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Hosts

Plant hosts of this pest include avocado, papaya, and plumeria.

Distribution

Leafhoppers belonging to the genus Empoasca are distributed worldwide, but the exact distribution of the Stevens leafhopper is unknown. It was first reported on Oahu (Beardsley, 1970) and has since been found on Hawaii and Kauai.

Damage

The nymphs and adults of this leafhopper feed in the phloem tissue of plants.

On papaya, feeding by heavy densities of this pest causes a phytotoxic reaction called hopperburn. This results from proteins or other foreign substances secreted by the insect into plant tissues during feeding. Symptoms of phytotoxemia include tip burn, wrinkling and cupping of leaves, marginal burning and stunting of smaller plants. Some observations have shown that younger plants are more susceptible to injury than older plants. Infested papaya leaves may abscise prematurely as a result of nymphal and adult feeding.

Hopperburn symptoms also occur on plumeria, the preferred host of the Stevens leafhopper. This type of feeding damage is characterized by wrinkling of leaves and marginal burning. In severe cases, premature defoliation occurs.

Like other leafhoppers, the Stevens leafhopper can vector in the transmission of plant diseases. While bunchy top disease of papaya does not occur in Hawaii, Empoasca leafhoppers have been shown to vector this disease in Trinidad (Haque, 1973). The causal organism of this disease is thought to be a mycoplasma-like organism carried by the leafhopper.

Biology

Life cycle duration of the Stevens leafhopper (egg to adult) is 27-37 days (Ebesu, 1985). The duration of developmental stages is greatly influenced by ambient temperature and host and less so by relative humidity.

EGGS

Eggs are somewhat cylindrical and slightly curved, measuring 4/125 inch in length and 1/125 inch in width. They are usually inserted into the veins on the underside of the leaves. Females prefer to oviposit in transparent, developing leaves and young fully expanded leaves. Hatching occurs in 7 to 14 days (Ebesu, 1985).

NYMPHS

There are 5 nymphal stages (Ebesu, 1985). The first stage nymphs are translucent with dark reddish brown eyes. The second stage nymphs are light green in color and have white eyes with a dark marking at the center. Wing pads, or developing wings, become visible on the third stage nymphs. The remaining 2 nymphal stages are similar in appearance, except for a slight darkening in color and an increase in the length of the wing pads. Nymphs generally remain on the leaf from which they emerged. Duration for the 1st, 2nd, 3rd, 4th, and 5th nymphal stages respectfully are 2, 2, 2, 3-4, and 11-13 days, based on laboratory rearing on papaya and cowpea (Ebesu, 1985). The entire nymphal period requires 20-23 days.

ADULTS

Adult leafhoppers are approximately 1/8 inch in length, light yellowish green with white longitudinal markings on the back. When folded over the abdomen, the wings have an orange hue. Virgin females reared on cowpea lived 5-20 weeks, and mated females lived 1-13 weeks on cowpea and papaya (Ebesu, 1985). Following a 6 to 8 day preoviposition period, females lay an average of 5-11 eggs per week for about 4 weeks (Ebesu, 1985).

Behavior

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Management

NON-CHEMICAL CONTROL

Natural enemies of the Stevens leafhopper have not been observed in Hawaii; however, it is likely that some non-specific predation by general predators does occur. This pest builds up to damaging numbers somewhat infrequently and damaging populations have not been reported to be widespread in growing areas. This suggests that farm practices by individual growers may greatly determine whether pest density grows to damaging levels.

CHEMICAL CONTROL

Papaya is quite sensitive to pesticides so there are few registered pesticides. However, Ebesu (1985) reported a 92% reduction in trap catches of leafhoppers caught following a single application of insecticide. This suggests that the pest is relatively sensitive to registered insecticides.

There are no listings for Ebesu, Trigard, and Avid as of April 2007.

References

Beardsley, J. W. 1970. Notes and Exhibitions. Proc. Hawaii Entomol. Soc. 20(3): 484-487.

Ebesu, R. H. 1985. The Biology of the Leafhopper Empoasca stevensi Young (Homoptera: Cicadellidae) and its Toxicity to Papaya. MS. Thesis. University of Hawaii, Department of Entomology.

Haque, S. Q. and S. Parasram. 1973. Empoasca stevensi, A New Vector of Bunchy Top Disease of Papaya. Plant Dis. Reptr. 57(5): 412-413.

MAR/1992.

E-STEVEN

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