Parasitic wasps may be the answer for horse owners seeking sustainable methods for fly control.
A new overview of equine fly management in the latest issue of the Journal of Integrated Pest Management suggests horse owners have been left in the dark about how best to manage flies because research just hasn’t been done.
However, one fly-management method that is gaining ground is the use of wasps that are parasitoids of fly pupae. The female wasp inserts an eggs into the fly puparium, and when the egg hatches, the wasp larva eats the fly pupa.
The authors conducted research on two wasp species that are sold commercially in the US to see what type of manure they preferred.
“In the lab, we found that the Muscidifurax species we tested preferred bovine manure, and the Spalangia species preferred equine manure, so there seems to be some sort of differentiation there, which could impact control on a farm,” said Erika Machtinger, one of the authors.
Because of this preference, the ability to identify fly species is important so the correct wasp parasitoid can be used, according to the authors.
The authors also provide other advice regarding when the wasps should be released, how often they should be released, and how many should be released.
“This is a really good article, and very useful in pointing out some directions, and things that need to be addressed,” said University of Kentucky insect specialist Lee Townsend, who was not involved with the study.
“People are looking for effective fly control. But they’re also looking for sustainable ways to do that, particularly those that avoid excessive insecticide use.”
The authors noted that biological control using pupal parasitoids had been used in livestock facilities for many years.
Husbandry practices in equine farms differed from cattle, swine, and poultry facilities, where most research on pupal parasitoid use had been conducted, they said.
They noted there were few guidelines available on the best execution of parasitoid release at equine facilities.
“While some recommendations are universal, others are based on information from use in other livestock facilities and what is known about parasitoid life history and preferences.”
They said that little was known about the basic biology of the wasps in equine farm systems.
“There is a pressing need to fill the knowledge gap on use of parasitoids on these facilities. With increased support for research directed at the equine industry, further improvements to recommendations for parasitoid use can be made.”
It had the potential to effectively reduce fly populations on equine farms, they said.
“With careful planning, horse owners can use pupal parasitoids as an environmentally sound method to reduce pest house fly and stable fly numbers and reduce the risks to horses and their owners.”
Use of Pupal Parasitoids as Biological Control Agents of Filth Flies on Equine Facilities
Erika T. Machtinger, Christopher J. Geden, Phillip E. Kaufman, Amanda M. House
The overview can be read here.
The overview was published as an open-access article.