Inhibition of Larval Growth in the Gypsy Moth (Lepidoptera: Lymantriidae) by Venom from the Parasitic Wasp Microbracon hebetor (Hymenoptera: Braconidae)

Abstract

Extract of the venom glands of the adult female ectoparasitic wasp Microbracon hebetor (Say) (Hymenoptera: Braconidae) inhibited larval growth in the gypsy moth Lymantria dispar (L.) (Lepidoptera: Lymantriidae). The inhibition was dose dependent and at 5 d after injection larval growth was reduced 50% by 2 × 10−3 μg venom gland protein per mg larval weight. Doses greater than 2.5 × 10−2 μg per mg larval weight prevented growth completely and accelerated larval death. Size-exclusion fractions of gland extract, which eluted between 35 kD and 66 kD molecular weight markers, inhibited growth and caused delayed pupation. At 5 d after injection of active chromatographic fractions, larval growth was reduced 50% by 2 × 10−4 μg fraction protein per mg larval weight. Doses greater than 1 × 10−3 μg fraction protein per mg larval weight stopped growth completely. Both crude extract and active column fractions caused their effects without evidence of extended paralysis.