American Journal of Experimental Agriculture 6(6): 416-423, 2015, Article no.AJEA.2015.099 ISSN: 2231-0606 SCIENCEDOMAIN international www.sciencedomain.org Strategy for Insect Pest Control in Cocoa Richard Adu-Acheampong1*, Joseph Easmon Sarfo1, Ernest Felix Appiah1, Abraham Nkansah1, Godfred Awudzi1, Emmanuel Obeng1, Phebe Tagbor1 and Richard Sem1 1Entomology Division, Cocoa Research Institute of Ghana, P.O.Box 8, Tafo-Akim, Ghana. Authors’ contributions This work was carried out in collaboration between all authors. Authors RAA, JES, EFA and GA defined the research theme and wrote the first draft of the manuscript. Authors AN, PT and RS co- worked on associated data collection and their interpretation. Author EO provided additional information from field experiments. PT reviewed all drafts of the manuscript. All authors read and approved the final manuscript. Article Information DOI: 10.9734/AJEA/2015/12956 Editor(s): (1) Marco Aurelio Cristancho, National Center for Coffee Research, CENICAFÉ, Colombia. Reviewers: (1) Anonymous, Greece. (2) Anonymous, South Africa. (3) Anonymous, India. (4) Anonymous, Ghana. (5) Anonymous, Italy. (6) Ian Mashezha, Zimbabwe Open University, Zimbabwe. Complete Peer review History: http://www.sciencedomain.org/review-history.php?iid=868&id=2&aid=7702 Received 25th July 2014 th Opinion Article Accepted 30 September 2014 Published 9th January 2015 ABSTRACT Farming systems in cocoa over the last three decades have involved the use of new hybrid plant varieties, which produce pods throughout the year, intensified fertilizer use, and misguided pesticide applications by some farmers. Resource availability in terms of abundance of feeding and breeding sites and ecological disruption as a consequence of climate change and bad agronomic practices have increased the importance of insect pests on cocoa. Historically the major management tool for hemipteran pests has been calendar spraying with conventional insecticides. Considerable progress was made at the turn of the last century by replacing organochlorine insecticides for cocoa mirid control. But inappropriate timing and inefficient application is probably reducing the viability of otherwise acceptable products in some areas. Integrated Pest Management (IPM) strategy for mirids and other insect control should involve great investment in pest surveillance, and be based primarily on the use of cultural practices of removal of excess chupons, shade management and _____________________________________________________________________________________________________ *Corresponding author: E-mail: [email protected]; Adu-Acheampong et al.; AJEA, 6(6): 416-423, 2015; Article no.AJEA.2015.099 host variety resistance. These practices must primarily aim at minimising mirid-associated dieback disease and stink bug deformation of pods, and should be supplemented in some cases by the use of insecticides (up to two applications in February to May at 28-days intervals) depending on the pest populations, damage levels as well as intensity of activity of pollinating insects, with additional two applications during September to December when pest problems may arise. Improved methods of monitoring and prediction should assist in early identification of specific problems in different farms. The rotational use of different active ingredients should also take into account factors such as application methods, compatibility and correct timing. Careful planning is necessary to formulate a flexible control system. Keywords: Mirid; pest control; cocoa; farming systems; control strategy; correct timing; dieback disease; insect pest; flexible control system. 1. INTRODUCTION Before discussing the strategy for mirid control in cocoa in Ghana it would be useful to examine the Mirids (Distantiella theobroma [Dist.] and history of this insect’s control. Sahlbergella singularis Hagl.) and stink bugs (Bathycoelia thalassina (Herrich-Schaeffer) are Before the 1970s damage caused by mirids was known for their importance in causing losses in well appreciated as well as the importance of cocoa (Theobroma cacao L.) in West Africa [1-3], dieback disease that follows mirid feeding on with the most prevalent in Ghana being S. green unhardened tissue (pods and stem). singularis. The authors have outlined the Efforts were concentrated on understanding problems associated with mirid and stink bug population fluctuations of mirids on different infestation. Both nymphal and adult stages feed varieties of cocoa, their distribution within trees and inject saliva to liquefy plant tissues. Their as well as the effect of water stress on the feeding punctures provide entry points for fungal incidence of pests. The tendency for average pathogens [4-7]. This secondary invasion of mirid population levels to remain low until a sharp rise feeding punctures causes dieback disease whilst in August or September was the basis for the that by stink bugs results in premature ripening establishment of the calendar spray regime and deformation of pods and beans. The main beginning in August until December (but omitting method of mirid control is by the application of November) [10]. This was to replace an older conventional insecticides, but stink bugs have recommendation of June, July followed by a often been controlled indirectly by treatments three-month gap [11]. Currently, two seasonal normally used for the control of mirids. peaks varying from September-December and February-May in different locations is an average In Ghana, new pests have emerged and their phenomenon. Plant breeders at the Cocoa control is difficult compared with three decades Research Institute of Ghana (CRIG) have ago [8]. There are several contributory reasons developed varieties of cocoa resistant to swollen for this: farmers still have to be familiarized with shoot and black pod which are also high yielding optimal techniques of using the new generation but unfortunately this resistance does not seem insecticides that have largely displaced the to be durable enough when the varieties are organochlorine and carbamate compounds. The challenged under farmer conditions. Very little global quality standards of insect pest control in effort was spent on breeding varieties with cocoa needed to guarantee high quality produce resistance to mirids or other insect pests. Field for global market outlets have increased, setting observations usually gave strong indications that targets for maximum residue limits of pesticides, mirids caused less damage to some Trinitario which in some instances are clearly not selections (e.g. SC1) than the common West attainable. African Amelonado [12]. This was confirmed later [13], with SC6 identified as one of the tolerant A fast and correct diagnosis of pest incidence is selections to fungal-induced dieback disease in the first important step in attempting any control cocoa. In compiling its list of recommended procedure. Earlier studies [9] have concluded varieties to the seed gardens, CRIG takes a firm that pest control systems in cocoa must be line in rejecting varieties susceptible to swollen revised as a result of changes in farming shoot disease and encourage the development systems, pest cycles and shifts in pest population of resistance to black pod disease. Unfortunately, peaks. 417 Adu-Acheampong et al.; AJEA, 6(6): 416-423, 2015; Article no.AJEA.2015.099 the Institute does not follow an equally firm policy For control of pod feeding insect pests, the for insect pests. present system of insecticide usage ensures that pests are kept at very low levels. A possible Insecticides (nicotine sulphate and DDT) were danger now is that famers faced with increased first introduced in the 1940s against mirids insecticide costs have tended to procure cheaper because accumulated knowledge highlighted unapproved insecticides and omit the registered these insects as the most important pests. In the insecticide treatment. This calls for an urgent following years, several insecticides including need to make the approved insecticide products endrin, dieldrin, heptachlor and lindane were sufficiently available (in pesticide retail shops) so introduced against mirids, which were also aimed as to cause a reduction in prices through market at the control of mealybugs (Planococcoides competition. njalensis (Laing), Planococcus citri (Risso) and Ferrisia virgata (Ckll)) which are vectors of cocoa Improvements in the monitoring and forecasting swollen shoot virus disease. Unfortunately, of the major pests on the new varieties of cocoa insecticides were applied prophylatically and at recently became evident [17], but the shift in times when the pests were already present at dominance between the two important mirid damaging levels. species is not adequately understood, and should be studied further. Cultural practices The percentage of cocoa trees that was treated which reduce serious insect pest attacks should with insecticides in the 1950s is difficult to obviously play an important part in a control estimate accurately, but it rapidly increased in system. Such practices may include pruning, the 1960s [14]. Cocoa output reached an all- chupon removal, agro-forestry, shade time high of 560,000 tonnes in 1964/1965. Nearly management, removal of alternative hosts, all the insecticides used were against mirids due weeding and fertilizer application [18]. Apart from to their relative high economic importance while these, the main emphasis in insect pest control the adoption of insecticide use for other insect will be