Among the insect species causing infestations and serious damages to stored commodities, the cigarette beetle, Lasiodermaserricorne (F.) and the tobacco moth, Ephestiaelutella (Hübner) are the major pests of both raw and manufactured tobacco. Post-harvest tobacco control is achieved through sanitation, insect monitoring, and fumigation with phosphine. However, insect resistance to phosphine and control failures have been reported, and increasing regulatory pressure is being exerted on fumigants. Biological control agents such as Bacillus thuringiensis (Bt) appear to be environmentally sound and potentially viable alternatives to chemical control. Bt is a bacterium that produces insecticidal crystal proteins during the sporulation phase and has been, for more than 40 years, the microorganism of choice for the biocontrol of phytophagous insect pests. It produces insecticidal crystal proteins that display specific activity against certain orders of insects and become active upon ingestion by the insect. Our laboratory has conducted extensive research and worldwide surveys to evaluate the presence of Bt in stored tobacco and has confirmed previous findings indicating that Bt may be considered part of the naturally occurring phylloplanemicroflora. Several Bt strains were isolated from tobacco and characterized by DNA and protein profiling. The insecticidal activity of selected strains and of two commercial products against the larvae of L. serricorne was determined by diet incorporation assays. Moreover, the stability of Bt spores and crystal proteins on cured tobacco leaves was assessed over a storage period of time of 30 months. Cigarette prototypes were made with Bt-treated tobacco. Standard cigarette and smoke evaluations did not show any significant difference between the test and control cigarettes. Although the tested Bt strains and products did not yield satisfactory levels of mortality at the required times and doses, the experimental results summarized in the present review indicate that B. thuringiensishas potential for the control of the cigarette beetle. The integration of conventional control approaches with novel systems based on biological agents with different modes of action should offer new avenues for the effective management of stored tobacco pests in line with integrated pest management (IPM) concepts.
