Crop Protection Ecology
Above: A honeybee (Apis mellifera) feeds on a silphium (Silphium integrifolium) flower. Honeybee hives at The Land Institute serve to pollinate our perennial crop species, as well as produce silphium-alfalfa, or “silfalfa,” honey (inset).
Insects and Perennial Crops
There are over 900,000 described species of insects worldwide, and like us most of them rely on plants for food. Many insect species are important for the growth and development of our perennial crops. Alfalfa, kura clover, sainfoin, and silphium are pollinated by honeybees, native bees, butterflies, and native flies. Perennial crops also provide excellent habitat for “natural enemies”: spiders, centipedes, and insects that feed on harmful insects.
Perennial crops also provide habitat for insects that feed on and damage the crop itself. Some of these pests are the same as those found in the annual equivalent of our crops, such as chinch bugs and sugarcane aphids in the perennial sorghum. Other pests are unique to our crops, such as the eucosma moth (Eucosma giganteana), a specialist pest that feeds only on plants in the Silphium genus. Managing pests in perennial systems can be challenging, as we cannot rely on annual tillage and crop rotation to disrupt pest populations. However, perennial systems can also provide unique opportunities for pest management, as the lack of soil disturbance can allow us to build beneficial soil organisms and natural enemy populations to defend the crops against pests. Selective intercropping of plant species can also help to build beneficial organism populations and reduce pest damage. The mission of the Crop Protection Ecology program is to determine how different crop management practices and synergistic relationships in diverse cropping systems can be employed to successfully increase beneficial insects and manage crop pests in perennial grains.
Management of Eucosma in Silphium
By definition, an insect is not considered an agricultural “pest” until it feeds on an agricultural crop. Nature abounds with insect species that specialize in feeding on native plant species. While these insects have been described, often very little is known about their behavior or ecology because they are not considered aesthetically or economically important. The eucosma moth was once a prime example of this. As a native specialist, it feeds on the flower buds and root crowns of Silphium integrifolium. Now that silphium is being domesticated for oilseed production, large fields of these flowers provide ideal habitat for eucosma and make it a significant pest of this crop. Our research objectives are to understand the eucosma life cycle and ecology, and to develop effective methods for managing this pest.
Perennial Crops Provide Multiple Ecosystem Services
Our perennial crops, in addition to providing a sustainable grain harvest, have the potential to provide other ecosystem services. Their biomass can be harvested for forage, their vegetative growth can provide habitat for natural enemies, and the flowering perennial crops can provide resources for native pollinators.
The Crop Protection Ecology lab is collaborating with the Perennial Oilseeds team, the Perennial Legumes team, and Dr. Tania Kim and Dr. Brian Spiesman at Kansas State University to determine the extent to which Kernza® (Thinopyrum intermedium), alfalfa (Medicago sativa), sainfoin, silphium, and cup plant (Silphium perfoliatum) provide each of these services, and which species provide the best balance of these services. This project will also provide us with valuable information about the pollinator and natural enemy species that colonize our perennial crops, and which plant traits are most attractive to these species, so that these traits may be selected for and preserved in our future breeding programs.
Arbuscular Mycorrhizae: Helping Plants to Defend Themselves
Breeding for pest and pathogen resistance is an important aspect of our perennial grains programs. Plants naturally produce chemicals to defend themselves against insect feeding and pathogen infections. However, the natural resistance of plants can be helped or hindered by its growing environment and ecological interactions. It is important for us to study these interactions so that we can determine how best to manage our perennial crops so that they can defend themselves.
Arbuscular mycorrhizal fungi (AMF) are symbiotic fungi that colonize the roots of more than 85% of all plant species. These AMF have long been known to increase nutrient uptake from the soil and improve plant growth. More recent research has shown that AMF can also boost a plant’s ability to release chemical defenses when the plant is infected with an insect pest or pathogen. In collaboration with Dr. Jared Ali, Dr. Swayamjit Ray, and Dr. Jason Kaye at Penn State University, we are conducting experiments to determine how AMF may affect plant defense against insects in our perennial crops, and how this compares to AMF colonization and plant defense in annual crops.