The disclosure provides nucleic acids, and variants and fragments thereof, derived from strains of Bacillus thuringiensis encoding variant polypeptides having increased pesticidal activity against insect pests, including Lepidoptera and Coleopteran. Particular embodiments of the disclosure provide isolated nucleic acids encoding pesticidal proteins, pesticidal compositions, DNA constructs, and transformed microorganisms and plants comprising a nucleic acid of the embodiments. These compositions find use in methods for controlling pests, especially plant pests.