Insecticides

Look closely at a plant in your local park, your garden or even your kitchen, and you’re likely to see some damage. Whether a caterpillar has chewed away part of a leaf or a mealybug is sucking on sap, animals are constantly feeding on plants. Of course, herbivory, or plant predation, is not ideal for a plant’s survival. So plants have evolved many different defense mechanisms to inhibit this threat, including physical and chemical weapons. For example, cactuses arm their bodies with skin-piercing spines. Herbs such as mint, lavender and rosemary produce volatile scent compounds that can help deter herbivores. Other plants resort to bribing personal bodyguards by secreting thick, sweet nectar. Nectar is most commonly associated with flowers, where it is used to entice bees, birds or butterflies to move pollen from one flower to another. But other plants produce different types of nectar glands called extrafloral nectaries. Plants produce these glands to bribe ants...

Citrus trees showing natural tolerance to citrus greening disease host bacteria that produce novel antimicrobials that can be used to fight off the disease, our recent study shows. We found the trees at an organic farm in Clermont, Florida. Citrus greening disease – known more formally as Huanglongbing, or HLB, is caused by the bacterium Candidatus Liberibacter asiaticus. It is spread by an insect called the Asian citrus psyllid. There is no known cure for the disease. We are Florida-based researchers who study sustainable farming practices, a discipline also known as agroecology. Our team has isolated these antimicrobial compounds in the lab and is now working to test them with the goal of producing an effective treatment for HLB. Why it matters HLB has dealt a massive blow to Florida’s iconic citrus industry. Since citrus greening disease was first detected in the state in 2005, Florida citrus production is down by more than 92%. The disease is just one factor....

In 1962 environmental scientist Rachel Carson published “Silent Spring,” a bestselling book that asserted that overuse of pesticides was harming the environment and threatening human health. Carson did not call for banning DDT, the most widely used pesticide at that time, but she argued for using it and similar products much more selectively and paying attention to their effects on nontargeted species. “Silent Spring” is widely viewed as an inspiration for the modern environmental movement. These articles from The Conversation’s archive spotlight ongoing questions about pesticides and their effects. 1. Against absolutes Although the chemical industry attacked “Silent Spring” as anti-science and anti-progress, Carson believed that chemicals had their place in agriculture. She “favored a restrained use of pesticides, but not a complete elimination, and did not oppose judicious use of manufactured fertilizers,” writes Harvard...