Population Dynamics of Immature Stages of Chilo suppressalis Walker (Lepidoptera: Pyralidae) on Different Rice Varieties in Mazandaran, Iran

Striped rice stem borer, Chilo suppressalis Walker (Lepidoptera: Pyralidae) is one of the key pests in north of Iran, which damages the rice fields and decreases yield, severely. With attention to the importance of population dynamics of pests in integrated pest management, the population dynamics of immature life stages (egg, larva, pupa) of C. suppressalis were analyzed on three dominant rice varieties including, Fajr, Khazar, and Nemat in Mazandaran. The results indicated that the population density of the pest on the Fajr variety was higher than the two other varieties; therefore Fajr is a susceptible variety to C. suppressalis. Means comparison of population density of immature stages in different dates (23 May until 15 August) indicated that the density was the lowest in early season (May) and then it was gradually increased and reached its highest rate in July and after that, the population density decreased again. With respect to the results of this research, application of controlling agents including, biological or chemical methods at maximum population density of pest and replacement of resistant varieties to the susceptible one (Fajr) are recommendable to the farmers of paddy fields.