Effects of Host-plant Density on Herbivores and Their Parasitoids: A Field Experiment with a Native Perennial Legume

Abstract

Professor Krishnaswamy Jayachandran, Major ProfessorSenna mexicana chapmanii (Fabaceae: Caesalpinoideae), an attractive and threatened species native to pine rocklands of southern Florida, is consumed by folivorous caterpillars of Sulfur butterflies (Lepidoptera: Pieridae). Caterpillars may be deterred or eaten by predators, but also very important are parasitoids, both flies and wasps. This study investigated the effects of plant density on Sulfur caterpillar numbers and rates of parasitization.Senna mexicana chapmanii plantations were established at agricultural and urban areas; both sites are adjacent to protected pine rockland areas. Sulfur butterfly immature stages were collected and reared to glean information regarding number of herbivores and rates of parasitization. Continuing this weekly monitoring protocol over the course of a year provided data to determine that higher plant density has an effect on levels of parisitization and is correlated with the number of herbivores. Elucidating these patterns has important implications understanding the factors that regulate interactions in this plant/herbivore/parasitoid system.

Weeds Enhance Insect Diversity and Abundance and May Improve Soil Conditions in Mango Cultivation of South Florida

“…This study also supports the practice of some local mango farmers who leave selected attractive and beneficial weeds, such as Bidens sp., around their trees [ 79 ]. Additionally, there are many other potential insectary plants, including flowers such as sweet alyssum and buckwheat [ 5 ], or native herbaceous plants such as the Bahama Senna [ 80 ], which may provide alternatives for farmers to support beneficial insects.…”