Insect Spotlight: Biofuel bugs

Farm Forum

I love the winter (or at least parts of it). Reading books, watching movies, playing games, sitting by the fire. The general pace of life slows down and gives time for reflection on the past year and planning for the future. But winter is only bearable when it is accompanied by two prerequisites: a steady and reliable source of heat, and a means to get around outside (e.g., planes, trains, and automobiles). Both of these require fuel.

Whether you love or hate the idea of growing our fuel, biofuels is quite a buzzword these days. As there are few degrees of separation between insects and most things in life (trust me, I’ve done the math), it should come as little surprise that insects are having important effects on biofuel production, and vice versa.

I often like to address the most troublesome issues first, so let’s cover this now: there are insect pests of biofuel crops.

As grasses are changed from their native communities into strict monocultures, nature tries to tip the balance straight. In come the insect herbivores to rebalance the plant community, and this not surprisingly is what is happening as we harness native biofuel plants into agronomic settings.

Researchers at South Dakota State University are showing that switchgrass and prairie cordgrass (two potential biofuel crops) can be hit hard by insect species that were almost entirely unknown from native stands of prairie. This is not a new introduction of some invasive species. It is nature trying to rebalance the plant community using insects that are at low densities in the natural systems.

But insect-biofuel interactions aren’t always bad. Driving through the landscape of the Great Plains can give bistanders the impression that things are pretty simple out there. To the unaided eye, much of the landscape looks to be corn, soybeans, wheat, etc. And this simplification has been exacerbated by corn-based ethanol production. These changes to the landscape have made it very difficult for some of the beneficial insects- things like pollinators or predators- to find habitat that they need to survive.

New crops, especially new flowering crops, can provide one answer to this simplification. Research throughout the US is showing just how useful some of these biofuel crops can be for friendly insects. Some of these investigations are showing how the usual suspects (Miscanthus and switchgrass) affect beneficial insects simply by providing some complexity to the landscape. But other research highlights how new crops might be used by beneficial insects.

Research going on at USDA-ARS in Brookings, SD, and Morris MN is trying to develop new flowering oilseed crops for the region that might be useful in conserving pollinators and predators in the landscape. By selecting a series of crops that flower at differing times of the season, flowers can be made available throughout the entire growing season, an important aspect of this study.

Finally, a major constraint on cellulosic biofuel production has been getting the right enzymes into the production systems that can efficiently digest the cellulose from plants. One location that might prove fruitful is looking into the stomachs of cellulose-digesting insects.

Gut bacteria of termites have been fermenting cellulose for eons, and efforts at Purdue University reveal some potential for using enzymes from this insect-microbe symbiosis for digesting plant cellulose. Thus, insects may soon unknowingly be helping us fuel our cars and homes.

As societal needs and technologies change, it is important to understand the broad implications of how these changes affect the world around us. Nowhere is this more true than in changes to farmland, which occupies such an important place in our economy, lives, and landscape. The rapid adaptation of entomologists to investigate the positive and negative interactions between biofuels and insect communities is a perfect case in point.

Jonathan Lundgren is a research entomologist with USDA in Brookings, S.D. Although interested in all aspects of insect biology, he specializes on insect conservation and reducing crop pests through the use of beneficial insects.