Beet leafhopper

Appearance

A lot of morphological diversity has been reported among populations of the beet leafhopper in the United States. Morphological descriptions of two different populations of beet leafhoppers from California and Mexico are presented here. The leaf hopper is described as a small insect, 3–3.5 mm in length, that is often greenish yellow, tan or olive in colour. The leaf hopper may have darker markings on its wings, pronotum, abdomen and head if it has developed during colder temperatures. The general shape of the body has been described as "wedge shaped" with the body tapering off at the posterior end of the insect.

The head of the insect is wider than the pronotum with distinct eyes and a curved anterior margin. The mouth parts, like that of all hemipterans, have stylets used for penetration into plants and sucking. The seta, or hair present on the body are uniceriate, meaning that they are arranged in a row are present on the hind tibia of the insect. One of the distinguishing feature of this species is also the presence of plates on males. For general information on insect anatomy see: Insect morphology.

Behavior

Beet leafhoppers are polyphagous generalists which means that they are able to feed on various different types of host plants. The fact that these insects migrate during the spring and summer time to cultivated fields also means that they show a lot of variation in their host plant choices by season: feeding on desert weeds in the winter and feeding on cultivated fields in the summer. They also show incredible variation in food choices between populations in different states, and these choices may change depending on host plant diversity, availability, defenses, etc. In one study on host plant preferences of beet leafhoppers from California and New Mexico, researchers found that beet leafhoppers from California preferred to feed on sugar beet plants while those from New Mexico preferred to feed on kochia, Russian thistle and redwood pigweed plants. The study also found differences in short term and long term feeding preferences where both kinds of leaf hoppers initially settled on beet plants and later moved to their preferred choices . Despite these differences, both species chose beet plants for laying eggs.

Studies of insect feeding patterns can be conducted using electrical penetration graphs which allow researchers to match electrical waveforms to specific feeding behaviors in insects. Insects may choose to feed on different parts of a plant. By studying the waveforms produced for different feeding behaviors and then matching them to video images and histology of insects feeding, researchers can classify which part of a plant an insect feeds on....hieroglyph snipped... These waveforms may also give other valuable feeding information like the speed at which an insect feeds.

For the beet leafhopper, understanding feeding is important as feeding is a mechanism through which insect borne plant diseases spread. So far, the beet leafhopper is the only known vector of the Beet curly top virus, which spreads through plant phloem tissues. Therefore, researchers conducted electrical penetration graph experiments of leaf hoppers in which they wired beet leafhoppers to an EPG machine and characterized the types of waveforms produced. The data showed that beet leafhoppers primarily ingested phloem sap along with xylem and mesophyll sap. What was surprising however was that the rate of phloem ingestion in beet leafhoppers is significantly lower than that in other sap feeding insects. This leads researchers to believe that beet leafhoppers are unable to use the natural turgor pressure of phloem sap in order to ingest fluid and may need to use muscles to actively draw sap from phloem.The life cycle of the beet leafhopper consists of three stages: eggs, nymphs and adults. The insects grow through 5 different molts during development which provides 5 instars before they reach adulthood. The growth patterns in the size of the instars follow a sigmoidal curve which means that there is greatest increase in size among younger instars and the rate of growth decreases as the instars reach adulthood.

Food

Beet leafhoppers are polyphagous generalists which means that they are able to feed on various different types of host plants. The fact that these insects migrate during the spring and summer time to cultivated fields also means that they show a lot of variation in their host plant choices by season: feeding on desert weeds in the winter and feeding on cultivated fields in the summer. They also show incredible variation in food choices between populations in different states, and these choices may change depending on host plant diversity, availability, defenses, etc. In one study on host plant preferences of beet leafhoppers from California and New Mexico, researchers found that beet leafhoppers from California preferred to feed on sugar beet plants while those from New Mexico preferred to feed on kochia, Russian thistle and redwood pigweed plants. The study also found differences in short term and long term feeding preferences where both kinds of leaf hoppers initially settled on beet plants and later moved to their preferred choices . Despite these differences, both species chose beet plants for laying eggs.

Studies of insect feeding patterns can be conducted using electrical penetration graphs which allow researchers to match electrical waveforms to specific feeding behaviors in insects. Insects may choose to feed on different parts of a plant. By studying the waveforms produced for different feeding behaviors and then matching them to video images and histology of insects feeding, researchers can classify which part of a plant an insect feeds on....hieroglyph snipped... These waveforms may also give other valuable feeding information like the speed at which an insect feeds.

For the beet leafhopper, understanding feeding is important as feeding is a mechanism through which insect borne plant diseases spread. So far, the beet leafhopper is the only known vector of the Beet curly top virus, which spreads through plant phloem tissues. Therefore, researchers conducted electrical penetration graph experiments of leaf hoppers in which they wired beet leafhoppers to an EPG machine and characterized the types of waveforms produced. The data showed that beet leafhoppers primarily ingested phloem sap along with xylem and mesophyll sap. What was surprising however was that the rate of phloem ingestion in beet leafhoppers is significantly lower than that in other sap feeding insects. This leads researchers to believe that beet leafhoppers are unable to use the natural turgor pressure of phloem sap in order to ingest fluid and may need to use muscles to actively draw sap from phloem.