Plantations in West Africa have several pests and diseases that are prone to affect the Cocoa plants.
Two insects that affect the cocoa trees very often are Mirids (Distantiella theobrama or Sahlbergella singularis) and so called stink bugs (Bathycoelia thalassina).

Figure 1: Mirid

Figure 2: Stink bug

Figure 3: Damage after punctures

An infestation with either of these two insects has severe consequences for the trees. They feed and inject their saliva into the plant leaves. The resulting punctures in the plant tissue make it possible for fungal pathogens to enter. This so-called "secondary invasion" results in dieback disease. Additionally, stink bugs causes premature ripening and also often deformations of the cocoa fruits.

The main pest management practice against Mirids is the application of insecticides. Stink bugs can also be controlled through this indirectly.
There has been very little research on breeding cocoa varities that are resistant against those two pests.

Starting in 1940, insecticides like endrin, heptachlor, lindane and dieldrin were sprayed on the cocoa plantations in West Africa. However, the insecticides were not used in the correct manner. Either they were sprayed prophylatically or when it was already too late and the plants were infected.
Since 2000, major developments have been introduced to the pest control of cocoa trees. There has been a lot of research and monitoring of the two most important pests, mirids and stink bugs. Additionally, the concerns about protecting the natural environment and the wildlife became more influential in pest management.
Major issues in the spraying of insecticides are that pest populations are very hard to predict, therefore it is difficult to say when thy have to be applied. Secondly, most farmers do not have the ability to spray large areas at short notice. That means it could already be too late for the application of insecticides.
Another very important concern when sprayng insecticides are the effects on the natural environment and animals .
Lastly, most of the farmers are smallholder farmers that simply cannot afford the chemicals or the needed equipment for a safe spraying of insecticides.

Another possible pest management practice is the use of aggregation pheromones. They are hormones which effect and confuse the insects in their mating behaviour. However, this method is not very established yet and needs further research.

Clearly, the pest management sector in West Africa still needs to develop further. More research about alternative practices such as pruning, agro-forestry, etc. has to be implemented. Furthermore, breeding and finding resistant cocoa varieties have to be emphasized.

Well-planned integrated pest management would include the use of resistant varieties, pheromones, alternative cultural practices and the use of chemicals when necessary. As already mentioned, this sector needs more research in order to establish best management practices for the crops, the people, as well as the natural environment.