California farmers could face more restrictions on how they combat crop-eating insects after a state report concluded that one class of pesticide poses a significant risk to bees that pollinate almonds and other crops.

The conclusion, published this week by the state Department of Pesticide Regulation, means growers of top crops such as nuts, wine grapes, citrus and berries will have to alter how they combat crop-destroying pests to strike a balance between losing crops and losing the bees that pollinate them.

“While it’s too soon to be specific, it is likely that we will be developing restrictions in the future that will require growers to modify when and where the pesticides are used,” said Charlotte Fadipe, spokeswoman for the California Department of Pesticide Regulation.

An outright ban on the pesticide class known as neonicotinoids, or neonics, is unlikely and unrealistic, Fadipe added. The agency already has a moratorium on any expansion of their use.

Large swaths of the state’s $45-billion agriculture industry depend on bee colonies brought in to pollinate crops. Almonds alone use about 1.8 million colonies, which can cost up to $190 apiece per season to rent, according to government and industry estimates.

Bee populations have been declining steadily for more than a decade, a trend blamed on the combined effects of pesticide exposure, predatory mites and the management practices of pollination service companies.

In the first three months of this year, nearly 78,000 colonies vanished from the nation’s commercial beekeeping stock, a phenomenon known as colony collapse, according to a newly released survey by the U.S. Department of Agriculture. That was a 15 percent increase in such collapses from the same period last year, according to the USDA.

Activists who have pushed for a ban on the pesticides said the report backs their case. “The more we learn about the toxicity of neonics, the more apparent it is that pretty much any plant with nectar or pollen sprayed with these poisons is unsafe for bees,” said Nathan Donley, a senior scientist with the Center for Biological Diversity.

The European Union banned some neonicotinoids on flowering plants in 2013, and earlier this year further restricted their use to greenhouses. Bayer Crop Science, which markets several pesticides based on neonicotinoids, has blasted the move as unfounded by science. A company representative was not available for comment.

Renee Pinel, president and chief executive of the Western Plant Health Assn., an agrochemical industry advocacy group, said the California report relied on “worst case scenarios and not real world or label application rates” commonly found on fields.