Diseases and Enemies of Honeybee

 

Honeybees are affected by many viral, bacterial, fungal and protozoan organisms. Prevention and control of honeybee diseases has been an essential aspect of management. Due to the presence of brood, adults, honey, pollen and wax in the colonies/nests, they are very attractive to pathogens and enemies. Additionally, their trophyllaxis, absconding, swarming, robbing, drifting, foraging and shifting/migration, etc. Behavioural characteristics help in very easy and fast spread of the diseases or pathogens within a colony, colony to colony and place to place.

1. Brood diseases: bacterial diseases, fungal diseases ,viral diseases.
2. Adult bee diseases: protozoan diseases, bacterial diseases and viral diseases.
3.Mixed infections.
4. Non infectious disorders: neglected brood, chilled brood, overheated bees, genetic lethality ,plant poisoning, pesticidal poisoning.
5. Honeybee mites.

i. Parasitic.
ii. Endoparasitic, Acarapis woodi.
iii. Ectoparasitic Tropilaelaps clareae, T. koenigerum, Varroa jacobsoni, V. destructor.
iv. Stored product mites.
v. Phoretic mites.

6. Pests waxmoth as, bee louse, hawk moths.
7. Predators wasps ,birds, small mammals.
8. Enemies: ants, toads, spiders, dragon flies, squirrels.

 

Brood Diseases

Honeybee brood suffer from variety of diseases. Loss of brood affects the colony strength. Adult bees are not affected by brood diseases by they can spread the casual organisms. Brood diseases are more serious than adult diseases. Thai sac brood viral disease has been very serious in Apis cerana indica in north India during 1980-1986 and loss of upto 95 per cent colonies is reported. But the virus does not infect mellifera colonies. Sac brood disease is encountered in western countries in A. melifera colonies but there is no report from India. Fungal brood diseases (stone brood and chalk brood) are not of frequent occurrence and these have not been encountered in India.

For ascertaining brood infection, it is important to observe:

• Age of brood at death
• abnormality in cell capping
• shape and position of dead brood
• colour of the dead brood
• scales of dried dead brood
• odour of the decaying brood and
• type (worker / drone / queen) of brood affected.

 

Adult bee diseases and enemies

Adult bees are affected by nosema, virus diseases and acarine mite in India. Nosema and acarine diseases are widely spread in India. Some viral diseases have been reported but iridescent virus was the most serious in Apis cerana indica in 1970's. Diagnosis of adult diseases is difficult in the initial stages and is possible only when large number of crawlers or dying bees are observed near the hive. Some of the points which should attract bee keeper's attention are:

(1) Time of the year
(2) Extent of effect
(3) Behaviour of affected bees
(4) Position of wings of crawler bees
(5) Egg laying and brood rearing.

 

 

Control of tracheal mite

• Use of folbex strips (a mixture of potassium nitrate and 500 mg. of chlorobenzilate) as a fumigant at the rate of 1 ½ - 2 strips per colony.
• Use of menthol crystals @ 50 g per two – story hive effectively controls mite infestation.
• Use of apistan (fluvalinate) strips can also control acarine disease.
• Use of menthol strips (300 mg) is effective.
• Use of formic acid, 5ml of 85% was also effective.

Control of Varroa mite

• Regular monitoring of colonies is essential.
• Application of sulphur, formic acid and laitic acid were found effective.
• Synthetic pyrethroids viz., Fluvalinate (Apistan) and Flumethrin (Bayvarol) are commonly used. Their fumes are released from impregnated strips of plywood or plastic. High mortality of mites is achieved within 6 – 8 weeks
• Two strips of Apistan or four strips of Bayvarol are used per colony.
• Synecar, a mixture of sugar powder + chloropropylate or bromopropylate @ 100 mg per colony depending upon the colony population is dusted in between the frames.
• Thymol 0.25 g powder dusted in passages of frames is also found effective.
• Oxalic acid (3.5%) when applied as spraying or trickling in the form of sugar solution is effective.

Management of Viral diseases

There is no specific and control measure for TSBV and SBV because virus becomes part of the host cell. However, following measures can help in minimizing the possibilities of further spread of the disease

• Keep colonies strong and exercise check on robbing, absconding, drifting and exchange of combs and equipment.
• Adopt general colony hygiene like frequent cleanliness of hives, handling of diseased and healthy colonies separately during manipulation, honey extraction, etc.
• Avoid hiving stray swarms.
• Isolate healthy colonies from infected ones.
• Create bloodlessness in colony by caging queen for 15 days.
• Check the colonies periodically for any abnormality.
• Destroy the severely infected colonies and combs.
• Multiply disease resistant colonies.
• Replace queens from diseased colonies with newly mated ones.
• Disinfect empty equipment and combs by soaking in a detergent (surf excel, 1%) solution containing 1% formalin for few hours. Then wash them with fresh water, dry and use, or Disinfect the empty and dry combs with UV- rays ach side for 20 min in protected chamber.
• Feed a dose of oxy tetracycline or ciprofloxacin @ 200 mg (5% a.i., vet. grade) per colony in sugar syrup (50%) to prevent secondary infection.

 

Control of foulbrood diseases

• Keep colonies strong with good egg laying queens.
• Isolate healthy colonies from diseased ones.
• Maintain colony hygiene. Prevent robbing, absconding, migration and drifting of bees.
• Select and multiply diseased resistant colonies.
• Kill the heavily infested colonies with about half pint of petrol by pouring in the top of the closed hive. Burn these alongwith brood combs in a pit (45 cm deep and wide enough) and afterwards fill it with soil. Remove the debris by scratching bottom boards, hive bodies, inner covers or outer covers, collect and burn in a pit. Flame the hives and equipments with blow torch.
• Disinfect the hives, combs and equipment with ethylene oxide (1 g/ lit) for 48 hours at 43 C in fumigation chamber. Reuse the material after proper aeration, or Sterilize the empty and dry infested combs with UV- rays for 20 minutes.
• Dust tylosin tartarate or lincomyacin hydrochloride @ 200mg in 20 mg sugar powder/hive between the combs at weekly interval or feed oxytetracyclin @ 250-400 mg / 5l sugar syrup (50%)/ colony.

 

Control of Nosema

• Overwinter the colonies with good strength and adequate food reserves.
• Keep the colonies in open sunny sites.
• Provide fresh and clean water in the apiary.
• Re-queen the colonies with newly mated queens.
• Give temperature treatment to the empty equipment at 49 C and 50% RH for 24 h for destroying spore, or sterilize the equipment and empty combs by fumigating with 80% acetic acid @ 150 ml/hive space in stacks for few days. Reuse them after proper aeration.
  
  Chemical treatments to the colonies should be avoided. If necessary, it should be given only when there is a long dearth period (>30 days) and honey should not be extracted from the treated colonies.

Wax Moth :

Two species of wax moth viz. Greater wax moth (Galleria mellonella L.) and Lesser wax moth (Achroia grisella F).are found causing considerable damage to honey bee colonies and frames in storage. Moth lays eggs on the stored combs or on the spare combs in the colony. Larvae develop by feeding on wax and pollen in comb cells. Wax moths are most active in summer, rainy season and fall.

 

Management :

• Regular inspection of bee hives.
• Though any colony is prone to the attack of wax moth, strong colonies are able to resist it.
• Keep the hives without cracks and crevices.
• Hive entrance should be reduced which can be effectively guarded by bees.
• Removal of all combs which are not covered with bees, especially during dearth periods.
• During the normal examination of colonies, the debris on the bottom board should be scrapped and cleaned with hive test.
• Tunnels of larvae in combs can be seen if it is held against the Sun rays. The larvae can be killed in the initial stages and silken webs are cleaned.
• All stages of wax moth are killed in combs at 46°C for 70 minutes .
• Sulphur dusting on the top bars of comb frames in hive body is suggested.
• Sulphur smoldering at 180 g per one cubic meter of space on a stack of 4-5 hive bodies in air tight condition in store. Fumigants such as acetic acid calcium cyanide, ethylene dibromide, pardichlorobenzene and phosphine have been used in different countries to protect honeybee products, especially combs from moths during storage.

 

Wasp management

Wasp can be effectively managed by:

• Strengthening of the bee colonies and reducing the size of the hive entrance and alighting board.
• Fitting of queen gate or queen guard board.
• Mechanical destruction of the wasp colonies by kerosene torches, CaCN fumigation, carbaryl spraying.
• Physical killing of the wasps by flappers.
• Physical barriers: use wire gauge and bird scaring ribbons.
• Baits/feeding attractants. e.g. Cypermethrin + rotten fish/Chicken or Cypermethrin + pear/ apple/ pumpkin/ banana/ pinapple or Cypermethrin + sweet candy or Fruit juice (Grapes juice fermented for three days) Mutton +0.075% diazinon.
• Anti wasp campaign should be taken on community basis.

 

Management of fungal diseases

• Bee stocks selected for hygienic behavior can be expected to minimize outbreaks of this disease.
• Hives that are drafty, damp, lying in low spots, or heavily overgrown with vegetation are susceptible to fungal diseases. Hives should lean forward slightly so that rain water runs out the entrance instead of accumulating inside.
• Old equipment should be replaced or repaired if it has large gaping holes that permit entry of moisture and drafts.
• old combs may harbor spores of the disease that persist to trigger the disease season after season and so should be replaced periodically to improve brood production.