The cocoa mirid (Hemiptera: Miridae) problem: evidence to support new recommendations on the timing of insecticide application on cocoa in Ghana

Mirids (Sahlbergella singularis and Distantiella theobroma) are the most important insect pests affecting cocoa production across West Africa. Understanding the population dynamics of mirids is key to their management; however, the current recommended hand‐height assessment method is labour intensive. The objective of the study was to compare recently developed mirid sex pheromone trapping and visual hand‐height assessment methods as monitoring tools on cocoa farms and to consider implications for a decision support system. Ten farms from the Eastern and Ashanti regions of Ghana were used for the study. Mirid numbers and damage were assessed fortnightly on twenty trees per farm, using both methods, from January 2012 to April 2013. The mirid population increased rapidly in June, reached a peak in September and began to decline in October. There was a significant linear relationship between numbers of mirids sampled to hand‐height and mirid damage. High numbers of male mirids were recorded in pheromone traps between January and April 2012 after which there was a gradual decline. There was a significant inverse relationship between numbers of trapped adult mirids and mirids sampled to hand‐height (predominantly nymphs). Higher temperatures and lower relative humidities in the first half of the year were associated with fewer mirids at hand‐height, but larger numbers of adult males were caught in pheromone traps. The study showed that relying solely on one method is not sufficient to provide accurate information on mirid population dynamics and a combination of the two methods is necessary.

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“…The results support a reappraisal of the optimum timing of insecticide application in Ghana (Adu‐Acheampong et al. ).…”

Section: Discussionsupporting

confidence: 82%

Optimizing mirid control on cocoa farms through complementary monitoring systems

Awudzi

Cudjoe

Hadley

et al. 2016

J Applied Entomology

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“…Our results suggest that the optimal density for mass‐trapping S. singularis , the dominant cacao mirid in most West Africa countries (Entwistle, ; Collingwood, ; Idowu, ; Babin et al., ; Mahob et al., ; Yede et al., ; Anikwe & Makanjuola, ), and often at sites in Ghana (Owusu‐Manu, ; Antwi‐Agyakwa, ; Adu‐Acheampong et al., ; Sarfo et al., ), is 150 traps ha −1 , but in order to offer a viable alternative to insecticides (Baker, ) trap efficiency needs improvement. Coating the outside of traps with a killing agent and raising traps to canopy level are easily deployable measures that would potentially improve capturing efficiency by about 50× (Sarfo et al., ).…”

Section: Discussionmentioning

confidence: 75%

“…Furthermore, cacao mirids may only slowly re‐invade plots previously treated with insecticide (Owusu‐Manu, ). In a 5‐year study, Owusu‐Manu () found that mirid populations were highest every year in June–August on Amazon hybrid cacao, but other studies show that populations may increase locally at almost any time of year on those genotypes (Gibbs et al., ; Adu‐Acheampong et al., ; Awudzi et al., ).…”

Section: Discussionmentioning

confidence: 99%

“…The seasonal population cycle of mirids on cacao fluctuates in response to changes in tree physiology, particularly the fruiting pattern (Gibbs et al, 1968;Owusu-Manu, 2002;Adu-Acheampong et al, 2014). On Amelonado cacao, which presents a unimodal cropping pattern, peak numbers occur usually in October-December around peak harvest (Williams, 1954), whereas on Upper Amazon hybrid cacao, which fruits throughout the year, population peaks seem to occur at almost any time (Gibbs et al, 1968;Adu-Acheampong et al, 2014, 2015.…”

Section: Introductionmentioning

confidence: 99%

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Optimal pheromone trap density for mass trapping cacao mirids

Sarfo

Campbell

Hall

2018

Entomologia Exp Applicata

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Sahlbergella singularis Haglund and Distantiella theobroma (Distant) (Heteroptera: Miridae) are the key insect pests of cacao in Ghana and elsewhere in West Africa. Since 1954, spraying with synthetic insecticides has been the principal means of controlling these pests. In West Africa, environmental concerns, economic stimuli, and unreliable access to insecticides have stimulated interest in ecologically more benign mirid control strategies as an alternative to a total reliance on insecticides. Males of both mirid species, and those of the less damaging Bryocoropsis laticollis Schumacher, respond to the same synthetic sex pheromone blend, so pheromone‐based strategies may provide control as well as monitoring opportunities. Pheromone traps were deployed for 3 months at nine densities between two and 30 traps per 0.1 ha plot (20–300 traps ha−1) plus an untreated control treatment in a replicated large‐scale field experiment on mature mixed Upper Amazon hybrid cacao in Ghana, in order to determine the optimal dispenser density for mass trapping, lure‐and‐kill, and/or lure‐and‐infect. At the end of the trapping period, mirid populations in the various treatments were assessed by insecticide knockdown on 400 trees and by searches to hand height on 1 200 trees, together with an assessment of mirid damage. In total 781 S. singularis and 235 D. theobroma were captured in the pheromone traps. The optimal dispenser density for S. singularis was 150 traps ha−1. Over 300 traps ha−1 was probably optimal for D. theobroma as a smaller proportion of the population was captured, and numbers caught per trap displayed no decline with increasing trap density. From insecticide knockdowns, mirid population density was estimated at 220–230 ha−1, 63% of which were D. theobroma. Too few pods and orthotropic shoots were damaged by mirids to establish the efficacy of pheromone trapping for mirid control.

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“…The experiments covered socio-technical and institutional issues identified by the cocoa IP's members and conducted by a PhD student (Quarmine et al, 2014), and by thematic studies Klerkx et al, 2013;van Paassen et al, 2014;Adu-Acheampong et al, 2014). This paper draws on the totality of this information.…”

Section: Methodsmentioning

confidence: 99%

An innovation platform for institutional change in Ghana's cocoa sector

Adu-Acheampong

Jiggins²,

Quartey

et al. 2017

Cah. Agric.

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-Cocoa is a major source of employment, smallholder farmers' incomes, and export revenue in Ghana. However, by 2010 institutional constraints throughout the value chain were failing to sustain bean quality and cocoa production. A national-level innovation platform, comprising key public and private actors in the cocoa sector, was established in 2010 to analyse and act to address this concern. The members' initial inquiries revealed that: farmers indirectly were paying for the national mass spraying and Hi-Tech input programmes, both provided free at the point of delivery. As the largest components in the cost structure, these programmes to a large extent accounted for the low price paid to farmers for their beans; a volatile exchange rate regime meant that often the prevailing rate was not equal to its equilibrium level; policies that heavily taxed cocoa were destroying farmers' expectation of long-term profitability. This paper draws on data recorded from the beginning 2009 to end 2013 by means of theory-guided process tracing (TGPT), to show how the platform contributed to increased prices for farmers, to subsequent reform of the input supply arrangements, and to changes to the mass spraying programme. The key causal mechanisms identified are policy learning and progressive amendment of existing institutions. The paper concludes by drawing lessons for the role of an innovation platform.Keywords: cocoa / price formation / value chain / pest control / stakeholder-led change Résumé -Une plate-forme d'innovation pour le changement institutionnel dans la filière cacao au Ghana. Au Ghana, le cacao est une source importante d'emplois, de revenus pour les petits agriculteurs et de recettes d'exportation. Cependant, en 2010, il a été diagnostiqué que des contraintes tout au long de la filière avaient un impact négatif sur la qualité et la production de fèves de cacao. Une plate-forme d'innovation nationale, comprenant les principaux acteurs publics et privés de la filière cacao, a donc été mise en place en 2010 pour analyser le problème et y répondre. Les enquêtes initiales ont révélé : que les agriculteurs payaient indirectement pour les programmes nationaux de « pulvérisation de pesticides » et d'intrants « Hi-Tech », tous deux soi-disant disponibles gratuitement ; or, en tant que composantes les plus importantes dans la structure des coûts, ces programmes étaient en fait largement responsables du faible prix payé aux * Corresponding

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The cocoa mirid (Hemiptera: Miridae) problem: evidence to support new recommendations on the timing of insecticide application on cocoa in Ghana

Cited by 38 publications

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Optimizing mirid control on cocoa farms through complementary monitoring systems

Optimizing mirid control on cocoa farms through complementary monitoring systems

Optimal pheromone trap density for mass trapping cacao mirids

An innovation platform for institutional change in Ghana's cocoa sector

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