L-aspartate decarboxylase; part of the gene cluster that mediates the biosynthesis of destruxins, insecticidal cyclic hexadepsipeptides which induce flaccid paralysis and visceral muscle contraction in insects through targeting the calcium channels and vacuolar-type ATPases (PubMed:22232661). The aldo-keto reductase dtxS3 converts alpha-ketoisocaproic acid from deaminated leucine into alpha-hydroxyisocaproic acid (HIC), which is the first substrate for destruxin assembly by dtxS1 (PubMed:22232661). L-aspartate decarboxylase dtxS4 converts aspartic acid into beta-alanine, the last substrate for the destruxin assembly line performed by dtxS1 (PubMed:22232661). The nonribosomal peptide synthetase dtxS1 synthesizes destruxins B and B2, whereas the cytochrome P450 monooxygenase dtxS2 is required to convert destruxin B into other destruxin derivatives, including destructins C, D, A and E (PubMed:22232661). Destruxin E-diol (ED) is further produced in a non-enzymatic manner from destruxin E (PubMed:22232661). Destruxins play an important role in virulence and escape from insect host immune defenses (PubMed:22232661). H(+) + L-aspartate = beta-alanine + CO2 Secondary metabolite biosynthesis. Impairs the production of destruxins (PubMed:22232661). Belongs to the group II decarboxylase family.