Pheromone mass trapping of bagworm moths, Metisa plana Walker (Lepidoptera: Psychidae), for its control in mature oil palms in Perak, Malaysia

The bagworm, Metisa plana Walker (Lepidoptera: Psychidae), is an important pest of oil palms in Malaysia. A serious infestation cause yield declines of 30–40% over 2 years after attack. Successful mass trapping depends on efficient removal of adults, which reduces the chances of mating, eventually causing a decline in the population. This study was conducted in three smallholder blocks where palm age varied from 6 to 16 years. Sticky vane traps were baited with four receptive females of M. plana and placed in three transects within each trapping plot. The percentage of female bags with eggs (i.e., those pupal bags housing the female with eggs that hatched) determined the effects of trapping on mating and reproduction success. Palm yield was compared between the trapping and control plots. The number of live larvae and the percentage of bags with eggs in the trapping plots were always relatively lower (9.1–28.2%) compared to the control plots (28.6–48.6%). Trapping plots had relatively higher bunch weight (7.8–14.3 kg) compared to the control plots (4.5–9.2 kg). The bunch weight in the trapping plots increased 22% after trapping compared to 15% in the control plot. Damage ratings on the fronds declined between 35–45% in the trapping blocks. Damage ratings declined between 20% and 27% in most control plots but increased 17% in one of the blocks with an increased bagworm population. There, mass trapping reduces the chances of bagworm mating and oviposition, which leads to lower populations and, therefore, lower frond damage and higher yields.