Stenocranus

Fieber, 1866

delphacid planthoppers

Stenocranus is a of in the Delphacidae, containing more than 70 described . Species within this genus exhibit , with (long-winged) and sub-macropterous forms occurring in at least some species. Several species are documented pests, particularly of corn, rice, and . The genus has a broad distribution with records from Europe, North America, and Asia, though individual species vary in their geographic ranges. Some species have shown potential, with range expansions into new regions documented in recent decades.

Stenocranus brunneus by no rights reserved, uploaded by Ken Kneidel. Used under a CC0 license.

Stenocranus vittatus by no rights reserved, uploaded by Ken Kneidel. Used under a CC0 license.

Stenocranus by (c) Bill Keim, some rights reserved (CC BY). Used under a CC-BY license.

Pronunciation

How to pronounce Stenocranus: //stɛˈnɒkrənəs//

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Images

Habitat

in this are associated with grasses and grass-like plants. Stenocranus minutus has been observed on Dactylis glomerata (cocksfoot grass). Stenocranus pacificus and related species occur in corn fields, rice paddies, and plantations. conditions influencing form development in S. minutus include wilting status and temperature.

Distribution

-level records from Denmark, Norway, Sweden, and Vermont, USA. Stenocranus pacificus: originally from tropical South Pacific islands; established in tropical and subtropical Asia by early 21st century; first recorded in temperate Asia (mainland Japan, Kumamoto Prefecture) in 2019–2020. Stenocranus nr. pseudopacificus reported from Kalinga, Luzon, Philippines. Stenocranus pacificus studied in West Sumatra, Indonesia.

Diet

Phloem-feeding on grasses (Poaceae). Documented include: Dactylis glomerata (cocksfoot grass) for S. minutus; Zea mays (corn), Oryza sativa (rice), Saccharum sp. (), and other grasses for S. pacificus.

Life Cycle

Stenocranus nr. pseudopacificus has four nymphal stages. incubation: 11–12 days. Nymphal stages: N1 4–5 days, N2 3–6 days, N3 6–7 days, N4 2–6 days. longevity: 9–13 days. Total excluding egg incubation: 24–37 days. present: and sub-macropterous adult forms occur in at least S. minutus.

Behavior

forms of S. minutus disperse by ; sub-macropterous forms hop but have reduced flight capability. Macropterous S. minutus migrate a few weeks after while still , coinciding with drying of . in S. minutus favored by relatively high temperature, low wind speeds, and limited sunlight hours. Both macropterous and sub-macropterous forms can hop under laboratory conditions; macropterous forms longer.

Ecological Role

for : S. minutus is for Cephalops curtifrons (: ), an . Subject to by including , , and in corn agroecosystems.

Human Relevance

Several are pests. Stenocranus pacificus is a serious pest of corn in Southeast Asia, also feeding on rice, , sorghum, and other grasses; potential in temperate Asia. Stenocranus nr. pseudopacificus identified as corn pest in Philippines. Potential for phytopathogens, though vectorial capacity not fully established for most species.