Controlling Metisa plana walker (Lepidoptera: Psychidae) outbreak using Bacillus thuringiensis at an oil palm plantation in Slim River, Perak, Malaysia

Aerial spraying of Bacillus thuringiensis (Bt)-based biopesticides, Ecobac-1 (EC) was carried out at an oil palm plantation in Slim River, Perak, Malaysia to control the outbreak of bagworm, Metisa plana. Close monitoring of bagworm census, precise timing and follow-up aerial spraying of Ecobac-1 (EC) were important strategies for controlling the multi-stage bagworm outbreak. The first aerial spraying of Ecobac-1 (EC) which was conducted on 11 October 2013 had successfully reduced the first generation larvae population from 187.1 larvae per frond (LPF) eight days prior to treatment to 77.6 LPF at 14 days after treatment (DAT), indicating 56.0% reduction in bagworm population. The second aerial spraying of Ecobac-1 (EC) undertaken on 19 December 2013, had reduced the second generation larvae population from 358.7 LPF a day prior to treatment to 105.2 LPF at 14 DAT, which resulted in 70.7% reduction in bagworm population. Whilst the third aerial spraying done on 7 March 2014 had further reduced the population from 51.3 LPF three days prior to treatment to 17.2 LPF at 14 DAT, indicated a 66.4% reduction. The three consecutive aerial spraying of Ecobac-1 (EC) to control the three generations of M. plana at an oil palm plantation in Slim River, Perak successfully reduced the overall bagworm population by 90.8%. Therefore, it is recommended for the management to conduct a constant vigilance and census for successive control of bagworm population below the economic threshold level