Mining The Field Around Dung Beetles And Dewormers

Beefs and Beliefs

New products and new papers renew the debate over value and conservation of dung beetles.

Published on: February 20, 2014
 

Sometimes reporters and editors walk into metaphorical minefields.

That was my experience with two somewhat paradoxical interviews I did at NCBA in Nashville just a few days ago.

One meeting was with Dr. Jody Wade, a staff veterinarian for Boehringer-Ingelheim, and the other with Dr. Joe Dedrickson, a staff veterinarian for Merial Animal Health.

One conversation was about using dewormers in a manner that saves or enlarges dung beetle populations and the other about the successes of the first long-term anthelmintic dewormer to hit the market -- brand named Longrange.

Do you smell the rat yet?

I did as soon as I sat down for the second interview.

It reminded me of the series of stories I did on the controversy last winter and spring over the modified-live versus killed vaccines for IBR, an abortifacient disease. This began with meetings at NCBA in the winter and my main story on the topic ran in the April edition.

Although this was certainly a valid story and well worth writing about it was, perhaps secondarily, a battle between two companies over their main product offerings in IBR vaccines.

This year, however, it's not nearly so contentious an issue and I think we can steer straight to the salient points without much ado.

First let's cover the points on dung beetle improvement or preservation. This started with a new "white paper" written by veterinarian Wade. The disclaimer for my part is that BI owns the Cydectin brand of dewormer and claims it has much lower damaging effect on dung beetle larvae.

For the record, as Wade noted, the larvae are the victims of dewormers when they are encased in dewormer-filled dung and buried underground by their adult parents. What normally is their food source becomes their poison potion.

However, as was also noted by Wade, Cydectin is not completely dung beetle friendly either.

The key here, if you recognize the tremendous value of dung beetles and want to improve habitat for them, is to minimize their exposure to all anthelmintics. Every day of exposure decreases beetle populations for future benefits and reproduction.

As for BI's Cydectin product, which uses the active ingredient moxidectin, a 1994 study in Australia suggests it is much less toxic to dung beetle larvae and its concentrations in the animals and their dung drops much more quickly. Wade says this depends on the dung beetle species, to a degree.

Also, he says, the milbemycin family to which moxidectins belong have a different chemical structure than the avermectins, which is the other major family of modern dewormers. That difference in structure makes it less persistent in the bovine body and therefore shedding of the compounds in dung drops below threshold damage levels to dung beetle larvae much quicker than do the avermectins.

Initial shedding of deworming products from all the products, however, can be deadly to dung beetle larvae, Wade says.

Dedrickson's talking points, of course, are that Merial's Longrange dewormer is providing tremendous deworming capacity with its encapsulated, time-release technology and its second peak in product release about 70 days after the product injection.

He says it is lasting as long in field trials as the initial trials and tests had shown it would and this is enough to break the 90-day cycle of many internal parasites.

So here's my take-away message from the two meetings.

Wade suggests deworming in cold or freezing weather to avoid damage to dung beetles. Of course he would like you to use Cydectin because it may be less harmful.

It appears to me that if Longrange is so effective for so long, it would be very damaging to dung beetle populations. That might be something to consider when you are planning your deworming programs.

I have seen little on the persistence of dewormers in soil or whether that has any effect on dung beetles, although I have met a number of ranchers who believe it does. Bob Steger in central Texas once noted to me how little insect activity in general there was in the first paddock near his receiving pens. This was the pasture into which sheep, goats and cattle were always grazed first after deworming.

And to throw a little salt in everyone's eyes I'll tell this story: I know several successful ranchers who have quit using all dewormers, who rotate their cattle through multiple paddocks with long rest periods that would easily meet the 90-day life-cycle requirement Dedrickson mentions, and who then select against cattle that appear poor and thin and for cattle that stay fat and sleek.

I do not think many are such purists they would never use a dewormer but it is my clear understanding they believe they have selected for less-susceptible cattle at the same time they have established management that decreases problems with most parasites.