Md Nuruzzaman

The synthesis of calcium carbonate (CaCO₃) nanoparticles has gained an increasing interest due to their improved properties and diverse industrial applications. Among various synthesis techniques, the mechanochemical synthesis process has emerged as a promising route for nano-CaCO₃ synthesis. A high-energy ball mill is required for synthesizing nano-CaCO₃, whereas post-milling heat treatment facilitates completing the reaction that remains incomplete during milling. Post-milling heat treatment may also influence the properties of synthesized CaCO₃, which has not yet been thoroughly investigated. This study investigated the influence of post-milling heat treatment on the polymorphs, micromorphology, and particle size distribution of CaCO₃. The results indicated that the heat treatment of the as-milled powder enhanced the homogeneity of crystal polymorphs while maintaining the particle sizes within the nano-range (3 nanoparticles and was influenced by both the milling and heating intensities. It was observed that 60 min heat applied to 30 min as-milled powder was enough to produce nano-CaCO₃ (<50 nm) where the percentage of larger particles (<250 nm) became negligible (~1%). Micromorphology images confirmed the transformation of crystal polymorphs and the reduction in particle size.

The Rugose spiraling whitefly (RSW), Aleurodicus rugioperculatus Martin, is a new invasive pest in Bangladesh that was first reported in May 2019 infesting coconut trees. In this context, the present study was carried out to respond to this pest immediately by evaluating the seasonal incidence of this pest and establishing a suitable management procedure to control it. Seasonal abundance of RSW populations was observed at weekly intervals from January 2021 to December 2022. Seasonal variations have been observed in RSW infestation of coconuts. The RSW populations prevailed throughout the year, peaking in April-May and September-October in both 2021 and 2022. Among different climatic factors, temperature played a significant role in the growth of these pest populations. Of six treatments tested, the chemical insecticide Acetamiprid (Tundra® 50 SP) was most effective, reducing pest numbers by over 80% after initial and follow-up applications. Initial application of bio-pesticides yielded a more modest 44.83-65.98% control, with D-Lemonine (Bio clean® 5% SL) performing best. A second spray of D-Lemonine lowered nymph, puparium, and adult populations by 82.11%, 82.12%, and 83.53% respectively compared to untreated trees. Furthermore, when Acetamiprid and D-Lemonine were used in combination, they demonstrated a high level of efficacy in controlling the RSW. Therefore, implementing a rotation spraying strategy that involves the use of Acetamiprid followed by D-Lemonine can be considered a sustainable management option to combat RSW infestation in coconut trees. This rotation utilizes chemical and organic options while avoiding the overuse of any single method.

In precision agriculture, nanotechnology has made significant contributions to the development of a smart cropping system through the support of unique properties of nanomaterials. Of the various nanomaterials, porous nanomaterials have an outstanding performance in building a sustainable delivery system for agrochemicals. In pesticide delivery, amorphous porous silica nanomaterials are considered as some of the most suitable options because of their easy synthesis processes, nontoxic nature, structural variation, tunable porous structure, physical and chemical stability, and ease of surface functionality. So far, multiple roles of these materials have been discussed in the literature; however, the influence of porous structure and structural variations toward developing a sustainable delivery system was not clear. A comprehensive review of the compatibility among the porous silica nanocarriers and pesticide molecules is also lacking. Thus, this review discusses the progress of porous amorphous silica nanomaterial synthesis, their structural variation, and surface modification for effective delivery of different pesticides to explore their potential as carriers.

The betel vine (Piper betle L.) is one of the plantation crops commercially cultivated for its leaf in South and Southeast Asia. The leaf production is often threatened by different insect pests such as Aleurocanthus rugosa Singh (Hemiptera: Aleyrodidae). Currently, infestations of A. rugosa in betel vine are primarily controlled using excessive conventional broad-spectrum chemical pesticides that poses serious human health risk due to masticatory nature of consumption. This study was carried out to investigate the performance of colored sticky traps and biopesticides against A. rugosa as an ecofriendly approach by conducting multilocation field trials from 2019 to 2021. It was observed that A. rugosa population prevailed throughout the year, however, reaching two peaks in May and October due to the high temperature. Among the sticky traps, A. rugosa was attracted mostly to yellow-colored traps compared to white or blue traps. Whereas alternating sprays of either D-lemonine (Bio clean® 5%SL) or spinosad (Success® 2.5% SC) with sodium lauryl ether sulphate (Fizimite® 10%) reduced the A. rugosa population by 71.4 to 79.0% over control. Further, combination of these spray regimes with yellow colored sticky traps as IPM packages showed improved results in reducing pest populations by 83.8 to 86.0% and increased leaf yield by 60.4 to 63.6% over control. Even the performance of the IPM packages were better than Farmers’ practice i.e., broad-spectrum chemical pesticides. Thus, outcome of this study indicating that the IPM program could be a sustainable and environmentally friendly method of controlling A. rugosa in betel vine production.