Life history and feeding behaviour of the oil palm bagworm, Metisa plana Walker (Lepidoptera: Psychidae)

Abstract

Bagworms were reared in a controlled environment room (CER) to obtain details of their life history. Eggs were pale and barrel-shaped, and their incubation period was 19.7 (plus minus) 0.3 days. Fecundity of laboratory-reared females was higher than that of wild-caught females (158.3 (plus minus) 0.3 vs 99.9 (plus minus) 5.7 eggs/female) yet lower than those recorded for several other species of Psychidae. Fertility was high (generally 90 percent). Sexual dimorphism in instar number was recorded (5-6 for males vs 6-7 for females). Head capsule widths, bag lengths and morphology can be used to determine instars. Most leaf tissue removed from oil palm foliage (66.8 percent) was used for maintenance and body growth, and the remainder for bag construction. Larvae preferred upper leaf surface for feeding and lower surface for resting and moulting. Sexual dimorphism was also noted in pupa; size (males smalller than females) and developmental time (males, 21.4 (plus minus) 0.3 days; females, 10.0 (plus minus) 0.4 days). Total developmental times of males and females did not differ, suggesting that overlapping generatons are not requisite for an outbreak. Sex ratio was male-biased (8.5:1)