AbstractHost diet is one of the key factors that shapes insect associated microbial communities, and the impact of dietary shift on abundance of microbial communities and insect fitness is poorly understood. Cigarette beetle (Lasioderma serricorne (F.)) are in close association with yeast symbionts for nutritional and defence benefits. The present study highlights that dietary source determines the yeast abundance in cigarette beetle and any change in diet induces a shift in yeast abundance. A general trendline of increase in yeast abundance during larval and pupal stage followed by a drop in adult stages of cigarette beetle was observed among all diet sources. The yeast abundance varied among diet sources and was significantly higher on natal (wheat) and reverted colonies compared to other exposed dietary sources. Yeast abundance in reverted colonies of soybean and bengal gram increased to the levels of those that were originally feeding on wheat suggesting a similar microbial structure among those diet sources. The correlation between yeast abundance and beetle biomass among diet guilds suggest a predictable relationship between yeast symbionts and diet source. The investigation can provide further insights on yeast symbiont abundance and food source specificity in cigarette beetle biology and management.