The hamu changes to bamu as an instance of rendaku (連濁). 蝕(むしば)む • (<span class="searchmatch">mushibamu</span>) godan (stem 蝕(むしば)み (mushibami), past 蝕(むしば)んだ (mushibanda)) (of bugs)...
(ebamu) 啄(ついば)む (tsuibamu) 一人(ひとり)食(ば)み (hitoribami) 蝕(むしば)む, 虫(むし)食(ば)む (<span class="searchmatch">mushibamu</span>) 物(もの)食(は)み, 膆(ものはみ) (monohami) もり食(は)む (morihamu) 金(かね)の轡(くつわ)を食(は)ます...
with 蝕 蝕 (Hyōgai kanji) Go-on: じき (jiki) Kan-on: しょく (shoku) Kun: むしばむ (<span class="searchmatch">mushibamu</span>, 蝕む) In modern Japanese, 蝕 is mostly replaced by 食, due to the deprecation...
For pronunciation and definitions of むしばむ – see the following entry. (This term, むしばむ (<span class="searchmatch">mushibamu</span>), is the hiragana spelling of the above term.)...
add to it, or discuss it at the Etymology scriptorium. Particularly: “possibly related to 食(は)む (hamu)? compare 虫食む/蝕む (<span class="searchmatch">mushibamu</span>, “to be worm-eaten”)”...