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Promecotheca cumingii (Coconut leafminer)
The adult Promecotheca cumingii (Source: Peter A.C. Ooi/Tropical Press Sdn Bhd, CABI ISC)
The leafminer, Promecotheca cumingii is considered a minor or occasional pest of species of palms. It attacks coconut palm, oil palm and betel palm. The pest outbreak occurs after long dry periods. The damage caused by this pest is usually extensive and widespread when outbreak happens. Pest outbreak is often due to reduced number of natural enemies in the field.
The symptoms of pest damage are divided into; adult feeding and larval feeding.
- Damage is observed more on the central, less mature leaves of the crown
- Longitudinal grooves of streaks on the lower surface of infested leaves
- In the initial stages, damage is heavier towards the distal ends of both the leaves and leaflets
- Subsequent feeding presents a uniform distribution of feeding streaks.
- With extensive adult feeding, the leaf tissue in the distal areas dries up more quickly than that in the thicker basal areas, causing dried up leaflet ends and leaf ends
- The palm seldom dies but the crop yield will be reduced for usually a year and a half
- Damage is observed more on mature lower whorls of leaves
- Blister mines appears
- Resembles damage caused by fire or scorch resulting from sea spray
Detection and Inspection
- Young larvae mine in the leaflets of mature leaves, and make tunnels around 10 cm long and 1 cm wide.
- Adults make long narrow feeding scars on the leaflets.
- Foliage withers and appears scorched.
Category - Insect
Domain - Eukaryota
Kingdom - Metazoa
Phylum - Arthropoda
Class - Insecta
Genus - Promecotheca
Species - cumingii
Common Name - Coconut leafminer
Scientific Name - Promecotheca cumingii
The coconut leaf miner was first detected in Sri Lanka in 1970. It is also reported in Indonesia, Malaysia, Philippines, Singapore and Thailand.
Prevention and Control
- Frequent monitoring of field infestations of P. cumingii are conducted to look out for signs of damage caused by larvae and adults. In Sri Lanka, 5-10 palms out of 50 palms are randomly selected to survey the pest population. One frond from a lower whorl is cut to take samples of leaflets.
- If the pest population is low, selective cutting and burning of the infested fronds is helpful. In the Philippines, it was recommended that ten old leaves should be cut off from each affected palm.
- Biological control programme is in place in Sri Lanka. De Souza (1972) provided details of the shipments of parasitoids from Fiji and Singapore to Sri Lanka. Several consignments of both Sympiesis javanicus and Achrysocharis promecothecae were received from Singapore in 1971.
- P. parvulus and P. painei were also introduced from Fiji, Singapore and Sabah (Malaysia). This control was also aided by local mortality factors such as diseases in eggs and larvae of P. cumingii (CABI ISC).
- Even though S. javanicus established rapidly in infested areas just after its introduction to Sri Lanka, presently it is P. parvulus that plays a very active role, controlling the pest at hot spots or sudden resurgences of the pest. The control of P. cumingii has been listed among 66 highly successful classical biological controls worldwide (CABI ISC).
- Amporn Winotai, 2014. Integrated Pest Management of Important Insect Pests of Coconut. CORD, 30(1). Paper presented at High Level Expert Consultation on Sector Development in Asia and the Pacific Region held in Bangkok, Thailand on October 30-November 1, 2013.
- Coconut Research Institute of Sri Lanka, 2006. Coconut Leaf Miner. Advisory Circular No. B1.
- P. Dharmadhikari, P. Perera, T. Hassen, 1977. short account of the biological control ofPromecotheca cumingi [Col.: Hispidae] the coconut leaf-miner, in Sri Lanka. Entomophaga, 22, pp 3-18.
- CABI ISC, 2022. Promecotheca cumingii (coconut leafminer). https://www.cabi.org/isc/datasheet/44532.