Essential for phagosome maturation and the innate immune response to bacteria. During phagosome maturation it is required for the fusion of late endosomes/lysosomes and phagosomes. Viable and fertile, with no obvious morphological defects. Strongly susceptible to bacterial infection, displaying reduced survival after infection with E.coli and E.faecalis. The initial phagocytic uptake of bacteria by the hemocytes is not affected, however bacterial clearance by the phagosomes is severely reduced. Phagosomes fail to fuse with late endosomes/lysosomes, preventing the phagosomes from acquiring their characteristics and maturing into fully acidified phagolysosomes. No effect on endocytic trafficking and starvation-induced autophagy. The Notch and EGF receptor pathways are also unaffected. Belongs to the VPS16 family.