What can beekeepers do, short of closing shop, if varroa mites infest their hives? While miticides effectively kill the mites, the trouble and costs involved in controlling the pests may be too much to bear. According to state Plant Pest Control Branch administrator Neil Reimer, miticides will kill 95-100 percent of the mites in a highly infested hive. However, he adds, there is evidence that mites on the mainland are developing a resistance to Apistan (fluvalinate), the most commonly used pesticide. Mite Away II (formic acid), ApiLife VAR (thymol), and ApiGuard (thymol), and as of December 2007, the DOA was working on two others, Sucrocide (sucrose octanoate esters) and Check Mite (coumaphos).
Michael Kliks, president of the Hawai`i Beekeepers’ Association, says that Apistan can contaminate beeswax, “but is safest [miticide] that still has punch.” While miticides effectively control the mites, they limit the amount of saleable honey a hive can produce. Apistan, for example, must be used on an infested hive for 42 days, during which time no honey can be taken. “You will suffer bee losses and you can’t take honey for two months. The most important time to treat is…the most productive time for honey. We’re losing a third of our annual production. I’ve lost close to 200,000 pounds of honey,” Kliks says. While he says only two of his colonies have “reverted to mite positivity” following treatments, he adds that maintenance costs per colony triple once they become infested.
Pesticides are not an option for organic honey producers and can also hurt the queen breeding industry. For those industries, Kliks says there is an organic gel that can be used. Reimer says that in other places, beekeepers have tried sprinkling bees with powdered sugar to make them too slippery for the mites to cling to. But, he says, this is expensive and what’s more, in humid Hawai`i, the high humidity might cause the sugar to clump.
Yet another possible control method is to shrink the combs from which the bees emerge, Reimer says. Smaller cells shorten the bees’ gestation period and result in smaller bees and would also prevent the mites that are encased in the cells with the bees from fully developing.
In addition to controlling mites in the hive, Kliks proposes that the state should establish a bee supply source on remote parts of the islands to make sure that there is always a cache of mite-free bees. He also favors imposition of strict protocols over interisland transport of bees. While Kliks says that the DOA believes its safe to send Kona bees to Moloka`i, since Kona is believed to still be mite-free, “The only way to really tell if a colony of bees is infested with varroa is if you kill all bees in the colony and you subject them to an alcohol shake, and then you look.” Short of doing that, Kliks suggests that large-scale beekeepers kill all of the bees in three percent of their colonies. If mites are not detected, all bees from every fifth colony should be killed and sampled. If mites are still not found, they should then do 500-bee sample from their remaining colonies. If mites are still not found, then Kliks believes the bees should be safe to ship, so long as they are dosed with Apistan. Once they arrive at their destination, they should be tested again.
This strict protocol, Kliks says, would reduce the risk to a “1 in 10,000 chance that you blew it.”
— Teresa Dawson
Volume 19, Number 5 November 2008
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