In order to understand the nuances of pesticide residue levels in plant pollen and nectar, we needed an experimental design with different active ingredients acting on different plant types.

Pesticides differ by their active ingredient(s). Depending on their molecular makeup, pesticides can vary in how they travel through a plant, how they manage a pest, or even how water-soluble they are. These differences mean that knowing pollen and nectar residues levels from one pesticide product doesn’t mean we know the pollen and nectar residue levels from another pesticide product. Along the same lines, even when focusing on one pesticide product, residue levels within different parts of the plant will also differ. For example, residue levels found in a plant’s flower tissue will differ from residue levels found in the same plant’s leaf tissue, nectar, or pollen.

Given these complexities, our team wanted to measure residues levels from products with different active ingredients on different types of plants. We are therefore testing five different active ingredients applied to annual, herbaceous perennial, and woody perennial environmental horticulture plants. We plan to test residue levels of all active ingredients in each nectar and pollen for model plant species which produce copious amounts of both. For some plants we will also test residue levels in flower petals and leaves. For most perennial species, we will first take baseline residue data before pesticides are applied, and then we will sample residue levels again—sometimes multiple times—after pesticides have been applied.

Table 1. List of pesticides being applied to all plant species listed in Table 2.

Pesticide Product Name Pesticide Active Ingredient
Marathon II Imidacloprid
Altus Flupyridiflurone
Safari 20SG Dinotefuron
Flagship 25SG Thiamethoxam
Mainspring Cyantraniliprole

Table 2. List of plants being treated with pesticides, then sampled for pesticide residue. Each plant is being tested in at least three different continental U.S.A. states.

Plant Type Plant Species Sampled for Pesticide Residue in Pollen Plant Species Sampled for Pesticide Residue in Nectar
Annual Sunflower ‘Taiyo’ Salvia splendens ‘Red Hot Sally’
Snapdragon Sonnet White
Herbaceous Perennial Dahlia ‘Bishop’ series Kniphofia uvaria
Salvia ‘Black & Blue’
Woody Perennial Rhododendron PJM or R. catawbiense boursault Rhododendron PJM or R. catawbiense boursault

Researchers: Drs. James Bethke, JC Chong, Dave Smitley,  Cristi Palmer, and Dan Gilrein

States: CA, MI, NJ, NY, SC