Common Components of Pesticide Formulations Technical grade chemical (active ingredient) Active Ingredient: Abamectin (CAS No.65195-56-4 and65195-55-3).1.9% Other Ingredients: 98.1% Adjuvants/synergists Total: 100.0% 1 gal.contains 0.15 lb.abamectin EPA Reg.No.100-897 EPA Est.39578-TX-001 ·“Inert"ingredients NCP897A-L1A1297 e.g.,formaldehyde,sulfuric acid, benzene,toluene,other organic solvents
Common Components of Pesticide Formulations • Technical grade chemical (active ingredient) • Adjuvants/synergists • “Inert” ingredients – e.g., formaldehyde, sulfuric acid, benzene, toluene, other organic solvents
Targets of Pesticides ACh Many different neurons have inputs into each nerve cell. Cholinergic(acetylcholine or ACh) neurons stimulate action potentials (+ GABA neurons stabilize cells in the brain,glycine in the periphery(-). Action potentials are initiated when positive stimulation overcomes negative modulation (+>-) The neuron integrates many inputs. AP initiation is a summation event. Glycine Pesticides disrupt neural function by affecting neurotransmission at the synapse or along the nerve
Targets of Pesticides
Organochlorine Pesticides First mass-produced pesticides Broad spectrum,killing many pests Neurotoxicants with effects on many systems Generally very persistent Fat soluble (lipophilic) Poorly metabolized Bioaccumulation,bioconcentration and biomagnification Most phased-out in the 1970s,though still used and can be a problem
DDT and Its Allies CI DDT-First mass produced synthetic pesticide-late 1940s DDT Poor dermal but effective oral availability in vertebrates C CI DDT is transformed to DDE in DDE animals and in the environment DDE and DDT bioconcentrate and CH,-O O-CH, biomagnify in biotic food webs cCl, Methoxychlor Many species developed resistance OH CI Methoxychlor and Dicofol are better metabolized-still in use Dicofol DDT still used in mosquito control
Electrophysiological Effects of DDT 50 msec Fig.1.Postsynaptic responses recorded extracellularly from the abdom- inal nerve cord of the cockroach as evoked by a presynaptic stimulus applied to the cercal nerve.A,control.B,after application of 28 uM DDT. Depolarizing after-potential of individual nerve fibers is greatly pro- longed.From Yamasaki and Ishii (1952)
Electrophysiological Effects of DDT