Free in his 2nd edition of Insect Pollination of Crops (1993) p.502 states:
"Stevenson and Clark (1937) reported that in some localities bumblebees and
honey bees are often seen visiting them[potato flower], and they thought
that insects may cause much more cross-pollination than commonly supposed.
Sanford and Hannemann (1981) observed bumble bees (Bombus impatiens) but no
honey bees foraging on potato flowers in the field in Wisconsin, USA, but
when colonies of honey bees and bumble bees (B.fervidus) were introduced to
cages of flowering potatoes the bees were not attracted to the flowers and
few fruits were produced."
Deleplane and Mayer in Crop Pollination by Bees (2000) p.66 state:
Bumble bees and certain solitary bees are capable of doing this
[buzz-pollinate], and this makes them valuable pollinators of
buzz-pollinated crops such as blueberry, eggplant, seed potato and tomato
(Plowright and Laverty, 1987; Cane and Payne, 1990)