|Crop Knowledge Master|
|The Two Spotted Leafhopper|
Vincent P. Jones
Mach T. Fukuda
Diane E. Ullman
John S. Hu
Wayne B. Borth
The twospotted leafhopper, Sophonia rufofascia, was first discovered in Hawaii on a farm in Waimanalo (Oahu) in 1987. Since that time, it has been found on all the major islands from sea level to 4,000 feet and on more than 235 host plants. Its wide distribution within the islands suggests that the insect may have been here before 1987, that it is extremely mobile, and/or its spread has been accelerated by movement of plant materials throughout the islands.
There are a total of 3 major life stages. The egg stage is inserted into plant tissue by the adult female. On most plants, there is no sign that the egg has been deposited, thus even closely inspected nursery plants may have leafhopper eggs present. There are 4 immature stages, each one being slightly larger and with longer wing pads than the previous stage . The immatures are transluecent yellow with two dark spots at the back part of the body. Movement of the immatures is by walking or jumping. As the insect passes between immature stages, it leaves a clear cast skin that has the two dark spots and which looks identical to the leafhopper except for color. These cast skins are an indicator that leafhoppers have been developing on a particular plant because they remain attached to the plant for long periods. If there are several different sized cast skins, it suggests that development on the particular plant is successful. Adults are the final developmental stage and have completely functional wings. Adults are darker yellow with a brown stripe down the center of the back and two prominent eye spots on the tail end (Fig. 1). Because its real eyes are the same yellow as the body, the leafhopper appears to be moving backwards when walking.
The life history of this insect is unknown. Graduate student, Mach Fukada, at the University of Hawaii, Entomology Department, is studying the development, host range, distribution and seasonality.
Although some host plants are unaffected by leafhopper feeding, most plants fed upon develop a prominent yellowing between leaf veins. In severe cases, feeding causes the leaf to collapse and a large brown or black patch appears, and/or the plant dies. Other common symptoms include leaf distortion and stunting of the plant.
Damage by the leafhopper is probably a reaction to the saliva injected dunng the feeding process. Leathoppers feed by what is known as "piercingsucking" mouthparts. These mouthparts are modified into a hypodermiclike process which can only ingest liquids. The leafhopper inserts its mouthparts and its saliva helps breakdown the plant tissue and keep the plant juices flowing. When it injects the saliva, it can also inject plant pathogens which may be involved in eventual plant death. Leafhoppers confined to a single leaf damage that leaf, but other leaves on the plant are not affected, nor is the new growth.
A research team led by Dr. Vincent Jones is studying the impact of this insect to agricultural and endemic plants.
Damage on Octopus Tree
Damage on Ti
Leafhopper populations can be high on certain plants in both agricultural and forest situations. However, on most plants they tend to be concentrated on the new growth. If samples are taken on only the old growth, it appears that the leafhoppers are rare. In studies on guava, the majority of the population is found on the 2 youngest leaves on a shoot, but damage is seen on virtually every leaf on the plant. Sampling should therefore be confined to the younger leaves where most of the population if found. The leafhoppers are typically found on the underside of the leaf and may be sampled visually if the underside can be seen without disturbing the plant too much. Leafhopper adults tend to quickly jump and fly when disturbed, but immatures tend to jump less readily. Sweep nets or beating sheets can also be used to sample for the leafhopper.
High populations of the leafhopper are not necessary to cause damage. For example, on uluhe, cast skins are more frequently found than are the immatures. It appears that leaflhoppers are very sensitive to damage they inflict upon the plant. If they are confined on a leaf, after 12 days they spend the majority of time trying to escape. In natural situations, they probably move between leaves quickly after feeding for just a short time. This means that leafhoppers damage the leaves when they are young and symptoms take several weeks to appear. This has been seen in laboratory studies.
Host plants of the leafhopper include crop plants (both tropical fruits and vegetables), shade trees, terns, ornamentals, weeds, and forest trees and shrubs (Table 1). The uluhe or falsestagehorn fern is particularly sensitive to leafhopper feeding. On the island of Oahu, large patches of fern are dying on the hillsides of Manoa and Palolo Valleys, Aiea, and Maunawilli. The reaction of the uluhe is a major cause of concern because uluhe covers a large portion of the watershed and damaged areas do not appear to grow back. These dead areas are thus sources for erosion and areas where alien weeds may invade. Similar patches of dying uluhe have been seen on Maui and Kauai. These symptoms have been reproduced in the laboratory with leafhoppers. In natural situations, the symptoms are probably intensified if the plant is stressed by drought or poor growing conditions.
Table 1. Representative Host Plants for Sophonia rufofascia in Hawaii.*
Common Name Scientific Name
Forest and Watershed Areas
firetree Myrica faya
Hawaiian Tree Fern Cibotium splendes
Hawaiian Sandlewood, Ili-ahi Santalum ellipticum
koa Acacia koa
Mamaki Pipturus albidus
ohia-lehua Metrosideros collina var. polymorpha
uluhe, false staghorn fern Dicranopteris linearis
Tropical Fruit and Nut Trees
Avocado Persea americana
Banana Musa sp.
Citrus (lemon, lime, orange) Citrus limon, C. aurantiifolia,
Coffee Coffea arabica
guava Psidium guajava
Macadamia Nut Macadamia integrifolia
Mango Mangifera indica
African tulip tree Spathodea campanulata
Fiddle wood Citharexylum spinosum
Kukui Aleurites moluccana
Trumpet tree, Guarumo Cercopia peltata
Wiliwili Erythrina sandwicensis
Hibiscus (red & wild yellow) Hibiscus rosasinensis,
Mock orange Murraya paniculata
Pittosporum Pittosporum spp.
Ti Cordyline terminalis
Chili Peppers Capsicum annuum
Sweet corn Zea mays
Sweet potato Ipomoea batatas
Taro, Kalo Colocasia esculenta
Caster bean Ricinus communis
Rattlepod Crotolaria spp.
Spanish clover Desmodium spp.
Spanish needles Bidens pilosa
Strawberry guava Psidium cattleianum
*total host list is more than 260 species (MTF, unpublished data)