Morphological and electrophysiological analysis of tarsal sensilla in the medfly Ceratitis capitata (Wiedemann, 1824) (Diptera: Tephritidae)

Abstract

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann, 1824) (Diptera: Tephritidae), is a polyphagous pest in horticulture, mainly targeting pomaceous and citrus fruits. To gain better knowledge about its chemosensory system related to taste, essential for behavioural strategies and localisation of host plants, we examined the tarsal external morphology by highresolution scanning electron microscopy, focusing on sensilla. Numerous trichoid and chaetica sensilla, related to taste and mechanoreceptor systems, and other types of sensilla are present in tarsal segments. The responses of specific trichoid chemosensilla were also studied through electrophysiological experiments by stimulation with sodium chloride, fructose and four bitter stimuli. Electrophysiological data allowed us to distinguish three types of different neurons: high ("H"), middle ("M") and small ("S"). Increasing concentrations of sodium chloride enhanced the activity of H cells, while fructose boosted M cells activity. On the contrary, S cells showed no increase in spike activity after stimulation with these substances. Bitter stimuli induced no significant response on these cells. Behavioural assays showed no statistical difference among the responses to sugars, bitter substances and citric acid. Our results on taste stimuli will be useful in increasing knowledge of Ceratitis chemoreception, fundamental in new integrated pest management.

Taste recognition through tarsal gustatory sensilla potentially important for host selection in leaf beetles (Coleoptera: Chrysomelidae)

“…In Diptera and Lepidoptera, a single tarsal gustatory sensillum responds to several tastes, such as sweet and bitter 6,42 . In Coleoptera, salt reception through tarsi has been shown electrophysiologically 24 ; however, sugar reception by tarsi has not been shown.…”

“…Each gustatory sensillum was stimulated by covering its tip with a glass micro pipette filled with a solution of the stimulant for 3 s. Sensillum response was recorded from the onset of stimulation. To minimize the adaptation of the tested sensilla, an interval of at least 3 min was allowed between consecutive recordings 6 . Action potentials generated by gustatory sensilla were amplified by Taste Probe DTP-1 (Syntech, Hilversum, Netherlands) and filtered using IDAC-4 (Syntech, Hilversum, Netherlands).…”

Taste input from tarsal sensilla is related to egg‐laying behavior in Papilio hospiton

“…Tarsi of adult females were collected and treated according to the technique described by Loy et al. (). Samples were sonicated twice in a Triton X‐100 1% solution in bidistilled water.…”

Fat storage in Drosophila suzukii is influenced by different dietary sugars in relation to their palatability

“…After washing in bidistilled water, samples were sonicated twice in a Triton X-100 1% solution and then dehydrated in acetone. Samples were later critical point dried and coated with 2 nm platinum by means of an Emitech K575 Sputter Coater [ 39 ]. Photos were collected by a Quartz PCI v. 5 software (Quartz Imaging Corporation, Vancouver, BC, Canada).”…”