Alfalfa is an important reservoir for natural enemies of insect pests. These natural enemy populations often develop in alfalfa fields and expand into other plantings such as cotton, melons, and beans.
Parasitic Wasps
Several species of parasitoid (parasite) wasps are found in alfalfa
- Hyposoter exigua prey on beet armyworm and western yellowstriped armyworm.
- Cotesia (Apanteles) medicaginis prey on alfalfa caterpillars.
- Trichogramma spp. prey on various caterpillar pests.
- Parasitoid wasps that attack aphids in alfalfa include: Aphidius spp., Diaeretiella spp., and Lysiphlebus spp.
- Bathyplectes curculionis and Oomyzus incertus are important parasitoids of the alfalfa weevil.
Predators
Several species of predaceous bugs are found in alfalfa. These predators feed on a variety of pests such as alfalfa weevil larvae, aphids, alfalfa caterpillars, beet armyworm, western yellowstriped armyworm, webworms, leafhoppers, and three-cornered alfalfa hopper.
- assassin bugs
- bigeyed bugs
- damsel bugs
- minute pirate bugs
- lady beetles
- collops beetles
- lacewings
- syrphid flies
- spiders
Birds are important predators of insect and rodent pests in alfalfa. Egrets, ibis, and gulls feed on crickets, cutworms, and other insects that are forced to move at the leading edge of flood irrigation water. Blackbirds eat alfalfa weevil larvae, aphids, cutworms, and other insect pests.
Treatment Considerations
Do not apply pesticides to alfalfa until the economic treatment level for a specific pest is reached and the predators and parasites have been assessed for their potential role in controlling the pest. Pesticides often harm natural enemies, leading to severe secondary pest outbreaks. See RELATIVE TOXICITIES OF INSECTICIDES AND MITICIDES to find out which pesticides are most compatible with natural enemies.
Natural Enemies and Their Common Prey in Alfalfa
| Scientific Name | Common Name | Prey |
|---|---|---|
| PARASITOID (PARASITE) WASPS | ||
| Anaphes sp. | — | Lygus bug eggs |
| Aphidius spp. | — | Aphids |
| Bathyplectes curculionis, B. anurus | — | Alfalfa weevil and Egyptian alfalfa weevil larvae |
| Cotesia (=Apanteles) medicaginis | — | Alfalfa caterpillar |
| Hyposoter exiguae | — | Beet armyworm and western yellowstriped armyworm |
| Oomyzus incertus | — | Alfalfa weevil and Egyptian alfalfa weevil larvae |
| Trichogramma spp. | — | Caterpillar eggs |
| PREDATORS | ||
| Chrysoperla sp., Chrysopa sp. and others | Lacewings | Aphids and small caterpillars |
| Coccinella septempunctata, Coccinella spp. | Sevenspotted lady beetle | Aphids and whitefly |
| Collops spp. | Collops beetles | Various small insects |
| Geocoris spp. | Bigeyed bugs | Aphids and small caterpillars |
| Hippodamia convergens | Convergent lady beetle | Aphids and whitefly |
| Nabis spp. | Damsel bugs | Caterpillars and other insects |
| Orius spp. | Minute pirate bugs | Aphids and small caterpillars |
| Scolothrips sexmaculatus | Sixspotted thrips | Various small insects, eggs, and mites |
| Various species | Spiders | Caterpillars and other insects |
| Zelus spp., Sinea spp. | Assassin bugs | Caterpillars and other insects |