Protecting honey bees from the adverse effect of pesticide use

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.

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 type 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 so 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 (organosilicone 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. 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 maybe 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.

Notify landowners and beekeepers of your intention to spray the crop. If a beekeeper elects to move his hives, give him suitable time before spraying to complete this action – they will most likely do this at night when all bees are in their hives.

Bees can travel significant distances to forage crops and gather nectar and honey. Normally they forage up to 3 to 5 kilometres from their hive, but in some circumstances they have been reported foraging at 8 to 12 kilometres from the hive.

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.

BACKGROUND INFORMATION

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

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

  1. 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:

  1. 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.

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