urban and suburban pesticide risk

The Two Bees in a Podcast discussion of "Finding Pesticide Residue in Nectar and Pollen" led me to dig into that journal article topic.

Honey Bee (Apis mellifera) Exposure to Pesticide Residues in Nectar and Pollen in Urban and Suburban Environments from Four Regions of the United States concludes:

• 27% of all nectar and pollen samples contained detectable pesticide residues
• more pesticides were detected in pollen than in nectar
• no seasonal or spatial pesticide trends
• 17 pesticides were detected in nectar samples and 60 in pollen samples. Where honey bee oral pesticide toxicity was known, those samples were entered into the EPA BeeREX risk assessment software and 4 pesticides showed a potential acute risk (survival) to honey bees - see table

 method and materials:

• 768 nectar and 862 pollen samples collected monthly over 2 years
  
• 8 locations in medium to large cities in California, Florida, Michigan, and Texas

 other links:

• Risk Quotient (RQ)
• Pesticide Properties Database
• EPA Will Ban A Farming Pesticide Linked To Health Problems In Children

Risk Quotient

As the RQ equation shows, a tiny "acute oral LD50" can create a large Risk Quotient for any sample containing a small "residue in nectar".  For this reason, the table below is sorted in LD50 order with Imidacloprid appearing in the first row.

Products containing Imidacloprid

Pesticide	Oral Acute LD50 (ug/bee)	Introduced	EPA banned	Pollen	Nectar
Imidacloprid	0.0037	1991		✓	✓
Deltamethrin	0.0700	1974		✓
Chlorpyrifos	0.1500	1965	2021	✓	✓
Esfenvalerate	0.2100	1987		✓	✓