Philippine Researchers Develop Biological Control for Cocoa Pests

The Philippines' geographical location, climate and soils are very well suited to growing cacao. Current national cacao output is about 12,000 metric tonnes (MT), and the Philippine Department of Agriculture and the Philippine Cacao Foundation estimate that by 2020 output could reach 100,000 MT.

However, rampant pests and diseases seriously threaten cacao yields and quality. In 2015, the International Cocoa Organization estimated that cacao production could fall by 30–40% because of pests and diseases. In the Philippines, the most damaging cacao pests are the cacao pod borer (CPB) and the cacao mirid bug (CMB). To tackle these problems, De La Salle University (DLSU) began research into biological control methods for CPB and CMB. The study is sponsored by the Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development (DOST-PCAARRD), part of the Department of Science and Technology, as part of the project "Cacao Pest Management Programme: Biological Control Methods (DOST-PCAARRD)", and is expected to run for two years.

DLSU researchers Dr Divina Amalin and Dr Alberto T. Barrion explain that biological control uses organisms such as insects, mites, weeds and plant pathogens to control pests through predation by natural enemies, host parasitism or other natural mechanisms. It has now become an effective alternative to conventional chemical pesticides.

Progress of the research is as follows:
1) Cacao pod borer (CPB)
Damage: it consumes the bean meal and pod tissue of cacao, causing deformity and stunted development, and in severe cases flattening and sticking together of the beans, yellowing of the pod, uneven growth or premature ripening.
Natural enemies: the researchers surveyed cacao-growing areas in Quezon, Bicol and Davao. Insects and spiders reported as pod borers or suspected natural enemies were found in these areas. One natural enemy of the pod borer, the egg parasitoid Trichogrammatoidea cojuancoi Nagaraja, is relatively active in South Davao province, especially in areas that have long been free of insecticide spraying. Because the area has since been converted to banana, however, this survey did not collect that egg parasitoid. Another possible natural enemy of the pod borer is the ichneumonid Paraphylax sp., found in some cacao-growing areas of South Davao, which can parasitise the pod borer. The researchers are currently trying to collect both natural enemies.

2) Cacao mirid bug (CMB)
Damage: it attacks the pods and young shoots of cacao, causing tissue decay and leaving the plant seedless.
Natural enemies: these include various wasps and spiders such as the lynx spider and Oxyopes javanus Thorell, as well as the parasitic wasp Erythmelus. The researchers are now mass-rearing mirid bugs to test the efficacy of natural enemies, and are also developing a diet for mass-rearing the lynx spider.