Taste sensitivity and divergence in host plant acceptance between adult females and larvae ofPapilio hospiton

Abstract

On the island of Sardinia the lepidopteran Papilio hospiton uses Ferula communis as exclusive host plant. However, on the small island of Tavolara, adult females lay eggs on Seseli tortuosum, a plant confined to the island. When raised in captivity on Seseli only few larvae grew beyond the first-second instar. Host specificity of lepidopterans is determined by female oviposition preferences, but also by larval food acceptance, and adult and larval taste sensitivity may be related to host selection in both cases. Aim of this work was: (i) to study the taste sensitivity of larvae and ovipositing females to saps of Ferula and Seseli; (ii) to cross-compare the spike activity of gustatory receptor neurons (GRNs) to both taste stimuli; (iii) to evaluate the discriminating capability between the two saps and determine which neural code/s is/are used. The results show that: (i) the spike responses of the tarsal GRNs of adult females to both plant saps are not different and therefore they cannot discriminate the two plants; (ii) larval L-lat GRN shows a higher activity in response to Seseli than Ferula, while the opposite occurs for the phagostimulant neurons, and larvae may discriminate between the two saps by means of multiple neural codes; (iii) the number of eggs laid on the two plants is the same, but the larval growth performance is better on Ferula than Seseli. Taste sensitivity differences may explain the absence of a positive relationship between oviposition preferences by adult females and plant acceptance and growth performance by larvae.

Plant Metabolites Drive Different Responses in Caterpillars of Two Closely Related Helicoverpa Species

“…At the level of metabolism, the capacity of degrading the capsaicinoids in H. assulta was overall higher than that in H. armigera (Zhu et al, 2020). Then, our data provide further evidence of adaptation of the specialist H. assulta to the toxic plant metabolites at the behavioral and chemosensory levels, which is similar to the attractive effects of "token stimuli, " the specific secondary metabolites from host plants, on other investigated specialist herbivores (Renwick and Lopez, 1999;del Campo et al, 2001;Miles et al, 2005;Sollai et al, 2018).…”

Association between olfactory sensitivity and behavioral responses of Drosophila suzukii to naturally occurring volatile compounds

“…Chemoreception plays a key role by regulating essential behaviors such as localization and discrimination of host plants suitable by females for laying eggs and by offspring as food source (Sollai, Biolchini, & Crnjar, 2018b). The goal of this study was to evaluate the olfactory sensitivity of D. suzukii females toward naturally occurring compounds, which showed deterrent or synergistic effects both in other species of insects and in different populations of D. suzukii (Del Fabbro & Nazzi, 2013; Kamsuk et al, 2007; Munerato et al, 2005; Park et al, 2016; Renkema et al, 2016; Renkema et al, 2017; Sobhy et al, 2017; Zeringota et al, 2013).…”

The contribution of gustatory input to larval acceptance and female oviposition choice of potential host plants in Papilio hospiton (Géné)

“…Stimuli were delivered for 2–3 s, in a random sequence with a 3‐min interval between consecutive stimulations to minimize adaptation phenomena. Leaf extracts were tested within 30 s after cold‐pressing, according to Dethier and Crnjar () and Sollai, Biolchini, Solari, et al (), Sollai, Biolchini, Loy, et al (). KCl was tested at the beginning and the end of the recording series to check for any shift in responsiveness; the experiment was discarded when significant variations between the initial and final KCl responses were found.…”

“…We have previously found that the sensory input coming from gustatory receptor neurons (GRNs), plays a key role in controlling the degree of acceptance of a plant as host, both in adult females (during the choice of the ovipositing sites) and in the larvae (during the choice to eat or not a food source; Sollai, Biolchini, & Crnjar, ; Sollai, Biolchini, Loy, Solari, & Crnjar, ; Sollai, Biolchini, Solari, & Crnjar, ; Sollai, Tomassini Barbarossa, Solari, & Crnjar, ). Furthermore, the specific pattern of activation of GRNs, in both adults and larvae, provides information to the central nervous system (CNS) to discriminate among different chemicals and plant saps (Dethier & Crnjar, ; Glendinning, Davis, & Rai, ; Sollai et al, ).…”

“…Furthermore, the specific pattern of activation of GRNs, in both adults and larvae, provides information to the central nervous system (CNS) to discriminate among different chemicals and plant saps (Dethier & Crnjar, ; Glendinning, Davis, & Rai, ; Sollai et al, ). Finally, chemical senses (taste and olfaction) play in general a primary role in insect–host interaction, providing information used in different behavioral paradigms, such as the choice of an oviposition site, a feeding substrate and mating partner (Biolchini et al, ; Chapman, ; Dangles, Irschick, Chittka, & Casas, ; del Campo & Miles, ; Masala, Solari, Sollai, Crnjar, & Liscia, ; Murata, Mori, & Nishida, ; Olianas et al, ; Solari et al, ; Ozaki et al, ; Solari et al, ; Sollai et al, ; Sollai, Solari, & Crnjar, ; Sollai, Solari, Masala, Crnjar, & Liscia, ). On the basis of all these considerations, our question was whether the peripheral taste sensitivity of adult females and larvae of P. hospiton , could also be involved in the rejection behavior of such plants as fennel and carrot.…”