Environmentally based maternal effects on development time in the seed beetle Stator pruininus (Coleoptera: Bruchidae): Consequences of larval density

In response to food limitation, many insects have evolved developmental plasticity in which larvae mature at a smaller body size. Here we investigate the consequences of this smaller body size for development of individuals in the next generation, after resource competition has been relaxed. Families of the seed beetle Stator pruininus (Horn) reared at high density (≃20 eggs per seed) matured at a substantially smaller adult body size than families reared at I egg per seed. Females emerging from high density seeds also laid smaller eggs than did females reared at low density (7-14% lighter). Progeny developing from these smaller eggs eventually attained the same adult body size as progeny developing from eggs laid by low-density mothers when all progeny were reared at low density (i.e., resource competition was relaxed). They achieved this by developing on average ≃0.5 d longer. Reciprocal crosses between high and low-density lines demonstrated that the differences among lines in development time was maternally inherited; only maternal lineage explained some of the variance in development time. Thus, larvae appear to compensate for the small eggs laid by their mothers by extending development time to mature at the same size as progeny from larger eggs.