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How to Manage Pests

UC Pest Management Guidelines

| More pests | More crops | About guidelines |

Lettuce

Lettuce Aphid

Scientific Name: Nasonovia ribis-nigri

(Reviewed 8/07, updated 8/07)

In this Guideline:

DESCRIPTION OF THE PEST

Lettuce aphid has several color forms, ranging from green to orange to pink. Adult winged and wingless lettuce aphids have black markings on the joints of the legs and antennae. Some of the wingless aphids have many black markings on the top of the abdomen as well. The winged adults are browner in color than the wingless forms, but also have various black markings.

Lettuce aphid is a relatively new pest of lettuce in California. It can be distinguished from green peach aphid by the fact that lettuce aphid does not have strongly converging antennal tubercles.

Lettuce aphid has a very short life cycle and populations can build rapidly. In California no eggs have been observed and it appears to pass the winter on lettuce, radicchio, Nicotiana spp., and some other composites.

DAMAGE

Lettuce aphid feeds deep inside the plant, toward the center on younger leaves. In head lettuce it is found almost exclusively at the heart of the plant. This aphid does not appear to be an important virus vector.

MANAGEMENT

Biological Control
Naturally occurring predators of the lettuce aphid include syrphid fly larvae and green lacewing larvae. (Lady beetles and parasites are not very important in lettuce aphid management.) Syrphid flies cannot be purchased from insectaries; they must migrate to an infested field from surrounding areas. Syrphid fly larvae are susceptible to many insecticides, especially spinosad (Entrust, Success).

Organic lettuce producers on California's Central Coast rely on naturally occurring predators to control aphid infestations before harvest. Syrphid fly adults and some other predators feed on nectar and pollen from flowers. Many organic lettuce producers intercrop lettuce with quick-flowering annuals to serve as insectary crops that provide floral resources to syrphid adults with the intention of increasing egg-laying by syrphids in nearby lettuce. Sweet alyssum and coriander are the most commonly used plants for this purpose in Central Coast lettuce.

Monitoring and Treatment Decisions
Monitoring requires care in order not to miss early infestations that are hidden within the lettuce. This aphid has a tendency to disperse in the plant rather than forming colonies as green peach aphid does. Control of this aphid is difficult because of its rapid population growth combined with its preferred locations deep within the head.

Common name Amount to Use** R.E.I.+ P.H.I.+
(trade name)   (hours) (days)
When choosing a pesticide, consider information relating to the impact on natural enemies and honey bees and environmental impact.
 
A. IMIDACLOPRID
  (Admire) Pro 7–10.5 fl oz/acre 12 21
  MODE OF ACTION GROUP NUMBER1: 4A
  COMMENTS: Apply as a soil application. Do not apply more than 0.5 lb a.i. of imidaclophid/acre/year.
  ...OR...
  (Provado) 1.6F 3.75 fl oz 12 7
  MODE OF ACTION GROUP NUMBER1: 4A
  COMMENTS: Do not apply more than 0.24 lb a.i. of imidaclophid/acre/year.
 
B. OXYDEMETON-METHYL*
  (MSR Spray) 1.5–2 pt/acre 48 see label
  MODE OF ACTION GROUP NUMBER1: 1B
  COMMENTS: Do not apply more than 3 times/season. Labeled for head lettuce only.
 
C. DIMETHOATE
  (Dimethoate E267) 0.75 pt 48 Head lettuce: 7
        Leaf lettuce: 14
  MODE OF ACTION GROUP NUMBER1: 1B
 
D. ACETAMIPRID
  (Assail) 70WP 0.8–1.2 oz/acre 12 7
  MODE OF ACTION GROUP NUMBER1: 4A
  COMMENTS: Foliar application. Allow 7 days between applications with a maximum of 5 applications/season.
 
E. PYMETROZINE
  (Fulfill) 2.75 oz 12 7
  MODE OF ACTION GROUP NUMBER1: 9B
 
 
**  Mix with enough water to provide complete coverage.
+ Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (P.H.I.) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest.
* Permit required from county agricultural commissioner for purchase or use.
1 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action is assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Lettuce
UC ANR Publication 3450
Insects and Other Arthropods
E. T. Natwick, UC Cooperative Extension, Imperial Co.
W. E. Chaney, UC Cooperative Extension, Monterey Co.
Acknowledgment for contributions to the insects and mites section:
N. C. Toscano, Entomology, UC Riverside

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Statewide IPM Program, Agriculture and Natural Resources, University of California
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