Biological Control of the Small Hive Beetle
By Ol’ Drone
Among the many diseases and parasites that pose health problems for honeybees, the small hive beetle (SHB) is unique and presents control challenges. Most other pests can be treated while they are residing and breeding within the hive, however this beetle reproduces outside the hive and worse yet has the ability to fly. Possessing a sharp sense of smell they can seek out honeybee colonies at quite a distance and if none are found, they can survive winter by finding food such as rotting fruit or veggies.
A native from Africa, it was found in Florida in 1998, has become well established in the Southern states and is gradually spreading North. Adult beetles lay hundreds of eggs within crevices in the hive and the larva feed on pollen, honey and brood. Larva can turn an entire colony into a slimy, stinking mess in a short time. The larva then crawl out of the hive and dig in the soil where they pupate. Upon emerging from the soil they can fly five miles to find a colony of honeybees. At first it was thought that they could not winter over in Northern states but that theory was proven wrong as live beetles were soon wintering over in Minnesota.
Many devices have been developed to control by trapping adult beetles in the hive, since the beetle hides from bees within small crevices around the frames. These traps attract the beetles and some traps contain a pesticide to kill them. Other traps expose the pests to oil to immobilize them. Also plastic sheets with cut-out slots are used. An insecticide “drench” solution can be soaked in the soil near the hive entrance to discourage larva from pupating. The best way to avoid damage from this pest is to keep the colony strong and vigorous. The worker bees do chase and kill the beetles if they find them in their hive. Bees also “corral” groups of beetles immobilizing them to prevent them from spreading eggs in the hive. A weak hive cannot fight and if beetles invade they usually lose the fight.
Nematodes are microscopic and small wiry worms. Hundreds of species are found in soil and many varieties are beneficial. (One type is used to control Japanese beetles). Garden centers and catalogs sell nematodes for various types of pest control. It has been found that if they are spread in the soil and if the SHB attempts to burrow for the winter, the nematodes will attack them. They quickly infect the beetle larva with bacteria and then proceed to consume the larva bodies.
In the mountain area where we live there is little or no problems with the SHB but just 30 miles south, the beekeepers consider the beetle a serious pest. Two theories have been identified for this geographic difference in beetle problem. Sandy soil makes it easy for the larva to burrow and winter over. By contrast, our local soil is not sandy but very rocky. Also the beetle has been found more prevalent in a 10 mile “corridor” including interstate highways. Remember that this pest is able to fly and could escape from the migratory pollinators flat-bed trucks, using interstate roads delivering bee hives.