Bee colonies damaged after almond pollination in Calif.

SACRAMENTO, Calif. — Some California beekeepers say pesticides may be to blame for the death or damage of as many as 80,000 bee colonies after the insects pollinated almond trees in the San Joaquin Valley.

Some believe pesticides used on almond orchards could be sickening or killing the bees, the Sacramento Bee reported Sunday.

“We’re a little mystified,” said John Miller, a beekeeper based in Newcastle. “We have some colonies that looked like they’ve been through some kind of brood die-off. It’s puzzling because it is intermittent and random.”

California’s almond orchards are pollinated by about 1.6 million bee colonies, which are mostly brought in from other states by some 1,300 commercial beekeepers.

Beekeepers have also been struggling with colony collapse disorder, which has led to the disappearance of large numbers of honeybees in North America.

The damaged beehives could hurt the broader agriculture industry. About 90 percent of honeybees that pollinate U.S. crops are used during the California almond bloom before being moved to pollinate other crops, such as apples, cherries and watermelons.

In March, beekeepers met with U.S. Environmental Protection Agency officials to discuss the problem. Seventy-five beekeepers said about three-quarters of their hives showed damage.

Michele Colopy, program director with the Pollinator Stewardship Council, an advocacy group for beekeepers, believes the hive damage is related to the practice of “tank mixing” certain insecticides as well as applying insecticides during the early daytime hours when bees are foraging.

Beekeepers are calling for labels warning of possible effects of tank mixing, as well as an effort to end daytime applications of the insecticides. But they don’t have scientific data linking the colony damage to the mixing of pesticides.

State and federal officials say they plan to work with the beekeepers to reduce the risks that bees face from pesticides applied during the almond bloom.