Comparative Life Histories, Demographic Statistics and Damage Potential of the Bagworms Pteroma pendula and Metisa plana in Oil Palm

Abstract

This article provides an accurate detail of the life history of the bagworms Pteroma pendula (P. pendula)  and Metisa plana (M. plana)  on oil palm. P. pendula was confirmed to possess four larval stages with no difference in the number of instars and pupal development time between the sexes. Life history of M. plana  followed reported by earlier workers of 5-6 larval instars for males and 6-7 for females were used. There was, however, no difference in pupal developmental time and size. Sex ratio for both species was nevertheless 1:1 and more representative rm and λ values were obtained. The last two statistics were nevertheless superior for P. pendula and insects bred in the field. The rm for P. pendula  was 0.06459 in the laboratory and 0.07327 in the field while the λ was 1.06672 in the laboratory and 1.07603 in the field; cf the rm . M. plana  was 0.04783 in the laboratory and 0.06061 in the field while the λ was 1.04899 in the laboratory and 1.06248 in the field. M. plana  clearly had the potential to be more damaging, requiring 3.5X and 3.0X more oil palm leaf area and biomass for the completion of its larval stages, however, in the field this is perhaps mitigated by its lower reproductive potential compared to P. pendula  thus balancing the deleterious impact of both species on oil palm.