NECTAR CONSUMERS - Nectaries and Nectar - page 301

Bernardello, 2004; Kaczorowski et al., 2005). In contrast, slow-flying, ectother-
mic butterflies feed at flowers with minute volumes of nectar, often massed
flowers in inflorescences, and expend little energy during feeding. The often
invasive Lantana camara (Verbenaceae) is a classic butterfly flower, and
Hainsworth et al. (1991) found that painted lady butterflies, Vanessa cardui,
foraging at its inflorescences required 49 min to consume an average meal of
28 µl (this includes the time required to move between inflorescences and to
probe empty flowers). Watt et al. (1974) investigated the use of nectar by
two species of Colias butterflies (Pieridae) feeding on a wide range of plants,
and stressed the importance of nectar as a water resource for these butter-
flies. Boggs (1987) reviewed the ecology of nectar feeding in Lepidoptera.
The fast hovering flight of hawkmoths and their high energy require-
ments make them important pollinators in warmer habitats (Raguso &
Willis, 2003). They remove large volumes of nectar from pale, fragrant,
long-tubed flowers opening at dusk. It has recently been suggested that high
levels of CO 2 emission by flowers opening at this time may indicate the
presence of abundant nectar to the moths (Guerenstein et al., 2004). The
high-performance flight of hawkmoths is powered by carbohydrates—
whereas early studies emphasized fat as a flight fuel in moths, conversion of
carbohydrate to fat is energetically expensive, and tethered flight in the diur-
nal hawkmoth Amphion floridensis is fuelled by carbohydrate, with only
unfed moths using fat (O'Brien, 1999). Many moths, and some butterflies,
do not feed as adults (Boggs, 1987; Miller, 1996). Nectar feeding in moths
other than Sphingidae has been little studied, except for pest species among
the Noctuidae (Wei et al., 1998). While herbivory and pollination are usually
studied separately, the herbivorous larvae of nectarivorous adults may spe-
cialize on the same plants, with consequences for pest outbreaks. The family
Sphingidae provides some good examples of herbivorous larvae that special-
ize on the plants they will pollinate as adults. Adler and Bronstein (2004)
recently showed that nectar supplementation in flowers of Datura stramo-
nium (Solanaceae) led to increased oviposition by its pollinator, the hawkmoth
Manduca sexta .
The suctorial proboscis of Lepidoptera evolved only once (Krenn et al.,
2005). This mode of feeding requires relatively dilute nectars and for Lepi-
doptera the most efficient energy intake has been predicted by various
authors to lie in the concentration range of 35-45% (Kingsolver & Daniel,
1995). Maximal energy intake has been measured in this range in several
butterfly species, and also in the diurnal hummingbird hawkmoth Macro-
glossum stellatarum (Table 3). Addition of tylose, an inert polysaccharide,