Glyphosate is the most commonly sprayed herbicide in the United States. The frequency and intensity this herbicide is applied to the environment has been constantly increasing to the point where groundwater and atmosphere are becoming contaminated by Glyphosate and its metabolites. Aminomethylphosphonic acid (AMPA) is the most abundant and persistent metabolite of Glyphosate found in the environment as a result of Glyphosate being broken down by soil and soil microbes. At this point, nearly all living organisms have been exposed to varying levels of Glyphosate and its metabolites like AMPA. Pollinators are among the most vulnerable to these chemicals as they are foraging and storing the contaminated pollen and nectar in the hive.
Previous studies have concluded sublethal effects of Glyphosate on metabolic processes, navigation and memory of honey bees. A diet laden with Glyphosate residues also disturbs microbial gut communities in honey bees. Effects of Glyphosate exposure on honey bees requires further investigation and there is a complete lack of knowledge regarding effects of AMPA exposure on honey bees.
In a recent publication, the impact of ingested Glyphosate and AMPA on honey bee gut microbiota was assessed using genetic analysis to measure significant changes in the abundance of major gut bacteria. Bees were exposed to both Glyphosate and Nosema ceranae spores to determine if Glyphosate and the metabolite AMPA could disturb the gut microbiota and lead to pathogen development. Results indicated that Glyphosate did not enhance N. ceranae infection but did cause a significant decrease in Snodgrassella alvi, a partial decrease in Gilliamella apicola and an increase in abundance of Lactobacillus spp. AMPA did not significantly alter microbial gut communities in honey bees, nor lead to N. ceranae infection. This research confirms Glyphosate as the active chemical responsible for sublethal effects on honey bee gut microbiota, not the metabolite AMPA. Further research is required to determine if other Glyphosate metabolites disturb the gut microbiota of honey bees or if AMPA may be responsible for other sublethal effects.
Lethal and sublethal synergistic effects of a new systemic pesticide, flupyradifurone (Sivanto®), on honeybees
Many target pests are becoming resistant to insecticides currently on the market. Chemists are continually on the hunt for the next development in chemical warfare against weeds and pests in conventional agriculture. Of the new pesticides on the market, Sivanto® by Bayer is on the rise. According to Bayers website:
Sivanto® precisely targets key damaging pests while helping safeguard beneficial insects to preserve the overall health of your plants and protect your investment in your crops.
Flupyradifurone (FPF) marketed as Sivanto®, shares similar properties to harmful neonicotinoids. Both FPF and neonicotinoids are systemic, broad spectrum insecticides that affect the same target site on insects (agonists of insects nAChRs, Insecticide Resistance Action Committee (IRAC) group 4). Unlike neonicotinoids, FPF can be applied while bees are foraging. FPF field tests did not show significant effects to exposed honey bees. Researchers found FPF contaminated pollen and nectar in control hives as a result of drifting bees. These “pollinator friendly” pesticides typically work as intended at no detriment to the bees unless additional pesticides are introduced, reducing the ability for pollinators to break down the pesticides and resulting in lethal and sublethal synergistic effects.
In this study, researchers assessed the synergistic effects of FPF with a common fungicide, propiconazole (PRO). Results showed increased frequency of “abnormal behavior” in honey bees after being exposed to FPF+PRO and “FPF can thus impair bee survival and behaviour at field-realistic (worst-case) doses when combined with an SBI fungicide.” FPF is likely to be introduced as a replacement for neonicotinoids. However, these results indicate that FPF may be as harmful as similar neonicotinoid compounds if combined with other pesticides like PRO. Further research will need to explore how other pesticides amplify FPF and how the synergistic effects impact pollinator health.