melanize
/ˈmɛlənʌɪz/(also melanise) Biology
verb
1 [with object] To subject to melanization; to cause the production or accumulation of melanin in or around (especially as a physiological defence mechanism in insects).
2 [no object] To undergo melanization; to darken as a result of melanin formation.
Origin
1960s. From melano- + -ize, after melanized and melanization.