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

Abstract

The proboscis is an important feeding organ for the glossatan moths, mainly adapted to the flower and non-flower visiting habits. The clover cutworm, Scotogramma trifolii Rottemberg, and the spotted clover moth, Protoschinia scutosa (Denis & Schiffermuller), are serious polyphagous pests, attacking numerous vegetables and crops, resulting in huge economic losses. However, the feeding behavior and mechanisms of the adult stage remain unsatisfactorily explored. In this study, the proboscis morphology of S. trifolii and P. scutosa are described in detail using scanning electron microscopy, with the aim of investigating the morphological differences and feeding behavior of these two species. The proboscises of S. trifolii and P. scutosa are similar in morphology and structure and are divided into three zones (Zone 1–3) based on the morphological changes of the dorsal legulae. Three sensillum types are located on the proboscises of both species, sensilla chaetica, sensilla basiconica, and sensilla styloconica. Significant differences were observed in the length of the proboscis and each zone between these two species, as well as in sensilla size and number. Based on the morphology of the proboscis and associated sensilla, S. trifolii and P. scutosa are potential flower visitors, which was also reinforced by the pollen observed at the proboscis tip. These results will strengthen our understanding of the structure of the proboscis related to the feeding behavior of Noctuidae.

A morphological comparative study of proboscis sensilla between Pierinae and Coliadinae (Lepidoptera: Pieridae)

“…It is of two types, inner and outer sensilla basiconica. The outer sensilla basiconica forms a single line on the entire surface of the galea, while the inner sensilla basiconica forms a single line in the digestive tract (Zhang et al 2021). The external sensilla basiconica consists of a short sylus and a blunt-tipped sensory cone in C. croceus, whereas P. edusa consists of a short sylus and a long cone.…”

The Morphology of the Sensilla on the Proboscis of Aporia crataegi (Linnaeus, 1758) (Lepidoptera: Pieridae)

“…In Pieris rapae (Linnaeus, 1758) (Pieridae) and Inachis nio (Linnaeus, 1758) (Nymphalidae), the number of coils varies from 3.5 to 7 coils (Krenn, 1990). The proboscis coil number of Helicoverpa armigera (Hübner, 1805) (Noctuidae), Mythimna separate Walker, 1865 (Noctuidae), Scotogramma trifolii (Hufnagel, 1766) (Noctuidae) and Protoschinia scutosa (Denis & Schiffermüller, 1775) (Noctuidae) is 4-5 (Chen et al, 2019;Zhang et al, 2021).…”

“…The proboscis of Vanessa cardui (Linnaeus, 1758) (Nymphalidae) is 11.5-15.5 mm long (Krenn, 1998). Sensilla are classified according to the presence or absence of pores and the morphology of the sensilla (basonica, chaetica, styloconica, filiformia, coeloconica, and campaniformia) (Faucheux, 2013) (Ma et al, 2019;Zhang et al,2021). Helicoverpa armigera (Hübner, 1805) (Noctuidae) has three major types of sensilla, including nine subtypes as sensilla basiconica (esb1, esb2, esb3, isb1, and isb2), sensilla chaetica (sch1 and sch2), and sensilla styloconica (ss1 and ss2) (Guo et al,2018).…”

Floral and genetic divergence across environmental gradients is moderated by inter-population gene flow in Platanthera dilatata (Orchidaceae)

“…Because hawkmoths have a longer proboscis (ca. 25 mm;Miller, 1997) than Noctuidae moths (< 11 mm; Zenker et al, 2011;Zhang et al, 2021), they may be more effective pollinators for longer-spurred orchids than are Noctuidae (Tao et al, 2018). Based on iNaturalist observations (n = 27), the median elevation at which H. gallii has been observed in SE Alaska is less than 50 m (range 1-285 m), much lower than the median elevation (215 m, range 10-600 m) of muskegs in the study area.…”