A few quotes from my (growing) bibliography on various chemical treatments:



" The majority of evidence of the sub-lethal impacts of insecticides has come from studies of the honeybee A. mellifera , but there is evidence of insecticides affecting the foraging of other bee taxa and species, predominantly bumblebees (Bombus  spp.). Slower foraging of Bombus impatiens  Cr. workers was observed after exposure to spinosad (a naturally derived insecticide) in pollen during larval development, at levels expected in agricultural systems treated with this insecticide (Morandin et al. 2005 )"





Morandin, L. A., Winston, M. L., Franklin, M. T., & Abbott, V. A. (2005). Lethal and sub-lethal effects of spinosad on bumble



bees (Bombus impatiens Cresson). Pest Management Science, 61, 619–626.





" One of the insecticide molecular target sites of growing importance (total market share in 2007 for agricultural use: 24%) is the nicotinic acetylcholine receptor (n AChR), which plays a central role in the mediation of fast excitatory synaptic transmission in the insect central nervous system (CNS). Despite the application of the alkaloid (S )-nicotine as a natural insecticide (aqueous tobacco extract) for a long time, the n AChR has been an underexploited biochemical target for agrochemisty, with an estimated total insecticide world market share of around 1.5% in 1987. Because of its high mammalian toxicity and relatively low level of insecticidal activity, no major class could be established through taking (S )-nicotine as lead structure. However, the n AChR has become an important target site in modern crop protection with the discovery and commercialization of three classes of insecticides:1  (i) the very small group of so-called nereistoxin analogues (4-N ,N -dimethylamino-1,2- dithiolane) such as the bis(thiocarbamate) proinsecticides cartap, bensultap, and thiocyclam; (ii) from the lead structure nithiazine (2-nitromethylenetetrahydro-1,3-thiazine), resulting neonicotinoid insecticides such as fi ve-membered ring systems (imidacloprid, thiacloprid) and six-membered ring systems (thiamethoxam) as well as noncyclic structures (nitenpyram, acetamiprid, clothianidin, dinotefuran); (iii) the spinosyns as a family of fermentation-derived insecticidal macrocyclic lactones, such as the bioinsecticides spinosad and the semisynthetic member spinetoram2  [because of their diff erent binding sites in comparison to neonicotinoids, spinosyns have a diff erent mode of action (MoA) classifi cation by the Insecticide Resistance Action Committee (IRAC; an expert committee of CropLife): n AChR allosteric activators, group 5]."





 Jeschke, Peter, et al. "Overview of the status and global strategy for neonicotinoids." Journal of Agricultural and Food Chemistry 59.7 (2010): 2897-2908.





" Spinosad (Fig. 2 ) is a mixture of two naturally occurring macrocyclic lactones (spinosyn A and spinosyn D), isolated from the actinomycete bacterium Saccharopolyspora spinosa . It was introduced as a commercial insecticide in 1997 (Thompson et al. 2000 ) and is active as a contact and stomach poison on a range of pest species (particularly those of the insect orders Lepidoptera, Diptera and Thysanoptera), causing prolonged over-excitation of the insect nervous system (Salgado 1998 ; Salgado et al. 1998 ). Spinosad is used widely for the control of agriculturally important pests, including leafworms (Spodoptera  spp.) and western flower thrips (Frankliniella occidentalis ). It has relatively low toxicity to mammals and birds, and only slight or moderate toxicity to aquatic organisms (Thompson et al. 2000 ; Sparks et al. 2001 ). Electrophysiological studies with cultured insect neurons have provided evidence that spinosyns may act on both nAChRs and c -aminobutyric acid (GABA) receptors (Salgado et al. 1997 ; Watson 2001 ). More recent studies performed with cockroach neurons have demonstrated that spinosad targets nAChRs but acts on a different population of nAChRs from those targeted by other insecticides such as neonicotinoids (Salgado and Saar 2004 )."





1. Millar, Neil S., and Ian Denholm. "Nicotinic acetylcholine receptors: targets for commercially important insecticides." Invertebrate Neuroscience 7.1 (2007): 53-66.





"Spinetoram was registered in September 2007 by the US Environmental Protection Agency, mainly because of its reduced-risk profile during preliminary risk assessments and its toxicological properties, which proved to be similar to those of spinosad.7 Therefore, spinetoram-based biopesticides (DelegateWG, Radiant SC) were first registered for use in the United States in September 2007,and they are currently on the market in Canada, New Zealand and the United States for management of various crop pests.8....Spinosad was first registered and commercialised in Korea and the United States in 1996–1997. It was initially formulated as a suspension concentrate for greenhouse and open-field spray applications (e.g. Tracer, Spintor, Success). In the last decade, this pesticide has also been commercialised as a prepacked sprayable bait formulation with low concentrations of spinosad mixed with a feeding attractant, mainly hydrolysed proteins, for Diptera Tephritidae adults (e.g. GF−120, Spintor-Isco, Spintor-Cebo).20,21 Spinosad is currently registered inmore than 80 countries throughout the world to control several pests belonging to Lepidoptera, Diptera, Thysanoptera and Coleoptera orders, in agricultural and forestry landscapes or in veterinary environments.3,8,22 In 2008, spinosad was included in Annex II of the EUCouncil Regulation 2092/91, and thus its use was authorised in organic farming in European member states.23..."





Of 19 studies conducted on honeybees to test lethal effects, the authors of this review documented adverse effects were found in 63% (i.e. 12 out of 19).  Of one study looking at sublethal effects, the authors didn't find any sublethal effect on honeybees in that study).  Eleven of these studies were field studies, and 45% found lethal effects on honeybees. (meaning 5 field studies showed lethality).





This is a review, the citation is:





Biondi, Antonio, et al. "The non‐target impact of spinosyns on beneficial arthropods." Pest management science 68.12 (2012): 1523-1536.





So it appears that Spinosad could be found in your environment just about anywhere and as it is related to neonics, it targets AChR in insects and is lethal to honeybees.  However, as we are told, when applied in "field-relevant doses" then, of course, there will be disagreement on whether it is toxic to bees,  because only about 1/2 of the studies found any effects.





Christina

















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