Host range of the oothecal parasitoid Aprostocetus hagenowii (Hymenoptera: Eulophidae).

Abstract

Aprostocetus hagenowii (Ratzburg) is a generalist parasitoid of cockroach (Blattodea) oothecae. Previous studies examining the host range of A. hagenowii have largely focused on cockroaches of economic and medical importance, which represent a minority of species in an order filled with species of diverse morphology, behavior, and ecology. The aim of this study was to expand the known host range of A. hagenowii with emphasis on nonpest as well as pest species from 3 cockroach families (Blattidae, Corydiidae, and Ectobiidae). Previously recorded host species were also reexamined. Oothecae from 17 cockroach species were exposed to A. hagenowii. Three new host species were recorded: Blatta lateralis (Walker) (Blattidae), Neostylopyga propinqua (Shelford) (Blattidae), and Parcoblatta fulvescens (Saussure and Zehntner) (Ectobiidae). Among the reexamined host species Periplaneta australasiae (Fab.) (Blattidae), Blatta orientalis L. (Blattidae), and Neostylopyga rhombifolia (Stoll) (Blattidae) were successfully parasitized. The cuticle thicknesses of 7 cockroach species' oothecae were also investigated. There were significant differences [Kruskal-Wallis: each zone (below keel, side, and bottom) measured P < 0.001] in cuticle thickness among the species measured. Polyphaga sassurei (Dohrn) (Corydiidae) and Eurycotis floridana (Walker) (Blattidae) had the thickest cuticles (each zone >0.09 mm) and Blattella germanica (L.) (Ectobiidae) had the thinnest (each zone <0.03 mm). However, the mean A. hagenowii ovipositor length (0.92 mm ± 0.01 mm) far exceeded the thickest oothecae measured. Oothecal cuticle thickness alone was not observed to determine the host suitability of each tested cockroach species for A. hagenowii.