Mysterious Mass Deaths of 3 Million Bees That Died Overnight in California Solved

(Photo: Wikimedia Commons/Virginia State Parks staff)
Mysterious Mass Deaths of 3 Million Bees That Died Overnight in California Solved

Millions of bees died overnight in California. Experts finally solved the mysterious mass deaths.

Bees Mass Deaths Solved

At a California refuge, around three million bees perished overnight in September. Scientists have now identified the enigmatic source of the mass mortality.

The Northern San Diego location's beekeepers were taken aback upon discovering heaps of deceased honeybees scattered across the yard, with some even whirling in a death spiral.

Experts at the US Department of Agriculture (USDA) conducted an inquiry after the discovery, and they found that the colony had been subjected to a "double lethal" amount of poison that was being used as an outdoor termiticide, which is prohibited.

This month, the USDA made its findings public, indicating that the deaths were caused by fipronil. Fipronil is an insecticide prohibited for landscape and agriculture because it causes disruptions to an insect's central nervous system.

The method by which the bees consumed the hazardous substance is uncertain; nevertheless, the sanctuary's personnel has surmised "malice" since the poison is not used by any farms or orchards nearby.

"We suspect malice because all nearby orchards had no reported use of Fipronil and nearby aperies did not have positioning either," said Dominic Peck, who works at the sanctuary.

"It seems to be directed towards us. We cannot say that for sure, but we are moving out of the area to be safe."

The poison is also toxic to humans, causing sweating, nausea, vomiting, headache, abdominal pain, dizziness, and seizures.

The millions of bees that had perished were discovered about 8 p.m. Pacific Time on Sept. 20, 2023. The beekeepers discovered "piles and piles of dead bees laid out in front of our hive stands" as they strolled around the sanctuary's yard.

The insects were "out fanning on the front porches of the hive boxes, cooling off the hives from a warm summer night" just a day before the mass deaths. To stop the surviving bees from foraging on contaminated plants, the team spent the day clearing dead bees off the ground and giving honey to the surviving ones.

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Bumblebees Cannot Taste Pesticides In Nectar.

Researchers from the University of Oxford learned that bees couldn't detect pesticides. According to one study, the insects cannot escape tainted nectar, which puts them at risk of chemical exposure and jeopardizes agricultural pollination.

The researchers used two methods to determine whether bumblebees (Bombus terrestris) would refrain from consuming pesticides at a variety of dosages and whether they could taste neonicotinoid and sulfoximine pesticides in nectar that resembled oilseed rape or rapeseed (Brassica napus).

First, they used electrophysiology to record the responses of neurons in taste sensilla, or "tastebuds," on the mouthparts of the bumblebee. This allowed scientists to track the frequency of "fires" in the neurons and, in turn, the degree of the taste response.

The researchers also looked at the bumblebees' feeding behaviors, giving them either pure sugar solutions or sugar solutions laced with pesticides.

The results demonstrated that whether the bees drank sugar solution or pesticides containing sugar, the neurons' responses were the same. This implies that bumblebee mouthparts cannot identify and avoid common pesticides present in nectar.

In the behavior test, the bees consumed the same amount of food regardless of the pesticides in the solution. This held even when pesticide concentrations were high enough to seriously harm bee health.

The findings are noteworthy because they show that bumblebees' capacity to employ taste as a defense against pesticide exposure is impaired.