Diversity and Density-Dependence Relationship between Hymenopteran Egg Parasitoids and the Corn Leafhopper (Hemiptera: Cicadellidae) in Maize Agroecosystem vs. Teosinte Wild Habitat

Little is known about the differences between the habitats of domesticated plants and their wild ancestors with respect to the third trophic level. A field study was conducted in the region of origin of domesticated maize to investigate the differences between a maize landrace and the teosinte Zea mays ssp. parviglumis Iltis & Doebley (Poaceae) (the maize ancestor) plants in diversity and density-dependence relationship in the egg parasitoids of corn leafhopper, Dalbulus maidis (DeLong) (Hemiptera: Cicadellidae), within the maize and teosinte habitats. Comparing exposure of both plants within the maize agroecosystem vs. the teosinte wild habitat, eggs of D. maidis were attacked by a community or complex of parasitoids. A higher diversity of adult parasitoids was found in teosinte plants (H′ = 0.73) than in maize landrace plants (H′ = 0.30) within the maize habitat. In addition, within the teosinte habitat a higher diversity of adult parasitoids was seen in the teosinte plants (H′ = 0.88) than in maize landrace plants (H′ = 0.40). Adult egg parasitoids were abundant within maize habitat and included Anagrus virlai Triapitsyn (Hymenoptera: Mymaridae), Paracentrobia sp., and Pseudoligosita sp. (both Hymenoptera: Trichogrammatidae). Within the teosinte habitat, the community of parasitoids included A. virlai, Anagrus incarnatus Haliday (Hymenoptera: Mymaridae), Paracentrobia sp., and Pseudoligosita sp. In the maize habitat, a strong positive density-dependent association was seen between the number of D. maidis eggs and the community of adult parasitoids, and A. virlai, the most abundant and common parasitoid. However, a weak density-dependent association was seen in the teosinte wild habitat. Differences in density-dependent association in D. maidis and the community of egg parasitoids between teosinte wild habitat and maize crop contribute to the understanding of changes in the third trophic level through maize domestication.