2 A. Pesticides A1. Pesticides are chemicals that kill pests A million tonnes of pesticides used yearlyA3. 75% used in agriculture
3 B-Types of pesticidesB1. Insecticides: kill insects by attacking their nervous systemB2. Herbicides: kill undesirableplants (weeds)B3. Bateriocides: kill bacteria.B4. Fungicides: kill fungi, mold
4 C-Benefits of using pesticides? C1- Protect, thus protecting industries’ and farmers’ profitsC2- Prevent epidemic outbreakDiscuss in pair
5 D- Problems with Pesticides Let’s brainstorm in pairs, with whiteboard
6 D- Problems with Pesticides? D1. Mutation randomly occur allows pest to develop resistance to pesticidesD2. Costs lots of time and resources to constantly develop new poisonsD3. They are often toxic substances and can accumulate and magnify in the food chain
8 FOOD FOR THOUGHT ACTIVITY You are what you eat!!!FOOD FOR THOUGHT ACTIVITYDue Monday Sep
9 E-BioaccumulationE1. refers to an increase in the concentration of a chemical in an organism over time.
10 F- Biomagnification (=bioamplification) F1. Biomagnification is the increase concentration of toxic chemicals, such as pesticides as it is passed upwards and maximized to the top predator of the food chainBioaccumulation worsens biomagnification
11 TROPHIC LEVELTrophic level is the position that an organism occupies in a food chain - what it eats, and what eats it.
12 G- Meet a pesticide DDT: (stands for Dichlorodiphenyltrichloroethane) - First produced in 1939a highly potent,fat soluble insecticidesTobacco extract (i.e. nicotine sulfate) as insecticidesPlants themselves developed chemicals that can kill animals that graze on thema DDT molecule
13 H- Case study 1: DDT and the bald eagle Bald eagles feed on fishThey disappear for many reasons:H1. Loss of habitat (industrialization, deforestation)H2. HuntingH3.Toxins in lakein lake
14 I-DDT in the Great Lakes I1. How DDT enter the Great Lakes?I2. In this food chain, what type of consumer is the bald eagle?I3. tertiary (top) consumerI4.How could DDT end up in the bald eagle with highest concentration?
15 J-Impacts of DDT on birds double-crested cormorantDDT was banned in Canada in 1971Egg shell thinning
16 K-DDT and Human HealthK1. Concentration of 6-10 mg/kg leads to such symptoms as headache, nausea, vomitingK2. Lethal (=deadly) dose :236 mg DDT per kg of body weight
17 L-DiscussionL1.There still countries haven’t banned DDT. Why would this be of concern to Canadians?L2. Breast milk contains fat. How breast-feeding might affect the concentration of DDT in a mother and in her baby?Throw in questions of scavenger (vulture)
18 M-Recent pesticide development -Water soluble pesticides-animals can remove them in livers-break down quickly-therefore need to apply them more frequently
19 R- Mercury Poisoning- Minamata disease Choose the most correct statement(s)The residents of Minamata have bioaccummulated mercury in their bodyThe residents of Minamata have biomagnified mercury in their bodyThe residents of Minamata display both bioaccummulation and biomagnificationThe residents of Minamata have also suffered from lead poisoning