Spectral sensitivity and visual conditioning in the parasitoid wasp Trybliographa rapae (Hymenoptera: Cynipidae)

Abstract

Spectral sensitivity of the wasp Trybliographa rapae (Westwood), a parasitoid of cabbage root fly larvae, was measured by the electroretinogram (ERG) technique and by a complimentary behavioural technique, to 15 selected wavelength bands from 340 to 670 nm. Peaks of electroretinogram sensitivity were found in the ultraviolet, blue and green-yellow regions of the spectrum. This corresponds to known classes of photoreceptor present in the Hymenoptera. Behavioural peaks of phototactic attraction were found in the ultraviolet and green-yellow regions, but not in the blue. No differences were observed between the sexes. We suggest that ultraviolet and green-yellow wavelengths initiated ‘escape’ and ‘foliage’ orientated behaviour respectively. Blue wavelengths appear to have a less specific function but may be important for colour discrimination. Blue wavelengths did, however, become significantly more attractive to female wasps after a pre-experimental conditioning period involving exposure to blue wavelengths in combination with swede infested with cabbage root fly larvae. Thus T. rapae has been demonstrated to show plasticity in its visually motivated behaviour. This may prove advantageous in the development of an artificial egg collecting technique for this species.

Phototaxis of <I>Grapholitha molesta</I> (Lepidoptera: Olethreutidae) to Different Light Sources

“…Insects have a weak ability to distinguish their hosts visually, so color provides one of the most important cues for long-distance searches (Brown et al 1998). Visual cues used by insects have been widely studied in parasitiods during host location from a distance and after landing (Fischer et al 2003).…”

Influence of visual cues on host‐searching and learning behaviour of the egg parasitoids Telenomus podisi and Trissolcus basalis

“…Orientation using visual cues, principally colours, for habitat or host detection has been reported for several parasitoid families, such as Aphelinidae, Aphidiidae, Braconidae, Cynipidae, Encyrtidae, Ichneumonidae, and Pteromalidae (Moreno et al, 1984;Schmidt et al, 1993;Michaud & Mackauer, 1994;Wäckers, 1994;Romeis & Zebitz, 1997;Brown et al, 1998;Oliai & King, 2000;Demas et al, 2002;Fischer et al, 2004;Rousse et al, 2007;Segura et al, 2007;Lucchetta et al, 2008). For egg parasitoids there is less information related to the use of colours during host searching with the exception of some studies on Trichogramma spp.…”

Perception of achromatic cues during host location of a pupal parasitoid

“…Plant‐derived visual cues include discolorations, lesions, entrance holes, emergence windows, leafmines, and galls created by feeding herbivores (Faeth, 1990; Pfannenstiel et al., 1992; Smith et al., 1993; Potting et al., 1997). Despite the importance of visual cues in host finding of hymenopteran parasitoids, there are only three electrophysiological studies addressing their spectral sensitivity (Peitsch et al., 1992; Mellor et al., 1997; Brown et al., 1998) and two behavioral studies on color vision, i.e., the sensation of chromatic contrast independent of intensity contrast (Wardle, 1990; Messing & Jang, 1992). While information on chromatic vision is scarce, the role of achromatic cues in parasitoid host location is largely unknown.…”