Antennal sensilla of three parasitic Hymenoptera

Abstract

Scanning electron microscopy studies were conducted on the antennal sensory sensilla of 3 species of parasitoid Hymenoptera which utilize Heliothis virescens (Fab.) as their habitual host. Two of the species, Cardiochiles nigriceps Viereck and Microplitis croceipes (Cresson), are braconids, while the third, Campoletis sonorensis (Cameron), is an ichneumonid. Two uniquely shaped basiconic sensilla—curved non-fluted and fluted bent-tipped—are present only on the antennal flagella of C. nigriceps. Trichoid sensilla are the most abundant sensory receptors on all species studied. Placoid and fluted basiconic sensilla are numerous on all flagellar segments. Smooth basiconic sensilla are restricted in number to one per flagellar segment in each of the 3 species. An analysis of the sensory sensilla seems to indicate that the ability to search for more than one host species is not dependent upon any one morphologically unique chemoreceptor.