Microstructure of mandibulate mouthparts in the greater rice weevil, Sitophilus zeamais (Coleoptera: Curculionidae)

Abstract

The greater rice weevil, Sitophilus zeamais, is a serious pest of stored grain. It chews a hole in the grain and deposits an egg inside. For the purpose of excavating a tunnel, these weevils are equipped with effective mandibulate mouthparts for penetrating and boring holes. The mouthparts of the weevil are a long slender snout, which consist of a labrum, a pair of mandibles, a pair of maxillae and a labium. Mothparts exhibit typical morphology of phytophagous coleopteran beetles and have characteristics of chewing mouthparts. Mandibles are connected to the head capsule through dicondyous articulation, which allows movement along one single rotating axis. Both labrum and labium are fused to the snout and form the upper and lower lips, respectively. Along the depressed surface of the snout, a number of short sensory hairs are sparsely arranged. The distal apexes of the maxillary and labial palpi are deeply depressed into a sensillar field, and only one type of the basiconic sensilla, which function as chemo-or gustatory receptors, occurs in both sexes.

Structure Comparison of Two Coexistent Weevil Rostra on Ailanthus: The Response to Ecological Demands of Egg Deposition

“…It was argued that natural selection drives the coevolutionary arms race between the weevil and its host plant, and the speci c morphological changes of the curculio's rostrum are the result of ecological morphological adaptation to the oviposition site. Bland compared the mouthparts and sensors of Hypera postica and Hypera brunneipennis and found that the types and number of tapered sensors at the end of the lower jaw were the same, but the shape and size of the mandibles were different [9].In our study, the gross morphological features of the mouthparts of E. scrobiculatus and E. brandti are similar to those reported for other weevils [32,[35][36][37][38][39], but their ne structure is slightly different. The highly sclerotized left and right mandibles, hinged to the later apical margin of the rostrum by well-developed dorsal and ventral articulations, and coming together medially, are massive and irregularly semi-globular.…”

Functional morphology of the mouthparts of lady beetle Coccinella transversoguttata (Coccinellidae, Coleoptera), with reference to their feeding mechanism

“…Although the units that constitute the mouthpart are the same in a specific group of insects, their morphology may differ among species of that group in adaptation to different feeding behaviors and/or food types (Karolyi, Hansal, Krenn, & Colville, ). Numerous studies have been conducted to describe the morphology of mouthpart in Coleoptera (Belhoucine, Bouhraoua, Prats, & Puladevillar, ; Chen, Zhang, & Dai, ; Eilers, Talarico, Hansson, Hilker, & Reinecke, ; Moon, ; Wilhelmi & Krenn, ), but only few reports have been found for predatory lady beetles (Thornham, Wakefield, Blackwell, Evans, & Walters, ). This study might be the first one to comprehensively describe the fine morphology of mouthpart of a predatory lady beetle.…”

Morphology and nanoindentation properties of mouthparts in Cyrtotrachelus longimanus (Coleoptera: curculionidae)

“…As a result of natural selection, the morphological changes in mouthparts are the biggest compared with the other organs, and these changes in mouthparts influence how the weevil feed. There are many related studies on the macrostructures/microstructures of the mouthparts for Curculionidae insect species previously (Davis, ; Hidayah, Wahida, Shafinaz, & Idris, ; Moon, ). Although there are numerous variations in the mouthparts, most insects have five basic parts: the Lbr, MD, Mx, Lb, and tongue.…”

“…The left and right MD are highly sclerotized and roughly symmetrical, which grinds the bamboo. The Mx are paired structures lying posterior to the MD, which are developed and roughly symmetrical (Ma, Huang, & Hua, 2013; Moon, ). The Lbr looks like a hard sheet that is equivalent to an upper lip and covers the MD in the weevil.…”

“…Cyrtotrachelus longimanus is a skillful driller and is able to effectively chew in holes and sucks on the bamboo. Many studies on weevil are focused on morphology, their biological characteristics, reproductive system, reproductive performance, and control strategy (Alonso‐Zarazaga et al, ; Andrew, Singh, Chawla, & Franz , ; Chen, Wang &Wang, ; Davis, ; Li, Xu, & Zhou, ; Moon, ; Wang, Chen, & Wang, ; Wang, Yang, & Liu, Zi, & Dong‐Hai, ) etc. Research on the mechanical properties of mouthparts in C. longimanus has not been reported so far.…”