Sensilla on different organs of female and male Telenomus dendrolimusi Chu (Hymenoptera: Scelionidae)

Abstract

Telenomus dendrolimusi Chu is a dominant egg parasitoid of Dendrolimus, which is the most serious conifer defoliator in China. However, the host locating mechanism of T. dendrolimusi is unclear. To take better advantage of this kind of parasitoid, it is necessary to clarify the basic knowledge of the organization of the wasp's sensory system. In this study, the external morphologies of the sensilla on the entire female and male T. dendrolimusi body were described using scanning electron microscopy. Antennae shape and sensilla types were sexually dimorphic. Ten segments and nine types of sensilla were found on the female antenna, including basiconic sensillum (BS), chaeticum sensillum (ChS), trichoid sensillum type 1 (TS1), trichoid sensillum type 2 (TS2), trichoid curvata sensillum (TCS), sickle-shaped sensillum (SSS), multiporous gustatory sensillum (MGS), campaniform sensillum (CS), and styloconica sensillum (STS). The distribution of the sensilla was directional on female antenna. The male antenna consisted of 12 segments, and 1-3 segments were similar to those of the female. Five types of sensilla were found on male antenna, including BS, ChS, TS1, TCS, and STS. The mouthparts, thoracic legs, eyes, mesonotum, and wings were all covered with longitudinally fluted TSs without hole. A tympana structure appeared on the thoracic legs. Special crevice-shaped structures were found on the abdomens of both T. dendrolimusi sexes. Possible sensilla functions are discussed according to their morphology. These results provide a solid basis for further researches about the parasitic mechanisms of T. dendrolimusi.

Morphological Structure of the Body Setae as Mechanoreceptor on the Mesonotum of Telenomus remus Nixon (Hymenoptera, Platygastridae)

“…Setae with respective characteristics were also observed in other insects' body, such as antennae, mouthpart, and legs. It is usually called as chaetica or trichoid sensilla (Yanagawa et al, 2009;S. Zhang et al, 2015;Zhang et al, 2016).…”

“…As a potential parasitoid, however, the exploration of the sensory organs of T. remus were very limited at this time. Some sensory receptors were recorded from the antennae of T. dendrolimusi and T. reynoldsi, such as basiconic, chaetica, trichoid, trichoid curvata, multiparous gustatory, campaniform, and stylonica sensilla (Cave & Gaylor, 1987;S. Zhang et al, 2015).…”