Placed on the Web 3/95 by the Department of Entomology, NCSU
Wildlife is a valuable natural resource. Most farmers enjoy seeing wildlife on their farm, and many benefit economically by leasing hunting and fishing rights to sportsmen. In North Carolina, more than $1.1 billion is spent annually by hunters and fishermen alone.
Tobacco fields provide both food and cover for wildlife. For example, quail and other birds nest in grassy strips alongside tobacco fields. Farm wildlife such as these are often called "edge species" because they live in noncrop areas such as hedgerows or along the edges of fields. Wildlife that live in these areas find food and grit in the adjacent crop fields. Pesticides applied to the fields are therefore likely to affect wildlife. For example, researchers tested quail that had been killed by hunters and found that 60 percent of the quail had insecticides in their bodies.
Wildlife that are directly exposed to toxic pesticides can get sick or die. In a 1978 study of quail living near fields that had been sprayed with methyl parathion, 35 percent had enough insecticide in their bodies to cause sickness or death. Birds made sick by insecticides may neglect their young, abandon their nests, and become more susceptible to predators and disease.
While direct poisoning from toxic pesticides is a concern, many pesticides that are not highly toxic can still be harmful to wildlife by reducing the food and cover that wildlife need in order to survive. Insecticides reduce insect foods, and herbicides decrease plant cover. Herbicide use can reduce gamebird populations on farms by disrupting habitats that chicks use to find insects and other foods. Similarly, pesticides can decrease the number of aquatic foods necessary to the survival of ducklings.
Careful selection and use of pesticides, however, can lessen their impact upon wildlife. This publication (1) describes how pesticides used on tobacco fields can harm wildlife and (2) describes how farmers can minimize adverse effects of pesticides on wildlife.
Exposure to highly toxic insecticides (mainly organophosphate and carbamate insecticides) can result in death of the animal. Sublethal exposure may cause sickness. Birds made sick by insecticides are more susceptible to predation, disease, and exposure. Birds exposed to organophosphate insecticides have been found to neglect their young or even abandon their nests.
Insecticides used on tobacco range from nontoxic to extremely toxic to wildlife. Many soil-applied insecticides are especially hazardous to wildlife; they include carbofuran (Furadan), aldicarb (Temik), fenamiphos (Nemacur), disulfoton (Di-Syston), and ethoprop (Mocap). All of these insecticides are extremely toxic to birds and have caused wildlife deaths.
Tables 1 and 2 list insecticides recommended in the North Carolina Agricultural Chemicals Manual for use on soybeans. Table 1 rates insecticides according to their toxicities to birds, mammals, and fish. The effects of insecticides on wildlife and fish can be minimized by using the least toxic alternative. Insecticides in Table 2 are rated low, moderate, or high based on the hazard their use presents to wildlife (birds and mammals). The hazard of an insecticide is based on its toxicity to wildlife, the way it is used, and other characteristics, such as its persistence in the environment. For example, methomyl (Lannate) is acutely toxic to birds and mammals (Table 1). However, because methomyl does not persist in the field, careful use of this chemical presents only a moderate hazard to wildlife (Table 2). Wildlife exposed to insecticides rated high may die or become sick. Insecticides rated moderate may also cause death or sickness, although death is unlikely. Insecticides rated low are unlikely to harm wildlife directly.
Table 1. Toxicity of Pesticides Used on Tobacco to Birds, Mammals, and Fish.*Wildlife hazards:
Pesticide (Brand Name) Birds* Mammals* Fish**
acephate (Orthene) M L L aldicarb (Temik) H*** H EH carbaryl (Sevin) L L M carbofuran (Furadan) H*** H H chlorpyrifos (Lorsban) H L EH diazinon (Diazinon) H*** M EH disulfoton (Di-Syston) H*** H H endosulfan (Iodan) M H EH ethyl parathion (Parathion) H*** H H fenamiphos (Nemacur) H*** H EH fonofos (Dyfonate) H H EH malathion L L EH methidathion (Supracide) H M EH methomyl (Lannate) H H H methyl parathion (Penncap-M) H*** H H oxamyl (Vydate) H H M
*Wildlife hazard is based on the following toxicities: H (Highly toxic) = LD50 less than 30 mg.kg and/or LC50 less than 500 ppm. M (Moderately toxic) = LD50 greater than 30 and less than 100 mg/kg and/or LC50 greater than 500 and less than 1,000 ppm.
L (Low toxicity) = LD50 greater than 100 mg/kg and LC50 greater than 1,000 ppm.
NT (Not toxic) **Fish 96-hour LC50 toxicities are as follows: EH (Extremely toxic) less than 0.1 ppm H (Highly toxic) 0.1-1.0 ppm M (Moderately toxic) 1-10 ppm L (Low toxicity) greater than 10 ppm To convert fish toxicities to pounds of active ingredient per acre-foot of water, multiply by 2.7. ***Active ingredient (not necessarily a specific product) has caused wildlife deaths. Table 2. Hazard of Tobacco Insecticides to Wildlife
Wildlife Pest Problem Insecticide (Brand Name) hazard* Kills** Comments
Aphids aldicarb (Temik 15G) high yes Temik granules exposed on the surface are a hazard to birds. (Flue-cured tobacco only.
Aphids (suppression acephate (Orthene 75SP) low no Di-Syston and Mocap Plus only) disulfoton (Di-Syston 15G) high yes granules on soil surface are disulfoton + ethoprop high yes a hazard to birds. (Mocap Plus 10 + 5G) fenamiphos (Nemacur 3E) high yes
Flea beetles oxamyl (Vydate L) low no Temik granules exposed on disulfoton (Dy-Syston 8) moderate yes the soil surface are a hazard ethoprop + disulfoton moderate yes to birds. (MoCap Plus EC) carbofuran (Furadan 4F) high yes aldicarb (Temik 15G) high yes (Flue-curred tobacco only)
Flea beetles and carbofuran (Furadan 4F) high yes Minimize drift into wildlife early-season habitat. hornworms
Wireworms chlorpyrifos (Losrban 4E) low no Fully incorporating granules chlorpyrifos (Lorsban 15G) moderate no reduces hazard. Disk under fonofos (Dyfonate 10G) moderate no granules spilled at row ends fonofos (Dyfonate 50W) low no or use liquid formulation. ethoprop (Mocap 10G, 6EC) high yes carbofuran (Furadan 4F) high yes (Flue-cured tobacco only) parathion (Parathion 4G, 10G) high yes (Flue-cured tobacco only)
Remedial Treatments for Insect Control In the Field
Aphids acephate (Orthene 75SP) low no Thiodan and Lannate are endosulfan (Thiodan 3EC) moderate no more toxic to birds and methomyl (Lannate 1.8L 90SP) moderate no mammals.
Budworms Bacillus thuringiensis safe no Orthene is safer than (Dipel, Javelin, Biobit) Supracide, Lannate, or acephate (Orthene 75SP) moderate no Thiodan. Liquid methyl methidathion (Supracide 2EC) moderate no parathion is more hazardous endosulfan (Thiodan 3EC) moderate no than Penncap-M. However, methomyl (Lannate 90SP, 1.8L) moderate no Penncap-M is a hazard methyl parathion (Penncap-M) moderate yes to bees.
Cutworms carbaryl (Sevin 5% bait) low no Dylox and Proxol are highly trichlorfon (Dylox, Proxol) low no toxic to fish and bees. acephate (Orthene 75SP) low no
Flea beetles carbaryl (Sevin 10D, 80S, 4F) low no See budworm comments for acephate (Orthene 75SP) low no Penncap-M. Supracide is less methidathion (Supracide 2EC) moderate no toxic than Lannate. methomyl (Lannate 90SP, 1.8L) moderate yes methyl parathion (Penncap-M) moderate yes
Grasshoppers malathion 5 lb/gal EC low no See budworm comments for acephate (Orthene 75SP) low no Penncap-M. carbaryl (Sevin 10D, 50W, 4F) low no methyl parathion (Penncap-M) moderate yes
Hornworms Bacillus thuringiensis safe no Lannate is hazardous when (Dipel, Javelin, Biobit) drift or spray reaches wildlife carbaryl (Sevin 80S, 10D, 4F) low no directly. See comments on acephate (Orthene 75SP) low no Penncap-M under budworm. methidathion (Supracide 2EC) moderate no methomyl (Lannate 90SP, 1.8L) moderate no methyl parathion (Penncap-M) moderate yes
Japanese beetles carbaryl (Sevin low no
Loopers Bacillus thuringiensis safe no See above for Lannate. (Dipel, Javelin, Biobit) acephate (Orthene 75SP) low no methomyl (Lannate 90SP, 1.8L) moderate no
Slugs metaldehyde + carbaryl bait high no Birds may be killed in hydrated lime low no methaldehyde-treated areas.
high indicates possible wildlife deaths;
moderate indicates possible wildlife sickness, deaths less likely;
low indicates sickness unlikely.
yes indicates wildlife deaths due to use of the insecticide (active
ingredient) have been reported.
no indicates wildlife deaths have not been reported when pesticide is used according to label.
To reduce the danger to wildlife from granular insecticides:
The hazard to wildlife posed by some soil-applied systemic insecticides may warrant forgoing their use. Before using soil- applied systemic insecticides, consider their advantages and disadvantages discussed in the "Insect Management" section of the Tobacco Information handbooks (AG-376 and AG-178) published by the North Carolina Cooperative Extension Service.
To reduce hazard to wildlife from liquid formulations:
Some fumigants are less hazardous to wildlife than nonfumigants because of their short duration of activity. These fumigants include dichloropropene (Telone II) and methyl bromide with chloropicrin (Brom-O-Sol).
Proper cultural practices, including crop rotation, stalk and root destruction, and use of resistant tobacco varieties, help to reduce the use of nematicides. For more information, see Extension Service publication AG-187, Tobacco Information.
Fungicide use can be reduced by controlling seedling diseases with cultural practices such as proper rotation, timely planting, and proper seed selection.
Many species of wildlife, including quail and rabbits, benefit from strip habitats. Where possible, consider maintaining these areas in wildlife cover. Protect these areas from herbicides and mow less frequently. Consider mowing filter strips and ditch banks only once per year, preferably in early spring. In fields where weeds have been a problem, prevention of weed seed production in non-crop habitats may be accomplished by using selective herbicides that allow grass cover to be maintained.
Additional publications in the Pesticides and Wildlife series include: