We find that the presence of Wolbachia in D. melanogaster larvae enhances the survival ability against S. carpocapsae symbiotic nematodes, Wolbachia numbers are reduced in larvae responding to symbiotic nematodes while Xenorhabdus numbers are unaffected, the absence of Wolbachia induces Toll pathway activation in response to axenic nematodes, and that endosymbionts can affect the metabolic state, and in particular the lipid droplet size, of D. melanogaster during parasitic nematode infection. The gene discussed is TLR4; the disease is Nematoda infectious disease.