Overwintering biology of egg parasitoids of dalbulus maidis (Hemiptera: Cicadellidae) on perennial grasses, volunteer maize, stubble, and drip-irrigated maize

Abstract

Dalbulus maidis (DeLong & Wolcott) (Hemiptera: Ciaadellidae) is the most important leafhopper vector of maize plant pathogens in the Americas. However, until now, no study has investigated the overwintering biology of its egg parasitoids. The objective in this study was to find egg parasitoids of D. maidis in perennial grass, volunteer maize, stubble, and drip-irrigated maize habitats in the winter season. Two-week-old D. maidis females were allowed to oviposit on young maize plants for 72 h under laboratory conditions. The oviposited healthy D. maidis eggs (sentinel eggs) on the young maize plants were exposed to natural parasitism maintained on perennial grasses, volunteer maize, and stubble 2 mo after the onset of winter, and on perennial grasses, volunteer maize, and drip-irrigated maize at the end of winter. The abundance of D. maidis adults in these habitats was also determined. Two months after the start of winter, D. maidis eggs were parasitized by the wasp Oligosita sp. from perennial grasses and volunteer maize, whereas at the end of winter, the eggs were parasitized by the wasps Oligosita sp. and Anagrus columbi Perkins from perennial grasses, volunteer maize, and drip-irrigated maize. Overall, more adult parasitoids of D. maidis eggs were found on perennial grasses. Adult corn leafhoppers were absent from perennial grasses at the end of winter; however, other Deltocephalinae leafhopper species were present, suggesting that egg parasitoids of D. maidis use another leafhopper host during winter. Furthermore, adults of five Deltocephalinae species were parasitized by dryinids and strepsipterans throughout the 2012-2013 winter in perennial grasses. © 2014 Entomological Society of America.