Arthropod Structure & Development最新文献

The ultrastructural study on the female reproductive system of the beetle M. brevicauda (Mordellidae) confirmed the positive correlation between the length of the sperm and the size of the female seminal receptacle (Spermatheca).

The spermatheca of the species is characterized by an apical bulb-like structure where the spermathecal duct forms numerous folds filled with sperm. At this level many bacterial cells are present intermingled with the duct folds. Some are organized in large structures, such as bacteriomes, while other are single bacteriocytes. The latter are often found near the basal lamina of duct epithelium. In addition, some bacteria are visible in the cytoplasm of the duct epithelial cells. Interestingly, bacterial cells have never been observed in the duct lumen. The possible function of the bacterial cells is discussed.

Acoustic behaviour plays a significant role in insect communications, but is rarely reported in their immature stages. Larvae of Lucanidae bear paired stridulatory organs on their thoracic legs, which could produce sounds as communicational signals. However, the species-specific differences on stridulatory organs and acoustic signals are far from fully investigated. In this study, the larval acoustic behaviours of three lucanid species, Lucanus dybowski, Prosopocoilus confucius and P. girafa were recorded and compared for the first time. The sound producing mechanism was described in detail based on video recordings, morphological observations, and acoustic analyses. The larvae of all three species are able to produce sounds by scraping the plectrum on the metatrochanter against the pars stridens on the mesocoxa during disturbance. The sounds exhibit species-specific differences in terms of acoustic parameters: the larvae of L. dybowski produce short-duration (140–200 ms), single-pulse and low-frequency (∼210 Hz) sounds; P. confucius produce long-duration (500–800 ms), triple-pulse and low-frequency (∼280 Hz) sounds; P. girafa produce long-duration (500–560 ms), double-pulse and low-frequency (∼260 Hz) sounds. The amounts and arrangements of the teeth on stridulatory organs also exhibit differences on specific level. The acoustic signals and stridulatory organs were compared using principal component analysis.

A remarkable characteristic of katydids (Orthoptera, Tettigoniidae) is the elongated ovipositor, which is associated with oviposition behavior. The high degree of complexity of both sclerites and muscles arrangement of the ovipositor, is only similar to the ovipositor of Hymenoptera. Here we describe the morphology of the ovipositor within Tettigoniidae, and add descriptions of known oviposition behavior. Fifteen skeletal structures can be recognized, of these, three pairs of muscles are new while nine pairs were already described in the literature. The new muscles are ap2vf, anterior projection of second valvifer; bcov, blade complex of the ovipositor; and dbl, dorsal blade. The morphology of the ovipositor blade complex (bcov), the shape of the first valvifer (1vf), posterior intervalvular sclerite (piv), tergite IX (T9), anterior projection of the second valvifer (ap2vf), and the second valvifer (2vf), and their related muscles affect oviposition in Tettigoniidae. This contribution helps to understand katydid's oviposition behavior. Additionally, the new descriptions help in the search for new characters in Tettigoniidae.

The Trichoptera, holometabolous aquatic insects found worldwide except in Antarctica, exhibit a unique feature in their sperm, which are solely nucleated (eupyrene). Current knowledge on Trichoptera sperm is limited to Old World species. To enhance our understanding of their reproductive biology and contribute to systematic discussions, we describe the male reproductive system and spermatozoa of Smicridea (Rhyacophylax) iguazu Flint, 1983 (Hydropsychidae). This species lacks seminal vesicles, possesses piriform to oval-shaped testes with spermatozoa grouped in apical bundles and dense filamentous material filling other areas. The vasa deferentia are long and a pair of elongated accessory glands displays distinct proximal and distal regions. The relatively short (∼40 μm) spermatozoa are nucleated, aflagellated, and immobile. Further research could explore variations and assess the taxonomic utility of these features for genus identification within Hydropsychidae.

Springtails are notable for their jumping apparatus and latch-mediated spring mechanism. The challenge, in the light of the tiny size and rapid movement of these organisms, has been to understand the morphological intricacies of this spring system. This study takes an approach that integrates SEM, MicroCT, cLSM and high-speed video recordings to understand the composition and functionality of the jumping apparatus in Megalothorax minimus (Neelipleona), Dicyrtomina ornata and Dicyrtomina minuta (Symphypleona). We focus on reconstructing, describing, and understanding the functioning of structures such as basal plates, musculature and furca. The dimensions of the jumping apparatus in Dicyrtomina and Megalothorax differ significantly from those in elongated springtails. A hypothesis of functional coherence between taxa, based on muscle connections and basal plates, is postulated. High-speed video recordings provide information on: 1) furca release timing and function during jumping and self-righting; 2) performance properties of manubrium, dens and mucro in interaction with the ground and in take-off; 3) possible pre-release furca moves. The study underscores the need for further research employing a variety of visualization methods in order to explore additional aspects such as retinaculum unlatching and furca flexion/extension muscles.

Aquatic insects represent a great portion of Arthropod diversity and the major fauna in inland waters. The sensory biology and neuroanatomy of these insects are, however, poorly investigated. This research aims to describe the antennal sensilla of nymphs of the stonefly Dinocras cephalotes using scanning electron microscopy and comparing them with the adult sensilla. Besides, central antennal pathways in nymphs and adults are investigated by neuron mass-tracing with tetramethylrhodamine, and their brain structures are visualized with an anti-synapsin antibody. No dramatic changes occur in the antennal sensilla during nymphal development, while antennal sensilla profoundly change from nymphs to adults when switching from an aquatic to an aerial lifestyle. However, similar brain structures are used in nymphs and adults to process diverging sensory information, perceived through different sensilla in water and air. These data provide valuable insights into the evolution of aquatic heterometabolous insects, maintaining a functional sensory system throughout development, including a distinct adaptation of the peripheral olfactory systems during the transition from detection of water-soluble chemicals to volatile compounds in the air. From a conservation biology perspective, the present data contribute to a better knowledge of the biology of stoneflies, which are very important bioindicators in rivers.

The large abundance of termites is partially achieved by their defensive abilities. Stylotermitidae represented by a single extant genus, Stylotermes, is a member of a termite group Neoisoptera that encompasses 83% of termite species and 94% of termite genera and is characterized by the presence of the frontal gland. Within Neoisoptera, Stylotermitidae represents a species-poor sister lineage of all other groups. We studied the structure of the frontal, labral and labial glands in soldiers and workers of Stylotermes faveolus, and the composition of the frontal gland secretion in S. faveolus and Stylotermes halumicus. We show that the frontal gland is a small active secretory organ in soldiers and workers. It produces a cocktail of monoterpenes in soldiers, and some of these monoterpenes and unidentified proteins in workers. The labral and labial glands are developed similarly to other termite species and contribute to defensive activities (labral in both castes, labial in soldiers) or to the production of digestive enzymes (labial in workers). Our results support the importance of the frontal gland in the evolution of Neoisoptera. Toxic, irritating and detectable monoterpenes play defensive and pheromonal functions and are likely critical novelties contributing to the ecological success of these termites.

A particularly conspicuous morphological feature in chalcidoid wasps are strikingly modified legs present in both males and females. It evolved convergently multiple times on either fore or hind legs implying strong evolutionary pressure and a prominent function in the wasps’ life history. We investigate the external and internal morphology of the modified legs of five species of chalcidoid wasps representing four families (Ooderidae, Heydeniidae, Chalcididae, and Leucospidae), using light microscopy, scanning electron microscopy and micro computed tomography. We aimed to identify shared characteristics as well as differences between genera/species, leg pairs and sexes and to draw first conclusions about the shared or different functions. All species and sexes share the same general leg morphology, with enlarged femur, curved tibia and a huge flexor tibiae muscle. However, there are also genus/species-specific differences such as distinctive spine-like setae on the femur of Oodera spp., or leg pair-specific differences in the position of the extensor tibiae muscle. Shared characteristics imply a common primary function in which strong forces are required to pull the tibia against the femur while differences imply different secondary functions. Both primary and secondary functions have yet to be revealed beyond informed speculations.

The parasitoid Torymus sinensis (Hymenoptera: Torymidae) has been successfully used in Italy since 2005 for biological control of the invasive cynipid Dryocosmus kuriphilus (Hymenoptera: Cynipidae), highly destructive for the economically relevant Castanea sativa (Fagales: Fagaceae). In order to investigate the morphological aspects related to sensorial behavior, a fine morphology study of the antennae and their sensilla was conducted by scanning electron microscopy on both sexes of T. sinensis. The antennae, composed of a scape, a pedicel and a flagellum with ten flagellomeres, had chaetic sensilla of six subtypes, placoid sensilla of three subtypes, trichoid sensilla, sensilla with a roundish grooved tip, and coeloconic sensilla. The chaetic sensilla of the first three subtypes were found in the scape and in the pedicel, and those of the last three subtypes, together with trichoid, roundish grooved tip and coeloconic sensilla, were found only on flagellomeres. Sexual dimorphism was detected in the morphology of the proper pedicel and the flagellum, and in the presence and distribution of the sensilla and their subtypes. The morphological aspects of the antenna of T. sinensis and of its sensilla were compared with those found in the family Torymidae and in other families of the extremely diverse superfamily Chalcidoidea.

The Asian corn borer, Ostrinia furnacalis (Guenée), is one of the most destructive lepidopteran pests affecting maize in Asia. Previous research on the feeding behavior of O. furnacalis has mostly focused on larvae, but the adult feeding preference has been unclear hitherto. In this study, we investigated the ultramorphology of the proboscis and sensilla of O. furnacalis using scanning electron microscopy and made morphological comparisons between the sexes, attempting to make predictions on the food preference and feeding behavior of the adults. The proboscis of O. furnacalis is divided into zones 1 and 2 with three types of sensilla, namely chaetica, basiconica, and styloconica. The entire proboscis and zone 2 of the females are significantly longer than those of the males. The main sexual difference in the sensilla is shown in the number of sensilla styloconica, which are eight in females but nine in males. The feeding preference of adult O. furnacalis is discussed based on the morphology of the proboscis and sensilla.