Orchard IPM - Protecting Honey Bees

European honey bees are the primary managed pollinators in orchards because their abundance can be managed from year to year.
Orchard IPM - Protecting Honey Bees - Articles

Updated: October 16, 2017

Orchard IPM - Protecting Honey Bees

Growers dependent on honey bees must constantly maintain a delicate balance between protecting their crops from pests and pathogens and protecting pollinators.

Due to competing demands, disease, the introduction of parasitic mites (mainly Varroa destructor), and likely impacts from insecticide and fungicide use in the field, the pollination picture has changed.Despite intense efforts to protect their bees, beekeepers are losing large numbers of colonies to mites and the diseases they transmit. In addition, since 2006 there have been additional dramatic die-offs of tens of thousands of honey bee colonies from a phenomenon known as Colony Collapse Disorder (CCD). The result has been annual losses of around 30 percent of commercial colonies, which has left many beekeepers devastated and some growers without the quantity and quality of bees needed to pollinate crops.

CCD is under investigation and pesticide exposure is one of several contributing factors being studied. Pesticides under investigation include those used within the hive for mite and disease control as well as those used on crops that may inadvertently find their way into hives. Honey bees are vulnerable to many of the pesticides used to control insects, pathogens, and weed species. Growers dependent on honey bees must constantly maintain a delicate balance between protecting their crops from pests and pathogens and protecting pollinators. Until we have more documented information, it is advisable to err on the precautionary side when using pesticides.

Recommendations for growers

  • Know the pesticides you are using and their toxicity to bees (do not depend on a third party to provide this information).
  • Read the label and follow the label directions.
  • Never use a pesticide on a blooming crop or on blooming weeds if honey bees are present.
  • The use of a pesticide prebloom, just before bees are brought onto a crop, is not recommended. If a pesticide must be used prebloom (for example, at pink in apples), select a material that has a lower toxicity to bees and a short residual toxicity, and apply only when bees are not foraging, preferably just after dark.
  • Do not apply insecticides postbloom (e.g., petal fall) until after the bees have been removed from the crop.
  • Blooming time varies depending on cultivars. Bees pollinating one variety or crop may be at risk while another crop or variety is being treated postbloom with insecticides. Also, while crops may have completed blooming, bees may be visiting blooming weeds in and around crops. Be aware of these situations and avoid the application of pesticides on a nonblooming crop if there is risk of drift onto blooming crops and weeds if bees are present. If a spray must be applied, use the least toxic material and apply only when bees are not foraging.
  • Protect water sources from contamination by pesticides. If necessary, provide a clean source of water close to honey bee colony locations prior to their arrival in the orchard or crop.
  • The mode of action of many fungicides in terms of toxicity to bees is unknown. Some are known to synergize with insecticides, and together these can be more toxic to bees. Avoid the application of the more toxic fungicides mancozeb and captan on blooming crops when bees are present. The use of and lime sulfur during bloom has been shown to be repellent to bees for several days as well.
  • For more information on toxicity, see also other resources online such as a Northeastern IPM guide on preserving wild pollinators and several online publications at a pesticide stewardship webpage.
  • Do not assume that organically approved compounds are safe to bees.

As a result of mites, diseases, and CCD, fewer beekeepers are providing fewer honey bee colonies for growers and at much higher prices. In addition, the quality of honey bee colonies, at times, may be marginal for the purpose of pollination. Never before has the pollination situation been so critical. To ensure maximum crop yields, growers now must give careful attention and consideration to crop pollination.

Table 1-9. Toxicity of insecticides, miticides, fungicides, and blossom- and fruit-thinning agents to honey bees. The toxicity ratings also apply to native pollinators.
Insecticide/ miticideHoney bee toxicity ratingDo not apply on blooming crops or weedsApply only during late evening*Apply only during late evening, night, or early morning*Apply at any time
Abamectin/ avermectin (Agri-Mek), ≤0.025 lb ai/A [8 hours]HTX
Abamectin/ avermectin (Agri-Mek), >0.025 lb ai/A [1-3 days]HTX
acequinocyl (Kanemite)NTX
acetamiprid (Assail)STX
azadirachtin (Azatin, Neemix) [<2 hours]X
azinphos-methyl WSP (Guthion) [4 days]HTX
Bacillus thuringiensis Bt (Dipel)NTX
bifenazate (Acramite)MTX
bifenthrin (Brigade), < 0.04 lb ai/AHTX
bifenthrin (Brigade), 0.04 lb ai/AHTX
bifenthrin (Brigade), ≥0.06 lb ai/A [>1 day]HTX
buprofezin (Centaur)NTX
carbaryl 4F (Sevin)*, 1 lb ai/A or lessHTX
carbaryl 4F (Sevin), 2 lb ai/AHTX
carbaryl WP (Sevin) [3-7 days]HTX
carbaryl XLR (Sevin), ≤1.5 lb ai/A [8 hours]HTX
carbaryl XLR (Sevin), ≥1.5 lb ai/A [>1 day]HTX
chlorpyrifos EC (Lorsban,) [4-6 days]HTX
clofentezine (Apollo)NTX
clothianidin (Clutch)HTX
Cydia pomonella granulosis virus (Carpovirusine, Cyd-X)NTX
cyfluthrin (Baythroid) [>1 day]HTX
deltamethrin (Decis) [<4 hours]HTX
diazinon EC or WP [2 days]HTX
dimethoate (Cygon) [3 days]HTX
emamectin benzoate (Proclaim) [<2 hours]HTX
endosulfan (Thiodan, Thionex), ≤0.5 lb ai/A [2-3 hours]MTX
endosulfan (Thiodan, Thionex), >0.5 lbai/acre [8 hours]MTX
esfenvalerate (Asana), ≤0.025 lb ai/AHTX
esfenvalerate (Asana), 0.0375 lb ai/A [1 day]HTX
ethephon (Ethrel)NTX
etoxazole WDG (Zeal)NTX
fenbutatin-oxide (Vendex)NTX
fenpropathrin (Danitol) [1 day]HTX
fenpyroximate (Portal)NTX
flonicamid (Beleaf 50SG)STX
flubendiamide (Belt)NTX
formetanateHCl (Carzol), ≥1 lb ai/A[<12 hours]HTX
hexythiazox (Onager, Savey)NTX
horticultural mineral oils [<3 hours]MTX
imidacloprid (Provado), ≤0.1 lb ai/A [<8 hours]HTX
indoxacarb (Avaunt) [3 hours]HTX
kaolin clay (Surround)NT (repellent)XX
lambda-cyhalothrin (Warrior), ≤0.02 lb ai/AHTX
lambda-cyhalothrin (Warrior), ≥0.03 lb ai/A [>1 day]HTX
lime sulfur (repellent for up to 7 days)NTXX
malathion EC [2-6 hours]HTX
malathion ULV, ≤3 fl oz ai/A [3 hours]HTX
malathion ULV, 8 fl oz ai/A [5.5 days]HTX
malathion WP [2 days]HTX
methidathion (Supracide) [1-3 days]HTX
methomyl (Lannate) [2 hours]MTX
methoxyfenozide (Intrepid)NTX
NAA/1-Naphthaleneacetic acidNT (possibly repellent)X
novaluron (Rimon) (sublethal reproductive effects on adults w/in 24 hours of application, contaminated pollen lethal to larvae)HT to larvae w/ contaminated pollenXX
oxamyl (Vydate),≤ 0.5 lb ai/A [3 hours]HTX
oxamyl (Vydate), ≥1 lb ai/A [8 hours]HTX
permethrin (Ambush, Pounce), 0.1 lb ai/A [0.5-2 days]HTX
phosmet (Imidan), 1 lb ai/acre [>3 days]HTX
potassium salts of fatty acids/soap (M-Pede)NTX
pyrethrins (Pyrenonee, Pyrocide) [<2 hours]X
pyridaben (Nexter) [<2 hours]X
pyriproxyfen (Esteem)NTX
renaxypyr (Altacor)X
spinosad (Entrust, Success) [<2 hours]HTX
spirodiclofen (Envidor)HTX
spinetoram (Delegate) [<2 hours]HTX
spirotetramat (Movento)NTX
tebufenozide (Confirm)NTX
thiacloprid (Calypso)STX
thiamethoxam (Actara) [7-14 days]HTX

Adapted from Riedl, H., E. Johansen, L. Brewer, and J. Barbour, How to Reduce Bee Poisoning from Pesticides (Pacific Northwest Extension, 2006), with local recommendations added based on:

*These materials are more hazardous to bees in a moist climate, such as East Coast fruit-growing regions.

Time periods in brackets refer to the length of the residual toxic effect. Do not return bees to the field within that time period.

Additional label restrictions may apply; see pesticide label.

Insecticide toxicity is generally measured using acute contact toxicity values LD50--the exposure level that causes 50 percent of the population exposed to die. Toxicity thresholds are generally as follows to adult bees:

  • HT, highly toxic (acute LD50 < 2 μg/bee)
  • MT, moderately toxic (acute LD50 2-10.99μg/bee)
  • ST, slightly toxic (acute LD50 11-100μg/bee)
  • NT, nontoxic (acute LD50 > 100μg/bee)

Source: Penn State Tree Fruit Production Guide