Diversity and Parasitism by Parasitic Wasps That AttackDalbulus maidis(Hemiptera: Cicadellidae) on Year-Round and Seasonal Maize Agroecosystems

Abstract

Agroecosystems undergo frequent anthropogenic disturbance that may affect the diversity, community, and abundance of natural enemies living there. In the tropics, annual crops such as maize are planted two times (year-round crops) or one time (seasonal crops) per year. Little is known about how natural enemies of insect pests respond to maize agroecosystems planted one vs. two times during each annual cycle. The objective was to investigate the diversity and parasitism of egg parasitoids of the pest Dalbulus maidis (DeLong) (Hemiptera: Cicadellidae) in maize agroecosystems planted year-round and seasonally. Potted maize plants with D. maidis eggs were placed within these two maize agroecosystems to attract egg parasitoids during the maize-growing wet season in Mexico. In these two maize agroecosystems, similar levels of diversity were found, using the Shannon-Wiener index (H'). Communities of parasitic wasps were found attacking the eggs of D. maidis in both maize agroecosystems, but there were differences in the composition of these communities. In the year-round maize agroecosystem, Paracentrobia sp. near subflava (Girault) (Hymenoptera: Trichogrammatidae) was the most common, while Anagrus virlai Triapitsyn (Hymenoptera: Mymaridae) was most common in the seasonal maize. A greater total abundance and total rate of parasitoid emergence were found in the year-round maize agroecosystem compared with the seasonal maize. In addition, a positive relationship between the number of D. maidis eggs and parasitoid abundance was found in both maize agroecosystems. However, a negative density dependence between the number of D. maidis eggs and the percentage of parasitism was found in both maize agroecosystems.