Not Led by the Nose: Volatiles from Undamaged Eucalyptus Hosts Do Not Influence Psyllid Orientation

Abstract

Psyllids (Hemiptera: Psylloidea) are small sucking insects with high host plant specificity. Despite the primitive olfactory system of psyllids, some species have been suggested to rely on host plant volatiles (HPVs) for seasonal migration between summer deciduous hosts and winter coniferous hosts. Similarly, enhanced attraction of psyllid vectors has been observed as a result of the manipulation of host odors by plant pathogens. As yet, there are no studies of olfaction in psyllids that utilize evergreen eucalypt hosts. We investigated the behavioral responses of adults of four Eucalyptus-feeding psyllids—Ctenarytaina eucalypti, C. bipartita, Anoeconeossa bundoorensis and Glycaspis brimblecombei—to their respective HPVs in Y-tube olfactometer bioassays. We also used existing physiological data for C. eucalypti to investigate potential olfactory tuning that may modulate the preference for morphologically juvenile leaves over morphologically adult leaves. Although adult C. eucalypti were consistently repelled by HPVs from damaged host leaves, none of the species exhibited positive chemotaxis to HPVs from undamaged leaves. Surprisingly, G. brimblecombei was repelled by HPVs from undamaged host leaves. Our findings provide little support for a significant role of olfaction in host location by Eucalyptus-feeding psyllids. We propose a number of ecological hypotheses to explain these unexpected findings.

Host plant preference of Trioza erytreae on lemon and bitter orange plants

“…Species such as Cacopsylla bidens (Šulc, 1907), the pear psyllid, has been observed to respond to volatile cues from both the host plant and conspecifics using olfactometric and electroantennographic assays (Soroker et al 2004). On the contrary, Farnier et al (2018) did not find patterns of positive chemotaxis to volatiles of undamaged leaves of Eucalyptus L'Hér on different Eucalyptus-feeding psyllids. However, little is still known regarding the preference of T. erytreae for olfactory stimuli emitted by different host plants.…”

Engineered Orange Ectopically Expressing the Arabidopsis β-Caryophyllene Synthase Is Not Attractive to Diaphorina citri, the Vector of the Bacterial Pathogen Associated to Huanglongbing

“…Thus, it seems that modulation of VOCs directed to disrupt pathogen–host plant interactions is a viable approach for pest management that would have no residual effects on the environment. Psyllid species rely on olfactory cues to find their hosts, but evidences are difficult to obtain by laboratory bioassays, as physiological stage, light intensity, and the presence of visual cues influence their behavior ( Nissinen et al, 2008 ; Wenninger et al, 2009 ; Farnier et al, 2018 ). However, different studies indicated that psyllids respond positively to their host odors, for example, the common pistachio psyllid Agonoscena pistaciae is attracted to volatiles of pistachio leaves ( Ghamari et al, 2018 ) and Cacopsylla pruni to those of apricot ( Andrianjaka-Camps et al, 2018 ).…”

Value‐adding in biosecurity surveillance and monitoring: Testing colour and non‐target semiochemical lures on Psylloidea and Pentatomoidea

“…Why C. longicauda was not attracted to ACP lures, which are derived from the plant volatiles of fresh citrus growth (Setamou et al, 2018), remains unknown. The congeneric Ctenarytaina eucalypti was repelled by volatiles produced by damaged host plant leaves (Farnier et al, 2018), and perhaps C. longicauda is similarly sensitive, being repelled by the concentrations or ratios of semiochemical in the ACP lures.…”