Part of an orally active toxin complex (TC) with strong insecticidal effects on larvae of the Coleoptera Costelytra zealandica, Acrossidius tasmania and Adoryphorus couloni and some Lepidoptera larvae (PubMed:21278295). The TC has an endochitinase activity (PubMed:21278295) (Probable). Toxin complex is secreted when grown at 25 degrees Celsius or less; at higher temperatures the proteins are present intracellularly but not secreted. Semipurified toxin complex consists of at least YenA1-YenA2-YenB-YenC1-YenC2-Chi1-Chi2 (PubMed:21278295). YenB and the N-terminus of YenC2 form a large hollow shell of beta-strands (PubMed:23913273). The shell is closed at both ends, within which the C-terminus of YenC2 is probably found (PubMed:23913273). The C-terminal region dissociates from the YenB-YenC2 complex at pH 4.5 but not 7.5 (PubMed:23913273). The Yen-TC:K9 subcomplex is about 26 nm tall and 22 nm in diameter with 5-fold symmetry and 5 copies of YenA1, YenA2, Chi1 and Chi2; the chitinase subunits may be solvent accessible on the exterior the complex (PubMed:22158901). The Yen-TC:K9 subcomplex has no insecticidal activity (PubMed:22158901). The native complex with additional YenB, YenC1 and YenC2 subunits is 16 nm taller and is insecticidal; the toxicity-conferring subunits are present at about 1 copy each (PubMed:22158901). Secreted when grown at 25 degrees Celsius or less, but not when grown at 30 or 37 degrees Celsius. Residues 610-690 form a beta-strand plug which closes one end of the shell; the other end of the shell is closed by the 5-bladed beta-propeller domain in YenB. A double yenC1-yenC2 deletion is no longer pathogenic in C.zealandica larvae. Belongs to the RHS family.