In a cultivation mutualism, where a host (farmer) cultures and consumes the symbiont (cultivar) as food, farmers sometimes retain a single cultivar in gardens. While cultivation can bring stable and abundant yield in a limited area, cultivars are often prone to infection by pests. Thus, farmers manage the gardens with various measures such as weeding, application of antibiotics and seclusion of gardens from the outside. Study of the non-social beelte Doubledaya bucculenta-yeast mutualism indicated that the yeast inhibited the growth of pest mold when it was dominant, which is the first report of garden management through self-defense by a cultivar.