Sahlbergella singularis is a major insect pest of cocoa in Cameroon. Conventional insecticides remain the most widely used option for mirid control, which unfortunately have adverse effects on the environment and human health. Improved methods of controlling this species, both environmentally friendly and inexpensive to farmers, are requirements. Varietal control based on the selection of resistant and/or tolerant genotypes can be an interesting approach. Nonetheless, the role of secondary metabolites (SMs) in cocoa defense against mirids is poorly documented; yet, these compounds are reported to be key elements in plant defense against herbivores. For this purpose, SMs of twelve cocoa genotypes were identified and quantified, as well as their impact on food preference by mirids. Food preference was assessed through microtests measuring cocoa attractiveness and antixenosis toward mirids. The results showed that cocoa genotypes were differently accepted as food by mirids, with a significant preference for hybrid IMC60 x SNK605 and a non-preference for T60/887. The ten other cocoa genotypes showed intermediate results. Five SMs classes: alkaloids, flavonoids, polyphenols, saponins, and tannins were identified. Their rates varied between cocoa genotypes: polyphenols > alkaloids > flavonoids > tannins, and saponins. Cocoa genotypes with high total phenolic contents were significantly preferred by S. singularis (rα = 0.86, R2 = 74.0%, P < 0.001), while those with low saponins contents were lowly accepted (rα = − 0.83, R2 = 68.9%, P < 0.015), independently of the levels of other SMs. Given SMs high potential to affect mirid feeding behavior, analyzing cocoa SMs composition may help in early selection of resistant cocoa varieties against S. singularis.

The African mirid bug (Sahlbergella singularis) is the most economically important insect pest in cocoa farms. Pesticide management, although controversial due to the adverse effects of these substances on the environment and on human health, remains the main option used for controlling this pest. In the recent decades, the development of alternative approaches to synthetic pesticides is a requirement. Therefore, we used neem oil (NO) and ethanolic extracts (EE) from leaves at different concentrations to evaluate, in vitro, their insecticidal potentials against mirids. Mirid mortality increased significantly with increase in concentrations, values ranged from 32.5 to 92.5 % for EE and 52.5 to 97.5 % for NO. Apart from negative controls, Tween 80 and distilled water, that showed significant low mortality rates, both extracts revealed effectiveness comparable to the reference insecticide used in controlling mirids, except for EE by ingestion. Mirids treated by contact showed significantly high mortality rates (72.5 to 97.5 %) compared to those treated by ingestion (32.5 to 70.0 %). The greatest biological effectiveness values were obtained at a concentration of 8 % by contact exposure: 0.88 ml/ml (NO) and 0.73 g/ml (EE) for LC50 and ≈1 day to both extracts for LT50. Given effectiveness comparable to that of the insecticide, both tested extracts should be considered as effective biopesticides for IPM against mirids, especially S. singularis.