:Over the past few decades deforestation has become the issue of global concern for its rapid reduction of biodiversity. The tropical moist deciduous Sal forest ecosystem of central Bangladesh is currently in a critical situation. Destructive anthropogenic and natural impacts coupled with overexploitation of forest resources have caused severe damage to the forest ecosystem. Due to rubber monoculture, expanding commercial fuel wood plantations & expanding agriculture, illegal cutting, encroachment of forest areas, and illegal poaching of wildlife, the Sal forest is losing biodiversity alarmingly. The study is based on intensive literature survey and tries to explore the overall deforestation situation and conservation practices for M adhupur Sal forest that comprises about 5% of the total forests in Bangladesh. The level of destruction of the natural Sal forest has pushed the forest-dwelling indigenous Garo community into cash crop production, forcing them to move away from their traditional subsistence economy. Now we need to address a joint conservation and improved management plan of the forest resources use. Thus all kinds of military establishments, construction of roads and highways for military purposes should be avoided and a policy of planned industrialization should be adopted to mitigate the adverse effect of industrialization. Findings of the study will help to identify the causes of deforestation and conservation of Madhupur Sal forest and also in other national parks in Bangladesh which ultimately conserve the biodiversity and help to maintain natural balance.

Bactrocera cucurbitae melon fruit fly is one of the most detrimental vegetable-damaging pests in Bangladesh. The toxicity of Bacillus thuringiensis Bt has been reported against a few genera of Bactrocera in addition to numerous other insect species. Bt strains, harbouring cry1A-type genes were, therefore, assayed in vivo against the 3 rd instar larvae of B. cucurbitae in this study. The biotype-based prevalence of cry1 and cry1A genes was calculated to be 30.8% and 11.16%, respectively, of the test strains n=224 while their prevalence was greatest in biotype kurstaki. Though three indigenous Bt strains from biotype kurstaki with close genetic relationship exhibited higher toxicity, maximum mortalities were recorded for Btk HD-73 96% and the indigenous Bt JSc1 93% . LC 50 and LC 99 values were determined to be 6.81 and 8.32 for Bt JSc1, 7.30 and 7.92 for Bt SSc2, and 6.99 and 7.67 for Btk HD-73, respectively. The cause of toxicity and its variation among the strains was found to be correlated with the synergistic toxic effects of cry1, cry2, cry3 and cry9 gene products, i.e. relevant Cry proteins. The novel toxicity of the B. thuringiensis strains against B. cucurbitae revealed in the present study thus will help in developing efficient and eco-friendly control measures such as Bt biopesticides and transgenic Bt cucurbits.