Diapause is an endocrine controlled arrested metabolic activity to delay development or reproduction under unfavorable conditions. To gain an understanding on importance of diapause for ecological adaptation, it is important to study diapause regulation in insects. We examined genetics of diapause in Chilo partellus using five parental populations viz., hibernating (HD), aestivating (AD), post-hibernating (PHB), post-aestivating (PAB), and nondiapause (ND) for making crosses in all possible combinations including reciprocals in a diallel fashion. Data were recorded on fecundity, egg hatching, larval survival, diapause induction and termination and adult emergence in the parents (P1, P2), F1 hybrids, and the reciprocal crosses. Genetic analysis showed that AD strain is general combiner, which also improved egg hatching, larval survival, diapause termination and adult emergence. The HD strain increased incidence of diapause in F1 hybrids. Incidence of diapause was highest in HD × AD, whereas termination was greatest in PHB × AD. However, ND strain and its reciprocal crosses with other strains did not exhibit any noticeable developmental response associated with diapause. Specific combining ability analysis revealed that pre-existence of PHD and ND or AD and PAD populations under unfavorable conditions might result in drastic reduction in active population, while co-existence of PHD and AD populations might reduce diapause incidence, increase survival and faster multiplication of their progenies resulting in outbreak of C. partellus. Degree of dominance estimates revealed that diapause and associated traits in C. partellus are governed by overdominance gene effects, and mainly depends on parental diapause history
