Cyto-differentiation of the neuroblasts from the neural ectodermal cells in grasshopper,Chortophaga viridifasciata (De Geer) (Orthoptera: Acrididae) embryos

The first sign of neurogenesis in the embryo of grasshopper, Chortophaga viridifasciata (Orthoptera: Acrididae), is signaled by a partition of the ectodermal cells into non-neural ectodermal cells and neural eetodermal cells. The neuroblasts are differentiated from neural ectodermal cells. In the present study, we examined the pattern of mitotic activity in the developing embryo by tracing the incorporation of BrdU in S phase nuclei. The results indicate that the ectodermal cells in 6-day old embryos do not show any signs of differentiation. In 7-day old embryos, in which ectodermal cells become partitioned into 2 types, almost no neural ectodermal cells are incorporated with BrdU, whereas a constant incorporation is revealed in non-neural ectodermal cells. Among the mitotically quiescent neural ectodermal cells, which are arrested at the GI stage of the cell cycle, in 8-day old embryos, the neuroblasts are the first to resume their mitotic activity, while the other cells are then released from the mitotic quiescence. It seems that the mitotic quiescence may be an essential process to acquire a neural fate.     

Detection of gamma-tubulin in spermatogonial cells of Bombyx mori (Lepidoptera) and Chortophaga viridifasciata (Orthoptera)

We detected a putative gamma-tubulin gene in silico and detected BACs containing the gene from a Bombyx mori BAC library. BAC-FISH mapping revealed that the gene is located on chromosome 5. To observe the distribution of gamma-tubulin, we employed antibodies against mammalian gamma-tubulin peptides. Western blot analysis disclosed a band very similar in size to gamma-tubulin protein in other species (approximately 48 kDa). In mitotic metaphase of B. mori spermatogonial cells, gamma-tubulin is exclusively localized in the spindle poles, where the centrosomes occur. We applied the same system to the grasshopper Chortophaga viridifasciata, as a representative of insect orders in which the gamma-tubulin distribution had not previously been studied. Gamma-tubulin was also found in the spindle poles during metaphase of spermatogonial cells in the grasshopper.     

Temporal constancy in grasshopper assemblies (Orthoptera: Acrididae)

ABSTRACT.

• 1 Temporal constancy in the structure of grasshopper assemblies (about forty-five species each) from two types of North American grasslands was assessed; one site was followed 25 years and the other 7 years.
• 2 Densities and relative abundances varied but composition of assemblies based on ranks suggested significant structure when three or more species were included in the analysis.
• 3 Results compared favourably with other insect herbivore assemblies which have been examined; variability in population change was intermediate along the spectrum of organisms which have been studied.

     

The behavior of isolated hearts of the grasshopper,Chortophaga viridifasciata,and the moth,Samia walkeri,in solutions with different concentrations of sodium,potassium, calcium,and magnesium

1. The blood of Chortophaga viridifasciata was analyzed. The average concentrations of inorganic cations expressed as milligrams per cent are: sodium, 250.66; potassium, 13.52; calcium, 11.40; and magnesium, 51.15. The osmotic pressure of the blood at 0°C. is 10.7 atmospheres. Protein and non-protein nitrogen, expressed as milligrams per cent, are 253.4 and 140.0, respectively. 2. The blood of Samia walkeri has an osmotic pressure of 13.36 atmospheres at 0°C. Its protein nitrogen is 628.58, and its non-protein nitrogen, 441.20 milligrams per cent. 3. The effects of isotonic chloride solutions of sodium, potassium, calcium, and magnesium and of distilled water on the heart beat of these two species were determined. The heart of the grasshopper failed to beat in isotonic solutions of KCl, MgCl₂, or in distilled water. For both insects, sodium was found to be the least toxic ion. In the case of the grasshopper, calcium ranks next in order. In the case of the moth, potassium ranks next after sodium and is followed by calcium and magnesium. 4. The ratio of sodium to potassium in milligrams per cent, necessary for maintaining the normal heart beat of Chortophaga viridifasciata is 3 to 1, but it may be increased to at least 34 to 1 without any appreciable effects. The ratio of potassium to calcium necessary for maintaining the normal heart beat of this insect is 1 to 1, and may be increased to as much as 3 to 1. 5. The ratio of sodium to potassium, in milligrams per cent, necessary for maintaining the normal heart beat of Samia walkeri was found to be equal to or to exceed 1 to 13.8. The sodium content may be increased so that the ratio of sodium to potassium is 34 to 1 without any toxic effects. The ratios of potassium to calcium required for normal heart beat in this insect may be 1 to 1, 2 to 1, or 3 to 1. 6. The hearts of the grasshoppers beat normally in isotonic solutions having an osmotic pressure of 10.7 atmospheres. They beat equally well in solutions having an osmotic pressure of 13.4 atmospheres. The hearts of the cynthia pupae beat normally in isotonic solutions having an osmotic pressure of 13.36 atmospheres. However, they also beat normally in solutions having an osmotic pressure of 10.02 atmospheres. Therefore, although the blood of the cynthia moth and of the grasshopper have different osmotic pressures, their hearts are tolerant to solutions having the same tonicity. Because of this, and since the ratios of potassium to calcium necessary for maintaining normal heart beats of both insects are the same, solutions favorable to the grasshopper may also be favorable to the cynthia moth.     

Populations of the northern grasshopper, Melanoplus borealis (Orthoptera: Acrididae), in Alaska are rarely food limited

In some systems, grasshoppers appear to be food limited in most years, whereas in other systems top down forces, for example, predators, are more often implicated in population regulation. Sustainable strategies to manage grasshopper populations through habitat management require knowledge of the forces that regulate grasshopper populations. This experiment was undertaken to determine whether populations of Melanoplus borealis (Fieber), a common pest species in Alaska, are food-limited in Alaska. Cages were set up in a fallow field near Delta Junction, AK, in 3 yr (2007-2009). In 2007 and 2008, fertilizer was added to half the plots to increase primary production, and, in all years, cages within each plot were stocked with 0, 5, 9, or 13 fourth-instar M. borealis (equivalent to 0, 20, 36, or 52 grasshoppers/m(2)). Grasshoppers in each cage were counted weekly. Near the end of the growing season, surviving female grasshoppers (≈40% of the original number) were collected. Femur length was taken as a measure of adult size, and functional ovarioles were counted as a measure of current fecundity. If the grasshoppers were food limited, we expected to see significant effects of either density or fertilizer on grasshopper survival, size, or fecundity. The fertilizer treatment greatly increased primary production in both years. Neither fertilizer treatment nor grasshopper density had consistent effects on survival, size, or potential fecundity, leading us to conclude that food is seldom limiting to populations in the interior of Alaska at densities <50 m(-2).     

Two new species of grasshopper from China (Orthoptera:Pyrgomorphidae)

The genus Chlorizeina Brunner von Wattenwyl, 1893 is firstly recorded for China. Two new species, Chlorizeina yunnana sp. nov. and Tagasta nigritibia sp. nov. are reported from China. All specimens are deposited in the Biological Science Museum, Dali University(BMDU).     

Visual behaviors of the migratory grasshopper,Melanoplus sanguinipes F. (Orthoptera: Acrididae)

The visual behavior of adult Melanoplus sanguinipesF. (Orthoptera: Acrididae) was investigated by placing individuals in the center of an arena and recording their orientation responses to visual targets at the perimeter of the arena. Targets that reflected more 540- to 570-nm light were approached more frequently; however, when reflectance in the 540 -to 570-nm region was combined with reflectance in the 400- to 520-nm region, orientation responses were reduced significantly. This suggests that spectral discrimination in M. sanguinipesinvolves at least two classes of photoreceptors, which respond to different regions of the wavelength spectrum. In addition, grasshoppers oriented to vertical, but not horizontal, contrasting stripes. However, when vertical stripes were added to targets reflecting 520- to 650-nm light, responses to verticals on these targets were not enhanced relative to verticals presented against a target background of 400- to 520-nm + 520- to 650-nm light. Thus, spectral discrimination and vertical stripe fixation appear to be two distinct visual behaviors, controlled by outputs from two classes of photoreceptors and a single class of photoreceptors, respectively, and may be used in different physiological or ecological contexts.     

The chemosensory system of the monophagus grasshopper,Bootettix argentatus bruner (Orthoptera : Acrididae)

Bootettix argentatus (Orthoptera : Acrididae) is a monophagous grasshopper in the subfamily Gomphocerinae. The numbers of chemoreceptors in most groups on the mouthparts increase with each molt and are generally similar in the 2 sexes. There are fewer sensilla in the A3 groups than in other gomphocerine grasshoppers, and the possibility that this is related to host-plant specificity is discussed. Only very small numbers of sensilla are present on the pulvillar pads of the tarsi and on the arolia. The number of sensilla on the antennae is proportional to the length of the flagellum and coeloconic sensilla comprise 30–35%. Most of the remainder are multiporous basiconic sensilla. Adult males have more antennal sensilla than adult females.     

Phylogeny of the grasshopper family Pyrgomorphidae (Caelifera,Orthoptera) based on morphology

The family P yrgomorphidae (O rthoptera: C aelifera) is considered one of the most colourful grasshopper families, which contains about 500 species distributed worldwide. Commonly referred to as gaudy or bush grasshoppers, many pyrgomorphs are known to be aposematic and capable of sequestering plant secondary compounds. Several species are considered important agricultural pests, while some species are culturally important. Nevertheless, the phylogeny of this family has never been proposed using modern cladistic methods. In this study, we present a phylogenetic analysis of P yrgomorphidae, based on 119 morphological characters with 269 character states, covering 28 out of 31 current recognized tribes. We recovered the monophyly of the family and one of the two currently recognized subfamilies, O rthacridinae. P yrgomorphinae was recovered as paraphyletic. Based on the most parsimonious tree, we propose four main clades and discuss the biology and biogeography of members of these clades. This is the first step towards building a natural classification for P yrgomorphidae, which is an excellent model system for studying the evolution of interesting traits such as wing development, warning coloration and chemical defence.     

Host plant-associated genetic differentiation in the snakeweed grasshopper, Hesperotettix viridis (Orthoptera: Acrididae)

Studies of herbivorous insects have played a major role in understanding how ecological divergence can facilitate genetic differentiation. In contrast to the majority of herbivorous insects, grasshoppers as a group are largely polyphagous. Due to this relative lack of intimate grasshopper-plant associations, grasshopper-plant systems have not played a large part in the study of host-associated genetic differentiation. The oligophagous grasshopper, Hesperotettix viridis (Thomas), is endemic to North America and feeds on composites (Asteraceae) within the tribe Astereae. Previous work has shown both preference and performance differences between H. viridis individuals feeding on either Solidago mollis or Gutierrezia sarothrae. Using 222 AFLP markers, we examined the genetic relationships among 38 H. viridis individuals feeding on these plants both in sympatry and allopatry. Neighbour-joining analysis resulted in two distinct host-associated clades with 71% bootstrap support for host-associated monophyly. Analyses of molecular variation (amova) revealed significant genetic structuring with host plant accounting for 20% of the total genetic variance while locality accounted for 0%. Significant genetic differentiation was detected between S. mollis-feeders and G. sarothrae-feeders even when the two were present at the same locality. These results are consistent with observed differences in preference and performance between H. viridis grasshoppers feeding on either G. sarothrae or S. mollis and indicate that H. viridis is comprised of at least two genetically distinct host plant-associated lineages.     

黄胫小车蝗受精囊的亚显微结构

利用组织学方法,观察了黄胫小车蝗Oedaleus infernalis 受精囊的显微与亚显微结构。结果表明,黄胫小车蝗受精囊为单个,由高度卷曲的受精囊管和蚕豆状的端囊构成。受精囊壁主要由表皮层、上皮层、基膜和肌肉层构成;上皮层包含上皮细胞、导管细胞和腺细胞。上皮细胞在靠表皮层的边缘有大量的微绒毛,两相邻上皮细胞的细胞膜相互嵌入,并有细微的突起延伸在导管细胞及腺细胞之间,直到基膜,达基膜处的上皮细胞膜折叠,与腺细胞膜的折叠,一起形成迷宫样的指状突起,附着在基膜上。导管细胞有一个较大的核和分泌导管,连接于腺细胞的细胞腔和受精囊腔,将腺细胞中分泌物运输到受精囊腔中。腺细胞具有典型的分泌细胞特征： 含发达内质网、高尔基复合体及不同大小的囊泡。肌肉层位于受精囊最外层,附在基膜上。在受精囊不同部位的结构有差异。在交配前和交配后,受精囊腺细胞的亚显微结构也有差异。