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Spatial relationships between dominant ants and the cocoa mirid Sahlbergella singularis in traditional cocoa-based agroforestry systems

Babin R., Piou C., Tadu Z., Mahob R.J., Ten Hoopen G.M., Bagny-Beilhe L.. 2012. In : COPAL. 17th Conférence Internationale sur la Recherche Cacaoyère, Yaounde, Cameroun, 15 - 20 Octobre 2012. s.l. : s.n., 6 p.. Conférence Internationale sur la Recherche Cacaoyère. 17, 2012-10-15/2012-10-20, Yaoundé (Cameroun).

Manipulating ant communities to control pests of cocoa has proven to be a promising strategy, especially in Asia. However, concerning African cocoa mirids, the main pests of cocoa in Africa, basic knowledge on mirid-ant relationships is still incomplete. Our study aimed to characterize the spatial relationships between dominant ant species and the mirid Sahlbergella singularis (Hemiptera: Miridae) in traditional cocoa-based agroforestry systems of Cameroon. Over two consecutive years, mirid and ant populations were assessed by a chemical knock-down sampling method in four plots of 100 cocoa trees, located in three different agroecological zones in the Centre region of Cameroon. Mapping procedures were used to display spatial distribution of mirid and ant populations. Also, we adapted spatial statistics methodologies of point pattern analysis to consider the regular tree position effects on insect positions. These techniques allow testing the statistical significance of Poisson null models, leading to the classification of the spatial patterns of insects into association vs. segregation. Our results clearly demonstrated spatial segregation between mirid and the dominant weaver ant Oecophylla longinoda, known as a key-predator in natural ecosystems. Weaver ant trumps, especially its dominant status in ant communities of cocoa ecosystems and its ecological preferences for open habitats, make it a promising candidate for conservation biocontrol against cocoa mirids in Africa.

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