South Dakota Grassland Coalition

by Pete Bauman

July 2020

Researchers from SDSU and the Ecdysis Foundation under the direction of Dr. Jon Lundgren continue to work on improving our understanding of the role of dung beetles and other insects in pasture management and the relationship between forage quality, livestock, soil health, insects, and chemical pesticide applications.

How do dung beetles generally function?

This is a question asked by a lot of people new to the conversation on dung beetles. Simply put, dung beetles forage, lay their eggs, and live their life cycle in and around the manure of a variety of animals. However, for the sake of this article, we’ll focus on dung beetles associated with live-stock manure in pastures.

Why should I care about dung beetles?

If you care about your cattle, you will want to care about dung beetles. They play a critical role in the cycle of pasture nutrients and forage production. As dung beetles and their larva occupy a manure pat, they bore holes and tunnels through the manure, helping cool the manure and reducing its ability to serve as a host for livestock pest species development. The holes and tunnels pave the way for small predators looking for a meal of pest eggs or larvae. In addition, depending on the specific species of dung beetle, they can consume and relocate much of the dung material, often burying it in the soil. This process is incredibly beneficial to soil health, nutrient cycling, fertilization, and ultimately grassland production. Further, by breaking up the dung pat quickly, vegetation is not smothered and thus pasture production potential is not only maintained, but in-creased.

What do I need to do to have dung beetles?

Managing dung beetles in your pasture has much less to do with what you should start doing than it does with what you should stop doing. Overall, chemical pesticide pourons or injectables have residual effects on dung beetles. These chemicals are designed to persist in manure with the intention of killing pest larva, such as flies. However, these chemicals can be toxic to dung beetles or their larva. Now, many producers are of the opinion that eliminating the pest is more important than protecting a few dung beetles, but this is proving to be a very short-sighted assumption. Re-search is showing that the reduction in dung beetles from systemic pesticides can also reduce the natural predators of these livestock pests. Further, and ironically, this research also found that livestock operations utilizing the most frequent treatments of pesticides, such as ivermectin, actually have more pest larva in the dung than do operations that choose to use no pourons!!.

From a pasture management perspective, there is much to be gained by considering the following options to spend less money and potentially grow more grass. If livestock management is based on fairly frequent rotation, livestock are moved away from the source of pests more frequently. If dung beetles are present and active, the dung is less hospitable to the pest species, and we have less pests and a healthier predator population to control them. If dung beetles break down the dung quickly nutrients are also recycled quickly, eliminating the false notion that artificial fertilizers are necessary. If dung pats are broken down and recycled, more grass grows in those areas where dung pats were smothering the grass.

If livestock are managed, overall production is increased. Well managed pastures have less opportunity for weeds, and thus less need to spend money on chemicals which can further degrade the system.

Profitability isn’t solely based on income, but on what you don’t spend. Consider these points. Now consider the irony of spending time and money on livestock treatments for pests, such as ivermectin, for cattle going out to pasture. Then, because there are no insects to break down the manure, the pasture appears underproductive, so you spend money on commercial fertilizer. Then, because the livestock are not being rotated frequently or at all, bare ground persists and becomes infested with weeds, which then you spend money on spraying!!!!

In this difficult farm economy, less can be more. Less inputs on pasture expenses and more emphasis on man-aging the herd can reap rewards of a functioning pasture system that requires very little artificial inputs.

Source: SDGC Newsletter

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