Comparative Analysis of Cuticular Hydrocarbons from the Ectoparasitoids Cephalonomia waterstoni and Laelius utilis (Hymenoptera: Bethylidae) and Their Respective Hosts, Cryptolestes ferrugineus (Coleoptera: Cucujidae) and Trogoderma variabile (Coleoptera: Dermestidae)

Abstract

Cuticular hydrocarbons have been identified from the immatures and adults of two bethylid wasps and their larval beetle hosts. Cephalonomia waterstoni Gahan is host specific on Cryptolestes ferrugineus (Stephens), whereas Laelius utilis Cockerell is commonly associated with a variety of dermestid larvae, including Trogoderma variabile Ballion. The cuticular hydrocarbons of C. waterstoni larvae consist of n-alkanes (C21-C33), 2-, 3-, 5-, 7-, 11-, and 13-methyl alkanes, one dimethyl alkane (11,15-dimethyl C27), and a C31 monoene and diene. The cuticular hydrocarbon composition of their beetle host differs somewhat, consisting of n-alkanes (C25-C32), 3-, 5-, 11-, and 13-methyl alkanes, a series of Z-8/Z-9-monoenes, and a series of dienes with the double bonds separated by 12 methylene units. No dimethyl alkanes are present in the C. ferrugineus larvae. Considerable ontogenetic changes in cuticular hydrocarbon composition occur when C. waterstoni eclose to adults. Although both sexes contain the same major cuticular hydrocarbons, their relative abundances vary. In addition to n-alkanes (C23-C27), 2-, 3-, and 5-methyl alkanes, 5,15-, 5,17-, and 5,19-dimethyl alkanes, and a series of Z-11-monoenes are present in both sexes. In addition, the males possess small quantities of Z-7-monoenes. The males have the monoenes as their major components, whereas the females have the 5-methyl alkanes and the dimethyl alkanes as their major components. The cuticular hydrocarbon composition of L. utilis and its host T. variabile differs considerably from the Cephalonomia-Cryptolestes pairing. The major components of the Laelius larvae consist of n-alkanes (C23-C33), 3-, 5-, 13-, and 15-methyl alkanes, and a series of Z-9-monoenes. The T. variabile larval hydrocarbons consist only of n-alkanes (C22-C35) and 3-, 5-, and 13-methyl alkanes. No unsaturated components were detected. As with C. waterstoni, considerable ontogenetic changes in hydrocarbon composition occur for L. utilis upon adult eclosion. Unlike C. waterstoni, however, only slight differences in composition occur between the sexes. The adult Laelius hydrocarbons consist of n-alkanes (C21-C29), 2-, 3-, 7-, 9-, and 13-methyl alkanes, and a series of Z-9-monoenes.