Keeping Cricket Farms Chirping
According to superstition, a cricket in the house means good luck. But the common brown or house cricket (Acheta domesticus) itself has been experiencing a great deal of bad luck lately due to the emergence of a virus that can cause high mortality (95% or more) in infected crickets.
While it may not seem like a big deal, losing crickets is worrisome for those who farm them.
The house cricket is the only species licensed by the USDA to be raised for commercial production. Food to innumerable species, notably reptiles and amphibians, raising crickets for commercial sales in a country where almost 5 million households own a reptile, not to mention the countless animals in zoos for which crickets are a dietary staple, is big business.
And so, when the virus, Acheta domesticus densovirus, started popping up in cricket farms in the U.S., Helen Aceto, PhD, VMD, was asked to get involved.
Dr. Aceto, an assistant professor of veterinary epidemiology and director of biosecurity at Penn Vet’s New Bolton Center, was first contacted by Ferdinand Visintainer, VMD (1985) of Country Doctor Veterinary Hospital. Dr. Visintainer’s client is Pennsylvania cricket farmer Dale Eldred. And while Eldred’s farm has been virus-free, he wants to ensure it stays that way.
A cricket newbie prior to this project, Dr. Aceto has learned a lot about both the insect and the virus. Acheta domesticus densovirus is a member of the parvovirus family that is related to canine parvovirus. The virus causes paralysis; diseased crickets flip onto their backs, unable to move, and ultimately die.
And it spreads quickly.
In 2002, the pathogen wiped out the commercial house cricket population in Europe. Now it is in North America and has affected cricket farms in both the U.S. and Canada. Bleach, ozone treatments and freezing have proven to be ineffective in eradicating the virus from affected farms. The infection has caused some producers to go out of business while others have suffered from periods of complete closure. Because of the devastating effect of the infection and persistence of the virus once introduced the best way to prevent problems is to keep it out in the first place. To this end, Eldred sought Dr. Aceto’s expertise on three fronts.
Eldred is planning a visit to his family in Michigan who also own a cricket farm, but one that unfortunately has had issues with the virus. Not wanting to put his own operation at risk, he sought the advice of a biosecurity expert to make sure he was doing all the right things in planning the visit. Dr. Aceto provided advice on measures that Eldred could take to ensure that he did not bring the virus back to his own farm, including contacts to avoid while visiting his family, appropriate disinfectant use and laundering of clothing, and even discussed items that might be best to discard rather than risk bringing the virus back with him.
In addition to advice for the trip, Eldred asked about the biosecurity practices he has instituted at his home farm to ensure that they remain virus-free.
“They are very diligent and seem to be doing everything correctly,” says Aceto. “For example, he will not now allow their vans and personnel to deliver the million or so crickets they produce each week directly to the wholesale distributor for fear of cross-contamination with crickets or contaminated items from other breeders. Like other parvoviruses, the cricket virus is very stable in the environment and is resistant to many disinfectants so it can be readily transferred on fomites.”
Clean By Design
Finally, to ensure all his biosecurity bases are covered, Eldred wants the input of a biosecurity expert on the design and operation of the new facility he has plans to build in the next year. As with any species raised in numbers, in captivity, “herd” health is crucial to the success of such a business.
Dr. Aceto is taking the project just as seriously as biosecurity issues encountered with more conventional livestock and the basic principles will be the same. Indeed, as she has been unable to find biosecurity recommendations specific to the commercial rearing of insects, the biosecurity program will have to be adapted from those available for other species, notably from the poultry and swine industries.
Need for Crickets
“The virus has led to shortages of crickets which obviously can affect the feeding of other species, particularly exotic pets,” explains Dr. Aceto. “Because the virus is a parvovirus, like other parvoviruses it is species-specific; the common house cricket is sensitive to the virus but other cricket species are not affected. This provides the opportunity for the industry to raise other species of cricket in place of the common house cricket.
“Possible replacements are being investigated by producers and the USDA, but it’s important to find a cricket species that can match or at least come close to the productivity of house crickets and that has the same nutritional qualities. In fact, after numerous attempts to decontaminate their cricket farm and a prolonged period of closure, Mr. Eldred’s family in Michigan is trying to re-establish their operation using the Jamaican field cricket but are finding the productivity of this species well below that of the house cricket.”
She also points out that neither humans, other animals in contact with the virus, nor those animals that ingest affected crickets, are susceptible to the virus. But the problem remains: how to contain a virus in a farm with many millions of crickets living in very dense quarters?
Dr. Aceto continues to learn more about the disease, how it is transmitted and actions that have been taken to try and prevent introduction of the virus or eradicate it once present. Her next step is a visit to Eldred’s Pennsylvania cricket farm to see for herself the process flow, and design a strategic biosecurity plan, the principle goal of which will be to keep the farm virus-free while also including a rapid response plan should the virus gain entry to the farm.