Sensilla of the antenna and proboscis of Athetis lepigone (Möschler) (Lepidoptera: Noctuidae)

Abstract

Sensory structures on the antennae and mouthparts of insects are associated with various activities, such as host location, feeding, attracting a mate, and identifying a suitable oviposition site. Athetis lepigone (Möschler) is an important polyphagous Eurasian pest with more than 30 species of host plants. The larvae target bud leaves, prop roots, and tender stems of many agricultural crops, but the feeding habits of the adults remain poorly known. Aiming to understand the feeding behavior of the species, we investigated the fine morphology of its antennae and proboscis using scanning electron microscopy. The antennae of both sexes are filiform, and bear eight types of sensilla: Böhm's bristles, sensilla squamiformia, trichodea, chaetica, basiconica, coeloconica, styloconica, and auricillica. Sensilla trichodea are the most abundant among these sensillum types. The proboscis consists of two elongated, interlocked maxillary galeae that enclose the food canal by dorsal and ventral legulae. The external galeal surface is covered with numerous triangular microtrichia on Zone 1 and abundant blunt microbumps on Zone 2. The surface of the food canal bears closely connected and smooth semicircular ridges, gradually tapering toward the proboscis tip. Three types of sensilla are noticeable on the proboscis: sensilla trichodea, basiconica, and styloconica. We briefly discuss the putative functional significance of the antennal and proboscis sensilla and, based on the specific structural modifications of the proboscis, predict a flower‐visiting habit for A. lepigone.

Ultramorphological Comparison of Proboscis and Associated Sensilla of Scotogramma trifolii and Protoschinia scutosa (Lepidoptera: Noctuidae)

“…The noctuid moths are mostly flower-visiting pollinators, and use the proboscis tip to pollinate [64][65][66]. These two species, S. trifolii and P. scutosa, are most likely to be flowervisiting noctuids, and characterized by elongated sensilla styloconica and modified dorsal legulae on the proboscis, as reported in previous studies [15,19,20,67,68]. The conclusion is also reinforced by the presence of floral pollen at the proboscis tip of P. scutosa (Figure 2).…”

“…Compared with S. trifolii, P. scutosa possess a long proboscis with a narrow tip, which might suggest that P. scutosa could better stretch into a long and slender flower tube than S. trifolii. In the potential flower visiting noctuids, Zone 3 is present on the proboscis tip of S. trifolii and P. scutosa, and absent on the proboscis tip of M. separata and A. lepigone [12,20,72]. The presence of Zone 3 might have adaptive value in facilitating the proboscis to enter narrow floral corollas, as described in Lehnert et al [22].…”

“…The proboscis structure is relatively conservative in Noctuidae, and sensilla morphology may not be useful for comparative studies of nearby species. In Noctuinae, Mythimna separata [12] and Athetis lepigone [20] were reported to lack Zone 3 at the proboscis tip, while S. trifolii possesses Zone 3 (Figure 3D), suggesting a somewhat complex pattern in proboscis morphology. By contrast, both P. scutosa and Helicoverpa armigera [12] bear Zone 3 at the proboscis tip, which might suggest that Zone 3 is relatively conservative in Heliothinae.…”

“…An array of mechano-and chemosensilla on the proboscis of Glossatan species, such as sensilla chaetica, basiconica, and styloconica, play important roles in host localization and feeding [16][17][18]. Previous studies on morphology of proboscis sensilla in Glossata have concentrated mainly on Noctuidae [12,16,19,20], and Nymphalidae [21][22][23][24].…”

Identification and expression analysis of chemosensory receptors in the tarsi of fall armyworm, Spodoptera frugiperda (J. E. Smith)

“…Furthermore, as shown in the RT-qPCR, in addition to be expressed in the tarsi, most of the annotated SfruGRs were also highly expressed in the proboscises. It has long been reported that many chemosensilla are distributed on the mouthpart and that the mouthpart functions in chemosensation in moths ( Krenn, 2010 ; Liu et al, 2014 ; Hu et al, 2021 ). Therefore, systematic analysis of GRs in other taste organs such as proboscis are still needed in the future.…”