Preliminary characterization of toxins from the straw itch mite, Pyemotes tritici, which induce paralysis in the larvae of a moth.

Homogenates of whole mites (Pyemotes tritici) paralyze larvae of the greater wax moth Galleria mellonella. Injection of these homogenates into larvae produces symptoms identical to those obtained by bites from female mites. Since the paralytic activity is destroyed by heat and proteolytic enzymes and retained during dialysis, the toxic compounds appear to be proteins. Two protein fractions which differ both in molecular weight and toxicity were found following gel filtration of whole mite extracts. Larvae that are injected with proteins from the high molecular weight (c. 250,000) fraction (designated TxP-HMW) develop flaccid-muscle paralysis after 4-12 hr, while proteins in the low molecular weight fraction (c. 21,000) (designated TxP-LMW) induce a rapid, muscle-contracting paralysis.