The earth would be one global ball of dung if it weren't for the activities of scarabs or dung beetles and other insects!
Careful chemical use must consider dung fauna preservation
Entomologists have been investigating the possible detrimental effects of the veterinary chemicals used to control parasites in livestock on beneficial organisms which live in and feed on animal dung.
- Rank grass grows around unburied dung which has not been dispersed by dung beetles, in a pasture. This is called the "ring of repugnance" as livestock will not eat this grass leaving a large proportion of the
- Dung beetles help keep pastures clean and palatable by breaking down and burying the dung.
The increasing dependence on broad-spectrum veterinary chemicals to control external and internal parasites in livestock may have long-term toxic effects on beneficial organisms living in dung.
There is mounting evidence that residues from many of the chemicals commonly used to protect livestock from parasites can impact on dung fauna, causing anything from reduced longevity and egg production to death.
- Many of these organisms, particularly dung beetles, play a vital role in dung dispersal and nutrient cycling in the environment.
- Scientists believe that, while it is important to maintain the advantages of controlling livestock pests by using veterinary chemicals, the adverse side effects of these on dung fauna are of considerable concern.
Dung beetle introduction
Australia’s native dung beetles were unable to cope with the dung produced by introduced livestock. This resulted in large scale fouling of pasture and ideal conditions for dung-breeding pest flies.
In a project which started during 1968 and lasted for almost twenty-five years, entomologists introduced many new species of dung beetles from overseas countries including Africa and Europe, with the objective of tackling these problems and returning nutrients to the soil.
- A large-scale beetle redistribution program was also carried out, once the new arrivals were established.
- Redistributions were continued in some areas by State agriculture departments until 1999 and are still being undertaken by farmers and other interested people who have witnessed the environmental and economic benefits of dung beetles.
Expanding concerns continue
As early as 1966, in the United States, there was concern over the possible detrimental effects of chemical additives in livestock feed on dung dwelling organisms: such as, dung beetles. Since then, there have been rapid and dramatic changes in the chemicals used to control internal and external parasites of
livestock with the development of new, highly active compounds.
These include the macrocyclic lactones (MLs), synthetic pyrethroids (SPs) and insect growth regulators. Growth regulators are not widely used but can have a long-term effect on dung fauna. Many of these chemicals are formulated to ensure they give protection for an extended period. Some sustained release formulations can remain active for up to 100 days or more.
Toxic effects of macrocyclic lactones
The macrocyclic lactones (MLs) are used mostly for gastrointestinal nematodes and lungworms that infect cattle, as well as, external parasites. Most of these chemicals are only partially metabolised on their way through the animal and will appear in the feces intact.
- Excretion periods depend on both the way the drug is formulated and the way it is applied.
- When in the dung, these chemicals have the potential to affect the insects and other invertebrates which break it down.
Scientists have been examining the growing volume of evidence that MLs, when applied at the recommended dose rate, can cause death in a wide range of dung-feeding invertebrates, particularly flies and dung beetles. They appear to be most toxic to the larval stages of these insects.
Oral preparations; such as, those used in sheep, are eliminated rapidly and are thought unlikely to have any lasting effect on the abundance of dung-feeding insects.
- Injectable and pour-on formulations, which are widely used by cattle producers, are excreted over much longer periods and have the potential to make a significant impact on beetle populations in the vicinity of the treated herd.
- Of greatest concern are the sustained release devices, which may result in the production of toxic dung for periods of 100 days or more.
- Their effect on populations of dung feeding arthropods will depend on the timing and frequency of the treatment in relation to insect activity, as well as on the proportion of graziers using them.
Since the avermectins are not water soluble and because they bind tightly to particulate matter, there is also a potential for residues to accumulate in the soil where dung is buried. This could prolong some of the effects of the residues on dung and soil fauna.
There is some research available showing dung is more attractive to earthworms after it has been colonised by flies and beetles, which means any chemical affecting these organisms may also affect earthworm activity.
Dung beetles are vital for dung dispersal and nutrient cycling in pastures; but increasing evidence shows
many of the chemicals used to treat parasites in livestock can adversely affect dung fauna; such as, dung
beetles, causing reduced longevity, egg production and even death.
Increasing evidence suggests that many of the broad-spectrum chemicals used to treat internal and external
parasites in livestock may have long-term toxic effects on dung fauna, including dung beetles.
The insect world is famous for its Olympian power-lifters, but the horned dung beetle (Onthophagus Taurus) takes the gold. A mere ten millimeters long, the beetle can pull up to 1141 times its own body weight; the equivalent of an average man lifting two fully-loaded 18-wheeler trucks.
That makes it a third stronger than the strongest known insect (the rhinoceros beetle), hundreds of times stronger than ants, and just a shade weaker than the world's strongest animal, a tiny yet tenacious mite known as Archegozetes longisetosus.
Scientists believe the beetle evolved such strength because brute force is the deciding factor in a males' competition over females, which is waged as head-to-head pushing matches in dung tunnels.
Here's more information about scarabs or dung beetles.
Contributions of dung beetles to healthier grazing animals.
Other "dung, feces, scarab, excrement" units:
A cross reference of other word family units that are related directly, or indirectly, with: "insects, bugs, worms; invertebrates":
Dung Beetles Important;
Mosquito, other Languages;
Mosquitoes, Pt. 1;
Mosquitoes, Pt. 2;