DNA hybridization probe for endoparasitism by Microplitis croceipes (Hymenoptera: Braconidae)

We describe a DNA hybridization assay for an insect endoparasitoid. The probe is a digoxigenin-labeled 438 bp fragment from a genomic library of the braconid Microplitis croceipes (Cresson), a larval endoparasitoid of heliothine noctuids. The assay is run on nylon membranes and can detect 125 pg of target DNA. Estimates of parasitization rate in large samples of simultaneously parasitized larvae of the host Helicoverpa zee (Boddie), made by hybridization probe assay of unamplified host homogenates and by dissection, are not statistically distinguishable for 1st or 2nd instar parasitoids. It should be possible to perform the entire procedure, from host collection and DNA extraction to evaluation of assay results: in 1 d, making this prototype technology useful as a monitoring and management tool.