pesticide, microbiota and seasonal diet

The Beekeeping Today Podcast discussion of "Winter Bees, Summer Bees and Imidacloprid" led me to dig into that journal article topic. The assumptions in the article are:

• Naïve lab bees fed clean syrup that had no transfer of bacteria and microbiota by contact with other adult bees are more sensitive to stressors and therefore avoid the highly toxic neonicotide Imidacloprid (IMP) in the caged challenge
  
• Winter bees live longer (estimated age of 2 to 3 months) and accumulate more intestinal microbiota and are therefore less sensitive to IMP
  

Influence of honey bee seasonal phenotype and emerging conditions on diet behavior and susceptibility to imidacloprid concludes:

• Winter bees preferred IMP-tainted syrup at both 5 and 20 PPB
  
• Summer bees' preference for IMP-tainted syrup was neutral
• Naïve summer bees that emerged in a lab (not exposed to other adult bees and fed clean syrup) avoided IMP-tainted syrup in the caged challenge
  

 method and materials:

• 2700 winter and summer bees in 27cages (100 bees/cage) were challenged with IMP tainted syrup (5 and 20 PPB)
  
• 3 syrup feeding setups
• 1:1 versus 1:1 untainted (clean) syrup; control 1 versus control 2
  
• swapped locations; 1:1 versus 5 PPB (sub-lethal, next to nothing concentration)
  
• swapped locations; 1:1 versus 20 PPB (lethal concentration)

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		✓	✓

my book picks

In Waterstones (UK bookseller), I discovered a phenomenal nature writer, Dave Goulson.   I read two of his books and recommend to beekeepers Goulson's 2014 book, A Buzz in the Meadow.  Then move onto Goulson's 2013 book, A Sting in the Tale.  In chapters 13 and 14 of A Buzz in the Meadow, Goulson discuses these interesting topics:

• sub-lethal effects of Imidacloprid (neonicotinoid)
• inbreeding leading to diploid males and triploid females

I'm reading The Lives of Bees by Thomas D Seeley.  If you are interested in honey bees living and evolving in the wild, then I recommend this 2019 book for you. Here's the first quote in the first chapter.