An Agriculture Canada study shows that four common parasite control
products all reduce insect activity in cattle manure, but to varying
degrees.
The findings are part of ongoing research to help cattle producers make
informed pest control decisions, says Kevin Floate, who led the
three-year study with Doug Colwell at Ag Canada’s research centre in
Lethbridge, Alta.
Learning more about the non-target impact of pesticides allows
producers to better balance their concerns for effective pest control
Read Also
Agriculture ministers agree to AgriStability changes
federal government proposed several months ago to increase the compensation rate from 80 to 90 per cent and double the maximum payment from $3 million to $6 million
while protecting the environment.
The recent study looked at the effects of four endectocide products on
insects breeding in the manure of treated cattle. Several hundred
insect species typically occur in cattle manure, but only a few are
considered pests. Researchers also studied whether these products have
any impact on manure degradation.
“Our previous research had shown that residue from one of these
endectocides – ivermectin – is excreted in cattle manure and affects
both pest and beneficial insects,” Floate said.
The current study sought to quantify the relative toxicity of
ivermectin residues in manure against that of three other endectocides
sold in Canada.
In the study, groups of cattle were treated with recommended doses of
doramectin, eprinomectin, ivermectin or moxidectin in pour-on
formulations.
Manure collected shortly before treatment and one to four weeks after
treatment was then compared for insect activity. The experiment was
repeated in each of three years.
“The research showed that each of the four compounds reduced numbers of
at least some insect species in the manure,” Floate said.
However, moxidectin had the least effect and doramectin had the
greatest effect. Eprinomectin and ivermectin were in the middle.
Floate and Colwell reached a similar conclusion in a laboratory study
last year that compared the toxicity of these compounds against three
species of pest fly. A recent study in Australia also supports the
conclusion, which Floate said was reassuring.
The Lethbridge study also looked at whether these compounds affect
manure degradation.
“The idea being that if you reduce the number of insects tunnelling in
the manure, you also may influence how quickly the dung pat breaks
down.”
The results were not clear.
“In some cases, treatment was associated with decreased dung
degradation. In other cases, there was no detectable reduction in
degradation associated with treatment.”
He attributes that to the fact that insect activity is not the only
factor in manure degradation.
