4/1/1999
Most pesticides are not water-soluble. [If it talks about petroleum distillates on the can, it is not water-soluble]. Current pesticides work in one of two ways: 1) nerve toxins (usually specific to insects or in low enough concentration as to not affect mammals significantly) or 2) hormonal, as in affecting development. Sometimes the insecticide will have a pheromone component to make it attractive to the kinds of insects in question. The problem is that pesticides rarely stay where they are put and affect other species than the intended ones. Concentration for water-insoluble compounds is hard to define, so rather than concentration this lab looks at contact.
MATERIALS:
3 - 4 cans of different pesticides
Latex or vinyl gloves
Disposable petri dishes
zip lock bags
Sea urchin eggs & sperm
PROCEDURE:
Spray two petri dishes with each pesticide. Wipe one clean with a paper towel [dispose of paper towel in zip lock bag, so janitor is not exposed]
Set up control petri dishes, one unwiped [no pesticide] and one wiped [no pesticide]
Add egg suspension and wait five minutes.
Add sperm suspension.
Wait five minutes
Score for fertilization, development at 2 hours and development at 24 hours
When done dispose of contaminated petri dishes in zip lock bags.
QUESTIONS:
Why did I include a petri dish that was wiped? You could carry this one step further and spray a petri dish and then try to clean it with soap and water (rinsed well). Does this remove the pesticide?
What about the "environmentally friendly" pesticides that are coming out on the market?
Can the results of this experiment be extrapolated to humans? Ecology concerns such as diversity?