Overview of The Cocoa Pod Borer Conopomorpha cramerella (Snellen) (Lepidoptera: Gracillariidae)

• Cocoa (Theobroma cacao L.) is a native species of the tropical humid forests of South America . It originated in the Amazon basin where Theobroma and other similar genera are found in geater number than in any other place.

• Cocoa was first introduced to South-East Asia by the Spaniards who arrived in the Philippines in the late sixteenth century. It was reported that cocoa had been in existence throughout the Sulu Islands .

• The first commercial planting of cocoa in South-East Asia was in the Manado area (Minahasa) of North-East Sulawesi in 1822. The cocoa grown in Minahasa was exported via Manado to traders in Manila , and until 1859, around 50 tons per year was exported. Cocoa was also planted in the mid nineteenth century in the Sangir Islands and Ternate , and in Ambon in the Moluccas , also for export to Manila .

• Elsewhere in Indonesia , experimental plantings was reported in East and Central Java and in West Sumatra . By the 1880’s, Central Java was exporting around 10 tons of beans per year.

• As had occurred in Sulawesi , cocoa growing in Java never became established on a very large scale, and in East Java , most cocoa had been abandoned in favour of coffee and rubber by 1936.

• During 1980s and 1990s cocoa planting in Southeast Asia has expanded, because Indonesia , Malaysia , Philippines , and Papua New Guinea (PNG) have made cocoa one of their major development priorities.

• There are over 500,000 smallholder families that farm cocoa in Southeast Asia with over 500,000 ha of cocoa in Sulawesi alone. Indonesia is the third largest cocoa producer in the world, after Ivory Coast and Ghana .

• In Indonesia , Philippines , and Malaysia , the cocoa pod borer (CPB) Conopomorpha cramerella (Snellen) (Lepidoptera: Gracillaridae) is a key pest and a major constraint to production.

• The species was originally described and named by P.C.T. Snellen from specimens collected in established cocoa plantations in Java at the beginning of the 19th Century. Prior to its transfer to the genus Conopomorpha, the species was generally referred to in the literature under name of Acrocercops cramerella Snellen.

• Although at the time, Conopomorpha cramerella had not yet been described, probably the first report of it causing damage to cocoa is by Jansen in 1860, who described symptoms observed in Minahasa in 1841 that are typical of those caused by CPB. Similar problems were experienced in the plantings in Ternate, and the very poor yields in Ambon were possibly also due to CPB.

• C. cramerella is also know to feed on the fruits of Pometia sp. (Sapindaceae), Nephelium spp. (Sapindaceae), Cynometra sp. (Leguminoseae), and Cola sp. (Sterculiaceae). Of these, only the sapindaceous species are indigenous to the region, so it seems likely that they were the original hosts, and that in the nineteenth century, an adaptation occurred in North Sulawesi enabling C. cramerella to exploit the newly abundant food resource. It was further suggested that such an adaptation occurred only once, and that all subsequent populations of CPB being derived from the area of the initial adaptation through transport of planting and associated materials.

• The theory is supported by the existence of only the non-cocoa attacking races of the CPB in Sri Lanka, Thailand and until recently Peninsular Malaysia. In the latter, non-adaptation of the local C. cramerella race is indicated in that moths attacking cocoa were only attracted to synthesized female pheromones that are specific to CPB of East Malaysia.

• From Sulawesi in the 1860s, the CPB was seen to have spread in westerly arc to Central Java in 1895. In 1901, the pest was found in East Java cocoa and as a result, cocoa cultivation in this region was abandoned by 1936. Cocoa was only replanted there in 1971 and todate CPB has not reestablished itself in the area. CPB was discovered in West Java in 1966 infesting 20-year old cocoa. Total uprooting of trees have eradicated the infestation. Infestation also occurred in Sumatera in 1978 and uprooting once again resulted in the eradication of the pest. From Sulawesi , the CPB have spead to the Philippines in 1936. The CPB has also spread from Sulawesi to the Maluku islands.

• Other than Maluku, CPB infestation in other islands is relatively new. In the 1980's CPB was reported in Sebalik, East Kalimantan . Then in June 1991, CPB was reported in the Tolitoti area of Central Sulawesi. This Central Sulawesi attack by the CPB on 14 hectares rapidly expanded to 6,037 in 1993. The CPB has also been reported in several other areas: mainland of East Kalimantan (1993), West Sumatra (1993), Labuhan Batu, North Sumatra (1994); Asahan, North Sumatra (1995), and Kolaka, South and Southeast Sulawesi (1995), and more recently in Bali and Flores.

• In Sabah, East Malaysia, an outbreak of CPB was first detected in Tawau, Quoin Hill area, covering ca. 5,000 ha of cocoa in late 1980. Within a period of two and half years, the CPB had spread to all districts. Further confirmation of this species on cocoa was reported in Sarawak in 1985. In Peninsular Malaysia it was first reported attacking ca. 800 ha of cocoa in Malacca in late September 1986 and appeared in Port Dickson, Negri Sembilan, in November 1986.

• In March 2006, cocoa pod borer was detected in East New Britain Province, Papua New Guinea. Infestation was very high, but restricted to a small area.  A large-scale eradication action started in April 2006. The eradication effort was very thorough and on February 7th, 2007 the province was declared free of cocoa pod borer based on their detection using pheromone traps.  

Eggs

• Eggs are laid singly anywhere on the pod surface although there appears some preferences for the furrows of pods. Eggs are also less iclined to be laid on pods smaller than 5 cm in length.

• Freshly laid eggs are orange in colour, flat and oval in shape, with a length of not more than 0.5 cm. Surface of eggs also have rectangular indentations. On hatching, the egg become translucent, the shell being whitish but darkened inside by faeces. The egg stage lasts for 2-7 days.

Larvae

• First-instar larva is trasparent white in colour and about 1 mm long. After hatching, the first-instar larva tunnels through the floor of the eggshell and bore perpendicular to the pod surface until it reaches the sclerotic layer of the husk. At this point, the larva would either tunnel directly through it or tunnel along the surface of the sclerotic layer for up to several centimeters before penetrating it.

• Once inside the pod, the larva tunnels in any direction and feeds randomly. The entire larval stage takes 14-18 days to complete, with 4-6 instars. The great majority of the larvae emerge from cocoa pods after they become ripe. The mature larvae, unlike the earlier instars, is light green in colour and is about 12 mm in length. The larva then tunnels out through the pod wall, leaving an easily identifiable exit hole of about 1 mm in diameter.

Pupae

• Once outside the pod, the larvae crawls to a suitable site for pupation. The pupation site could be in the furrow of the pod, or on green or dried leaves and other debris. Once at the site, the larvae spins and oval-shaped cocoon over itself and enter a short prepupal stage before forming an obtect pupa.

• The pupal stage normally takes 6-8 days to complete. Therefore, the pest is most likely to be transported by man to other cocoa areas through pods, leaves and other objects to which pupae are attached.

Adults

• Adult moths are about 7 mm long with a wing span of about 12 mm. The moths are characterized by white zig-zags on their forewings that end in a yellow-orange patch at the tips. Antennae of the moths are longer than the wings and in their natural resting position, are swept backwards.

• The moth are most active at night, mating and laying of eggs being carried out at this time. There is no indication that the moths can fly long distances, and long-distance movement of CPB must almost certainly have taken place through movement of infested pods. A female can normally produce 50-100 egss in her lifetime.

• During the day, adult moths normally rest underneath more or less horizontal branches of the cocoa tree. Their cryptic coloration blending with the resting place makes them difficult to spot. Adults generally live for about a week. In total, the entire life cycle takes about 1 month to complete.

• Damage is caused by the larva while tunnelling in the pod. The young larva feeds on placenta or pulp inside the pod until fully grown. It attaks pods from 4-5 cm to mature pods and affects the pods by interupting their development and produces deformed beans by feeding on mucilage. Young pods damaged by larvae often ripen prematurely. In general, infested pods always show uneven yellowing with beans being stuck together inside the pod. These pods do not rattle when shaken or produce the characteristic sound of ripe pods when the pod wall is tapped.

• The degree of damage depends upon the total number of larvae and the period of larval feeding. In the beginning of the harvest, which last about 6 weeks, only a small percentage of the pods is infested. Those infested pods may contain 6-8 larvae each. In the course of the harvest, the proportion of infested pods increases progressively, and at the end of the harvest all pods are infested, each may contain 30-40 larvae.

• Losses in cocoa production also depends on age of infested pods, with older pods generally with less loss. The beans from seriously infested pods are completely unusable and in heavy infestations over half the potential crop can be lost. A severe podborer infestation can reduce yield by 60-80 percent.

• It is estimated that CPB infestation causes around 25%-40% yield loss in Sulawesi , and resulted in industry losses worth US$300 million in 2005.

Rampasan

• The aim of rampasan (complete harvesting) is to remove all the pods from the tree to break the cycle of CPB in the field. The method is based on the fact that very few pods of length 6-7 cm is infested. Therefore if all pods are removed from the trees, such that for a period of time there will be no pods on the trees of that size or above, the life cycle of the pest would be broken.

• The main weaknness for rampasan is the migration of female moths from uncontrolled cocoa farms, unless communal action is taken. Also, without appropriate pruning, complete elimination of a population of pod borer through rampasan is difficult.

Frequent harvesting and bagging of husks

• This method is based on the fact that great majority of CPB larvae emerge from cocoa pods after they become ripe, and that if pods are picked at the earliest stage of ripeness (just as they begin to show yellow) then most (almost 90%) larvae will still be inside the pods.

• Since large numbers of fully grown larvae can emerge from harvested pods and husk within a short time, it is necessary to split the pods and bag the husk, as soon as possible after the harvest.

• The aim of bagging is to prevent the full grown larvae from pupating and developing into adults. Polywoven bags are used to bag the husk. The bags are closed and tied with a string and left in the field. The husk is generally left in bags for 14 days or more after which the bags are emptied and re-used if in good condition. If plastic bag is not available, the husks can be destroyed and buried.

• Frequent harvesting and rapid splitting of pods together with subsequent destruction of husk by burying or bagging would thus reduce emergence of mature larvae and subsequently the resulting number of adult moths. Unsplitted pods can also be kept in plastic bags for several days, either to contain emerging larvae or to kill them through over-heating inside the bag.

• Alternatively, all harvested pods can be piled up on a plastic sheet and put dried cocoa leaves on the heap. Pupae formed on the leaves are collected after 3 days and then destroyed.

• The interval between harvesting should be 14 days or less. Such harvesting should be continued regularly throughout the year to prevent CPB populations growing.

• Complete, frequent, regular harvesting (CFRH) is to some extent an extension of the principle of rampasan but aimed at larval emergence rather than oviposition. The greatest effect of (CFRH) is likely to be gained if it is done during the low crop period thorough the first half of the rising crop.

Pruning

• Cocoa pruning aims to find out a balanced frame among stem, branch, and leaf; so the highest net photosynthetic will be achieved, reflected by the high yield of cocoa pods. Pruning also make aeration better, lowering air humidity between cocoa trees, and this condition is unfavorable for disease microbes. By pruning the disease infected branch/leaf/pod will be cleaned and the next infection stopped. Pruning should be done with light intensity (less branch removal) but more frequently.

• In situation where high branches result in pods being left unharvested, top prunning with complete collection of the pods on the prunned branches could contribute towards a reduction in field infestations.

• This due to the following reason: removal of highly infested high pods, reducing the production of high pods which are preferred by CPB, and improving the efficiency of insecticide sprays.

• Frequent harvesting, better pruning, sanitation of pod husks and improving fertilizer use, both chemical and organic, are know in Indonesian as PsPSP (Panen Sering, Pemangkasan, Sanitasi and Pemupukan).

• The PRIMA project in Indonesia has actively advocated implementation of PsPSP as part of integrated cocoa management, and as the backbone of Good Farming Practices in cocoa. Results suggest that farms implementing PsPSP have significantly higher yield than those not. Such results support evidence elsewhere that PsPSP can reduce levels of CPB infestation. ACDI-VOCA in particular, through the Success and Success Alliance Projects, has been instrumental in promoting these techniques in the cocoa regions of Sulawesi and elsewhere.

• The purpose of the sleeving is to physically prevent the female moth from laying eggs on the pods. Transparent polythene bags , with open bottoms for ventilation, are placed on very young pods and left throughout the pod maturation period. It is effective if properly implemented.

• The other benefit of sleeving is that it protects the cocoa pod from every other insect as well.

• Continuous sleeving of young pods for 16 months can reduce the number of damaged pods from 80% to less than 1%, thereby increasing dry bean production by more than 300%. The length of the young pods to be sleeved is 10-12 cm for Trinitario and 8-10 cm for Amelonado cocoa.

• Using a simple pipe and stick technique, a worker can cover more than 500 pods/hour.

• One major side effect of this control technique is the environmental pollution caused by the thousands of plastic sleeves. IPM-CRSP project for Southeast Asia , with the support from Degradable Polymer Products Inc. and Masterfoods, is now conducting field studies in South and North Sulawesi to test biodegradable plastic sleeves for CPB control. The sleeves degrade to carbon dioxide and water in about 4 months, leaving no residue.

Parasitoids

• The parasitoids of CPB include egg parasitoid Trichogrammatoidea bactrae fumata (Hymenoptera: Trichogrammatidae) , pupal parasitoid Diagliphtidae roepkie Vier , Photoptera erythronata Vier , Mesostenus sp, Paraphyax spp . , Goryphus javanicus Roman, G. fasciatipennis Szepl, (Hymenoptera: Ichneumonidae), Ceraphrons spp. (Hymenoptera: Ceraphronidae), Phaenocarpa sp. (Hymenoptera: Braconidae), and Megaselia sp. (Diptera: Phoridae).

• Trichogrammatoidea bactrae fumata has been mass-reared on an alternative host ( Corcyra cephalonica – rice moths) in laboratories and commercial breeding rooms. Satisfacory control is achieved when the parasitoid is released at the rate 25,000 wasps/ha/day.

Predators

• The predators includes ants Oecophylla smaragdina, Iridomyremex anceps, Anoplolepis longipes, Crematogaster sp and , Dolichoderus thoracicus, as well as spiders and carabid beetles that feed on larvae.

• Ants such as the black ant (Dolichoderus thoracicus) and the weaver ant (Oecophylla smaragdina) are effective if present in large quantity but not easy to establish in the fields.

• PRIMA investigates appropriate methods of introduction and suitability of black ants in the smallholders of Sulawesi . The results of field trials show that successful introduction is primarily dependent on at least four preconditions: good human built nests, the presence of mealy bugs as a food source, the absence of antagonist species of ants and the highly restricted use of insecticides.

Entomopatogens

• Six genera of fungi are reported to infect larvae and pupae of CPB. The most effective is Beauveria bassiana, causing 100% death during pupation if larvae are exposed to the fungus on emerging from the pod. More than 40% of larvae that emerge from infected pods that have been dipped in a spore suspension of B. bassiana, die during pupation. Field study shows that up to 83.33% reduction of CPB infestation with B. bassiana.

• Other fungus species infecting CPB are Paecilomyces fumosoroseus, Penicillium, Acrostalagmus, Verticillium, Fusarium and Spicaria have been successful, but aren’t used on a large scale.

• The entomopathogenic nematode, Steinernema carpocapsae, is isolated from cocoa stem borer and is effective in controlling CPB. Field trials show up to 88% reduction of infestation. The nematode can penetrate the pod through CPB entry holes and destroy larvae in the pod.

Host Plant Resistance

• Early Dutch interest in host-plant resistance in Indonesia focused on the surface of the pod. Eggs were generally found in the grooves on the pod surface, smoother pods being less attractive than deeply ridged cultivars. However, recent studies show that the surface texture and colour do not influence ovipositional preference of CPB.

• It is suggested that the CPB resistance in cocoa is due to an antibiotic component and that the sclerotic layer is the principle site of this effect. Greater mortality occurred in pods with either thicker or harder stony endocarp layers in the pod wall. Larval survival was as much as 10 times greater in soft/thin-walled cultivars.

• Efforts are focused on developing genotypes with harder walls in their pods. Higher mortality from larval instar is found in genotypes with either thicker or harder endocarp. Attempts are being made to screen selections for resistant material from the diversity of genotypes planted in Sulawesi .

• Recent innovations in side-grafting may allow partial host-plant resistance to play a much greater part in cocoa pod borer control in the future.

• Most farmers in Sulawesi apply insecticides to control the pest. The most important insecticides used include chlorpyrifos, pyrethroids (notably lambda-cyhalothrin, cypermethrin or deltamethrin) and endosulfan.

• Since adult moths rest by day on the underside of lower branches in the cocoa, a relatively small amounts of contact insecticides applied to these resting sites during the low crop period can keep CPB populations below economic levels during the subsequent peak pod production periods. Sprays applied at peak pod periods will have little effect on infestations in the several following months.

• Frequent spraying can reduce infestation rate and improve yields, but this may cause adverse effect on natural enemy population and environment in general.

• Pesticide application also gives a slight risk of residues on, or in, the cocoa beans. As food regulations become increasingly stringent, there must inevitably be reductions in the amount of pesticides applied to cocoa.

• We need to identify the most efficient and least harmful pesticides as short-medium term solutions, as a part of an IPM strategy.

• This method of using synthetic sex pheromone is a practical approach and will permit various integrated control systems to be set up.

• Work is currently being undertaken to scale-up the production of the pheromones, to perform chemical analysis for quality control, to improve field testing and eventually the economics and application by small farmers in Asia .

• New synthetic processes and better traps available should enable much greater refinement of the pheromone production and the development of cost-effective pest management strategies such as pheromone-based monitoring, mass trapping and mating disruption for controlling CPB.

• Keane P.J., C.A.J. Putter. 1992. Cocoa pest and disease management in Southeast Asia and Australia . FAO Plant Production and Protection Paper No. 112. 223 pp.

• Ooi P.A.C. et al. 1987. Management of the cocoa pod borer. The Malaysian Plant Protection Society (MAPPS), Kuala Lumpur . 192 pp.

• Toxopeus H., P.C. Wessel. 1983. Cocoa research in Indonesia 1900-1950. American Cocoa Research Insitute. 291 pp.

• More references: CPB E-Library.

• World Cocoa Foundation.
• International Cocoa Organization.
• Ohio State University.
• Dropdata.
• ACDI/VOCA.
• Indonesian Coffee and Cocoa Research Institute (ICCRI).