Factors influencing flight activity of Apis florea F, an important pollinator of Daucus carota L

Abstract

SummaryForaging ecology of insect pollinators visiting carrot flowers (Daucus carota L.) was studied in relation to five environmental variables. The dwarf honeybee Apis florea L. was the most abundant flower visitor and comprised more than 94% of flower visiting insects. Commencement of flight activity occurred when a minimum threshold of environmental variables was surpassed, while cessation was governed mainly by declining values of light intensity and radiation. In between commencement and cessation, the foraging population correlated significantly and positively with air temperature, light intensity, solar radiation and nectar-sugar concentration and negatively with relative humidity. Path coefficient analysis, however, revealed that the direct effect of temperature was high and positive followed by light intensity and solar radiation while the direct effect of relative humidity was high and negative. The direct effect of nectar-sugar concentration was negative and negligible. Path coefficient analysis gave a more comprehensive picture of effects than did simple correlation analysis. Apis florea on average visited 1.14 ∀ 0.23 and 22.78 ∀ 2.57 umbels and flowers/min, respectively, during different hours of the day. Furthermore, the insect pollinated plots produced significantly more seeds with heavier weights than those isolated from insect visits.