Arthropod Structure & Development最新文献

Micro air vehicles (MAVs) have wide application prospects in environmental monitoring, disaster rescue and other civil fields because of their flexibility and maneuverability. Compared with fixed wing and rotary wing aircraft, flapping wing micro air vehicles (FWMAVs) have higher energy utilization efficiency and lower cost and have attracted extensive attention from scientists. Insects have become excellent bionic objects for the study of FWMAVs due to their characteristics of low Reynolds number, low noise, hoverability, small size and light weight. By mimicking flying insects, it may be possible to create highly efficient biomimetic FWMAVs. In this paper, insect flight aerodynamics are reviewed, and the mechanism designs of insect-inspired FWMAVs and their aerodynamics are summarized, including the wing type effect, vibration characteristics and aerodynamic characteristics of the flapping wing.

The effect of chronic oxygen exposure on growth and development of insects is an active field of research. It seeks to unravel the triggers and limitations to molting and growth across many insect groups, although even now there are gaps in our knowledge and inconsistencies that need to be addressed. The oxygen dependent induction of molting (ODIM) hypothesis states that the impetus for molting is triggered by the development of hypoxic tissue due to the rapid increase in mass coupled with the fixed nature of tracheal systems between molts. In this study, we raised Manduca sexta in three chronic oxygen treatments (10, 21, & 30% O₂). We measured the mass of these insects throughout their larval development and as adults. We found that both hyperoxia and hypoxia had marked effects on size and developmental times. Hyperoxia exposure resulted in increased mass throughout development and into adulthood while increasing developmental times. Hypoxia also increased developmental time and decreased mass of adult moths. We show that pupation is a critical window for exposure to altered oxygen levels. This suggests that oxygen may play a role in affecting the timing of eclosion at the end of pupation.

The onion thrips, Thrips tabaci Lindeman, is a cryptic species complex of three distinct lineages: L1, L2, and T, which exhibit considerable variation in their biological and ecological traits. The most accurate method for their identification is based on molecular techniques. This study aimed to investigate the morphometric variation of T. tabaci cryptic species complex and to distinguish characters that may be useful in discriminating the lineages. For this purpose, morphometric measurements were performed on the eggs, newly hatched first instar larvae, and newly emerged adults. Our results revealed significant differences in egg size between the three lineages. Moreover, the PCA analysis conducted on morphometric measurements of the first instar larvae and adults showed that females of the T lineage are very well separated from the females of the L lineages in the adult stage but not in the first instar larval stage. The distinction between the females is partially congruent with the results of genetic studies. Moreover, our results indicate that adult sexual dimorphism with regard to size in L1 and T lineages is not mediated by the size of eggs and first instar larvae, and this may be due to the different growth rates of males and females.

Compound eyes are the prominent visual organs of insects and can provide valuable information for the reconstruction of insect phylogeny. Although the largest butterfly family (Nymphalidae) has been well defined, the infrafamilial phylogenetic relationships remain controversial hitherto. In the present study the ultrastructure of the compound eyes of three nymphalids Neptis beroe, Childrena zenobia, and Palaeonympha opalina was investigated using light and transmission electron microscopy in an attempt to seek potentially important phylogenetic characters. The compound eyes of the nymphalids share a tracheal system in a “1–4−8” branching pattern. The eight tracheal subbranches exhibit distinct distribution patterns along the basal retinula cell as follows: the tracheal subbranches of Palaeonympha opaline are close to the rhabdom in the distance from the distalmost part of the basal retinula cell to the rhabdom end, while those of N. beroe and C. zenobia are on the periphery of the retinula along almost the whole basal retinula cell and become close to the rhabdom just at the proximal end of the basal retinula cell. The tracheal structure of the three nymphalids is discussed for their potential phylogenetic implications.

Relatively few studies have focused on evolutionary losses of sexually selected male traits. We use light and electron microscopy to study the male and female reproductive anatomy of Apotomus ground beetles (Coleoptera, Carabidae), a lineage that we reconstruct as likely having lost sperm conjugation, a putative sexually selected trait. We pay particular attention to the structure of the testes and spermatheca. Both of these organs share a strikingly similar shape–consisting of long blind canals arranged into several concentric overlapping rings measuring approximately 18 mm and 19.5 mm in total length, respectively. The similarity of these structures suggests a positive evolutionary correlation between female and male genital organs. Males are characterized by unifollicular testes with numerous germ cysts, which contain 64 sperm cells each, and we record a novel occurrence of sperm cyst “looping”, a spermatogenic innovation previously only known from some fruit fly and Tenebrionid beetle sperm. The sperm are very long (about 2.7 mm) and include an extraordinarily long helicoidal acrosome, a short nucleus, and a long flagellum. These findings confirm the structural peculiarity of sperm, testis, and female reproductive tract (FRT) of Apotomus species relative to other ground beetles, which could possibly be the result of shifts in sexual selection.

In holometabolous insects, metamorphosis involves restructuring the musculature to accommodate adult-specific anatomy and behaviors. Evidence from experiments on remodeled muscles, as well as those that develop de novo, suggests that signals from the nervous system support adult muscle development by controlling myoblast proliferation rate. However, the dorsolongitudinal flight muscles (DLMs) of Manduca sexta undergo a mixed developmental program involving larval muscle fibers, and it is not known if neurons play the same role in the formation of these muscles. To address this question, we have blocked the most promising candidate pathways for neural input and examined the DLMs for changes in proliferation. Our results show that DLM development does not depend on neural activity, Hedgehog signaling, or EGF signaling. It remains to be determined how DLM growth is controlled and why neurally mediated proliferation differs between individual muscles.

Homology of the posterior midgut regions (PMG) in different phylogenetic lineages of acariform mites (superorder Acariformes) remains unresolved. In the order Trombidiformes, the ultrastructure of the PMG is known primarily in derived groups; thus this study focuses on species belonging to a relatively basal trombidiform family.

PMG of Anystis baccarum consists of the colon and postcolon separated by a small intercolon. The fine structure of the colon and postcolon is close to that of the corresponding organs of sarcoptiform mites with the epithelium showing absorptive and endocytotic activity. The epithelial cells produce a variety of excretory vacuoles and a peritrophic matrix around the feces. Morover, the epithelium of the postcolon is characterized by the highest apical brush border and especially numerous mitochondria suggesting involvement in water and ion absorption. The intercolon functions as a sphincter lined with an epithelium capable of producing excretory granules. A pair of short blind extensions arises assimmetrically from the intercolon into the body cavity. Ultrastructurally, these extensions are similar to the arachnid Malpighian tubules and may be their reduced version. Rare endocrine-like cells have been observed in the colon and postcolon.

The complete larval development of Parasacculina pilosella (Van Kampen et Boschma, 1925) and Sacculina pugettiae Shiino, 1943 including five naupliar stages and one cypris stage is described and illustrated using SEM. P. pilosella and S. pugettiae have a sacculinid type of development. Nauplii possess a naupliar eye, short frontolateral horns with terminal processes, and a ventral process between the furcal rami. Larvae lack a flotation collar, seta 6 on the antennule and a seta on the antennal basis. Cyprids have a nearly straight LO2. Breakage zone and a spinous process are present only in male larvae. Nauplii of the two species differ by the morphology of the furca: in P. pilosella, the furcal rami are longer and not drowned into cuticular sockets. Naupliar antenna of S. pugettiae has a lateral seta on the endopod which is lacking in P. pilosella. Dorsal head shield setae 1 and 2a are present in S. pugettiae nauplii and not found in P. pilosella larvae. In P. pilosella, all dorsal setae have subterminal pores, whereas in S. pugettiae, pores of the setae 2 are shifted proximally. It is possible that the presence/absence of setae 1 and 2a is the distinctive feature of nauplii of the families Sacculinidae and Polyascidae.

Oxelytrum discicolle is a necrophagous beetle occurring in Central and South America, with potential use in forensic entomology for investigations in the context of legal medicine. The present work aimed to describe the morphology of the digestive tract of larvae and adults and contributes to the knowledge about the digestion associated with necrophagy. In the three larval instars, the foregut is short and narrow, the midgut is a dilated tube, elongated with a smooth surface, and the hindgut is narrow and long, with small lateral projections and a dilated terminal region. The gut epithelium in the second and third instar larvae is vacuolated in the mid- and hindgut, with high production of apocrine secretions in the midgut lumen. In adults, the foregut is short, with small spines in the cuticular intima that covers the flattened epithelium. The midgut is dilated, with many short gastric caeca with regenerative cells in the blind portion, which differentiate in digestive columnar cells towards the midgut lumen. The hindgut is long and narrow, with an enlarged distal portion with folded epithelium lined by a thin cuticle. The histochemical tests reveal the absence of protein storage granules in the gut epithelium of larvae and adults. The gut characteristics of the carrion beetle O. discicolle are similar to those of other predatory and phytophagous Coleoptera, which may indicate that ancestry may influence the alimentary canal morphology more than the feeding habits.