Distribution of [¹⁴C]Imidacloprid in Sunflowers (Helianthus annuus L.) following Seed Treatment

Abstract

Imidacloprid, a neonicotinic insecticide, has been used as a seed dressing (Gaucho) to protect crops against soil and aerial insects. However, French beekeepers observed abnormal behavior of bees foraging on sunflowers and suspected a link between the imidacloprid seed treatment and the observed bee syndrome. This work studies the distribution of [(14)C-imidazolidin]imidacloprid (1 mg/seed) in three stages of Gaucho-treated sunflowers grown in an outdoor lysimeter. Plants absorbed <10% of [(14)C]imidacloprid spiked on seeds, and 75% of that absorbed radioactivity was found in cotyledons. Concentrations in the upper leaves were 20 times lower than in the first leaves. From the extracted radioactivity, imidacloprid accounted for 50% and metabolites for the other 50%. Four major metabolites can be detected, in variable concentrations, among which the hydroxy- and olefin-imidacloprid have toxicities equivalent to that of imidacloprid. In pollen, concentrations of imidacloprid were 13 ng x g(-1). Thus, imidacloprid residues from Gaucho seed treatment contaminated sunflower pollen, involving the translocation of imidacloprid within the plant.

Honey Bees (Apis mellifera L.) and Pollination Issues: Current status, impacts and potential drivers of decline

“…Increased probability of Nosema infection was reported in bees that consumed pollen with a higher fungicide load (Pettis, Lichtenberg, Andree, Stitzinger, & Rose, 2013). Likewise, the residues of insecticide imidacloprid in nectar and pollen at high levels may be dangerous to bees (Laurent & Rathahao, 2003;Chauzat et al, 2006). Widespread losses of colonies in France is due to imidacloprid (Laurent & Rathahao, 2003).…”

“…Likewise, the residues of insecticide imidacloprid in nectar and pollen at high levels may be dangerous to bees (Laurent & Rathahao, 2003;Chauzat et al, 2006). Widespread losses of colonies in France is due to imidacloprid (Laurent & Rathahao, 2003). Similarly, other pesticides "acaricides" have also been found harmful for bees' health (Harz, Muller, & Rademacher, 2010).…”

Non-target effects of chlorantraniliprole and thiamethoxam on Chrysoperla carnea when employed as sunflower seed treatments

“…Residues of such insecticides can be translocated to various plant parts (Dively and Kamel 2012;Goulson 2013). For example, residues of imidacloprid have been found at 13 ppb in sunflower pollen following its application as a seed treatment (Laurent and Rathahao 2003). Chlorantraniliprole and thiamethoxam represent two systemic insecticides used in seed treatments, belonging to two different groups, diamides and neonicotinoids, respectively.…”

Pollen Toxicity from Seed-Treated Cotton on Bees and Pollen Collection Capacity

“…Imidacloprid residues have been found at concentrations of up to 13 ng in sunflower plants (Laurent & Rathahao, 2003). Chauzat et al (2006) identified 36 different types of residues in pollen loads in apiaries of France.…”