Pesticide Effects on Nontarget Organisms
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Pesticide Effects on Nontarget Organisms

   

Pesticide Effects on Nontarget Organisms1

Frederick M. Fishel2

This guide addresses the effects of various types of pesticides on nontarget organisms, including natural enemies and beneficial organisms such as honey bees, wildlife, fish, and nontarget plants.

Pesticides are an integral part of agriculture and Florida's climate fosters an environment conducive to major pest outbreaks throughout the year. Our environment also is favorable for the development and presence of beneficial organisms that positively affect our agricultural production and enhance our wildlife and plant communities. A side effect of usage of some pesticides results in unfortunate consequences to our nontarget organisms. Before making a pesticide application, it's important to become familiar with the area to be treated and the surroundings. Some pesticides are more "environmentally friendly" than others and may be selected for sites where there are special concerns.

Bees and Other Pollinators

Wild bees, certain wasps, honey bees, and other insects are important pollinating agents of crops ( Figure 1 ). Some pesticides are harmful to these pollinators, causing direct losses of the insect populations and indirect losses of crop yield due to the lack of adequate pollination. The value of honey produced in Florida during 2003 alone was over $2,000,000 according to the Florida Department of Agriculture and Consumer Services. Avoiding the use of materials that are toxic to these pollinators is the best method to enhance their survival. Specifically with honeybees, pesticide labels will have statements in their "Environmental Hazards" section if there is a toxicity concern. For example, this statement was taken directly from a label:

ENVIRONMENTAL HAZARDS

BEE CAUTION: MAY KILL HONEYBEES IN SUBSTANTIAL NUMBERS.

This product is highly toxic to bees exposed to direct treatment or residues on blooming crops or weeds. Do not apply this product or allow it to drift to blooming crops or weeds if bees are visiting the treatment area. Contact your local Cooperative Agricultural Extension Service or your local company representative for further information.

There are methods to reduce exposure problems for bees, including:

CREDITS: UF/IFAS Photo.
Figure 1. Many types of insects are important pollinators of crops.

Beneficial Organisms

Beneficial organisms include various insects, mites, nematodes, fungi, bacteria, and other microorganisms that feed on or parasitize pest species (Figures 2 and 3 ). Some of these species are well-known and have been researched in Florida and other locations; however, many more are lesser known species. The value of these organisms to agriculture and the environment are likely underestimated.
Figure 2. Predatory spider.
Figure 3. Big-eyed bug feeding on aphids.

Soil Microorganisms

Soil organisms are responsible for contributing to the decomposition of dead animal and plant material into organic matter, an important component of our soil fraction. Others are involved in the natural control of soil pests. Aside from their direct effects on pest organisms, soil microbes are a major agent in degrading pesticides. The breakdown of pesticides is beneficial for crop rotation and food residue concerns, and provides herbicide selectivity in some instances. The value of certain soil bacteria that have a symbiotic relationship with leguminous plants in fixing nitrogen translates into reduced synthetic nitrogen fertilizer inputs and increased crop yields. Fortunately, the effect of soil-applied pesticides is short-lived; in fact, in some instances they may enhance the population of certain soil microorganisms.

Fish and Wildlife

The most obvious effects of pesticides on fish and other wildlife are direct effects of acute poisoning. At times, pesticides are solely blamed for fish kills; however, in many cases, indirect effects of pesticides that cause dissolved oxygen depletion are the reason for the kill ( Figure 4 ). Pesticides can enter water sources through drift, runoff, soil erosion, leaching, and occasionally, accidental or deliberate release ( Figure 5 ). Table 2 lists pesticides which are classified as very highly- or highly-toxic to fish. These pesticides, ranging in concentrations of less than 0.1 to 1.0 ppm, can kill fish. Pesticides can kill birds in several ways. Direct ingestion of granules, baits, or treated seeds and direct exposure from sprays are obvious ways. Indirect bird kills may result from consumption of treated crops, contaminated water, or feeding on contaminated prey. Birds and other wildlife can be poisoned when baits, such as those targeting rodents, are improperly placed or not recovered in a timely fashion. Pellet and granular-formulated pesticides may be mistaken for food and consumed by birds and other wildlife. Table 3 lists pesticides that are classified as very highly- to highly-toxic to birds. These pesticides have bird acute oral LD50 values ranging from less than 10 to 50 mg/kg of body weight. Some pesticides have been implicated in negatively affecting the reproductive potential of certain birds and wildlife. Certain practices can minimize harmful effects of pesticides on fish and wildlife:
Figure 4. Many fish kills are caused by oxygen depletion rather than direct pesticide effects.
Figure 5. Fortunately, this is not a common sight in Florida.

Plants and Phytotoxicity

Phytotoxicity refers to plant injury. Of all pesticide types as a group, herbicides are considered to have the greatest potential for causing phytotoxicity, since they are designed to control unwanted vegetation ( Figure 6 ). Inert ingredients in pesticide formulations may also be capable of causing phytotoxicity.

There are many species of plants in natural and undeveloped areas that are desirable because they protect the watershed by reducing erosion and runoff; they provide food and cover for wildlife, and are part of an ecosystem's balance. A disruption of this balance may increase the likelihood of undesirable vegetation becoming more prevalent. There are situations where desirable plants are injured because of one or more of the following reasons:

Positive confirmation of phytotoxicity caused by pesticides can be difficult. Keeping accurate application records can assist in trying to determine if a pesticide is responsible for the suspected injury. Even with accurate records, pesticide injury can easily be confused with environmental disorders.
Figure 6. Pepper showing symptoms of herbicide injury.

Summary

Very strict laws have been enacted to protect wildlife and other non-target organisms; be aware of these ( Figure 7 ). In many instances, following the directions on the pesticide label will prevent injury to non-target organisms. However, when these directions are not followed, benefits from pesticides can be outweighed by the risks and harm associated with them.
Figure 7. Very strict laws protect non-target organisms from pesticide exposure.

Additional Information

Tables

Table 1. Toxicity to honeybees and mode of action class (MoA) of insecticides.

Insecticide (MoA Class)

Toxicity*

Insecticide (MoA Class)

Toxicity*

Insecticide (MoA Class)

Toxicity*
Abamectin (6)

H

 Dicofol (unknown)

S

 Oxamyl (1)

H
Acephate (1)

H

 Dimethoate (1)

H

 Oxydemeton-methyl (1)

H
Acetamiprid (4)

M

 Dinotefuran (4)

H

 Permethrin (3)

H
Azadirachtin (18)

S

 Emamectin (6)

H

 Pymetrozine (9)

O
Azinphos-methyl (1)

H

 Endosulfan (2)

H

 Pyrethrins + Rotenone (3)

H
Bifenazate (25)

M

 Esfenvalerate (3)

H

 Pyrethrins + PBO (3)

H
Bifenthrin (3)

H

 Fenpropathrin (3)

H

 Pyriproxyfen (7)

O
Buprofezin (16)

O

 Imidacloprid (4)

H

 Soaps (none)

O
Carbaryl (1)

H

 Indoxacarb (22)

H

 Spinosad (5)

H
Chlorpyrifos (1)

H

 Malathion (1)

H

 Spiromesifen (23)

O
Cryolite(9)

O

 Meth-amidophos (1)

H

 Sulfur (8)

S
Cyfluthrin (3)

H

 Methomyl (1)

H

 Tebufenozide (18)

O
Cyhalothrin gamma/lambda) (3)

H

 Methoxyfen-

Ozide (18)

O

 Thiameth-

oxam (4)

H
Cyromazine (17)

O

 Naled (1)

H

 zeta-Cyper-methrin (3)

H
Diazinon (1)

H

 Oils (none)

O
*O = nontoxic; S = slightly toxic; M = moderately toxic; H = highly toxic.

Table 2. Pesticides that are classified as very highly- to highly-toxic to fish.

Pesticide

Type*

Toxicity**

 Pesticide

Type*

Toxicity**
Alachlor

H

HT

 Maneb

F

HT
Aldicarb

I

HT

 Maneb + streptomycin

F

HT
Amitraz

I

HT

 Metam-sodium

F

HT
Azinphos-ethyl

I

VHT

 Methyl parathion

I

HT
Beta-cypermethrin

I

HT

 Methyl-isothiocyanate

FM

HT
Beta-cypermethrin

I

HT

 Naled

I

HT
Bifenazate

A

HT

 Niclosamide

I

HT
Bifenthrin

I

HT

 Oxadiazon

H

HT
Bromadiolone

R

HT

 Oxyfluorfen

H

HT
Bromoxynil

H

HT

 Pendimethalin

H

HT
Butylate

H

HT

 Permethrin

I

HT
Captan

F

HT

 Petroleum distillate

I

HT
Carbaryl

I

HT

 Pirimiphos-methyl

I

HT
Chloropicrin

FM

HT

 Prometryn

H

HT
Chlorothalonil

F

HT

 Propargite

I

HT
Chlorpyrifos

I

HT

 Pyraclostrobin

F

HT
Dazomet

F

HT

 Pyraclostrobin

F

HT
Deltamethrin

I

HT

 Pyrazophos

F

HT
Diazinon

I

HT

 Quizalofop-ethyl

H

HT
Dichlorvos

I

HT

 Resmethrin

I

HT
Diclofop-methyl

H

HT

 Rotenone

I

HT

Dicofol

I

HT

 Tau-fluvalinate

I

HT
d-trans-allethrin

I

HT

 Tefluthrin

I

HT
Endothall

H

HT

 Tetramethrin

I

HT
Esfenvalerate

I

HT

 Thiodicarb

I

HT
Ethion

I

HT

 Thiophanate-methyl

F

HT
Ethoprop

I

HT

 Thiram

F

HT
Fenbutatin-oxide

I

VHT

 Tralomethrin

I

HT
Fenvalerate

I

HT

 Tribufos

D

HT
Fludioxonil

F

HT

 Triflumizole

F

HT
Folpet

F

HT

 Zeta-cypermethrin

I

HT
Malathion

I

HT
*Type: A = acaricide; D = defoliant; F = fungicide; FM = fumigant; H = herbicide; I = insecticide; R = rodenticide.
**Toxicity: VHT = <0.1 ppm; HT = 0.1 - 1.0 ppm.

Table 3. Pesticides that are classified as very highly- to highly-toxic to birds.

Pesticide

Type*

Toxicity**
Pirimiphos-methyl

I

HT
Aldicarb

I

HT
Dicamba

H

HT
Carbofuran

I

HT
Chlorpyrifos

I

HT
Diazinon

I

HT
Dimethoate

I

HT
Ethoprop

I

HT
Dichlorvos

I

HT
Thiodicarb

I

HT
Metaldehyde

M

HT
Methamidophos

A/I

HT
Methyl parathion

I

HT
Phorate

I

VHT
*Type: A = acaricide; H = herbicide; I = insecticide; M = molluscicide.


**Toxicity (Bird LD50): VHT = <10 mg/kg; HT = 10 - 50 mg/kg.

Footnotes

1. This document is PI-85, one of a series of the Pesticide Information Office, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date November, 2005. Visit the EDIS Web Site at http://edis.ifas.ufl.edu.

2. Frederick M. Fishel, Associate Professor, Agronomy Department, and Director, Pesticide Information Office; Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.

The use of trade names in this publication is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication does not signify our approval to the exclusion of other products of suitable composition. Use pesticides safely. Read and follow directions on the manufacturer's label.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Larry Arrington, Dean.


Copyright Information

This document is copyrighted by the University of Florida, Institute of Food and Agricultural Sciences (UF/IFAS) for the people of the State of Florida. UF/IFAS retains all rights under all conventions, but permits free reproduction by all agents and offices of the Cooperative Extension Service and the people of the State of Florida. Permission is granted to others to use these materials in part or in full for educational purposes, provided that full credit is given to the UF/IFAS, citing the publication, its source, and date of publication.