There are several species of wasps that are naturally occurring parasitoids of diamondback moth in Thailand and Japan. Some of these, as well as other species, are commercially available in the United States. Which is the best species or strain of Trichogramma for use against diamondback moth?
Five commercially available trichogrammatid egg parasitoids (Trichogramma pretiosum, T. ostriniae, T. platneri, T. minutum and T. brassicae) and one species under development as a commercial product (Trichogrammatoidea bactrae) were tested against diamondback moth eggs in laboratory experiments.
These wasps kill eggs not only by laying their eggs in them, but also by host feeding. Therefore, assessment of host mortality included both parasitism and direct mortality caused by host feeding. T. bactrae, T. pretiosum, and T. minutum caused 95-98% mortality. T. bactrae and T. pretiosum produced the highest rates of parasitism (69-72%), while T. minutum and T. platneri caused the highest direct mortality (60-63%).
Unfortunately, inconsistent responses between shipments were observed with most of the products, indicating potential problems with quality control.
Vasquez, L. A., A. M. Shelton, M. P. Hoffman, and R. T. Roush. 1997. Laboratory evaluation of commercial trichogrammatid products for potential use against Plutella xylostella (L.) (Lepidoptera: Plutellidae). Biological Control 9: 143-148.
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