Polinización con abejas nativas del melón

Native Bee Pollination
of Watermelon
Prepared by the Xerces Society for Invertebrate Conservation
(This fact sheet is based on research conducted by Claire Kremen,
Neal Williams, Sarah Greenleaf, and Robbin Thorp)
© National Watermelon Promotion Board

Pollination by bees is critical for a successful watermelon crop. While the
European honey bee is often used effectively to pollinatewatermelon (at 2
hives per acre), native bees are also significant pollinators. In fact, on some
organic farms in Yolo County, California, native bees provide all of the pollination needed. On a bee-per-bee basis, they are more effective than honey
bees. They forage earlier in the day and transfer pollen more efficiently than
the introduced honey bee. Plus, in the right situation, they may beabundant on
your farm. Here we describe the importance of native bees for watermelon pollination and how to increase their populations and your bottom line.
Yellow-faced bumble bee

INS AND OUTS OF MELON POLLINATION

Photo by Mace Vaughan

Watermelon is a cucurbit, a family of crops that includes cucumber, muskmelon, and squash. As with all cucurbits, watermelon has separate male and
femaleflowers. Watermelon do not self-pollinate, not even seedless varieties.
To ensure pollination, a bee must transfer large, sticky pollen grains from male
to female flowers. Female flowers are open for six to seven hours on one day
only and during this time they must receive 500 to 1000 pollen grains to produce a marketable melon. Delivering this much pollen requires several bee visits. If honeybees are present in sufficient densities, they can provide adequate
pollination. However, native bees deliver much more pollen per visit. Heavily
pollinated flowers make larger fruit of more uniform size and lower costs by
accelerating the harvest period and reducing the number of picks.
California bumble bee

NATIVE BEE POLLINATORS
At least 23 native bee species visit watermelon in YoloCounty, CA. Our research demonstrates that most of the native bees that visit watermelon flowers
deposit more pollen on each visit than do imported honey bees; although, if
honey bees are present in sufficient densities, they can provide adequate pollination for the crop. The table below lists five of the best native pollinators of
watermelon in Yolo County, CA. The bumble bees on this list nestin cavities
either underground or in old rodent burrows. They are social insects and may
have more than 200 workThe five most important native bees for
ers in a nest. The other bees
pollinating watermelon in Yolo County, CA
listed are ground-nesting
Common name
Latin name
solitary species. Sometimes,
they nest together in large
Yellow face bumble bee
Bombus vosnesenskii
numbers, buteach female
California bumble bee
Bombus californicus
works alone, digging tunSquash bee
Peponapis pruinosa
nels underground in which
Long-horned bees
Melissodes species
she constructs cells to lay
Sweat bees
Halictus species
her brood.

Photo by Mace Vaughan

Squash bee
Photo by Jim Cane, USDA ARS

NATIVE BEE HABITAT AND WATERMELON POLLINATION
Recent research has demonstratedthat natural areas are vitally important for
crop pollination by native bees. In a study conducted in Yolo County, 80 percent of organic farms located near wild habitat could have received all of their
pollination from native bees. In this same study, only 50 percent of organic
farms located far from natural habitat could have received all of the pollination
they needed from native bees. And,native bees alone could not provide enough
pollination for any of the conventional farms studied.
Some of the most important pollinator species never occurred on farms far
from natural habitat. Nevertheless, although farms far from natural habitat
might not be able to rely solely on native bees to provide all of their pollination
needs, native bees still contributed, on average, 28 percent of...