Effects of host species and host age on biological parameters of Anagrus virlai (Hymenoptera: Mymaridae), an egg parasitoid of Dalbulus maidis (Hemiptera: Cicadellidae) and Peregrinus maidis (Hemiptera: Delphacidae)

Abstract

Dalbulus maidis (DeLong) (Hemiptera: Cicadellidae) and Peregrinus maidis (Ashmead) (Hemiptera: Delphacidae) are important pests for maize production in America. Anagrus virlai Triapitsyn (Hymenoptera: Mymaridae) is a potential biological control agent for both hopper species. We provide information on the effects of size, age and host species on the time of development, parasitism and emergence, and morphometry of A. virlai. Additionally, we evaluate if A. virlai females can discriminate between the eggs of both host species using a Y-tube olfactometer. The wasps were reared in breeding chambers under controlled conditions, and one, three and five days-old eggs of D. maidis and P. maidis were used for bioassays. Anagrus virlai developed in eggs from the three age classes of both hopper species; however, the number of parasitized eggs and emergence of wasps was significantly higher on eggs of D. maidis than on those of P. maidis. Wasps that emerged from D. maidis eggs presented larger size compared to those reared on P. maidis eggs. Host species not only influenced the parasitism, emergence, and size of the wasps, but also development time. In olfactometric tests, A. virlai chose maize leaves containing D. maidis eggs, instead of those containing P. maidis eggs. Our results show that A. virlai, formerly known as generalist parasitoid, would only use the planthopper P. maidis as an occasional host.