Foraging Small White Butterflies, Pieris rapae, Search Flowers Using Color Vision

We demonstrate that the small white butterfly, Pieris rapae, uses color vision when searching flowers for foraging. We first trained newly emerged butterflies in a series of indoor behavioral experiments to take sucrose solution on paper disks, colored either blue, green, yellow, or red. After confirming that the butterflies were trained to visit a certain colored disk, we presented all disks simultaneously. The butterflies selected the disk of trained color, even among an array of disks with different shades of gray. We performed the training using monochromatic lights and measured the action spectrum of the feeding behavior to determine the targets’ Pieris-subjective brightness. We used the subjective brightness information to evaluate the behavioral results and concluded that Pieris rapae butterflies discriminate visual stimuli based on the chromatic content independent of the intensity: they have true color vision. We also found that Pieris butterflies innately prefer blue and yellow disks, which appears to match with their flower preference in the field, at least in part.

Flower Preferences of the Wrocław Botanical Garden Bumblebees (Bombus spp.)

Bumblebees (Bombus spp.) are morphologically different from each other as determined by the length of their tongue. Seven species of bumblebees were identified in the Wrocław Botanical Garden: the long-tongued Bombus hortorum, and the medium-tongued B. pascuorum, and the 5 short-tongued species, Bombus hypnorum, Bombus lapidarius, Bombus terrestris, Bombus lucorum, and Bombus pratorum. Bumblebees were observed so that their choice of food within the botanical family could be determined. The shape and colour choice of the flower was particularly noted. Bumblebees showed the highest degree of preference for the Lamiaceae family. The Boraginaceae family was also used by all of the recorded species. Bumblebees found pink and purple, lipped, capitular/ globular, and saucer-shaped flowers to be most attractive. The individual species of bumblebees showed different preferences, which may be explained by the differences in their morphology. However, bumblebee flower preference and selection seems to be more complex and requires further, detailed research.

469 Some Citrus Flower Characteristics Limit Bee Preference of Hybrids and Their Pollination

Except for `Orlando' and `Minneola' tangelos, most citrus hybrids grown in Florida are small-flowered and produced less than half the nectar of large-flowered cultivars. Sugar contents in large- and small-flowered cultivars were not different in 1997, but the concentration of sugars doubled in 1998 over 1997 for small-flowered hybrids, while nectar volume was about one-half of that in the previous year. Nectar volume of large-flowered cultivars increased slightly in 1998 compared to 1997. Of four aromatic volatiles measured from headspace over flowers, `Robinson' and `Ambersweet' were lowest in total while other cultivars had only some specific differences. Grapefruit flowers produced high limonene levels, while `Sunburst', `Fallglo', and `Valencia' gave off the most myrcene. Bees were tested for flower preference in a round, white screenhouse using a mini-hive and duplicated fresh-cut flower bouquets each day. Bees preferred large-flowered cultivars with more nectar. Some other preferences also were observed. In the field, hedge-rows limited cross movement of bees in mature blocks of hybrids, which limits the number of contiguous rows of the preferred cultivar for good pollinization. Timing of bee hive placement was also critical to get bee movement into the intended block because flowering times differ for some cultivars and bees develop inital preferences.

THE RESPONSE OF AMPHICOMA SPP. (COLEOPTERA; GLAPHYRIDAE) BEETLES TO RED MODELS DIFFERING IN AREA, SHAPE, AND SYMMETRY

Field experiments investigating the attraction of Amphicoma spp. beetles to red, nonrewarding, scentless models have shown that (1) attractiveness is positively and linearly related to model size; (2) for models of similar size, contour density does not affect attractiveness; (3) bilateral models are more attractive than radially symmetrical models with the same area. The results are discussed in comparison to the spatial vision of honeybees and with regard to the flower preference of beetles.