INFLUENCE OF FLOWER CHARACTERISTICS, WEATHER, TIME OF DAY, AND SEASON ON INSECT VISITATION RATES IN THREE PLANT COMMUNITIES

Abstract

Pollination biology at the community level was investigated using quantitative techniques, comparative methodology, measurements of the physical habitat, and consideration of floral characteristics. The frequency of insect visits to flowers was investigated in three contrasting communities: a deciduous woodland-meadow site in eastern Massachusetts, alpine tundra in New Hampshire, and Mediterranean scrub (fynbos) in South Africa. Visits to flowers were most common in woodland-meadow, followed by alpine tundra, and least frequent in fynbos. Bees were the most common visitor in the woodland-meadow and the fynbos, but flies were the most common visitor in the tundra. Flower color often influenced visitation rates and had a weak but significant effect on the type of insect that visited flowers. Preferences for color by different types of insects often changed in different communities, which suggests that floral syndromes may be community-specific. In all communities, tubular flowers were visited less often than open flowers. Less specialized insects were more common on open than tubular flowers, but large variances made few differences statistically significant. Combining measurements of temperature, light, humidity, wind speed, time of day, and season (using cluster analysis) with the shape of a flower, it was predicted that a 10-minute observation would include at least one visit. Flower shape, temperature, light, and season appear to be the most important variables influencing insect visitation rates. Results of this study indicate that relationships between insects and flowers are nonspecific and vary among communities.