Eight bee colonies, a pyrethroid spray and a foul-smelling comb
A farmer in western Uttar Pradesh wants to add beekeeping to his 2 ha of mustard. In January he buys 8 colonies of Apis mellifera from a dealer, places them in his open courtyard beside a tube-well shed facing east, and feeds 1:1 sugar syrup every day. In early March, at full bloom, he sprays the mustard at 9 a.m. with a pyrethroid for aphids. Within ten days, five colonies show piles of dead bees at the entrance, workers removing larvae, and a queen that has stopped laying. Two of the other colonies have bees with crumpled, shortened wings, and one comb smells foul. He plans to merge all the surviving colonies into two, treat them with sugar syrup and move them 3 km to a mango orchard. He has no veil, no smoker and no record of the spray. The mustard is his main cash crop and the local cooperative buys honey at ₹250 a kg.
1. Separate the causes behind the dead bees, the deformed wings and the foul smell, explaining which observations decide each diagnosis and which are ambiguous.
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Three separate problems need three different actions.
1. Acute adulticide poisoning - the dead bees at the entrance The timing is the giveaway: a pyrethroid sprayed at 9 a.m. on flowering mustard, when foragers are in the field. Dead and dying bees at the entrance, aggression and a queen that stops laying all follow a forager kill. Pyrethroids are highly toxic to bees and persist on bloom for hours. This is a spray-timing problem, not a disease.
2. Deformed wing virus with Varroa - the crumpled, shortened wings Crinkled wings in emerging bees with scattered brood is the classic picture of deformed wing virus transmitted by Varroa destructor (or Tropilaelaps in India). It is chronic and was present before the spray; it is not a pesticide effect.
3. Foul brood - the foul smell A foul smell from the comb means brood disease. American foulbrood gives sunken, perforated, darkened cappings, a ropy larva that stretches 2-3 cm on a stick, and a hard scale on the floor. European foulbrood gives a coiled, displaced larva and a sour smell. The deciding test is the ropy test plus the brood pattern, and it must be done before anything else because a foul-brood colony cannot simply be merged into another.
What is ambiguous Workers removing larvae can mean pesticide-killed brood being cleaned out, or hygienic removal of diseased brood. On its own it decides nothing. The dead foragers, the deformed wings and the smell each have their own explanation; only one of the three is a spraying accident.
2. Critically assess his plan to merge the survivors, feed syrup and shift 3 km. Give the correct sequence of hive, disease and spray-management actions.
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What is wrong with the plan
- Merging the foul-smelling colonies into the healthy ones spreads American foulbrood spores through honey and comb and can turn two sick colonies into eight. Merging is only for queenless or weak colonies that are disease-free.
- Treating everything with sugar syrup is not a treatment. Daily 1:1 syrup during a mustard flow causes robbing, dilutes the honey crop and can end up in the extracted honey. Feed only in a genuine dearth, with a division-board feeder.
- Moving 3 km is correct in principle (under 3 km the foragers fly back to the old site and die), but it must be done at night with entrances closed and ventilation screens, and opened the next morning at the new site.
Correct sequence
- Diagnose before moving anything: ropy test and brood-pattern check on the foul-smelling comb.
- If AFB is confirmed, burn the combs and frames, scorch the box, and requeen after cleaning; use antibiotics only under veterinary direction and label, never in a colony from which honey will be taken.
- Treat Varroa in the two affected colonies with an approved product and requeen if the brood pattern is poor.
- Do not merge until the disease status is known; merge only clean, queenless units, using a newspaper barrier.
- Move the apiary at night to the mango orchard, provide water and shade, and give a pollen supplement since mango gives nectar but little pollen.
- Change the spray policy on his own mustard: no spraying during bloom in the morning; spray after 5 p.m. when foragers have returned, and choose the least bee-toxic option.
- Buy a veil and a smoker before handling colonies; both are basic safety and management equipment.
3. Weigh the pollination value of the colonies against the honey income when he decides whether to spray the mustard, and state the stock rate and decision rules he should follow.
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Pollination value Mustard is largely self-fertile, but bee visits raise pod set and yield by roughly 15-30%. Eight colonies on or beside 2 ha is worth more to the mustard crop than the honey they produce, so a spray that kills foragers costs twice: the colony and the yield.
A rough comparison
- Honey: a healthy A. mellifera colony in mustard can give 15-25 kg in a good season, so 8 colonies might yield 100-150 kg. At the cooperative's ₹250/kg that is ₹25,000-37,500, plus wax and new colonies.
- Mustard yield: if bee pollination lifts 2 ha by even 15% over 1.5 t/ha at ₹5,000-6,000 per quintal, the extra is several thousand rupees.
- The pyrethroid spray costs a few hundred rupees. The comparison is not close; the insecticide is the expensive item once pollinators are counted.
Stock rate 8 colonies for 2 ha is appropriate; 3-5 colonies per hectare is the usual recommendation for mustard pollination, so he has enough and could even hire out colonies.
Decision rules
- Spray only above the economic threshold, not on a calendar.
- Spray after 5 p.m. or before the crop flowers, never at 9 a.m. in full bloom.
- If a bee-toxic spray is unavoidable, close the hives in the evening, keep them closed for the residual period with water and shade, or move them out.
- Record and photograph any dead-bee event with the insecticide label; damage to beekeeping from pesticide application is compensable and he is the applicator.
Take-home He bought the colonies as a pollination enterprise; treating them as a honey-only sideline leads to the wrong spraying decisions.