Pollination Efficiency of <i>Amegilla calens</i> (Hymenoptera: Apidae) on <i>Gossypium hirsutum</i> L. (Malvaceae) Variety L457 Flowers at Meskine (Maroua, Cameroon)

Abstract

Animal pollination is a key of reproduction of more plants species including Gossypium hirsutum . This Malvaceae is the best cultivated oilseed plant in tropical and subtropical regions in the world. This research evaluates the interaction between Amegilla calens and Gossypium hirsutum from 2018 to 2019 based on the activities of the solitary bee on the flowers of this plant and their productive impact in field. The experiment was focused on four repeated treatments during the flowering phase: the first two were characterised by the existence or absence of protection of the flowers regarding all insects and the other two made up of flowers designed for the exclusive visit of A. calens or open then protected again without a visit from an insect or any other organism. Daily rhythm of activity, behavioural ecology, the pollination efficiency, the fruiting rate, the number of seeds per capsule and the percentage of normal seeds were evaluated. Among twenty insects species recorded A. calens is the most abundant with 30.72% of 655 visits and the most efficient pollinator. Amegilla calens is active on G. hirsutum flowers from 6 a.m. to 5 p.m. with a maximum activity situated from 8 a.m. to 9 a.m. All visits of this solitary bee are able to fertilize the flowers of Malvaceae. The mean duration of a visit per flower for pollen harvest is also more important (23.57 ± 0.96 sec) than nectar collection (13.69 ± 0.72 sec). For the two years, through its pollination efficiency, A. calens increased the fruiting rate by 20.30%, as well as the percentage of normal seeds by 32.39%. Therefore, we concluded that A. calens is the important pollinator and increases the fecundity and number of normal seeds of G. hirsutum .