April 19, 2018

Leafhoppers

Suzanne Wold-Burkness, Department of Entomology, University of Minnesota

Leafhoppers are small insects which feed on a wide variety of plants.  The name leafhopper is derived from the ability of the adults to rapidly initiate flight when disturbed.  This habit creates the impression of a hopping motion.  The potato leafhopper, PLH, Empoasca fabae (Hemiptera: Cicadellidae), is the most common leafhopper in Minnesota vineyards.  The grape leafhopper, Erythroneura spp., can also be present in Minnesota, however it is less common.

Identification

PLH nymphs (on left) and adult (on right) (E.C. Burkness, U of MN)

PLH nymphs (on left) and adult (on right) (E.C. Burkness, U of MN)

PLH adults are lime green, slender, small (0.3 cm long), and somewhat wedge-shaped with heads that are slightly broader than the rest of their bodies.  They usually have 6 small white dots directly behind their head that can be seen with magnification.  The nymphs are similar to the adults except that they are smaller, wingless, and paler green (see image, left).

Grape leafhoppers are orange-yellow in color, and have dark spots and yellow lines on the forewings.  Both the adults and nymphs are very active.  The adults jump or fly away as you walk through the vineyard or brush your hand over plants.  If you disturb the nymphs, they move very quickly in a distinctive sideways movement across the leaf in an effort to hide on the underside of the leaf.  Grape leafhoppers, in contrast, move forward.

Biology & Life Cycle

PLH do not overwinter in the upper Midwest. They migrate from the southern U.S. on wind currents and start arriving in the upper Midwest in mid to late May.  Because of this migratory habit populations can vary greatly from one region to another and can even vary within the state. The females, often fertilized, are usually the first to arrive.  Large populations continue to migrate through June and early July.  PLH lays eggs in the stems of susceptible plants.  Eggs hatch in 7 to10 days.  Development from egg to adult takes about two weeks.  Nymphs feed primarily on the underside of the leaf.  Given their limited mobility, nymphs are considered more damaging than adults.  There are usually two generations per year in the upper Midwest.  However, because of the long oviposition period, infestations usually consist of overlapping generations.

Damage

In general, PLH feeding is concentrated on the youngest grape leaves.  Leafhoppers have piercing-sucking mouthparts, and both adults and nymphs cause damage.  As PLH feed, they also inject saliva and create physical damage that plugs the vascular tissue.  The first signs of feeding are pale leaf veins and curling leaves.  Continued heavy feeding can result in premature leaf drop. The fruit may also be affected by lowered sugar content, increased acid, and poor color.

Management

Cultural Control
Using cover crops between trellise has been shown to reduce leafhopper populations (Costello and Daane 2003).

Monitoring/Thresholds
Grapevines can tolerate populations of up to 15 leafhoppers per leaf with little or no economic damage.

Chemical Control
Several insecticides provide good control of leafhoppers, and can be found in the Midwest Small Fruit Pest Management Handbook.

References

Costello, M. J. and K. M Daane.  2003. Spider and Leafhopper (Erythroneura spp.) Response to Vineyard Ground Cover.  Environmental Entomology.  32: 1085-1098.

Medley, J.C.  2003.  Key to Leafhoppers and Sharpshooters.  Texas A&M University.  http://beaumont.tamu.edu/research/agroecosystems/grapes/KeyToLeafhoppers.htm

Metcalf, R.L. and R.A. Metcalf.  1993.  Destructive and Useful Insects. 5th Edition.  McGraw-Hill, Inc.  New York.

 


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