Information for farmers and growers

Honey bees are important value creators for all farmers, in that they pollinate many crops.  This pollination can produce seed crops, some of which self-sow, perpetuating the crop’s value for the farmer e.g. clover in permanent pasture.

To ensure that this partnership prospers, it is important to protect honey bees when using pesticides on the farm.

These steps should help farmers and growers protect honey bees when spraying any pesticide.

  • What evidence is there to support the spraying of this crop at this time?
  • Consider pest pressure, weed size and disease symptoms. Survey your crop to determine if pests have reached thresholds where control with pesticides is necessary.
  • Avoid prophylactic use of pesticides – it costs money and is often of little benefit.
  • Evaluate if spraying is really necessary by following Integrated Pest Management (IPM) guidelines.[1][2]

Read the product label or labels (when tank mixing) and follow all the warnings on the label. Note: Not all pesticides and tank mix adjuvants have warnings about bee safety.

Manufacturers test pesticides for chemical ecotoxicity to bees; that is, acute oral (ingestion), dermal contact (on the thorax only), and larvae (oral and dermal).

Bees are invertebrates and do not have lungs. They breathe through tiny holes called spiracles on the exoskeleton, and if a substance blocks these spiracles the bee will suffocate and die. This is considered a physical effect and not a chemical effect. This can be caused by these types of spray tank adjuvants; spraying oils, wetter sticker surfactants, penetrants, anti-foaming agents, emulsifiers etc.

Many spray tank adjuvants do not have label warnings specific bees, consult your supplier and request that data if concerned.

Only use bee-safe products if risks to honey bees are likely.

But always remember, it is what is in the spray tank that will kill the bees and not what is in the packet. This caution is necessary, as today spray tank mixtures with adjuvants such as drift control agents, surfactants, dyes, foam control products, stickers, penetrants etc., can make the spray mixture hazardous to foraging honey bees.

Honey bees can be killed in the field due to chemical toxicological action or from substance physical activity. Chemical toxicological death is the chemical reaction induced in the bee that leads to its death.

Physical activity can include inhalation of product through the breathing spiracles on the exoskeleton of the bee, blocking of the bee’s trachea to prevent the ability to breathe through the coating of a foaming product, or coating the wings and preventing flight – all of which can bring about bee death. Sub-lethal doses of penetrants (organosilicon surfactants) have been documented to affect bee learning.

Read the labels of all the products added to the spray tank. If there is no bee safety information, speak to the supplier and request it. The only 100% bee friendly spray is clean water. A spray may be labelled or listed as bee safe (based on chemical toxicology) but be damaging to bees through its physical actions.

Bees forage flowers to gather nectar and pollen, their major food sources. During this foraging action, bees successfully pollinate the crop, increasing its value to the farmer.

Many spray programmes for export produce do not allow spraying during flowering, defined from bud burst to petal fall. For example, Zespri’s spray programme for exporting kiwifruit.

Mow flowering weeds under fruit tree crops before spraying.

Avoid spraying gorse and broom (winter flowering) when in flower. The herbicide may be safe to bees, but the surfactants (normally penetrants) are not. Many beekeepers experience severe hive losses during this period caused by spraying during the day on flowering weeds.

Bees forage during daylight hours when temperatures are warm. Avoid spraying at this time.

If you have to spray a flowering crop likely to be visited by bees, we recommend spraying very early in the morning (day break) or at dusk (sunset), even spraying in the dark. Bees are normally in their hives at this time.

Do not make assumptions, as many spray tank adjuvants do not have bee safety warnings but are ecotoxic to bees. If in doubt seek knowledge and help from your supplier and the manufacturer’s representative.

Pesticides – In New Zealand, there is no definition of the word pesticide in any government statute.

The Agricultural Compounds and Veterinary Medicines Act 1997 refers to agricultural compounds and defines them as follows:

Agricultural compound means:

  • any substance, mixture of substances, or biological compound, used or intended for use in the direct management of plants and animals, or to be applied to the land, place, or water on or in which the plants and animals are managed, for the purposes of—
  • Managing or eradicating pests, including vertebrate pests; or

The Hazardous Substances and New Organisms Act 1996 does not define the word pesticide or use the ACVM Act definition of Agricultural Compounds. Instead, it focuses on the ecotoxic properties of a substance and defines ecotoxic as follows:

Ecotoxic means capable of causing ill health, injury, or death to any living organism, effect includes:

  • any potential or probable effect; and
  • any positive or adverse effect; and
  • any temporary or permanent effect; and
  • any past, present, or future effects; and

any acute or chronic effect; and

any cumulative effect which arises over time or in combination with other effects.

Information for beekeepers

A fear that is very real amongst beekeepers is finding their hives have been poisoned by pesticides, which can be used by anyone on a range of different environments, making it difficult to manage and prevent.

As a beekeeper, it is important to be aware of the risk of pesticides. A poisoning event is difficult to predict, but there are effective ways of managing the threat.

If you suspect that your hive has been poisoned, you can report this to the Environmental Protection Authority using their pollinator incident report form here.

Although it is important to have prevention measures in place to ensure pesticide poisonings do not occur, it is also important to understand how to respond to a poisoning event if it affects your bees.

Bee poisonings have several common symptoms, such as:

  • Large numbers of dead bees at the entrance of the hive. Thousands of dead bees at once suggest that they have been poisoned.
  • Live bees outside the entrance that look sick and have slow and jerky movements.
  • In severe cases, dead adult bees will also be found inside the hives and brood will die from starvation, overheating, or chilling (due to the inability of adult bees to feed brood and regulate hive temperature).
  • Most or all hives in the apiary may be affected.
  • Dead adult bees often have their wings unhooked and at odd angles to their body, their proboscis full extended, and their hind pair of legs outstretched behind them.
  • A lack of foraging bees can be observed leaving the hive.
  • Remaining bees may behave aggressively.
  • Queen failure may occur within 30 days.

There are effective ways of managing affected hives:

  • Move hives to a safe area, away from possible pesticide exposure.
  • Remove excess supers so that colonies can stay warm.
  • Consider removing pollen and honey which may be contaminated and dispose of appropriately if necessary.
  • Feed colonies inside the hive with a 1:1 sugar and water solution until recovery. This helps compensate for the lack of fresh nectar resulting from reduced bee numbers. It may also be necessary to feed either pollen or pollen substitute.
  • Add sealed brood and adult bees from healthy hives if needed. Ensure that young bees are added as well to assist with the feeding of unsealed brood in the weakened hive.
  • Observe hives for signs of queen failure, which may occur several weeks after the poisoning event.

It is important to understand how pesticide poisoning occurs in order to prevent it. Pesticide poisoning may occur in a number of ways:

  • When a chemical is applied directly to a flowering crop while bees are foraging.
  • When a chemical is applied to a crop that is flowering and bees subsequently forage on contaminated nectar, pollen, water, or alight on a contaminated plant part.
  • When a chemical is applied to a crop, not in flower but is also applied to non-target plants that are flowering (e.g. weeds), at the same time.
  • When pesticide drifts onto bees, flowering plants, hives, or the bees’ water source.
  • When a worker bee carries contaminated nectar, pollen or water back to the hive, contaminating the colony.
  • When an area within the bees’ flight path is sprayed.

Beekeepers can reduce the risk of a honey bee pesticide poisoning event by following these management practices:

  • Before placing the hives on site, ensure that farmers and neighbouring landowners have your full contact details so that you can be contacted quickly if they need to apply chemicals. You can discuss when this will occur and how the risk can be managed. For example, the hives may be able to be placed on site after chemical application or removed prior to chemical application.
  • Advise other nearby land managers, such as local councils.
  • Select sheltered areas that offer some protection against spray drift. Consider the prevailing wind and seek advice from locals.
  • Ensure that bees have access to clean water. Bees require a lot of fresh water, and if it isn’t readily available, they may search further afield and drink chemically contaminated water from flowers and other sources.
  • Identify an appropriate area nearby (but at least 3 km away) that hives can be temporarily relocated to if needed.
  • Inspect hives regularly so symptoms of bee poisoning can be identified early.
  • Relocate hives before bees are forced to forage across a wider area than was originally intended. Bees have been known to forage up to a 12 km away from hives when necessary.