Cacao mirids (Sahlbergella singularis, Distantiella theobroma and Bryocoropsis laticollis) were captured in pheromone traps releasing a 2:1 blend of the sex pheromone components of the two first named species in a series of five experiments on cacao (Theobroma cacao) plantations in Ghana. A total of 835 cacao mirids were caught, all male, 95% of which were S. singularis, 3% D. theobroma and 2% B. laticollis. Two sticky trap and two water trap designs made from locally available materials were as effective for capturing S. singularis and total mirids as the best sticky trap from previously reported studies. Coating the outer surface of a large water trap with sticker increased the catch 4.4×, and 2.7× for a cylindrical sticky trap. Sticker on the outside of the water trap also increased the inside catch of S. singularis by 76% and total mirids by 71%. The numbers of S. singularis and D. theobroma trapped increased with increasing trap elevation and were highest around canopy level. Those traps caught an average 12× more mirids than traps at 1.8 m, the height recommended currently. Therefore, large water traps coated with sticker and aligned with the cacao canopy should raise the current capture rates of pheromone traps for cacao mirids about 50×, which may be sufficient for effective pest management by mass trapping without synthetic insecticides.

The brown cocoa mirid, Sahlbergella singularis is the most important insect pest of cocoa for field damage has been classified into three categories that include blast, stagheadedness and mirid pocket. The mirid attack predisposes the cocoa plant to secondary infection by opportunistic pathogenic fungi. This study evaluated the dieback conditions associated with mirid damage due to associated fungi from lesions on pods, twigs and pin punctures. The relationship between Phytophthora black pod infection and mirid infestation in the field was also established. The results indicated that dieback progression from the mirid lesions (8.5 mm) was significantly different (P< 0.05) from that of pin punctures (7.8 mm). Lasiodiplodia theobromae had the highest proportion of isolates from pods (33%), twigs (47%), and pin punctures (38%). Fusarium decemcellulare (Albonectria rigidiuscula) accounted for 27.8% and 31.6% from pods and twigs; however, it was not recovered from pin punctures. Other isolated pathogens were Aspergillus species and Rhizoctonia species. There was a significantly strong positive correlation coefficient of 0.74 between the mirid population and the black pod disease infection in the field. The major fruit-bearing season of cocoa witnessed an increase in mirid infestation and blackpod infection. The effect of mirid–pathogenic fungi-associated damage could be ameliorated through effective crop husbandry practices to ensure that cocoa plant tissues are not unduly exposed to biological and mechanical injuries.

Cacao genotypes of various origins were evaluated for resistance to the cocoa mirid (Sahlbergella singularis (Haglund)) based on field damage, antixenosis, antibiosis and tolerance. Field damage was assessed by scoring recent and cumulative damage by the mirid to the major genetic groups of cacao. Antixenosis assessment was based on the number of feeding lesions on twig segments using a choice test. Antibiosis was measured through survival of young mirid nymphs on shoots and pods, whereas tolerance was assessed through the reaction of the twigs to mirid feeding punctures. Among the genetic groups of cocoa, the Upper Amazon, the materials from Guiana and hybrid genotypes were the least damaged by the mirids, both for recent and cumulative damage. The Catongo group was, by far, the most susceptible group with more than 50% of the canopy showing both recent dieback and cumulative canker damage. With regard to antixenosis, antibiosis and tolerance, significant differences (P < 0.05) were found between the genotypes. The least preferred clones sustained between 2 and 3 lesions compared with the most preferred ones with 6–8 lesions per twig segment. Clones UPA402, T79/501 and IMC67 gave the lowest rate of mirid nymph survival, indicating that they exhibit antibiosis. The clones PA107, SCA6 and C151-61 sustained high numbers of mirid feeding lesions and relatively high levels of shoot death, but have a good ability for re-growth and can be considered as tolerant genotypes.

Cocoa (Theobroma cacao L.) is an important foreign exchange earner for Ghana. However, production is constrained by a high incidence of pests and diseases. Based on farmers' needs, this study focused on the control of capsids, mainly Sahlbergella singularis Haglund and Distantiella theobroma (Distant) (both Hemiptera: Miridae). Annual crop loss caused by capsids is estimated at 25–30%. To control capsids, formal research recommends application of synthetic insecticides four times between August and December. However, farmers hardly adopt this recommendation, which they consider unsuitable for their conditions and context. Three alternative control methods were tested with farmers: mass trapping, using sex pheromones; applying crude aqueous neem Azadirachta indica A. Juss. (Meliaceae) seed extract (ANSE) and using the predatory ant Oecophylla longinoda Latreille (Hymenoptera: Formicidae) as a biological control agent. Contrary to most previous reports, studies on temporal distribution of cocoa capsids indicated that the population peaked in March. ANSE was effective against capsids and other cocoa insect pests and did not affect the predatory ant. When O. longinoda occurred in high numbers, capsid incidence was low. Shade did not influence ant or capsid abundance significantly. ANSE caused 100% mortality of capsids in cage and 79–88% in field experiments. The sex pheromone was as effective as ANSE or ants in suppressing capsids. All the three methods were effective and compatible; hence, they can be used in an integrated pest management strategy for cocoa, including organic production in Ghana.