Kytorhinus

Associated with leguminous host plants; larvae develop inside seeds of legume pods. Specific habitat preferences for the genus beyond host plant association are not documented.

Genus distribution not well documented; Kytorhinus sharpianus occurs in Japan (northeastern Honshu, Kanto district) from 36°05′N to 40°46′N latitude.

Multivoltine with generation number varying by latitude; in Japan, ranges from univoltine/partially bivoltine in northern populations to bivoltine/partially trivoltine in southern populations. Adult emergence timing varies with host plant phenology and latitude.

Seed predator; larvae feed internally on developing seeds of leguminous host plants.

• Sophora flavescens - primary host plantLeguminous plant; pods serve as oviposition site and seeds as larval food source
• Sophola flavescens - primary host plantAlternative spelling/older name for Sophora flavescens

Complex multivoltine life cycle with 1-3 generations per year depending on latitude and climate. Larval development occurs entirely within seeds. Larval diapause is induced at the fourth instar by short daylength; critical photoperiod approximately 14-14.5 hours depending on temperature. Diapause termination is temperature-dependent, with low temperature exposure synchronizing emergence. Some third-generation larvae may overwinter in immature stages. Only one adult emerges per seed due to intraspecific larval competition.

Females distribute eggs contagiously (clumped) across host pods rather than uniformly. Females avoid ovipositing on pods that already bear eggs, apparently mediated by an oviposition marker pheromone; egg shells reinforce this avoidance response. This behavior may reduce intraspecific larval competition or egg predation risk. Larval competition within seeds is intense, with typically one survivor per seed when multiple eggs hatch.

Seed predator; reduces seed production of host legumes. Population dynamics linked to host plant phenology and seasonal heat availability.

• Other Bruchinae genera (e.g., Bruchus, Callosobruchus, Acanthoscelides)Similar seed beetle morphology and life history; distinguished by taxonomic placement in tribe Kytorhinini and specific host associations
• Other Chrysomelidae: BruchinaeShare subfamily characteristics of seed-feeding larvae; Kytorhinus distinguished by tribal and generic morphological characters

• seed beetle
• bruchid
• legume pest
• diapause
• multivoltine
• sex ratio bias
• oviposition behavior
• Japan
• Sophora
• larval competition
• photoperiodism

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Photoperiodic induction of larval diapause and temperature‐dependent termination in a wild multivoltine bruchid, Kytorhinus sharpianus
• Female‐biased sex ratio in a wild bruchid seed‐predator, Kytorhinus sharpianus. I. Larval competition and other factors
• Contagious egg‐distribution on host pods and avoidance of pods received eggs in a wild bruchid Kytorhinus sharpianus
• Bi‐ and trivoltine complex life cycles in a Kanto (Japan) population of a wild bruchid Kytorhinus sharpianus
• Geographical variation in insect developmental period: effect of host plant phenology on the life cycle of the bruchid seed feeder Kytorhinus sharpianus