Department of Biomedical Sciences, Section of Physiology, University of Cagliari, 09042, Monserrato (CA), Italy.
Insect Sci. 2018 Oct;25(5):809-822. doi: 10.1111/1744-7917.12581. Epub 2018 Apr 15.
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.
在撒丁岛，蝴蝶 Papilio hospiton 将 Ferula communis 作为其唯一的宿主植物。然而，在塔沃拉拉小岛上，成年雌性蝴蝶会在 Seseli tortuosum 上产卵，而 Seseli tortuosum 是一种仅限于该岛的植物。当在 Seseli 上人工饲养幼虫时，只有少数幼虫能够长到第一至第二龄。鳞翅目昆虫的寄主特异性取决于雌性产卵偏好，但也取决于幼虫对食物的接受程度，成虫和幼虫的味觉敏感性可能与这两种情况的寄主选择有关。本研究的目的是：（i）研究幼虫和产卵雌虫对 Ferula 和 Seseli 汁液的味觉敏感性；（ii）交叉比较味觉受体神经元（GRN）对两种味觉刺激的尖峰活动；（iii）评估两种汁液之间的辨别能力，并确定使用的是哪种神经编码。结果表明：（i）成年雌性的跗节 GRN 对两种植物汁液的尖峰反应没有差异，因此它们无法区分这两种植物；（ii）幼虫 L-lat GRN 对 Seseli 的反应活性高于 Ferula，而对取食刺激神经元则相反，幼虫可能通过多种神经编码来区分两种汁液；（iii）在两种植物上产卵的数量相同，但幼虫在 Ferula 上的生长表现优于 Seseli。味觉敏感性的差异可能解释了成年雌性的产卵偏好与幼虫对植物的接受程度和生长表现之间没有正相关关系。
