Age-Specific Survival Rate and Fecundity of the Adult Japanese Pine Sawyer : Monochamus alternatus HOPE (Coleoptera : Cerambycidae), at Different Emergence Times

Abstract

The adults of the Japanese pine sawyer, Monochamus alternatus HOPE, emerged from mid June to late July. Ten pairs from the early, middle, and late periods of emergence were reared in field cages, and the age-specific fecundity and survival rate were investigated. Mean fecundity diminished as the time of emergence was delayed, a result of the decrease in both the fecundity and longevity of the females. The remarkable decrease in fecundity of the late-emerged females was attributed both to sterile females, which amounted to about forty percent, and to the death of the fertile females in the early stages of adult life. Mean fecundity shown by the 3 caged populations was 86.2. The sex ratio of adult was 0.5. Thus, the net reproduction rate (R₀) was estimated as 26.9 when the survival rate past immature stages was 0.623 (in Ishikawa Prefecture) and as 12.5 when the survival rate was 0.289 (in Kochi Prefecture).