An unusual mitochondrial DNA polymorphism in the Chorthippus biguttulus species group (Orthoptera: Acrididae)

Mitochondrial DNA restriction fragment patterns have been used to investigate the Chorthippus biguttulus group: a group of morphologically similar grasshopper species with very distinct male calling songs. Ten haplotypes were identified in 21 populations, representing six species. Haplotype diversity was as great within species, and in some case within populations, as it was among species and no clear geographical patterns of haplotype distribution were revealed. In the light of grasshopper range changes since the last glaciation it is unlikely that these data can be explained entirely by the retention of ancestral polymorphism. This suggests that hybridization has occurred during periods of grasshopper range expansion since the last glacial maximum, allowing mtDNA transfer between populations that have previously diverged in allopatry.     

DNA synthesis in the neo-X neo-Y sex determination system of Dichroplus bergi (Orthoptera: Acrididae)

DNA replication in the neo-X neo-Y sex determining system was studied by means of tritiated thymidine and autoradiography. Asynchronous replication was found in the X arm of the neo-X and the long arm of the neo-Y. In addition, striking asynchrony was also found for short isopycnotic homologous regions at the distal end of the autosmal arm of neo-X and the short arm of neo-Y to which pairing during meiosis is restricted. These short regions are asynchronous with respect to the heterochromatic segments as well as to the remaining proximal region of the autosomal euchromatic arm of neo-X. This difference in replication pattern within the same chromosome arm may be related to a differentiation between regions which are homozygous in both sexes and regions which are hemizygous in males.This work was supported by U.S. Atomic Energy Commission Contract N AT (30-1) 3517 to Prof. F. A. Saez.     

Aging and chiasma frequency in Eyprepocnemis plorans (Orthoptera: Acrididae)

The mean frequency of chiasmata was analysed in 29 males of the grasshopper Eyprepocnemis plorans at three different ages considered representative of the whole adult life in this species. In the factors which could potentially affect the parameter studied—namely age, family, individual and the presence or absence of B chromosomes—significant differences were only observed at the individual level. Aging produces no general effect but interacts strongly with the individuals though the age-induced variations in chiasma frequency are not directional. The fact that the range of chiasma frequency variation found within individuals at different ages is comparable to that existing among individuals indicates that the adaptive role of such variations in natural populations must be taken with caution.     

Ontogeny of territoriality in the desert clickerLigurotettix coquilletti (Orthoptera: Acrididae)

Field observations and experiments showed that settlement prior to reproductive maturation strongly influenced territorial success in the desert clicker(Ligurotettix coquilletti), an acridid grasshopper in which males defend individual host plants (Larrea tridentata bushes) as mating arenas. High tendencies to move and reposition among the host plants were displayed in two distinct episodes. The first occurred during early nymphal development, and it resulted in many individuals settling on high-qualityLarrea bushes. Prior work showed thatL. coquilletti that fed on foliage from these specific bushes exhibited higher relative growth rates and therefore were expected to eclose sooner. Early-eclosing males enjoyed a priority advantage in defending high-quality bushes as mating territories, and they consequently encountered more females and mated more frequently. Despite the distribution of most insects on high-quality bushes at the time of eclosion, though, a second movement episode occurred shortly thereafter. This reshuffling contrasts markedly with the site fidelity of mature adult males, most of which settle on mating territories, and it may function as a means of examining an enlarged sample of potential sites. The above results imply that territorial success of maleL. coquilletti does not result from retaining sites defended by the parents. This point is also supported by the finding that females do not oviposit particularly close to theLarrea bushes in which they reside regardless of their quality; most egg pods are deposited in bare soil midway between the bushes. Nonetheless, certain oviposition sites may be conducive to earlier hatch, and this can lead to earlier eclosion and ultimately to defense of a valuable territory. Therefore, the parental generation, through selective oviposition, may yet influence the success of their male offspring.     

Thermoregulation in four species of British grasshoppers (Orthoptera: Acrididae)

1. This study examines the extent to which thermal balance and thermoregulatory ability may contribute to habitat partitioning in insect herbivores.
2. The distribution of four species of grasshopper on a Breckland grass heath is described. Myrmeleotettix maculatus is restricted to short swards, Omocestus viridulus is restricted to long swards, and Chorthippus brunneus and Stenobothrus lineatus are found on swards of intermediate length.
3. Short swards are warmer on average than long swards, but lack cooler refuges on hot days.
4. Chorthippus brunneus and O. viridulus are better able to raise their body temperatures at low ambient temperatures than M. maculatus and S. lineatus . Omocestus viridulus is less able to reduce body temperature at high ambient temperature.
5. Myrmeleotettix maculatus may be precluded from inhabiting cooler long swards because of its inability to raise body temperatures at low ambient temperatures. Omocestus viridulus may avoid short swards because of the danger of overheating.
6. Thermoregulatory ability is a good predictor of the distribution of the grasshoppers in swards of differing length and microclimate.     

Genetic divergence in the Chorthippus parallelus species group (Orthoptera: Acrididae)

Specimens of Chorthippus parallelus parallelus, C. p. erythropus, C. montanus, C. curtipennis and C. dorsatus were examined electrophoretically. This analysis indicates that C. curtipennis is very closely related to C. p. parallelus and C.p. erythropus (Nei's I = 0.97) while C. montanus is more distantly related ( I = 0.88). The values are consistent with divergence of C. p. erythropus from C. p. parallelus since its separation by the Pyrenean ice sheet during the Pleistocene and of C. curtipennis since invasion of North America by C. parallelus at the same time. A much earlier divergence of C. montanus is implied.     

Evolution of chromosome number in grasshoppers (Orthoptera: Caelifera: Acrididae)

Organisms Diversity & Evolution - Orthoptera have some of the largest genomes of all insects. At the same time, the architecture of their genomes remains poorly understood. Comparative...     

马来西亚蝗科及一新种记述（直翅目：蝗总科）

记述了采自马来西亚的蝗科6亚科22属30种,包括一新种Vitalisia bangiensus sp. nov.。 并首次发现和描述了Sedulia perakensis Willemse的雄性及Eucoptacra minima Ramme和Pagdenia rufipes Miller的雌性。还发现Meltripata bolivari Willemse 和Pagdenia rufipes Miller具二型：全翅型和退化翅型。提供了马来西亚已记录属和种的检索表。     

Laboratory studies on the locomotor activity of Coryphosima stenoptera and other West African Acrididae (Insecta: Orthoptera)

The activity of nymphs and adults of C. stenoptera (Schaum) and some other Acrididae was tested in an actograph. Sexually mature females were more active than immature; males were intermediate in activity, while nymphs, females with eggs in the oviducts and those in a condition of reproductive inactivity were least active. There was evidence that the activity of females increases with age, and that individuals differ in the mean level of activity. There appears to be little possibility at present of relating these changes to the neurosecretory and endocrine systems.