Shows strong antibacterial activity against numerous Gram-positive bacteria. It selectively inhibits peptidoglycan biosynthesis through complex formation with the cell wall precursor lipid II (1:1 molar ratio) thus inhibiting cell wall synthesis (PubMed:20508130). Shows antibacterial activity against the Gram-positive bacteria M.luteus, E.fecalis (MIC=32 mg/L), S.aureus (MIC=16 mg/L), S.carnosus (MIC=2 mg/L), S.pneumoniae (MIC=2 mg/L) and S.pyogenes (MIC=2 mg/L) and against a number of methicillin-resistant S.aureus and glycopeptide-intermediate S.aureus isolates (PubMed:20542901, PubMed:19921400, PubMed:21560219). Does not show antibacterial activity against Gram-negative bacteria or antifungal activity against C.utilis (PubMed:20542901). Shows slight antifungal activity against C.albicans (PubMed:21560219). Larval fat body, hemolymph and salivary glands (at protein level) (PubMed:19921400). Expressed in the salivary glands of all larval stages (PubMed:23624615). In the salivary glands, there is no expression in early larval stages with expression beginning 5-6 hours after hatching (PubMed:23624615). Maximum expression is reached about 24 hours after hatching, remains strong during the second and third instars and declines at the end of the third instar before the wandering stage (PubMed:23624615). No expression is detected at the wandering stage (PubMed:23624615). Induced in the hemolymph by septic injury caused by dorsolateral puncturing with a needle contaminated with lipopolysaccharide (LPS) solution (PubMed:25182719). Induced in the salivary glands by feeding (PubMed:23624615). Induced in the fat body and the grease coupler of the salivary glands in response to oral ingestion of S.aureus and P.aeruginosa (PubMed:23624615). The disulfide bonds are essential for antimicrobial activity. During maggot debridement therapy which involves the controlled application of cultured sterile larvae to an infected chronic non-healing wound, one of the key factors which protects larvae against the infectious wound environment and contributes to wound healing through its antimicrobial activity. Belongs to the invertebrate defensin family. Type 1 subfamily.