In the development of numerous yields in agriculture, regardless of whether developed in large farms or little plantations, pests and diseases avoid ordinary solid development and cause huge decrease of crop yield. Oil palm is a vital industry for Malaysia. Nonetheless, being planted to a great extent as a monocrop, the oil palm is inclined to the invasion of endemic insects and diseases. Malaysian Palm Oil Board (MPOB) has throughout the years created and distributed numerous innovations on pests’ identification, discovery, control and supervision, for the benefit of oil palm industry. Nevertheless, with successive generation of oil palm planted on a similar land, these pests normally developed to be more terrible.
Oil palm plantations are invaded by few leaf-eating pests. Bagworms, nettle caterpillars and tussock moths are the most essential ones in Southeast Asia. Bagworm which is also known as Thyridopteryx ephemeraeformis is a pest from family Psychidae and belongs to the order Lepidoptera. According to Barlow (1982), they are leaf eating caterpillars and construct their bags which are made of silk and dried plant materials, for example, leaves and little twigs. The regular bagworm species found in oil palm plantations are Pteroma pendula, Mahasena corbetti and Metisa plana (Wood, 1968; Sakaran, 1970). A recent study done by Norman and Basri (2007) demonstrates that in oil palm plantations of Peninsular Malaysia, M. plana was most generally disseminated species and the second was P. pendula. These bagworms cause severe harm to the oil palms which might decrease crop production up to 43% for consequent two years. The presence of bagworms can be easily noticeable by the holes in the leaves because they eat through the oil palm leaf. In seriously infected palms, the palm could not capture ample of sunlight as only the midribs of the leaflets are left and the crop yield will be significantly decreased.
Hence, prevention and controlling of pests distribution is essential. Natural enemies are insects which reduce the number of pests by killing them, for instance by laying their eggs in the pest larvae. The natural enemies of leaf-eating pests normally live in the weeds in and around the plantation. Moreover, the natural enemies will move away or die if all weeds are destroyed and spreading of leaf-eating pests will turn out to be more probable. Thus, sufficient attention should be given to the beneficial plants which are host plants of the natural enemies. Examples of the beneficial plants in oil palm plantations are Turnera ulmifolia, Turnera subulata, Cassia cobanensis and Antigonon leptopus. These beneficial plants will contribute shelter and supplementary sustenance, for example, nectar and attract the predators and parasites. The bright colour flowers of these plants will attract the natural enemies. In most cases these plants are left without getting enough nutrients. Fertilizers are not applied to these plants as they are categorized as weeds and do not need proper maintenance. By the application of fertilizers to these beneficial plants, the growth rate and the flowering of the plants will increase rapidly and healthier. Therefore, more natural enemies will be attracted and decreases the population of the bagworms.