Spinosad

Q. What exactly is spinosad?

A. Spinosad is an insecticide used to control a 

variety of insect pests, including fruit flies, caterpillars, leafminers, thrips, drywood termites, and certain

beetles. Spinosad is the common name of a mixture

of spinosyn A and spinosyn D, two molecules derived

naturally from a bacteria through fermentation.

Spinosad is the active ingredient in several pesticides

that are registered with the U.S. Environmental

Protection Agency (EPA): DowAgro’s Conserve®,

SpinTor®, Success®, and Tracer®.

Q. How does the U.S. Department of Agriculture

(USDA) use spinosad in efforts to eradicate fruit

flies?

A. USDA’s Animal and Plant Health Inspection

Service (APHIS) and the California Department of

Food and Agriculture (CDFA) are using a spinosadbased bait spray to control fruit flies. A small amount

of spinosad is mixed with bait that includes sugar and

a protein byproduct of corn.

Q. How does spinosad work?

A. Spinosad kills susceptible species by causing

rapid excitation of the insect nervous system. To

affect the target species, fruit flies must feed on the

bait mixture and ingest the insecticide.

Q. How is spinosad applied?

A. Both aerial and ground applications of spinosad

bait spray may be used in fruit fly programs, depending upon the size and location of the outbreak. Aerial

applications are performed with helicopters or fixedwing aircraft. Ground applications involve the use of

backpack or hand sprayers or those mounted on allterrain vehicles for eradication, and hydraulic

sprayers for crop certification in commercial, hostplant nurseries or orchards.

Q. What is the rate of application for spinosad

bait spray?

A. The application rate per acre includes a mixture

of 0.008 percent spinosad and 28 percent sugar and

attractants. The mixture is diluted in water. This

application rate results in actual deposition of

0.00025 pounds active ingredient per acre of 

spinosad, or 0.01 oz/acre contained in 48 fl oz 

(6 cups) of bait-spray product per acre.

Q. How does USDA determine whether to use

aerial spray or ground applications of spinosad?

A. Currently, USDA and CDFA use aerial application

of spinosad and bait in areas that are predominately

in commercial production. In urban areas, USDA

uses ground applications of spinosad, unless the size

of the infested area or severity of the infestation

requires an aerial spray application. Control actions

are typically prompted by the detection of a 

reproducing population of exotic fruit flies. The size of

the application area will depend on the location of

detections.

Q. What effect does spinosad have on nontarget

species?

A. The use of a bait mixture that targets fruit flies

limits the impact to nontarget species attracted to the

bait. The formulation of spinosad used in this 

program has a low concentration of active ingredient

that is not toxic to bees.

Q. How long do treatments last?

A. Spinosad applications usually are administered 5

days apart until eradication is achieved, as 

determined by the absence of detections in baited

traps. Applications may continue for two life cycles of

the pest beyond the date of the last detection in the

treatment area to ensure that immature life stages,

such as eggs and larvae, develop and are exposed to

the treatment. APHIS is often able to reduce the

number of applications when the situation allows the

use of sterile fruit flies, the preferred eradication 

strategy.

Q. Are there any health risks associated with the

spinosad treatments?

A. Health risks from exposure to spinosad bait spray

treatments depend upon the amount of exposure and

individual susceptibility. Spinosad poses low hazards

and negligible risks when handled properly.

Extremely large doses of spinosad (at least 2,000

times the application rate for the program) are 

necessary for acute intoxication of humans and other

mammals. The small amount of exposure that 

members of the public have with spinosad bait spray

is well below what is known to cause acute toxicity

for humans.

Factsheet

Plant Protection and Quarantine December 2002

APHIS
Q. Does spinosad cause cancer or birth defects?

A. There is no evidence of carcinogenicity of 

spinosad based on chronic rodent feeding studies.

Reproductive and developmental toxicity occur only at

exposures much greater than any exposures that

could occur from applications of spinosad bait spray.

Q. Can spinosad damage the eyes?

A. Spinosad showed slight conjunctival irritation, or

agitation of the membranes lining the eyelids, in 

primary eye irritation tests. The low levels of exposure

from spinosad bait spray applications are insufficient

to cause visual problems.

Q. How does spinosad affect people with 

allergies, chemical sensitivity, and other special

health problems?

A. Immunological responses to chemical exposure

within a population vary. Spinosad is not a skin 

sensitizer, but some individuals may have allergic or

hypersensitive reactions to spinosad or the bait.

Q. What precautions should people take in the

treatment area?

A. People should do their best to minimize exposure.

Avoid unnecessary contact with pesticides. Remain

indoors during spinosad bait spray applications. Do

yard work before treatment begins rather than after.

Rinse off outdoor play areas. Wash skin and clothing

if contact occurs. There is no need for people to 

relocate during aerial applications of spinosad bait

spray if they take proper precautions to avoid potential

exposure.

Q. Is it okay to eat fruits and vegetables exposed

to treatments?

A. Before cooking or eating homegrown vegetables,

rinse them with water, just as you would those 

purchased from the grocery store. Washing further

minimizes any potential exposure.

Q. What is the swimming pool re-entry interval

after an area has been treated with spinosad?

A. There is no re-entry interval, and the low rate of

applications ensures that exposure from swimming is

not of concern.

Q. How long will spinosad residue remain in

yards?

A. Residues from applications of spinosad bait spray

are short-lived. The half-life of spinosad on cotton is

only a few hours on a sunny day. The average length

of persistence depends on the amount of sunlight and

precipitation. Increased exposure to sunlight and

increased rainfall accelerate the breakdown of spinosad.

Q. What effect will treatment have on wildlife?

A. Spinosad as applied in fruit fly eradication 

programs does not pose any hazard to mammals,

birds, reptiles, amphibians, fish, or aquatic insects.

Under normal circumstances, spinosad poses no 

hazard to most pets. It can be toxic to those invertebrate species that ingest the bait, and temporary

reductions in the populations of some terrestrial

insects could occur.

Q. Why is it that these applications of spinosad

are toxic to insects but not to people?

A. The sensitivity of insects to spinosad is far greater

than humans because of difference in physiology, site

of toxic action, and types of enzymes present. The

bait treatment used in the eradication programs is

attractive to flies and stimulate their feeding. As a

result, flies eat the pesticide, resulting in greater 

exposure and better pest control.

Q. Could there be any cumulative effects from

other exposures that I could receive?

A. The low application rate ensures that exposures

are unlikely to have any effects on humans. The rapid

degradation rate of spinosad ensures that it will not

persist long in the natural environment. Spinosad is

readily eliminated from or broken down by enzymes in

the human body. Cumulative exposures would require

multiple exposures within a short period of time. This

is highly unlikely for fruit fly program applications.

Q. Can fruit flies become resistant to spinosad?

A. Resistance to spinosad would require the survival

of multiple generations of flies exposed to spinosad.

The eradication program applications of spinosad bait

spray do not allow survival of fruit flies, so the 

development of resistance is highly unlikely. The rapid

degradation of spinosad also ensures that sublethal

exposures to flies are unlikely to result from residues.

Q. Has EPA authorized the use of spinosad for

fruit fly eradication?

A. Yes, temporary tolerances are in place to allow

use in fruit flies programs. Spinosad has been 

granted permanent tolerances for some fruits 

(including citrus), nuts, vegetables, cotton, and meat.

Q. Will spinosad contaminate groundwater?

A. Spinosad adheres readily to organic matter and is

relatively immobile in soil. Spinosad is not expected

to leak into groundwater. Test results indicate that

spinosad typically decomposes before reaching

groundwater.
Q. Where can I get more information on the fruit

fly eradication program?

A. If you have questions about the fruit fly eradication

program, contact APHIS’ Plant Protection and

Quarantine (PPQ) headquarters at (301) 734–8645.

You can also call your State’s regulatory officials,

usually listed under department of agriculture, plant

protection, or regulatory division, in the State 

government section of your telephone directory.

In addition, APHIS’ Internet home page

(http://www.aphis.usda.gov) provides up-to-date 

information on various agricultural pests and disease

and other related topics.

United States Department of Agriculture • Animal and Plant Health Inspection Service • Safeguarding American Agriculture

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pesticides must be registered by appropriate State and/or Federal

agencies before they can be recommended.

CAUTION: Pesticides can be injurious to humans, domestic animals, desirable plants, and fish or other wildlife--if they are not handled or applied properly. Use all pesticides selectively and carefully. Follow recommended practices for the disposal of surplus pesticides and pesticide containers.