• Link to SK Organic Resources
  • Driving Near Recently Sprayed Fields Exposes People to Pesticides
  • Weeds Can Be Managed Without Chemical Pesticides
  • Learn to Manage Pests Naturally
  • SNAP Display at Event
  • Learn About Colony Collapse Disorder and How to Protect Bees
  • Grow a Lush Garden Organically
  • LIving Near Fields Increases Pesticide Exposure
  • Learn to Keep Insects Out of your Crops
  • Learn To Manage Weeds Without Chemical Pesticides

Mixtures Effects

also see insectsbirds fungicides, mixture effectsdigestive tract/microbiome, Bee Die-off, microbiota changes

Neonicotinoids Combined with Other Pesticides Elevate Hazards to Honey Bee  (Beyond Pesticides, February 22, 2023)   'Among the eight pesticides tested, honey bee toxicity was as follows from most to least toxic: the neonicotinoid insecticide thiamethoxam, the organophosphate insecticide dimethoate, the carbamate insecticide methomyl, the synthetic pyrethroid insecticides permethrin, and then cypermethrin, the triazole fungicide tetraconazole, and the synthetic pyrethroids cyfluthrin and then esfenvalerateThese results did change based on different treatment lengths, yet thiamethoxam was found to remain the most toxic throughout all studies.  In the study, scientists evaluate a total of 98 different mixtures, from binary combinations of two different chemicals to octonary combinations of all eight different pesticides. Within these tests, approximately 30% of these were found to be synergistic to honey bees, exhibiting toxicity greater than each individual material in the mixture.  Perhaps the most concerning interaction came from combinations that included thiamethoxam and the fungicide tetraconazole. Any variation of pesticide combinations that include these two chemicals have a roughly 55% chance of exhibiting synergistic toxicity to honey bees.'

Pesticide Mixtures Reduce Life Span of Honey Bees, Damage Gut Microbiome    (Beyond Pesticides, November 1, 2022) Study done with field relevant concentrations. 'Honey bees exposed to a combination of multiple pesticides suffer a reduced lifespan and experience adverse changes to their gut microbiome, increasing susceptibility to pathogens and disease. This finding comes from a study published recently in Science of the Total Environment, which examines the interactions between the insecticides flupyradifurone and sulfoxaflor and the fungicide azoxystrobin on honey bee health.   As the present study reveals, pesticide risk assessments do not inadequately capture the range of harm that can result when pesticides are combined, necessitating a shift toward safer, alternative, and regenerative organic farming systems that do not use these dangerous chemicals.For the initial experiment on individual bees, those exposed to flupyradifurone fared the worst, experiencing significantly reduced survival (50% reduction). The addition of azoxystrobin did not significantly add to this effect. However, with sulfoxaflor, it did. Bees subjected tsulfoxaflor and azoxystrobin in combination experienced significantly reduced survival when compared to a sole sulfoxaflor exposure.'     All experimental groups 'show significantly increased abundance of Serratia spp. This rod-shaped bacteria can serious harm honey bee fitness. “These bacteria are pathogenic and harmful to bees’ health,” said Dr. Al Naggar. “They can make it harder for the insects to fight off infection, leading to premature death.” 

Ingestion of Real-World Pesticide Residues in Grain Threatens Bird Offspring More than Parents    (Beyond Pesticides, September 8, 2022) A study published in Environmental Pollution finds parental exposure to real-world, sublethal concentrations of pesticide residues on grains is a major contributor to unfavorable offspring development among foraging birds. Parents’ ingestion of grains with conventional pesticide residues, whether from contaminated or pesticide-treated seeds, results in chronic exposure that adversely affects offspring health, even at low doses.    However, researchers find that ingestion of low pesticide residues in grain has consequences on reproduction and offspring quality without altering mortality. Chicks whose parents consume grains with pesticide residues are more petite in size, lack proper skeletal growth, and have lower red blood cell counts with increasing body mass index as a trade-off.

Direct pesticide exposure of insects in nature conservation areas in Germany  (Carsten A. Brühl et al; Scientific Reports,16 December 2021)    In total, residues of 47 current use pesticides were detected, and insect samples were on average contaminated with 16.7 pesticides. Residues of the herbicides metolachlor-S, prosulfocarb and terbuthylazine, and the fungicides azoxystrobin and fluopyram were recorded at all sites. The neonicotinoid thiacloprid was detected in 16 of 21 nature conservation areas, most likely due to final use before an EU-wide ban. The individual chemicals reflect sales volume of each.  A change in residue mixture composition was noticeable due to higher herbicide use in spring and increasing fungicide applications in summer. The number of substances of recorded residues is related to the proportion of agricultural production area in a radius of 2000 m. Therefore, a drastic pesticide reduction in large buffers around nature conservation areas is necessary to avoid contamination of their insect fauna.   see also Insects in Nature Preserves Contaminated with Over a Dozen Pesticides (Beyond Pesticides, January 13, 2022)   SNAP Comment: As mentioned in the article, the higher chemical detection reflects volume of sales so a similarly designed study in other locations would have to reflect pesticide use and persistence in the area. There are currently 32 PMRA registered pesticide products containing metolachlor in Canada, 0 present or historical containing prosulfocarb, 0 present or historical containing terbuthylazine,  44 (down from 49) containing azoxystrobin, 18 containing fluopyram and 4 containing the neonicotinoid thiacloprid.