Morphological and Ultrastructural Characterization of Antennal Sensilla and the Detection of Floral Scent Volatiles in Eupeodes corollae (Diptera: Syrphidae)

Abstract

The olfactory sensing system of the syrphid fly Eupeodes corollae is essential in pollination and prey localization, but little is known about the ultrastructural organization of their olfactory organs. In this study, the morphology, distribution, and ultrastructural organization of antennal sensilla of E. corollae in both sexes were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Neuronal responses of a subtype of sensilla basiconica to floral scent compounds were recorded by single sensillum recording (SSR). Ten morphological types, including Böhm bristles, sensilla chaetica, microtrichiae, sensilla trichodea, sensilla basiconica, sensilla clavate, sensilla coeloconica, sensilla styloconica, sensilla placodea, and sensory pit, were identified. Except for Böhm bristles and sensilla chaetica, which were distributed on the scape and pedicel of E. corollae antennae, innervated sensilla were densely distributed on the flagellum, a vital sensory organ. Further, observing ultrastructural organization showed that the sensilla trichodea, basiconica, and clavate are single-walled with multiple nanoscale pores perforating the cuticle. Sensilla coeloconica are double-walled and have no wall pores, but instead, have longitudinal grooves along with the pegs. Sensilla chaetica, Böhm bristles, and microtrichiae did not have wall pores on the cuticle or sensory cells at the base. The SSR results indicated that neuron B housed in the subtype of sensilla basiconica I (SBI) mainly responded to methyl eugenol and other aromatic compounds. Overall, our results provide valuable information to understand the morphology and ultrastructure of antennal sensilla from E. corollae. These findings are beneficial for the studies of the neuronal function map of olfactory sensilla and for determining evolutionary relationships in Diptera.

The Antennal Sensory Structures of <em>Anagyrus vladimiri</em> Female (Hymenoptera: Encyrtidae)

“…Differently from MPS, ST II were mainly located dorsally on the apical antennomere and at the distal region of the sub-apical antennomere. The ultrastructural organization was similar to the same sensilla in Paysandisia archon (Lepidoptera: Castniidae) [43], Scleroderma guani (Bethylidae) [44] and Eupeodes corollae (Diptera: Syrphidae) [45]. The occurrence of different type of olfactory sensilla is a common trait that can be found in several insects belonging to diverse, unrelated groups (i.e.…”

Comparative morphology and plant volatile responses of antennal sensilla in Cinara cedri (Hemiptera: Lachninae), Eriosoma lanigerum (Hemiptera: Eriosomatinae), and Therioaphis trifolii (Hemiptera: Calaphidinae)

“…In the dose-dependent manner, chemicals were tested at a range of dose from 10 −7 to 10 −3 g, respectively. A sample containing only paraffin oil served as a control, tested at the beginning and at the end of each recording (Dong et al, 2021 ; Wang et al, 2022a ). The order of the stimuli was randomized, and the time between two consecutive stimuli was 60 s. An airflow maintained at constant 1.2 L/min across an aluminum tube (10-mm inner diameter) was delivered to the antennae throughout the experiment.…”

“…Tested odorants flowed into the air stream (0.5 L/min) through the hole and were then delivered to the antennal sensilla for 300 ms using a Syntech Stimulus controller (CS-55 model, Syntech). For most of the sampled responses, the action potentials (spikes of all sizes) of ORNs in each sensillum were counted offline over a 1 s period (500 ms before and 500 after stimulation onset) by the software package Autospike v. 3.9 (Syntech, Kirchzarten, Germany) (Liu et al, 2013 ; Dong et al, 2021 ; Wang et al, 2022a ). To accurately assess the spikes generated by chemicals, we plotted the difference of the number of action potentials fired after minus before the stimulus onset.…”

An Odorant Receptor Expressed in Both Antennae and Ovipositors Regulates Benzothiazole-Induced Oviposition Behavior in Bactrocera dorsalis

“…The 15-day-old female B. dorsalis adults were anesthetized in a freezer (−20 °C) for 90 s. The ovipositors were carefully excised from the base under a stereomicroscope and sonicated in phosphate buffer saline (PBS, pH = 7.2) three times in an ultrasonic bath to wash away impurities on the surface of the ovipositor. 25 The cleaned ovipositors were immersed in 4% paraformaldehyde and fixed at 4 °C for 48 h, followed by a PBS rinse. Afterward, the samples were sequentially rinsed at 50, 60, 70, 80, 90, and 100% ethanol for 5 min each, with each concentration repeated three times.…”