7 research outputs found
Intrapopulation heterogeneity in floral nectar attributes and foraging insects of an ecotonal Mediterranean species
A population of Buglossoides purpurocaerulea
(L.) I.M. Johnst. (Boraginaceae–Lithospermeae)
located in Lecceto (Siena Province, Tuscany,
central Italy) has been studied to compare floral nectar
attributes and forager species between sun-exposed
and shaded plants. Flower anthesis and maturity of
sexual organs were also investigated. Average flower
anthesis lasted 3–4 days. Stigma receptivity and
anther dehiscence occurred on the first day. Nectar
production also began on the first day and maximum
production occurred on second-third day. Significantly
greater volumes and total sugars were recorded
in individuals exposed to the sun. Nectar HPLC
analysis showed a similar hexose-dominant sugar
profile for all the individuals with percentages of
sucrose, glucose and fructose around 5, 48 and 47 %,
respectively. Protein amino acids represent the 90 %
of the overall free amino acids profile. Significant
differences between relative percentages of serine and
proline were found between sun-exposed and shaded
individuals. Empis pennipes and Bombilyus major
were the most frequent insect visitors to shaded and
sun-exposed individuals, respectively. The hexose
dominance of the nectar of B. purpurocaerulea, an
exception among the Mediterranean Lithospermeae,
may be related to the habitat where this plant generally
grows, i.e. the forest-edge, and to pollination mainly
performed by dipterans