Biology Reference
In-Depth Information
diets and then fed nectar mimics with amino acids, but no effect was seen
after rearing on high-quality larval diets (Mevi-Schütz & Erhardt, 2005). The
importance of nectar amino acids for butterfly fitness thus varies with the
nutritional history of females.
While female butterflies are more responsive to amino acids in nectar,
mud puddling is an activity restricted almost entirely to males. This drinking
at puddles or decaying organic matter is thought to be directed at the acquisi-
tion of minerals or nitrogenous compounds (Beck et al., 1999). Sodium gained
by males during puddling is transferred to females at mating for use in egg
production (Pivnick & McNeil, 1987). Although this behaviour suggests that
sodium is scarce in nectar, it does not seem to occur in other flower-visiting
orders of insects.
3.4
Hymenoptera
3.4.1
Wasps
Wasps provide their brood with animal material but many feed on nectar,
honeydew and fruit juices as adults. The carbohydrate intake of social wasps
(Vespidae) is supplemented with salivary secretions solicited from the lar-
vae, and Hunt et al. (1982) suggested that this behaviour may have arisen
because of nutritional similarities between the larval secretions and the pri-
mary adult food, floral nectar. Wasps have unspecialized mouthparts and are
common visitors to flowers with exposed nectar and to extrafloral nectaries,
where both parasitoid and predatory wasps provide anti-herbivore protection
to the plants. Koptur (1992) lists many families of nectar-drinking wasps.
Larger wasps from the families Pompilidae, Vespidae, and Sphecidae are more
likely to drink at floral nectaries and play a role in pollination. The impact of
wasp sugar feeding has been felt on a major scale in New Zealand beech for-
ests, which have been invaded by
Vespula vulgaris
because of their abundant
honeydew (Beggs, 2001).
Foraging at small flowers with accessible nectaries is common among the
species-rich parasitic Hymenoptera (Jervis et al., 1993; Patt et al., 1997).
Adult females of parasitoid wasps (e.g., Ichneumonidae, Braconidae, Encyr-
tidae, Eulophidae) feed on both host insects and sugary food such as nectar
and honeydew, and this has led to the use of flowering plants and sugar
sprays to increase populations of these wasps in agro-ecosystems for pur-
poses of biological control (Idris & Grafius, 1995; Patt et al., 1997; Rogers
& Potter, 2004). In this context, Wäckers (2001) carried out a detailed study
of the nutritional suitability of a broad range of honeydew and nectar sugars
