The effectiveness of Bacillus thuringiensis preparations and the survival of the spores of the bacterium are considered to be among the parameters that influence the choice of the preparation to be employed, both in agricultural and in forest environment, for biological control of insect pests. The effectiveness and the persistence of the insecticidal activity of various commercial preparations of Bt has been tested against the Pine Processionary Caterpillar and the European Grapevine Moth in various trials carried over in pine forests and vineyards of Tuscany. Moreover the survival of the bacterial spores has been verified by measuring the population consistence, on pine needles, and on grapevine leaves and berries, at different time points after the treatment (0, 1, 4, 6, 8, 11, 14 days in the case of grapevine and 0, 2, 5, 12, 16, 23 days in the case of pines). The trials were carried out when young PPC and EGM larvae (I and II instar) were present in the environment. Three commercial preparations were used in the trials: Bactucide P, against EGM, Biobit, against PPC, and Thuricide HP against both pests. Larval mortality, caused by all products tested, was noted from 3 to 4 days after the distribution and persisted for 2 weeks. It was also noted that the numerical fluctuations of the bacterial population size varied according to the preparation employed. In fact spore density of Thuricide HP, sprayed on grapevine, remained constant during the first 8 days after the distribution and sharply decreased there after. In the case of Bactucide instead population density varied in a much less regular way and differences were observed in relation to the plant organ considered and to the sampling date. Thuricide HP, when employed on pines, showed a high decrease in spore density already 2 days after the treatment, but this density remained stable there after. Spore density of Biobit instead varied, from the time of distribution to the last sampling date, in a more regular way.
Persistence and survival in the environment of Bacillus thuringiensis Berliner spores / G.Marchi ; D.Benassai ; F.Nori ; T.Panzavolta; A.Niccoli ; G.Surico ; R.Tiberi. - STAMPA. - (2005), pp. 104-104. (Intervento presentato al convegno 10th European Meeting "Invertebrate pathogens in biological control: Present and Future" tenutosi a Locorotondo, Bari, Italy, nel June 10-15, 2005).
Persistence and survival in the environment of Bacillus thuringiensis Berliner spores
MARCHI, GUIDO;PANZAVOLTA, TIZIANA;SURICO, GIUSEPPE;TIBERI, RIZIERO
2005
Abstract
The effectiveness of Bacillus thuringiensis preparations and the survival of the spores of the bacterium are considered to be among the parameters that influence the choice of the preparation to be employed, both in agricultural and in forest environment, for biological control of insect pests. The effectiveness and the persistence of the insecticidal activity of various commercial preparations of Bt has been tested against the Pine Processionary Caterpillar and the European Grapevine Moth in various trials carried over in pine forests and vineyards of Tuscany. Moreover the survival of the bacterial spores has been verified by measuring the population consistence, on pine needles, and on grapevine leaves and berries, at different time points after the treatment (0, 1, 4, 6, 8, 11, 14 days in the case of grapevine and 0, 2, 5, 12, 16, 23 days in the case of pines). The trials were carried out when young PPC and EGM larvae (I and II instar) were present in the environment. Three commercial preparations were used in the trials: Bactucide P, against EGM, Biobit, against PPC, and Thuricide HP against both pests. Larval mortality, caused by all products tested, was noted from 3 to 4 days after the distribution and persisted for 2 weeks. It was also noted that the numerical fluctuations of the bacterial population size varied according to the preparation employed. In fact spore density of Thuricide HP, sprayed on grapevine, remained constant during the first 8 days after the distribution and sharply decreased there after. In the case of Bactucide instead population density varied in a much less regular way and differences were observed in relation to the plant organ considered and to the sampling date. Thuricide HP, when employed on pines, showed a high decrease in spore density already 2 days after the treatment, but this density remained stable there after. Spore density of Biobit instead varied, from the time of distribution to the last sampling date, in a more regular way.
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