Economic Importance

Although the vast majority of species of Auchenorrhyncha are benign, the group contains some of the most destructive pests of agriculture. Among the most important are the brown planthopper, sugarcane planthopper (Perkinsiella saccharicida), corn planthopper (Peregrinus maidis), meadow spittlebug, beet leafhopper (Neoaliturus tenellus), potato leafhopper, corn leafhopper (Dalbulus spp.), African maize leafhopper (Cicadulina spp.), green rice leafhopper (Nephotettix spp.), and various grape leafhoppers (Arboridia and Erythroneura spp.).

Auchenorrhyncha injure plants directly through feeding or oviposition or, more often, indirectly through the transmission of plant pathogens. Economic injury to plants involving cicadas, which occurs rarely, is mainly due to oviposition, although some species occasionally inflict feeding damage (e.g., on sugarcane). Spittlebugs injure plants primarily through feeding and through transmission of xylem-limited bacterial pathogens. Species of Cercopidae are the most significant pests of forage grasses in pastures in Latin America and are also destructive of sugarcane. Interestingly, much if not most of the economic damage done by spittlebugs is due to native spittle-bug species colonizing nonnative hosts (e.g., introduced forage grasses, clovers, etc.). Presumably, such plants lack natural resistance to spittlebugs and are more susceptible to injury.

Leafhoppers and planthoppers are among the most significant groups of vectors of plant pathogens, transmitting viruses, bacteria, and mycoplasma-like organisms. Over 150 species are known vectors of economically important plant pathogens. The insects usually acquire the pathogen by feeding on an infected plant, but some pathogens may be transmitted transovarially from mother to offspring. Phloem-limited viral and mycoplasma-like pathogens typically multiply within the vector and enter the plant when the insect injects saliva during feeding. Some xylem-limited bacterial pathogens (e.g., Xylella) are apparently unable to travel from the gut to the salivary glands and require regurgitation from the foregut during vector feeding to infect the plant. Annual losses to maize, rice, and sugarcane attributed to pathogens spread by leafhoppers and planthoppers are estimated in the hundreds of millions of dollars. Xylem-feeding cicadelline leafhoppers are also the main vectors of Xylella fastidiosa, which causes X diseases of stone fruits (Prunus spp.), Pierce's disease of grape, citrus variegated chlorosis, and alfalfa dwarf.

Some Auchenorrhyncha species are considered to be beneficial. Cicadas are used as food by several human cultures. The use of Auchenorrhyncha in biocontrol of weeds has also begun to be explored. For example, a Neotropical tree-hopper species (Aconophora compressa) has been introduced into Australia for control of Lantana (Verbenaceae).

0 0

Post a comment