The orange groves in Fort Myers, Florida, have turned to poison for David Mendes honeybees. The onetime winter havens for bees have been treated with a popular pesticide that he says kills his livelihood.

States and the federal government are searching for ways to protect managed bees like Mendes and their wild counterparts. The White House issued a strategy in May to promote the health of honeybees and at least 24 states have enacted laws to protect bees and other pollinators such as bats, birds and butterflies.

Of the 100 crops that supply about 90 percent of the food for most of the world, 71 are pollinated by bees. Pollination has a direct effect on the quality of food and the diversity of crops. Declines in bee populations mean fruit and vegetables are less available and more expensive.

Though the number of honeybee colonies managed by beekeepers appears to be on the rise for the first time since colony collapse disorder was identified in 2006, U.S. bee populations have not returned to what they had been before a devastating parasite appeared in the late 1980s, causing the loss of up to 70 percent of managed bee colonies.

Advocates hope they can stem future colony losses by addressing pesticide use and protecting habitats. But states have yet to prohibit neonicotinoids, or neonics, pesticides used on agricultural crops, which scientists and many beekeepers say are killing bee species both native and farmed.

It is less clear just how broadly native populations of bees are affected by pesticides and habitat loss.

Mendes, one the largest beekeepers in the country, has kept as many as 20,000 hives of bees for almost 40 years. He said it is typical for roughly 10 to 15 percent of a colony to perish during the winter months, but now the annual loss of some colonies is more than half.

The decline in honeybees, which were first imported by European settlers, has contributed to the increased cost of honey and of food in general, as beekeepers are forced to continually buy more bees to replenish their hives.

Addressing Neonicotinoids

Large-scale farmers and chemical companies point to the relative safety of neonics . Introduced in the 1990s as a low-level toxin to deter crop-damaging pests, neonics work by attacking the nervous system.

Chemical companies say neonics, which can be sprayed on plants, used to coat seeds before they germinate or applied directly to soil, are safer than older pesticides. They dispute research showing the chemical can be toxic to bees, saying it relies on overexposing laboratory bees to the chemicals.

But Mendes is confident the chemicals have an impact on his bees as he moves them around the country to pollinate crops.

Finding safe places to raise bees has gotten more difficult, he said. Keeping his hives next to crops like citrus or watermelons mean the colonies just wont thrive.

Others agree. The chemicals can affect an entire colony, making it difficult for bees to return to the hive, and cause reproductive problems and other long-term ailments, said Rikki Seguin, state director for the advocacy group Environment Oregon .

Oregon has been on the forefront of targeting neonics use in the U.S. In 2014, the Eugene City Council banned their use on city property, the first ban of its kind in the country. The Portland City Council followed suit in 2015, but the Oregon Legislature failed to advance a similar proposal this year.

If were eliminating the species that is responsible for pollinating these crops, we should be alarmed about our food security and our food future, Seguin said. For us, its a ban, its very simple that banning the neonics is the single best thing we can do to stem the loss of our pollinators.

Across the country, 18 bills in 10 states were introduced this year regarding neonics, including measures to ban or limit their use. None passed, though some are still pending before legislatures with multiyear sessions.

While some advocacy groups are eager to push for state bans on neonics, Vicki Wojcik, research director for the San Francisco-based nonprofit Pollinator Partnership , said the science showing a connection between neonics and bee death in real hives is not strong. Her group does not promote outright chemical bans but advocates reduced use of chemicals overall.

Banning neonics would just lead farmers to seek other, potentially more damaging chemicals to protect their crops, she said.

Would removing one product from the list of 200 products people are using in agriculture make a significant difference? Wojcik said. It probably wont. People will use something else.

This year in Maryland, an attempt to require the labeling of seeds and plants treated with neonics, and to limit who can use the chemical, was met with opposition from the state Department of Agriculture and the nonprofit Maryland Farm Bureau .

Colby Ferguson, the nonprofits director of government relations, contests the science behind neonics studies, citing the chemicals relative safety for humans.

Ferguson said bees only suffer significantly from neonics when exposed to large quantities.

The bees maybe get a slight exposure to it, he said. Theyll be OK. They can tolerate it because its at such a low level.

Ferguson said the Maryland measure did not address the real causes of bee death: largely starvation during recent winters, which have been excessively cold, and lack of habitat.

It was too narrow, Ferguson said of the bill. It was not really going to address the problem they were trying to fix in the state of Maryland, which is bees dying.

Mendes, who recently sold his bee operation to Paramount Farming, an almond and pistachio producer, said his anecdotal evidence is enough to identify neonics as problematic.

Companies will argue that its not at a toxic level, but what the observant beekeepers are seeing is that if youre next to certain agricultural crops, your bees are always sick, Mendes said.