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Extension > Garden > Landscape, Nursery and Greenhouse Management > 2015 Toxicity to Pollinators of Insecticides Used in Greenhouse, Nursery, and Landscapes

2015 Toxicity to Pollinators of Insecticides Used in Greenhouse, Nursery, and Landscapes

Vera Krischik

The conservation of beneficial insects, that includes bees, insect predators, parasitic wasps, and butterflies, is an essential part of Integrated Pest management (IPM) programs. IPM promotes multiple tactics to manage pests and to suppress the population size below levels that will damage the plant. IPM tactics include cultural control, sanitation, biological control, using insecticides friendly to beneficial insects, and finally the use of conventional insecticides. IPM recognizes that the few remaining pest insects will support beneficial predators and parasitic wasps. When scouting plants for pest insects, check for populations of both pest and beneficial insects, such as lady beetles and bees. If beneficial insects are present, wait to spray insecticides to see if the beneficial insects control the pest insects or use specific insecticides that only target the pest insect. Do not apply insecticides while plants are in full bloom. If possible avoid beneficial insects by spraying leaves in the evening when bees and lady beetles are not foraging.

Neonicotinoid systemic insecticides have been implicated in the decline of bees and other beneficial insects. The European Union banned the use of neonicotinoid insecticides from 2014-2016 on crops and plants that bee’s visit. The concern was the residue in pollen and nectar and their negative effects on survival and foraging behavior of bees.

There are few systemic insecticides, while there are many systemic herbicides and fungicides. Systemic, neonicotinoid insecticides are the most widely used insecticides in the world, due to their low mammalian toxicity and the ability of the insecticide to move systemically from soil into the entire plant, including pollen and nectar. Application methods include seed treatments, foliar sprays, soil and trunk drenches, and trunk-injections. Flowers that open after being sprayed with contact insecticides do not contain insecticide residue, while toxicity to pests lasts for 1-3 weeks. However, flowers that open after systemic insecticides are sprayed can contain the insecticide residue for many months in both the leaves and pollen and nectar.

There are six neonicotinoid active ingredients, imidacloprid, dinotefuran, thiamethoxam, and clothianidin, of which acetamiprid and thiacloprid are the least toxic to bees. There is another systemic insecticide, fipronil that is used around structures that is also toxic to bees. You will find these active ingredients listed on the insecticide label in small print. The neonicotinyl class of insecticides is highly toxic to bees and kills bees at around 180 ppb in flower nectar or pollen. However, sublethal doses of neonicotinyl insecticide starting around 10 ppb, causes bees to lose navigation and foraging skills. The longevity and amount of the neonicotinoid in the pollen and nectar will depend on application method, concentration applied, and binding capacity of the soil.

The use of neonicotinyl insecticides as trunk injections and soil drenches for ash trees is important to slow the spread of the exotic, invasive Emerald Ash Borer and other invasive pests. As bees do not collect ash pollen in quantities, the risk to bee pollinators is low. In contrast, the use of neonicotinyl insecticides on flowering garden plants, shrubs and trees, including linden and basswood trees can kill bees and beneficial insects that utilize the flowers for pollen and nectar. It is wise to avoid using systemic neonicotinyl insecticides on flowering plants that bees visit regularly. Instead use spot treatments of contact insecticides.

New EPA labeling for neonicotinoid insecticides as of March 2014

Application restrictions exist for this product because of risk to bees and other insect pollinators. Follow application restrictions found in the directions for use to protect pollinators.

The new EPA bee hazard icon in the directions for use on insecticide labels EPA has added new language to neonicotinyl insecticide products (imidacloprid, dinotefuran, thiamethoxam, and clothianidin) to protect bees and other insect pollinators. The bee icon above signals that the pesticide has potential to harm bees. The language in the new bee advisory box explains application restrictions to protect bees.

Bee and other insect pollinators can be exposed to the product from:

  1. Direct contact during foliar application or contact with residues on plant surfaces after foliar application.
  2. Ingestion of residues in nectar and pollen when the pesticide is applied as a seed treatment, soil, tree injection, as well as foliar application.

When using this product take steps to:

  1. Minimize exposure when bees are foraging on pollinator attractive plants around the application site.
  2. Minimize drift of this product onto beehives or to off-site pollinator attractive habitat. Drift of this product onto beehives can result in bee kills. Bee kills should be reported to Minnesota Department of Agriculture (type bee kill into search), National Pesticide Information Center, and the EPA.

Nursery and greenhouse growers have alternatives to systemic insecticides

The EPA has been registering selective, insecticides that conserve beneficial insects and pollinators:

New Minnesota bee labeling laws July 1, 2014

The following list of potential systemic insecticides affected by the law, the use of which (depending on their product labels) may render the labelling of plants as non-compliant with the law if residues are detected in the plant material, include:

On the list, but not registered for use on nursery, greenhouse, and landscape by the EPA (24 insecticides) are: aldicarb, bendiocarb, demeton-S-methyl, ethoprop, dichlorvos, dicrotophos (cotton only), fensulfothion (field crops), fenthion (mosquitoes in Florida), fipronil, methamidophos, methomyl, methyl bromide, mevinphos, oxydemeton-methyl, phosphamidon, sulfoxaflor, terbufos, tralomethrin (roach), carbofuran (U.S. cancelled), dimethoate (U.S. cancelled), disulfoton (U.S. cancelled), mexacarbate (U.S. cancelled), phorate (U.S. cancelled), ronnel (U.S. cancelled).

Here is the list of systemic insecticides identified by the law as not approved on bee-friendly-labeled plants. These insecticides are registered for use on nursery, greenhouse, and landscape by the EPA (18 insecticides): abamectin, acephate, acetamiprid, avermectin, bifenazate, carbaryl, chlorfenapyr, clothianidin, cyantraniliprole, dinotefuran, emamectin benzoate, imidacloprid, milbemectin, oxamyl, pymetrozine, spinosad, thiacloprid, thiamethoxam.

Toxicity to Pollinators of Insecticides Used in Greenhouse, Nursery, and Landscapes

Bolded are insecticides not permitted by the MDA on bee-friendly-labeled plants. Systemic neonicotinoid insecticides (imidacloprid, clothianidin, dinotefuran, and thiamethoxam) are translocated to pollen and nectar for some time after application. Contact insecticides should not be translocated to pollen and nectar and should not be present in new flowers. Many contact insecticides are toxic to bees and should not be sprayed directly on foraging bees or flowers. In greenhouse structures, if you use contact insecticides during cultivation, the residue should be minimal after 5 weeks.

Chemical class Common name Examples of trade names LD 50* Toxicity to honeybees**
ug/bee
Non
Mod Toxic
Highly
Carbamates carbaryl
methomyl
Sevin,
Lannate
0.014
0.816
x
x
Neonicotinoids imidacloprid (I)
thiamethoxam (T)
clothianidin (C)
dinotefuran (D)
imid+bifenthrin (I,B)
Merit, Marathon
Flagship, Meridian
Arena, Aloft
Safari
Allectus
Field crops
Gaucho (I), Poncho (C), Cruiser(T) (seed treatments), Admire/Provado (I), Venom (C), Platinum (T)
0.004
0.004
0.005
0.023
x
x
x
x
less toxic: acetamiprid
thiacloprid
Tristar (A), Assail (A) Calypso (T) 14.5
27.8
x
x
Organophosphates acephate
chlorpyrifos
dimethoate
malathion
phosmet
Orthene
Dursban/Lorsban
Dimethoate
Malathion
Imidan
0.1082
0.06
0.038
0.16
0.1
x
x
x
x
x
Pyrethroids bifenthrin
cyfluthrin,
fenpropathrin
lambda-cyhalothrin
permethrin
resmethrin
Attain/Talstar
Tempo, Decathalon
Tame,
Scimitar
Astro, Pounce
foggers
0.1
0.001
0.05
0.038
0.029
0.065
x
x
x
x
x
Botanical pyrethrin Pyganic 0.15 x
Insect growth regulators diflubenzuron
tebufenozide
Adept, Dimilin
Confirm
25
234
x
x
azadirachtin
buprofezin
pyriproxyfen
Aza-Direct, Azatin
Talus,
Distance
2.5
163
100

x
x
x
novaluron Pedestal 150 x
cyromazine Citation 25 x
Juvenile hormone s-kinoprene Enstar II 35 x
Anthranilic Diamides chlorantraniliprole
cyantraniliprole
Acelepryn
Mainspring
>104
0.116
x
x
Macrocyclic lactones abamectin
avermectin
emamectin-benzoate
Avid
Sirocco
Tree-age, Enfold
0.009
0.41
0.285
x
x
x
Miticides acequinocyl
etoxazole
fenpyroximate
fenbutatin-oxide
halofenozide
Shuttle
TetraSan, Beethoven
Akari,
Vendex
Mach II
>100
200
162
3982
100
x
x
x
x
x
clofentezine,
hexythiazox
Ovation
Hexygon
111
200
x
x
bifenazate Floramite, Sirocco 7.8 x
pyridaben Sanmite 0.024 x
chlorfenapyr Judo 0.12 x
Spinosyns spinosad, less toxic when dry Conserve/Entrust less toxic dried 0.05 x
Tetronic acids spirotetramat
spiromesifen
Kontos
Judo, Forbid
107
200
x
x
GABA-channel fipronil Fipronil, Termidor 0.004 x
Pyridine carboxamide flonicamid Aria 60.5 x
Pyridine azomethines pymetrozine Endeavor 158.5 x
Other insecticides Bacillus thuringiensis Bt/Dipel N/A x
potassium salts fatty acids soaps Surround, M-Pede x
horticultural mineral oils Monterey Oil x

The information given herein is supplied with the understanding that no discrimination is intended and no endorsement by the University of Minnesota Extension. Remember, the label is law.

**Toxicity Category I, highly toxic to bees, Acute Contact LD50 is < 2 µg/bee
Toxicity Category II, moderately toxic to bees, the LD50 is 2-10.99 µg/bee
Toxicity Category III, Relatively nontoxic, NT, to bees, the LD50 is 11-100 µg/bee
*1. Protecting honeybees from pesticides, Purdue Extension, E-53W, Krupke, C., G. Hunt, and R. Foster, June 2014
2. How to reduce bee poisoning from pesticides, A Pacific Northwest Extension Publication, OSU, UI, WSU, PNW 591, Hooven, L., Sagili, and E. Johansen; Pesticide toxicity to bees
3. Pesticide stewardship
4. Farmland birds, list of EPA 2011 pesticides and LD50
5. University of Hertfordshire PPDB, pesticide properties database
6. Pesticide Target Interaction Base
7. Safety and use of neonicotinoids insecticides in turfgrass, Doug Richmond, Purdue University

Contact

Vera Krischik from the Department of Entomology at the University of Minnesota can be contacted by email at krisc001@umn.edu, or by phone at 612-625-7044.

Revised 2015

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