Dounia and Fernand-Nestor Tchuenguem Fohouo
To evaluate the impact of Apis mellifera adansonii (Hymenoptera: Apidae) on boll and seed of Gossypium hirsutum, its foraging and pollinating activities were studied in Maroua, during two years of flowering (August-October 2010 and 2011). Treatments included unlimited floral access by all visitors, bagged flowers to avoid all visits and limited visits of A. m. adansonii. Observations were made on 100 flowers per treatment. In addition, all flower visitors were recorded. The worker bee’s seasonal rhythm of activity, its foraging behavior on flowers, its pollination efficiency, the fruiting rate, the number of seeds per fruit and the percentage of normal seeds were recorded. Individuals from 40 species of insects were recorded on flowers of G. hirsutum, after two years of observations. Apis mellifera adansonii was the most frequent with 32.10% and 40.99% of visits in 2010 and 2011 respectively. This bee intensely and preferably foraged for pollen, almost throughout the day, with a peak between 6 am and 7 am. The foraging speed was 17.56 ± 6.69 flowers per minute. The fruiting rate, the number of seeds per fruit and the percentage of normal seeds of unprotected flowers were significantly higher than those of flowers protected from insects. Apis mellifera adansonii foraging resulted in a significant increase in the fruiting rate by 38% in 2010 and 33% in 2011, as well as the number of seeds per fruit by 49.36% in 2010 and 45.42 in 2001, and the percentage of normal seeds by 26.21 in 2010 and 23.65 in 2011. The installation of A. m. adansonii colonies in c o t t o n p l a n t a t i o n s i s recommended to increase fruits and seeds production of this species.
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