Temperature affects interaction of visual and vibrational cues in parasitoid host location

Abstract

Parasitoid host location in nature is facilitated by simultaneously using different information sources. How multisensory orientation on the same spatial scale is influenced by environmental conditions is however poorly understood. Here we test whether changes in reliability of cues can cause parasitoids to alter multisensory orientation and to switch to cues that are more reliable under extreme temperatures. In the ichneumonid wasp Pimpla turionellae, multisensory use of thermally insensitive vision and thermally sensitive mechanosensory host location by vibrational sounding (echolocation on solid substrate) was investigated with choice experiments on plant-stem models under optimum temperature (18 degrees C), at high- (28 degrees C) and low-temperature limits (8 degrees C) of vibrational sounding. Temperature affected relative importance of vibrational sounding whereas visual orientation did not vary. At 18 degrees C, parasitoids used visual and vibrational cues with comparable relative importance. At 8 and 28 degrees C, the role of vibrational sounding in multisensory orientation was significantly reduced in line with decreased reliability. Wasps nearly exclusively chose visual cues at 8 degrees C. The parasitoids switch between cues and sensory systems depending on temperature. As overall precision of ovipositor insertions was not affected by temperature, the parasitoids fully compensate the loss of one cue provided another reliable cue is available on the same spatial scale.

Bacterial volatiles elicit differential olfactory responses in insect species from the same and different trophic levels

“…Whereas herbivorous insects predominantly use plant volatiles and colors to find suitable host plants during long‐range foraging, higher trophic levels such as parasitoids mainly use herbivore‐induced plant volatiles (HIPVs) and volatiles from herbivore feces, as well as visual and mechanosensory cues to locate suitable hosts (Wäckers & Lewis, 1994; Fischer et al. , 2001; van Oudenhove et al. , 2017).…”

Eavesdropping on sexual vibratory signals of stink bugs (Hemiptera: Pentatomidae) by the egg parasitoid Telenomus podisi

“…Chemical cues are used mainly on a long-range scale (Vinson 1985;Godfray 1994), whereas over short distances, visual and mechanical cues may also be included (Vinson 1985;Godfray 1994). This information can be used separately, hierarchically or in a combined, integrated multimodal signal (Fischer et al 2001).…”

Associative learning of visual cues in the fruit fly parasitoid Diachasmimorpha longicaudata: temporal dynamics and potential consequences on females' fitness

“…If the hosts develop concealed inside plant structures, visual cues from the host are not available, making the host habitat an important source of visual information. Visual cues from the host habitat, such as colour, shape, and patterns, have been shown to be a valuable source of information for parasitic wasps during host location (Wäckers & Lewis, 1994, 1999; Battaglia et al., 2000; Fischer et al., 2001; Stireman, 2002; Rousse et al., 2007; Segura et al., 2007; Benelli & Canale, 2012; Pérez et al., 2012; Giunti et al., 2015). Because compound eyes allow image resolution only at fixed focal distances, colour and contrast are the most important visual cues at long distances, whereas shapes and patterns affect host‐seeking behaviour only over short distances (Giunti et al., 2015; Cochard et al., 2018).…”