Chemical association in symbiosis: sterol donors in planthoppers

The role of intracellular symbionts contributing to their host has been investigated in the planthoppers,Nilaparvata lugens Stal andLaodelphax striatellus Fallen. We have found that the isolated yeastlike symbionts, identified as a member of the genusCandida, from the host's egg produce ergosterol when cultured. A comparative study of sterols in the cultured symbionts, the host insects, aposymbiotic host insects, and dietary plants demonstrated that ergosterol produced in the symbiotes is provided to the host insects and possibly transformed in the host insects into cholesterol via 24-methylenecholesterol. The conversion of injected 24-methylenecholesterol-d3 into cholesterol has been shown in the brown planthopper (N. lugens).