Sudden Adult Bee Mortality in a Migrated Mustard Apiary
Ramesh keeps 14 Apis mellifera colonies in Langstroth hives, now placed beside a flowering mustard (Brassica juncea) crop near a village in Etawah district. On 22 January a neighbouring farmer sprayed a wheat field in the late afternoon; a strip of the mustard, 60 m from the hives, was also in flower and was wetted by the same spray. The next morning, 9 of the 14 colonies had 2,000–3,000 dead bees piled at the entrance. The dead bees are heavy with yellow pollen, several have the proboscis extended, and a few hundred more are crawling on the ground with trembling wings. All 14 queens are alive and laying, the sealed worker brood looks normal with no sunken or discoloured cells, and no dead larvae have been thrown out. There is no dysentery streaking the hive front. Three colonies standing 400 m away beside a tube-well show no mortality at all. The farmer says only that he used "a powder mixed in water" and will not give the name. The honey crop is barely half-filled, and shifting the colonies would cost about ₹500 per colony.
1. Diagnose the problem and justify the diagnosis by ruling out the two or three conditions it most resembles.
Read the worked answer
Diagnosis: acute pesticide poisoning of the foraging force.
The pattern is the diagnosis:
- Only adults died, and they died suddenly and in thousands at the entrance - brood disease does not kill foragers overnight.
- Dead bees carry pollen loads and have the proboscis extended - they died in flight or on landing, returning from the sprayed flowers.
- Trembling, crawling bees are the classic symptom of organophosphate and neonicotinoid action on the nervous system.
- Queens alive, brood normal, no ejected larvae rules out brood diseases.
Differential ruling out:
- Nosema / dysentery - would show faecal streaking on the hive front, distended abdomens, crawling but not thousands of corpses with pollen loads.
- Thai sacbrood or American foulbrood - would show discoloured, sunken, perforated brood cells and dead larvae/pupae, not adult mortality.
- Absconding or robbing - absconding leaves an empty hive, not a carpet of dead bees; robbing produces fighting clusters and wax debris, not pollen-laden corpses.
- The three unaffected colonies 400 m away match a drift/edge-of-field exposure, not an infectious agent, which would spread with the beekeeper's own movements.
Note that the exact chemical cannot be confirmed by eye - the name is being withheld. The reasoning above narrows it to an insecticide, and a sample should still go to a laboratory for record.
2. What should Ramesh do in the first 72 hours, and what should he deliberately NOT do?
Read the worked answer
Do, in this order:
- Stop the exposure first. Do not open and disturb the hives any more than necessary; reduce entrances to a small mesh and move the colonies at night, after all foragers have returned, at least 3–5 km to a clean area with shade and clean water. Half-filled combs are not worth re-poisoning the colony.
- Do not harvest or sell the stored honey from affected colonies; the nectar may carry residues. Keep it out of the food chain and do not feed it back.
- Feed 1:1 sugar syrup and give clean water in shaded feeders - the colony has lost its foragers and needs energy to raise the remaining brood.
- Collect evidence: 100–200 dead bees in 50% alcohol or a sealed dry container, plus a comb sample, photographs of the entrance and the spray date/time, and a written complaint to the agriculture officer or KVK. This is the only basis for a compensation claim.
- Watch the next brood cycle: with foragers gone, the colony may abandon brood; if the queen stops laying, unite weak survivors.
Do NOT:
- Administer antibiotics, "antidotes" or any hive chemical - there is no antidote and it contaminates honey.
- Add supers or expect a honey flow from these colonies this season.
- Move the bees back to the same field until the spraying schedule is confirmed.
- Assume the three clean colonies are safe - check them daily for delayed mortality.
3. Design a preventive arrangement for next season so that the same loss is unlikely to repeat, and say how it can be enforced in practice.
Read the worked answer
1. Move from reacting to coordinating. Before migration, meet the farmers whose fields are within 1 km and agree a written spray calendar: no spraying while the crop is in open flower, and if a spray is unavoidable, apply it after sunset when foragers are in the hive, so the residue is largely dry by the next flight period. Record the product name and dose - a beekeeper who knows the molecule can predict risk (neonicotinoids and dust formulations are the worst).
2. Site selection with a buffer. Keep hives on the field margin away from the prevailing spray drift path, with a hedge or tall crop between hives and the treated field, and keep the water source clean - bees carry contaminated water back too.
3. Use information channels. Register with the state agriculture department/KVK advisory SMS or WhatsApp group, and with the village panchayat, so spray notices reach the beekeeper, not just the farmer.
4. Contract terms. In a pollination or honey-flow arrangement, put two clauses in writing: prior notice of any pesticide application, and compensation for colony loss verified by a sample. This is enforceable in practice only if notice is given to a named person with a phone number and if the beekeeper keeps dated inspection records - an undocumented loss becomes a quarrel, not a claim.
5. Insurance and diversification. Enquire about colony insurance under the national beekeeping mission schemes and split the apiary into two locations so that one spray event cannot wipe out the whole operation, as it nearly did here.