Thursday, January 20, 2005

Small Hive Beetle

This paper on the Small Hive Beetle was written for the Piedmont Beekeeper's Association, Virginia, USA. Use as you wish. Please send corrections! I used the internet and the articles in ABJ. There is less information than I would like, so send any you have. Thanks, Susi

Small Hive Beetle (Aethina Tumida Murray)
A type of sap beetle, the Small Hive Beetle (SHB) is considered a minor pest in its native Southern Africa. Arriving in the mid-Nineties in the US, perhaps in a fruit shipment in either South Carolina or Georgia, it was first recognized in beehives in Florida in 1998. In year round warm, humid, areas it can go through five lifecycles a year, and has become a serious pest in coastal regions of North America. It is in Virginia, on the coast, and moving inland steadily. It is established in North Carolina and Pennsylvania. The Commonwealth is prohibiting movement of hives out of infested areas and aggressively treating infested hives. Beekeepers must report suspected infestations to the Virginia Apiarist, (804) 786-3515, who will work with them to eradicate the infestation and salvage the bees.
The mature beetle is tan or reddish (newly hatched), turning to black as it ages, about 1/3 the size of a honeybee. Quickness and a fuzzy coat make it very hard to catch. As it ages it prefers a dark area of the hive, often just under the cover, or on the inner cover. In areas with few bees beetles might be on the comb. Reportedly they can fly up to 15 miles. The newly hatched beetles are the most active, flying readily. They are attracted to sweet smells and can reproduce on fruit, from apples to melons. Cantaloupe is a reputed favorite.
The females can lay up to 2000 eggs, living up to six-months. The eggs are oval, similar, but smaller, than bee eggs; usually hidden in cracks. Irregular masses may be found openly in untenanted hive areas. Hatching is heat dependent: 1-16 days. Since disturbance triggers egg laying, larvae will hatch in groups.
Upon hatching the larvae will wander, openly or by burrowing, through the comb, seeking protein (pollen or brood) and honey. Higher protein food produces more female beetles. The bees attempt to remove larvae or corral them. Guard bees feed the corralled larvae when the larvae stimulate the bee's mandibles causing regurgitation of honey and pollen, as do bee brood. Until the hive is overrun with larvae this strategy will work. However the hive is weakened by the assignment of bees to guard and feed the beetle larvae.
The larvae look like small wax moth larvae, less than 1/2 inch long. However, they have three front leg pairs, close behind a darker head, spiny protuberances along their backs and twin dark spines at the tail end. The wax moth larva has legs all along its sides and is thinner skinned, and easily punctured. The SHB larvae are very tough skinned, and have noticeable circular constrictions around the body, like tight bands around a soft tube, pointed at the ends. They can be found in masses in the 'corrals' or scattered over the comb. There are no silken tunnels with the SHB larvae, since they do not spin a cocoon, but harden into light colored pupae in the soil. Instead, the combs may have a greasy or wet appearance from larval feces. This is the slime that will ferment the honey, causing a smell akin to rotting oranges. Like foulbrood, knowledgeable beekeepers can identify infested hives by smell.
Once the larvae are ready for pupation, usually 10-16 days after hatching, they will drop out of the hive at night. Their tough skin and the large numbers of fellow larvae protect them. They head for light, and can move across hundreds of meters of rough concrete. This is their most vulnerable period. They burrow in the dirt, preferably loose and moist, but they can survive in hard clay. In wet dirt the larvae will leave an air hole to the surface. The pupa is a light tan color and the same size as the beetle. Pupation takes 3-4 weeks and more will survive in moist soil. Tests are showing that soil borne fungus can cause death of the beetles while pupating, and fire ants are a common predator in the south.
Upon hatching the red or tan new beetles mate and fly to food sources, drawn by smell. In a week the females start laying.
Once the hive is so full of larvae that the bee's control strategy is overwhelmed, and the uncapped bee brood are dying from the burrowing larvae the bees will often abscond, swarming as a whole hive and look for new quarters. Before they abscond they usually eject all the open brood from the nest.
In the USA the Small Hive Beetle has become a major honeybee pest. Absent its normal enemies in Africa the beetle has been able to breed inside European honeybee hives rapidly enough to overwhelm even strong hives. Current research has found funguses and pests, mainly ants, which target the beetle larvae and pupae, limiting the number of maturing beetles


* Check any packages and gang boxes of queens. Larvae are accidentally shaken in.
* Check and watch your beehives. If you suspect SHB call the State Apiary Inspector (804) 786-3515.
* Don't sell or buy hives without getting an inspection from the State Apiary Inspector (804) 786-3515. Don't buy used equipment from infested areas.
* Keep your bee yards clean so you notice signs of infestation.
* When you extract, watch for larvae.
* Keep an eye on fruit, especially if you bring some in from infested areas.
* Signs of infestation: smell, ejected brood, absconding, dripping honey, larvae and beetles.
* Keep strong hives, don't give more comb than the bees can defend.
* Re-queen with hygienic stock. Their hygienic traits work against SHB also.
* Keep bait hives in the apiary throughout the year for absconding hives. CHANGE EXTRACTING PRACTICES:
* Keep the honey house very clean, so you notice the larvae and beetles.
* Raise supers off the floor and provide a light to attract the larvae that drop out of them. Sweep up the larvae and drown them in deep water.
* Use lots of ventilation and a dehumidifier to dry the air. This slows down the eggs and larvae. It also helps keep your honey dry. Some processors will chill the super storage rooms to lower the activity and hatch rate.
* Process rapidly. Don¹t let the supers sit, or you may lose the honey to the larvae slime. Process cappings quickly also.
* If you store comb after extraction, freeze it (-12C/24 Hrs), or return it to the original hive, or use PDB to fumigate it.
* Check your frames before extracting. Slimy frames should be discarded. Larvae will collect in your extractor if they are present. This may be your first sign you have SHB. Levels of acceptance haven't been discussed, but too much slime will ferment the batch.
* Assume all supers have at least eggs in them. Freeze if possible, Return to a strong hive that can protect them, preferably the original hive.
* Don't separate bees from comb, which will allow the beetles to proliferate.
* Combining hives, splitting, or other manipulations can transfer infestations. Assume all hives in an apiary are infested.
* Replacing supers after extraction can infest other hives.
* All unprotected comb is vulnerable. Dispose of any old comb carefully, since the beetles can grow to maturity on its higher protein content.
* Treat the ground with the proper permethrin product. Repeat at 30-day intervals. Cut grass first, protect bees and foragers and apply at dusk.
* As needed, use the Dadant traps (Checkmite stapled to a corrugated paper)
* Move hives to prevent beetles from building up in any one area.
* Requeen with hygienic stock. Kill vulnerable queens.
* Try drowning traps under or in front of the hive, depending on the bottom board. Mineral oil and alcohol kill the beetles and larvae quickly; water will drown the larvae but not the beetles. Damp dirt may encourage the larvae to pupate in the trap.
* Remember that disturbances triggers egg laying. Figure out your strategy.
* Set out baited traps (like wasp or Japanese beetle traps). Vinegar attracts, mineral oil and alcohol kills. Put these away from your hives so you don't lure beetles in.
* Bait interior traps with honey/brood, with small openings to save bees.
* If you do get ‘Slimed’ by the SHB larvae, use a strong water jet and rinse the frames pretty clean; the bees will finish cleaning them.

The Virginia (USA) Bee Inspector added:
There are two additional products that have been developed for SHB control in the hive. There is a bottom board beetle trap available from most suppliers. The West SHB trap has proven effective in trapping and killing adults and migrating larvae. Also, the USDA in Florida is developing a chemical lure for the beetles. The lure, a yeast based compound, is effective in attracting adult beetles. Unfortunately, an in-hive trap for the lure is still in development. The latter product (and trap) may be available next year. At present the lure is being used by researchers and inspectors for detection of SHB in an apiary.

1 comment:

valerie said...

Thanks for the up to date and informative article. I was glad for the information. With SHB now in both my hives, I plan to start controlling them with the West Trap. This will probably be difficult, as my hives are on a slight tilt, to help prevent condensation from falling on the winter cluster, but the West trap requires the hive to be level. Wish me luck. -Valerie