20 Pest Management in Organic Cacao

20 Pest Management in Organic Cacao Régis Babin* International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya Introduction Americas produced around 14% of total world production of cocoa (FAOSTAT, 2014). General information on cacao Cacao crop expansion in Africa and Asia came with the emergence of major pests Cacao, Theobroma cacao, is a small tree and diseases, which have adapted to the from the family Malvaceae, and originated crop from their local host plants. The most in different forest areas of South and Central infamous examples are the cocoa mirids America (Wood, 1985). During the 20th cen- Sahlbergella singularis Hagl. and Distantiel- tury, the cacao-growing belt spread consid- la theobroma Dist. (Hemiptera: Miridae), and erably over tropical areas of America, Africa the black pod disease due to Phytophthora and Asia, and is around 10 million ha today palmivora Butler and Phytophthora mega- (FAOSTAT, 2014). Cocoa beans are pro- karya, which became major threats for West duced for butter and powder that are used African-producing countries in the 1960s mainly in chocolate manufacture. In 2014, and 1970s, respectively (Entwistle, 1985; chocolate confectionery produced revenues Lass, 1985). In Latin America, witches’ of around US$120 bn, and these are ex- broom disease due to the basidiomycete fun- pected to grow with the developing markets gus Moniliophthora perniciosa highly im- in countries with rising middle classes pacted production of cocoa in Brazil in the (Hawkins and Chen, 2014). At the same time, 1990s (Meinhardt et al., 2008), while the cocoa world production rose constantly for frosty pod rot, due to Moniliophthora roreri, decades and reached 5 million t in 2012 that is widely spread in Latin America, cur- (FAOSTAT, 2014). In 2012, Africa alone rently leads to low yield and crop abandon- produced around 66% of total world pro- ment (Phillips-Mora et al., 2007). The cocoa duction with four countries in the top five pod borer Conopomorpha cramerella be- cocoa-producing nations, namely Ivory came a major pest of cacao in South-east Coast (with 1.6 million t), Ghana, Nigeria Asia in the mid-1980s and is considered the and Cameroon. Asia produced around 19% main threat for cocoa production in most of world production, with Indonesia being Asian-producing countries since the early the world’s second largest producer. The 2000s (Posada et al., 2011). * [email protected] © CAB International 2018. Handbook of Pest Management in Organic Farming 502 (eds V. Vacante and S. Kreiter) Pest Management in Organic Cacao 503 Cacao pests and diseases are numerous cacao farmers unprepared for facing the and no part of the plant is spared. Some in- threats (Sonwa et al., 2008). The private sec- sects are disease vectors, such as mealybugs tor was not able to offer support to the farmers, of the Pseudococcidae family, which trans- and so pest and disease pressure worsened mit the cacao swollen shoot virus (CSSV), a in the next three decades, contributing to plant pathogenic virus that infects cacao low yields and cocoa beans of poor quality. trees in West Africa, affecting yields and However, certified organic cacao exists, often killing the trees within a few years in low but growing proportions worldwide. (Domfeh et al., 2011). Global crop losses Latest statistics from the International due to these pests and diseases are usually Cocoa Organization (ICCO) estimate pro- assessed at 30–40% of the world cocoa production of certified organic cocoa at 15,000 duction (ICCO, 2013). But pest and disease t, less than 0.5% of the world production pressure is also responsible for higher costs (ICCO, 2014). A recent world survey con- of production, health and environmental ducted by the Research Institute of Organic issues due to the use of pesticides and Agriculture (FiBL) and the International farmer despondency leading to lower in- Federation of Organic Agriculture Move- vestment in cacao farming. Indeed, pest and ments (IFOAM) gives a more optimistic re- disease management is usually problematic port with the total area under organic cacao for cacao farmers, especially in Africa and assessed at 220,000 ha in 2011, around Asia, because of inadequate farmer know- 2.3% of the world cacao-growing area. This ledge and practices, as well as limited ac- is more than twice the proportion of the cess to resistant varieties and agrochemicals world’s organic agricultural land, estimated (ICCO, 2013). at 0.9% in 2011 (Willer and Lernoud, 2013). The same survey indicates that the area under organic cacao increased fivefold General considerations of organic since 2004, which is much more than most cocoa production other crops (Willer and Lernoud, 2013). The fact is that countries with the highest vol- It is important to consider that cacao is not umes of certified organic cocoa are the an industrial crop like other crops in devel- minor producers of Latin America such as oped countries. Cacao (90%) is grown by Bolivia, Mexico, Honduras and Peru, or smallholders. Their number has been esti- other minor cocoa-producing countries like mated at around 5 million worldwide (Haw- the Dominican Republic, the United Repub- kins and Chen, 2014). Although cacao is the lic of Tanzania, Madagascar and São Tomé main income source for most of them, farm- and Príncipe. By contrast, the largest cocoa ing practices still suffer from insufficient producers produce low levels of certified knowledge and capital investment (Haw- organic cocoa, with Ivory Coast producing kins and Chen, 2014). Thus cacao is often 0.0%, Indonesia 0.1%, Ghana 0.5% and grown with little or no use of synthetic in- Nigeria 0.4% (Willer and Lernoud, 2013). puts, which are usually too expensive for farmers. In Africa, this situation is due to cocoa sector evolution in the last five decades. From the 1960s, governments pro- Cacao pest management, organic moted cacao cultivation and invested a lot by default of money in supporting farmers, especially for pest and disease management. In Camer- While the proportion of certified organic oon, for instance, government subsidized cocoa production is globally low worldwide, spraying campaigns for cocoa mirids and pest management on cacao is conducted for fungicide distribution for black pod disease. a significant part through ecologically sound Because of the 1990s’ economic crisis, the practices, for two main reasons: (i) some pesticide and cocoa sectors were liberalized pests have proven to be totally immune to and subsidies dropped in a few years, leaving chemical spraying because of their biology 504 R. Babin or because they develop resistance to in- and to two different tribes, the Odoniellini secticides; and (ii) the difficulties in access- and the Monaloniini. The two tribes have ing chemical inputs for smallholder farmers very different morphological traits: mirids has resulted in use of more economic prac- from tribe Odoniellini are usually robust in- tices including the evaluation of the farm sects and brownish in colour, while tribe natural environment. In fact, a significant Monaloniini are gracile and brightly coloured part of recommended (or traditional) prac- insects. Synthetic publications were de- tices currently used by farmers for insect voted to cocoa mirid systematics, biogeog- pest management are fully compatible with raphy, biology, ecology and management, in organic production standards. However, it the 1970s (Entwistle, 1972; Lavabre, 1977). has to be noted that, currently, there is no Sahlbergella singularis Hagl. and Dis- single organic solution for the control of the tantiella theobroma Distant, of the tribe Od- major pests of cacao. Farmers are usually oniellini, are two closely related species told to employ several practices to keep pest native to the forest area of West and Central infestations under economic thresholds, Africa. They were described for the first and organic pest management practices are time on cacao around the beginning of the sometimes associated with inappropriate 20th century, and since then, have consider- chemical spraying. ably spread with the crop throughout the The aim of this chapter is to collate the current cocoa-producing countries of the re- existing knowledge of the pest management gion. S. singularis and D. theobroma are practices and tactics that could be used in 10 mm long in the adult stage, and brown in organic cacao farming. The main pests of colour. Their overall appearance mimics cacao are reviewed followed by details on the bark of trees where they usually rest the strategies compatible with organic during the day. On cacao, eggs are inserted farming that have been developed for their into pods and green shoots. Mirid popula- management. tion density is usually low in cacao plant- ations with seasonal maximum density of 2500 individuals/ha (around two individuals per tree). However, damage to the crop Pests of Cacao is considerable, due to mirid feeding behav- iour. Like most Hemiptera, the mouthparts Major pests (stylets) are inserted in fruits at different de- velopmental stages, as well as buds and Cacao crop development in tropical Africa green shoots. A large supply of saliva with and Asia came with the emergence of major hydrolytic enzymes is injected, leading to insect pests, which adapted to the crop from the liquefaction of plant tissues, which are their local host plants. Currently, in Latin finally ingested by the bug. Mirid feeding le- America, its native continent, the crop is sions on cacao pods and shoots appear as a relatively unaffected by insect pests com- black plug of dead tissue. On young pods, pared with Africa and Asia, where some this damage may cause distortion during major pests are widely distributed causing growth, sometimes leading to yellowing extensive damage to the crop. and fruit abortion. But the main damage is on vegetative parts of trees with the death of Cocoa mirids the terminal part of branches as well as many lesions.

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