Foraging behavior of insect pollinators visiting onion flowers (Alluim cepa L.) was studied in relation to five environmental variables. The dwarf honey bee Apis florea L., was the most abundant flower visitor and comprised more than 94% of the total flower visitors. Commencement of flight activity occurred when a minimum threshold of environmental variables was surpassed while the cessation was governed mainly by decline in values of light intensity and radiation. In between the 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 direct effect of temperature was high and positive followed by light intensity and solar radiation while the direct effect of relative humidity was low and negative. The direct effect of nectar-sugar concentration was positive and negligible. Evidently, path coefficient analysis gave a more clear picture of effects than did the simple correlation analysis. The studies further revealed that the average amount of nectar and energy per umbel was significantly positively correlated with the number of bee visit. Apis florea on an average visited 1. 33+0. 41 and 6. 17±0. 63 umbels and flowers/min, during different hours of the day. Furthermore, the insect pollinated plots produced significantly more seeds with heavier weights than those isolated from insect visits.
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Эту запись предоставил Indian Council of Agricultural Research