Efficacy and emergence of parasitic wasps that attack herbivorous insects on maize and its relatives in their region of origin

Abstract

Maize (Zea mays subsp. mays), an important cereal crop worldwide, was domesticated directly from the annual teosinte (Zea mays subsp. parviglumis), and teosintes originated from gamagrass (Tripsacum) plants. Some herbivorous insects of maize began their association on Tripsacum; however, little is known about the interaction between these herbivores and their parasitoids in this ancestral Tripsacum habitat. A field experiment was conducted in the Mesoamerican region of origin of maize, using sentinel eggs of the hopper Dalbulus quinquenotatus on Tripsacum dactyloides, and eggs of the insect pest Dalbulus maidis on annual teosinte, landrace maize, and modern maize. A community of egg parasitoids formed by Anagrus naulti (Mymaridae), Paracentrobia sp., and Pseudoligosita sp. (Trichogrammatidae) was found attacking eggs of both species of hoppers on the tested host plants. The largest abundance of parasitoids adult emergence and rate of parasitism was found in D. quinquenotatus eggs laid on T. dactyloides. The rate of parasitism was similar for the other three treatments: D. maidis on teosinte, landrace maize, and modern maize. In the D. quinquenotatus-Tripsacum treatment, D. maidis-annual teosinte treatment, and D. maidis-hybrid maize treatment more Paracentrobia sp. adults emerged than A. naulti adults. These results suggest that the interaction between hoppers and their egg parasitoids occurs on Tripsacum plants, and probably has been in place since before maize domestication.