Comparing the Environmental and Economic Advantages of Organic and Conventional Farming

by Coco Coyle

In the Niayes region in Senegal, a country on Africa’s western coast, over three quarters of the population rely on local agriculture for their livelihood as well as for food. Furthermore, agriculture causes approximately one-third of all greenhouse gas emissions, so investigation of more sustainable farming practices may assist in reducing agriculture’s contribution to global warming. Binta and Barbier (2015) found that in the Niayes region, for farms of the same size, conventional practices are more economically profitable than organic practices. Thus while organic farming results in lesser greenhouse gas emissions and better health for farmers and consumers, conventional practices utilizing inorganic fertilizers and pesticides are more common. Ways to encourage more organic farming would be to develop local markets for organic produce, and to invest in research to improve organic management. Continue reading

Cholinergic Pesticides Cause Negative Neuronal Effects in Honeybees

by Lia Metzger

Recently, pesticides that target cholinergic neurotransmission have been found to aid in the decline of insect pollinators. In particular, neonicotinoids (nicotinic receptor agonists) and organophosphate miticides (acetylcholinesterase inhibitors) are commonly used and thus, frequently come in contact with honey bees. Palmer et al. (2013) investigated how these pesticides affect the neurophysiology of honey bees by using recordings from mushroom body Kenyon cells. Instead of studying the learning and behavior of honey bees that are exposed to neonicotinoids and organophosphate miticides, the authors used whole-cell recordings from Kenyon cells in honey bee brains, and assessed the native connectivity and nAChR expression in KCs. They found that the two neonicotinoids, imidacloprid and clothianidin, and coumaphos oxon decreased the KC excitability by inhibiting action-potential firing and reduced KC responsiveness to ACh. When the honey bee brains were exposed to both neonicotinoids and miticides as is common in large crops, the combined exposure added to the effects on KC excitability and nAChR-mediated responses. The honey bees are usually exposed to much higher concentrations of cholinergic pesticides, which indicates that the negative effects on the neurophysiological responses of the mushroom body cells would be heightened in reality. Continue reading

Pesticide Exposure May Degrade Human Cognitive Function

by Kahea Kanua

Pesticides are widely used toxins, yet research is only beginning to understand their effects on human brain and body functioning. In the United States, it is estimated that close to 8 billion dollars is spent on pesticides each year, yet only a few studies have examined the cognitive and neuropsychological impact of pesticide exposure, to mixed results. Schultz and Ferraro (2013) compared neuropsychological test performance of individuals with an occupational history of pesticide exposure to individuals with no such exposure history. The results suggested that occupational exposure to pesticides results in significant, and age-related, decline in some aspects of neuropsychological performance and information processing. Continue reading

Organophosphate Pesticides Cause DNA Damage in Rats

by Kahea Kanuha

The growing use of pesticides in large-scale agricultural applications as well as for household purposes has resulted in their widespread distribution in the environment. To see if pesticide exposure damaged DNA, Ojha et al. (2011) evaluated the genotoxicity of chlorpyrifos (CPF), methyl parathion (MPT), and malathion (MLT), three organophosphate pesticides, when given individually or in combination to rats. The results showed that even a single dose of CPF, MPT, or MLT caused significantly high levels of DNA damage in all the rat tissues examined. DNA damage was also observed in microscopic examinations of tissue samples from the liver, brain, kidney, and spleen of rats exposed to one or more pesticides. It was also observed that the damaged DNA is repaired by the endogenous repair systems with time. When the pesticides are given together, they do not potentiate …

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Honeybees Exposed to Acetylcholinesterase Inhibitors Exhibit Impaired Motor Function

Stress from parasites, pathogens, and pesticides have been contributing to the global decline of populations of honeybees and many pollinators for the past two decades. Specifically, the use of pesticides that affect neuromuscular functioning and kill parasitic mites have caused the accumulation of acaricides, or mite pesticides, in the wax combs of bees’ hives. To investigate the possibility of this accumulation contributing to the decline of bee populations, Williamson et al. (2013) studied the effects of prolonged exposure to pesticides that inhibit acetylcholinesterase (AChE) on the physiology and behavior of bees. Adult worker bees were fed sub-lethal concentrations of four AChE inhibitors in sucrose solutions and then were observed for walking, stopped, grooming, and upside down behavior. After the behavioral study, the bees were dissected to confirm that the four compounds they assayed or their metabolites were responsible for the change in behavior by testing for transcript expression levels of two honeybee AChE inhibitors and through biochemical assays. All AChE inhibitors caused increased grooming behavior, but coumaphos in particular caused more grooming and symptoms of sickness as the concentration increased. The authors found that the effects of pesticides that inhibit AChE on the motor functioning of bees could reduce their survival and contribute to the decline of bee colonies. —Lia Metzger

 
                  Williamson, S.M., Moffat, C., Gomerall, M.A., Saranzewa, N., Connolly, C.N., Wright, G.A., 2013. Exposure to acetylcholinesterase inhibitors alters the physiology and motor function of honeybees. Frontiers in physiology 4.

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