Sustainable Oil Palm Farming / Leaf-eating insects

Download: Module 5: Pests and Diseases

Background

Figure 8: Nettle caterpillar

Figure 9: Damage caused by leaf-eating insects

There are several leaf-eating pests which sometimes infest oil palm plantations. The most important ones in Southeast Asia are bagworms (Pteroma pendula, Metisa plana, Mahasena corbetti), tussock moths (Dasychira spp., Orgyia spp.), and nettle caterpillars (Darna trima, Setora nitens, Setothosea asigna; see Figure 8).

Each of these insects eats through the oil palm leaf, so their presence is easily recognisable by the holes in the leaves (see Figure 9). In severely infested palms, only the midribs of the leaflets are left, so the palm cannot capture much sunlight and the yield will be strongly reduced. Prevention and management of outbreaks is therefore important.

Natural enemies are insects which kill pests, for example by laying their eggs in the pest larvae. The natural enemies of leaf-eating pests live in the weeds in and around the plantation (see Module 3: Plantation Maintenance for suggestions on how to manage weeds). If all weeds are killed, the natural enemies will die or move away, and outbreaks of leaf-eating pests will become more likely. But even in well-maintained plantations, outbreaks can still occur.

Managing pests requires careful monitoring and the correct use of hazardous chemicals. Both the monitoring and the application of chemicals should be carried out by trained workers. If farmer groups want to establish monitoring and spraying teams, it is necessary to ask for help from extension workers or nearby plantation companies. In this handbook, we discuss only preventive measures, because monitoring and spraying need to be taught in the field by specialised professionals.

Goal

Keep leaf-eating insect damage to oil palms to a minimum.

Standard

Maintenance of the plantation is up to standard and promotes the biological control of leaf-eating insect populations.

Equipment and materials

Seeds and beneficial plants.

Table 1: Beneficial plants

Scientific name	English name
Turnera subulata (white flower)	White buttercup
Turnera ulmifolia (yellow flower)	Yellow alder
Cassia tora, Cassia cobanensis	Senna
Spermacoce alata	Winged false buttonweed
Elephantopus tomentosus	Common elephant’s foot
Antigonon leptopus	Mexican creeper
Euphorbia heterophylla	Lechosa

Timing

• Planting beneficial weeds: at the start of plantation rehabilitation;
• Doing correct weed maintenance: continuously.

Labour time requirement

Depending on the number of beneficial weeds planted.

Who

Farmers and their family or hired labourers.

How

Figure 10: Bunga pukul delapan

• Maintain a dense ground cover canopy (see Module 3: Plantation Maintenance);
• Plant weeds that are specifically attractive for natural enemies of pests (e.g. Cassia cobanensis, Euphorbia heterophylla, Antigonon leptopus, Turnera subulata) (see Figure 10).
  Note: These weeds are usually not shade tolerant and should therefore be planted at roadsides or in open spots where palms have died.

Data recording

Every pest prevention activity should be recorded in a logbook as shown in the example below.

Date	Time	Location	Activity	Input type	Input amount	Input costs	Labour input		Labour costs
							People	Hours
16/01/13		Field 3	Planting Euphorbia heterophylla	Euphorbia heterophylla seed			3	8	240000

Acknowledgements

The material from Leaf-eating insects is sourced from Smallholder Oil Palm Handbook and put together by Lotte Suzanne Woittiez (Wageningen Universit) and Haryono Sadikin, Sri Turhina, Hidayat Dani, Tri Purba Dukan, and Hans Smit (SNV) in August 2016. See Module 5: Pests and Diseases for more information.