Some aspects of pollination ecology and effect of pesticides on the flower visitors and yield of the watermelon crop citrullus lanatus (thunb.) (cucurbitales: cucurbitaceae) in the Shai-Osudoku District of Ghana

The purpose of the study was to investigate the influence of pesticide application on the abundance and diversity of watermelon flower visitors as well as its effect on the crop yield. This was to help identify the most beneficial insecticide application regime to ensure pollinator health and the control of insect pests whiles ensuring maximum yield. Insects that visited watermelon flowers were collected weekly with the use of sweep nets and pan traps from plots with pesticide application twice a week, once a week and no application. Phenologically the plants promoted male fitness by producing more male flowers than female flowers. The plot with no pesticide application had the highest diversity of flower visitors present with a value of 1.50 on the Shannon Weiner index, and the highest species richness of eight. The most abundant and most efficient pollinator of the watermelon plant according to this study was the honey bee Apis mellifera L. There was a significant difference between the number of insect flower visitors collected from the different treatments used in the study (p< 0.05). It was also established from the study that there was no significant difference (p> 0.05) in fruit yield from plots with different pesticide application regimes. In effect, the application of pesticides once a week after flowering is best to achieve protection of pollinators and still ensure maximum fruit yield. (Author)