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The efficiency of cocoa pollination in agroforestry systems under bio-fertilizer application

Deheuvels O., Cordoba Obando C., Cerda R., Somarriba Chavez E.. 2014. In : Wachira Mary Anne (ed.), Rabar Betty (ed.), Magaju Christine (ed.), Borah Gulshan (ed.). Abstracts of the 3rd World Congress of Agroforestry 'Trees for life: accelerating the impact of agroforestry' : abstracts. Nairobi : WCA [Nairobi], p. 293-293. World Congress on Agroforestry, 2014-02-10/2014-02-14, Delhi (Inde).

In the humid tropics, a significant amount of the agricultural landscape where cocoa (Theobroma cacao) is grown is managed as agroforestry systems and pressures to intensify cocoa production are likely to increase. The current trend for agricultural intensification in cocoa cultivation worldwide aims at significant reductions or total elimination of the shade canopy. However, losing the shade canopy implies losing the potential to produce valuable ecosystem services and particularly cocoa pollination. Pollination is a limiting factor of cocoa production that has been investigated in the 70's and 80's essentially by trapping methods. The genus Forcypomia sp. is acknowledged to be the main insect responsible for cocoa pollination, when other insects such as ants and Trips sp. would play a secondary role, essentially for self-compatible varieties of cocoa. However, these species were trapped in the immediate surrounding of the tiny cocoa flowers and no study has succeeded so far in observing and describing the insects actually visiting the inside of the cocoa flowers. We used a digital video recording system that allowed us to monitor and record all insects visiting cocoa flowers of three self-incompatible clones Catie-R4, Catie-R6 and PCMT-58 from 6:30 am to 11:30 am. The cocoa trees were monitored in low-flowering season and in high-flowering season in Turrialba, Costa Rica. The leaf litter was collected around the cocoa trees to investigate the presence of eggs of pollinators or predators. The cocoa trees were planted at 1111 trees per ha, associated with Cordia alliodora, Cedrela odorata, Erythrina poepiggiana and Musa sp. They were compared with and without bio-fertilizer application. Our results show that the diversity and the frequency of insects visiting cocoa flowers are influenced by the flowering period and do not rely specifically on the Forcypomia genus. Video recording and further histological cuttings made on visited flowers demonstrated the important ro

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