New insight into the antennal chemosensory function ofopius concolor(hymenoptera, Braconidae)

Abstract

The presence of taste and olfactory chemosensilla is demonstrated by using both morphological and electrophysiological techniques on antennae of Opius concolor, a parasitoid of tephritid larvae. Observation under the Scanning Electron Microscope revealed the presence of large sensilla trichodea with an apical pore, and of flat plates (sensilla placodea) extending almost the entire length of each antennomere. By means of currently used electrophysiological techniques, it was possible to record both the gustatory activity generated by sensilla trichodea following contact with KC1 100 mM and sucrose 100 mM solutions, and olfactory activity probably generated by sensilla placodea in response to volatile stimuli. The analysis of gustatory activity showed that each sensillum trichodeum consisted of at least three chemosensory units. This supports the assumption that in O. concolor single sensilla may, by providing different spike discharge patterns, which depend on the quality and intensity of the stimulus, provide the CNS with adequate information for peripheral discrimination among stimulating chemicals. Study of the sensory input of O. concolor with electrophysiological techniques may be of great scientific importance for possible applications in biocontrol of the olive fly.

Scanning electron microscopy studies of antennal sensilla of Pteromalus cerealellae (Hymenoptera: Pteromalidae)

“…Their morphology and location is similar to some previously described sensilla in many insects including the ''thick-walled chemoreceptors'' of the pteromalid, N. vitripennis (Slifer, 1969;Wibel et al, 1984), the ''uniporous pit pore sensilla trichodea D'' in T. nubilale (Olson and Andow, 1993), the ''uniporous gustatory sensilla'' described on the antennae of many parasitic wasps (Isidoro et al, 1996), and the ''curved trichoid formation with an apical pore'' described in Opius concolor by Barbarossa et al (1998). The ChS-UP have also been described as ''fluted basiconic sensilla'' in the braconid Cardiochiles nigriceps Vireck (Norton and Vinson, 1974) ''aporous, socketed hairs'' in the eulophid T. hagenowii , and as ''tapering fluted setae'' in the eulophid Melittobia australica Girault (Dahms, 1984).…”

“…The ChS-UP have also been described as ''fluted basiconic sensilla'' in the braconid Cardiochiles nigriceps Vireck (Norton and Vinson, 1974) ''aporous, socketed hairs'' in the eulophid T. hagenowii , and as ''tapering fluted setae'' in the eulophid Melittobia australica Girault (Dahms, 1984). The ChS-UP have also been described in other wasps as having a terminal pore suggesting that they may be involved in contact chemoreception (Altner and Prillinger, 1980;Olson and Andow, 1993;Pettersson et al, 2001), including gustatory function (Isidoro et al, 1996;Barbarossa et al, 1998). The ChS-UP are confined to the apices of the antennae of P. cerealellae and many other pteromalids, further suggesting their role as contact chemoreceptors (Slifer, 1969;Wibel et al, 1984;Pettersson et al, 2001) and probable involvement in host recognition and host acceptance (Weseloh, 1972;Borden et al, 1973).…”

Antennal sensilla of female Encarsia guadeloupae Viggiani (Hymenoptera: Aphelinidae), a nymphal parasitoid of the spiraling whitefly Aleurodicus dispersus (Hemiptera: Aleyrodidae)

“…ST-UP have been described as fluted basiconic sensilla in Cardiochiles nigriceps (Norton and Vinson, 1974b), s. basiconica A in Microplitis croceipes (Navasaro and Elzen, 1991), or curved trichoid formations with an apical pore in Opius concolor (Barbarossa et al, 1998), uniporous sensillum trichoideum in Trichogramma galloi and Trichogramma pretiosum (Cônsoli et al, 1999), sensilla trichodea TP in Cotesia glomerata (Bleeker et al, 2004), Basiconica sensilla I in A. cypris (Zhou et al, 2011). ST-UP is similar to the Ch-UP with a flexible socket and apical pore.…”

“…Their morphology and location are similar to the "rod-like sensilla" of the E. asterobemisiae (Viggiani, 1982), but RO-UP is remarkably different in shape with the other "uniporous sensilla" observed in many insects including the "uniporous pit pore sensilla trichodea D" in T. nubilale (Olson and Andow, 1993), the "uniporous gustatory sensilla" described on the antennae sensilla of many parasitic wasps (Isidoro et al, 1996), and the "curved trichoid formation with an apical pore" described in Opius concolor by Barbarossa et al (1998). The RO-UP may have the function of contact chemoreception for having a terminal pore (Altner and Prillinger, 1980;Olson and Andow, 1993;Pettersson et al, 2001), or gustatory function (Isidoro et al, 1996;Barbarossa et al, 1998). They are probably related to host recognition and host acceptance (Weseloh, 1972;Borden et al, 1973).…”

Antennal sensory receptors of Pteromalus puparum female (Hymenoptera: Pteromalidae), a gregarious pupal endoparasitoid of Pieris rapae

“…The uniporous sensilla trichodea type 4 occur on the 12th flagellar subsegment and the ventral surface of the 11th flagellar subsegment and are similar in morphology and location to some previously described sensilla in other parasitic wasps including the ''thick-walled chemoreceptors'' of the pteromalid, N. vitripennis (Slifer, 1969;Miller, 1972;Wibel et al, 1984), the ''uniporous chaetica sensilla'' of the pteromalid, P. cerealellae (Onagbola and Fadamiro, 2008), the ''uniporous pit pore sensilla trichodea D'' in Trichogramma (Olson and Andow, 1993), the ''uniporous gustatory sensilla'' described on the antennae of many parasitic wasps (Isidoro et al, 1996), and the ''curved trichoid formation with an apical pore'' described in Opius concolor by Barbarossa et al (1998). They have also been described as ''aporous, socketed hairs'' in the eulophid Tetrastichus hagenowii , and as ''tapering fluted setae'' in the eulophid Melittobia australica (Dahms, 1984).…”