The invention relates to the identification and isolation of a polynucleotide molecule encoding a new class of protein insecticidal toxin produced by the bacteria Photorhabdus luminescens. The polynucleotide molecule may be incorporated into, for example, insect-specific viruses (including entomopox and nuclear polyhedrosis viruses), bacteria (including Gracilicutes, Firmicutes, Tenericutes and Mendosicutes), protozoa, yeast and plants for control of pest insects.