Midterm 2 Flashcards
What does PMRA stand for?
Pest Management Regulatory Agency
Where are pesticides found?
- In air, water, soil, sediment and food
- In the tissues of many aquatic species
How are pesticides transported to groundwater?
-mostly by recharge resulting from rainfall or irrigation within agricultural and urban areas where they are used
How do pesticides get to the atmosphere?
Transfer after application via volatization, spray drift and wind erosion
What happens to pesticides in the atomosphere?
-they are returned to earth by precipitation and dry deposition and can reach streams and ground water
What regulate the use of pesticides?
-there are provincial and municipal laws regarding the use of pesticides
What is a pesticide?
-any substance or mixture of substances used to destroy, suppress or alter the life cycle of any pest
What are the most common categories of pesticides?
-bactericides, fungicides, herbicides, insecticides, rodenticides and repellents
Where are pesticides used?
-in commercial, domestic and urban environments
What is a popular organochlorine?
DDT
When were neonicotinoids introduced?
In the 1990s
Derived from nicotine
How are neonicotinoids used?
- applied onto seeds or soil prior to planting
- and or sprayed onto foliage
What is the target pest for neonicotinoids?
- piercing-sucking insects (aphids, leafhoppers and whiteflies)
- also has a broad spectrum toxicity to a wide range of pests
Who gave the ted talk on bees?
-Marla Spivak, University of Minnesota
What is the mode of action of neonicotinoids?
-binds to nAChR(nicotine acetylcholine receptor) in postsynaptic neurons
What do neonicotinoids do when it is in the host?
- acts as a false neurotransmitter
- causes continuous activation of the receptor, leading to symptoms of neurotoxicity
What are the effects of receptor binding? (Neonics)
-receptor binding is irreversible so permanent effects are cumulative with time, and delayed toxicity exhibited
What class seems to be the most sensitive to neonicotinoids?
-class insecta
What is one of the biggest impacts of insect loss?
-cascading effects on insect eating species (birds, reptiles, amphibians and fish)
How do we know the amount of pesticide use in canada?
- pesticide reporting is confidential
- estimated via application rates and crop type
What is biotransformation?
The sum of the chemical reactions that occur within the body to alter the structure of a xenobiotic/endogenous compound
What is part of phase 1 of biotransformation?
- oxidation, hydrolysis, reduction
- make it hydrophilic to be excreted
What is phase 2 of biotransformation?
- conjugation/synthetic reactions
- something like a surface group is added to make it more excretable
What is the problem with using commonly used lab species for neonicotinoid testing?
- lab species used in standard toxicity tests are not always the most sensitive to neonicotinoids
- wide range of differences in sensitivities between invertebrate taxa
What are environmental quality guidelines based on?
-data for lab species
What is more useful for deriving environmental quality guidelines for neonicotinoids?
Species Sensitivity Distributions (SSDs)
What does a Species Sensitivity Distribution do?
-models the variation in sensitivity of a species to a particular stressor
How are species sensitivity distributions generated?
-by fitting a statistical function to the proportion of species affected as a function of toxicant concentration or dose
What is the goal of a species sensitivity distribution?
To predict the concentration that will protect a given percentage of species in the environment
What are the impacts of neonicotinoids on ecosystems?
- moderate to high acute toxicity to most invertebrates
- chronic low level exposure in water bodies and in plants
- birds and fish may have indirect effects because there are fewer insects to eat
What are three major neonicotinoid pesticides?
- imidacloprid
- thiamethoxam
- clothianidin
What is the toxicity modifying factor?
-when toxicity of a substance is affected by some environmental, chemical or biological factor
What are the basic components of the endocrine system?
- Endocrine gland/cell
- Hormone
- Target organ
What does the endocrine gland/cell do?
- secretes hormones
- effects distal target
What is the path of thyroid hormones?
- Higher brain center
- Hypothalamus
- TRH
- Pituitary
- TSH
- Thyroid
- T4, T3
- Target Tissues
What is the process of metamorphisis controlled by?
-thyroid hormone
What is an endocrine disrupting substance?
-exogenous substance or mixture that alter function of the endocrine system and consequently cause cause adverse health effects in an intact organism, or its progeny or (sub)populations
What are the critical windows of exposure for endocrine disrupting substance?
-exposure during early life stages may cause irreversible effects on organisms
What are the possible causes for sockeye salmon decline?
- climate change
- fishing pressures
- habitat destruction
- disease/ parasites
- environmental contaminants/ pollutants
Why are sockeye important?
- culturally important
- economically important
- ecologically important
What are neonicotinoids?
-class of neurotoxic, systemic, broad spectrum insecticides used in agriculture, around the home and on pets
What are the fates of neonicotinoids?
- uptake by plant
- enter waterways via runoff, leeching and spray drift
- soil
- target pests
- nontarget organisms
What did previous marlatt lab results show?
- increased whole body concentration of estradiol
- neonics could be a slight endocrine system disruptor
- possibility of feminization of gonads
