in the prospect of their future exploitation for the management of invertebrate pests of agricultural and medical-veterinary importance.

The thesis had the objective of studying some emerging entomopathogenic bacteria determining their potential against invertebrate pests (i.e., insects and nematodes) and evaluating their safety profile for non-targets insects. Accordingly, experiments involved different strains of the spore former Brevibacillus laterosporus and of the multitalented plant growth promoting species Pseudomonas protegens. More in detail, spores of an insecticidal strain of B. laterosporus (UNISS 18) were assayed on a range of water-dwelling invertebrates including mosquito larvae and some non-target species, revealing a high susceptibility of mosquito larvae, and different degrees of susceptibility of other species, which suggests a careful use of this bacterium in the aquatic environment. A honeybee-borne strain of B. laterosporus (F5) was instead assayed on soildwelling nematodes including the pest species Meloidogyne incognita. A protein fraction containing different virulence factors extracted from the culture supernatant of this bacterial strains proved to be effective in causing a significant nematode mortality. The biocidal potential against Culex pipiens and Aedes albopictus of a recently isolated strain of P. protegens (COI) was determined by laboratory bioassays in which this bacterium was found to be active against both species. In addition to biocidal effects, when larvae were exposed to sub-lethal concentrations, also immature development was significantly affected. Comparative experiments including reference strain CHA0 were also conducted, which confirmed for the first time the potential of P. protegens against mosquitoes. To investigate the safety of this bacterial species that has primary importance for the agroecosystem management, investigations were conducted on the lacewing Chrysoperla carnea. This study confirmed the safety of this entomopathogenic bacterium to green lacewing immatures and adults, with no significant effects on development and adult reproductive potential. According to the results of this thesis, both entomopathogenic bacterial species appears promising in the prospect of their future exploitation for the management of invertebrate pests of agricultural and medical-veterinary importance.