Morphology and distribution of antennal multiporous gustatory sensilla related to host recognition in some Trichogramma spp.

Trichogramma spp. (Hymenoptera Trichogrammatidae) are endoparasitic wasps that attack the eggs of mainly Lepidoptera species. The morphology of the antennal multiporous gustatory sensilla of five Trichogramma species is studied and compared: Trichogramma cacoeciae Marchal, Trichogramma chilonis Ishii, Trichogramma dendrolimi Matsumura, Trichogramma turkestanica Meyer, and Trichogramma sibericum Sorokina. Scanning electron microscopy of the female antennae shows the presence of numerous peculiar sensilla on the ventral apical side of the club, for which a gustatory function is hypothesized. These appear as multiporous sensilla, although the pores are not distributed all over the surface of the hair, as they are only on the ventral margin. Also, these sensilla are located exclusively on antennal areas that come into contact with the substrate. Variations in the numbers and distributions of the multiporous gustatory sensilla were found between the species examined, as well as within individuals belonging to the same species. Functional aspects and variations in the distributions of these sensilla are discussed.