Seasonal differences in abundance and distribution of cocoa-pollinating midges in relation to flowering and fruit set between shaded and sunny habitats of the La Lola Cocoa Farm in Costa Rica.

Published online
28 Jun 1988
Content type
Journal article
Journal title
Journal of Applied Ecology
DOI
10.2307/2403127

Author(s)
Young, A. M.

Publication language
English
Location
Costa Rica

Abstract

The distribution and abundance of adults, larvae and pupae of ceratopogonid midges in shaded and sunny habitats was investigated in relation to phenological patterns of flowering and fruit set on cocoa trees. Midge population densities were greatest in rotting banana tree trunk discs in the dry season in both habitats, but they continued to be at a high level in the shaded habitat to the middle of the subsequent rainy season. Peaks of flowering occurred in both habitats late in the dry season and through the middle of the rainy season, with a marked decline in flowering late in the rainy season. Flower production was considerably higher in the sunny habitat than in the shaded habitat, although levels of fruit set were very similar. Two of the most abundant midges, Forcipomyia youngi and F. quatei, were shown to be effective pollinators of cocoa. The use of discs of rotting banana tree trunk throughout the year in cocoa farms would provide an effective means of managing pollinators and also a mechanism by which pollinator populations could thrive during the dry season.newline˜D.G. Lowe.<new para>ADDITIONAL ABSTRACT:<new para>The distribution and abundance of adults, larvae and pupae of cocoa-pollinating ceratopogonids was investigated in shaded and sunny habitats in Costa Rica in relation to phenological patterns of flowering and fruit set on cocoa trees. Midge population densities were greatest in rotting banana tree trunk discs and at their greatest densities in the dry season in both habitats, but continued at a similarly high level in the shaded habitat to the middle of the subsequent rainy season. Two of the most abundant midge species in the treatments, Forcipomyia youngi Wirth and F. quatei Wirth were demonstrated to be effective cocoa pollinators. The use of discs of rotting banana tree trunks throughout the year provides a very effective means of managing pollinators as well as providing a mechanism by which pollinator populations can thrive during the dry season and therefore pollinate more cocoa flowers late in the dry season.

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