Time Of Eclosion Research Articles

Changes in temperature, not photoperiod, control the pattern of adult eclosion in the tsetse, Glossina morsitans

Abstract. The timing of adult eclosion in tsetse, an event that normally occurs in mid‐afternoon, is regulated by the daily cycle of temperature elevation. If a temperature cycle is maintained, the rhythm of eclosion persists under continuous light or continuous darkness. Artificially shifting the temperature peak to the scotophase results in a concomitant shift in the eclosion pattern. Daily temperature variations as small as 0.4°C are sufficient to establish the rhythm. Eclosion activity tracks the temperature peak, even if the pulses are of short duration (4 h) or with irregular frequencies of 12 or 36 h. The temperature‐induced rhythm offers a simple mechanism for separating females and males. Individuals that pupariate on the same day eclose as adults over a 4–5 day period at 25°C, and in such collections, females are the first to eclose. This distinction makes it possible to collect samples of predominately one sex, a feature that may facilitate the collecting of males for use in the sterile‐male technique.

Melittin synthesis in the venom system of the honey bee ( Apis mellifera L.)

The amount of melittin (measured by a direct haemolytic assay) contained in the venom system of single honey bees ( Apis mellifera), of known age, increases from the time of eclosion to an age of about 4 weeks when about 500 μg of melittin is present. In older bees (5–6 weeks) the melittin level falls to about 250 μg. Measurements of the incorporation of [ 3H]leucine (injected into the haemolymph) into melittin show that melittin synthesis is most active in bees aged between 1 and 2 weeks after eclosion. The melittin content of the venom system changes as the summer progresses. Melittin levels in a bee of any age greater than 1 week are lower in mid-August than in a bee of the same age in early June.

The influence of eclosion timing on winter survival and triacylglycerol accumulation in four temperate species of Drosophila

Abstract. Diapause incidence, winter survival and triacylglycerol content were studied in temperate species of Drosophila by outdoor rearing in Sapporo (a cool‐temperate region), northern Japan. In strains of D.subauraria and D.triauraria (cool‐temperate species) from northern Japan, diapause was induced in adults having eclosed after early September, but in those having eclosed after mid October in strains of D.rufa and D.lutescens (warm‐temperate species) from southern Japan. A subtropical strain of D.triauraria did not enter diapause. In the strains of cool‐temperate species from northern Japan, about 70% survived until spring when eclosed in mid autumn, whereas when eclosed earlier and later flies had a lower ability to overwinter. The warm‐temperate species and a subtropical strain of D.triauraria also survived longer when eclosed in mid autumn than when eclosed later, but they were unable to survive until spring. The triacylglycerol content was higher in the cool‐temperate species from northern Japan than in the warm‐temperate species and a subtropical strain of D.trauraria. In each species the triacylglycerol content of adults was higher when they eclosed in early and mid than in late autumn. It is assumed that triacylglycerol plays an important role in overwintering of these Drosophila species and the low triacylglycerol level is the primary cause of the low overwintering capacity of individuals eclosing in late autumn.

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-quality”Larrea 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.

Alteration of the eclosion rhythm and eclosion behavior in the flesh fly, Sarcophaga crassipalpis, by low and high temperature stress

Heat shock (45°C), cold shock (−10°C), and indirect chilling injury (a prolonged exposure to 2°C) did not interfere with the continuation of pharate adult development in the flesh fly, Sarcophaga crassipalpis, but such flies failed to eclose properly when the exposure was of sufficient duration. In all three forms of injury, development following the temperature treatments was also retarded. Among flies that were less severely affected and still capable of emerging as adults, the circadian time of adult eclosion shifted from near dawn to near the middle of the photophase, thus suggesting that the neurally-based clock is among the systems most vulnerable to heat-shock and cold-shock injury. Tensiometric records of ptilinum expansion revealed important differences in the nature of the injury caused by the different temperature stresses. Heat-shocked flies and those subjected to indirect chilling injury displayed the two behavioral programs normally associated with adult eclosion, the program for obstacle removal (POR) and the program for forward movement (PFM), but such flies failed to eclose because the muscle contractions generated by these motor patterns were insufficient for successful eclosion. In contrast, cold-shocked flies retained the capacity for strong muscle contraction, but the centrally-generated POR and PFM programs were altered. As the duration of cold shock increased, both patterns became more erratic; the PFM program was then lost completely, and in the most severe cases of cold-shock injury, flies lost the capacity to generate both programs. This suggests that neuronal damage is the likely cause of injury inflicted by cold shock.

A new biological rhythm mutant of Drosophila melanogaster that identifies a gene with an essential embryonic function.

To identify components of a circadian pacemaker output pathway, we have sought Drosophila mutations that alter the timing of eclosion but do not perturb circadian period or the expression of the activity rhythm. A mutant named lark has been identified, for which daily peaks of eclosion occur abnormally early while populations are synchronized to either light/dark or temperature cycles. The temporal phasing of locomotor activity in lark mutants, however, is entirely normal, as is the free-running period of the circadian pacemaker. The lark strain carries a single P-element insertion which, interestingly, has a dominant effect on the timing of eclosion, but is also associated with a recessive embryonic lethal phenotype. The analysis of excision-generated alleles suggests that the lark gene encodes an essential function. This function is apparently mediated by a transcription unit that is interrupted by the P-induced lark mutation. A combination of in situ hybridization analysis and reporter (beta-gal) staining indicates that this transcription unit expresses mRNAs throughout the embryonic central nervous system and in a defined subset of cells in the nervous system of pharate adults. RNAs are first detected at about embryonic stage 11, just prior to the stage at which lethality occurs in lark homozygotes. Based primarily on the observed mutant phenotypes, a function is proposed for the LARK product(s) that is consistent with the pleiotropic nature of lark mutations.

The effects of climate, host plant phenology and host fidelity on the genetics of apple and hawthorn infesting races of Rhagoletis pomonella

AbstractTrue fruit flies belonging to the Rhagoletis pomonella (Walsh) sibling species complex have been proposed to speciate sympatrically by shifting and adapting to new host plants. Here, we report the results from a series of ecological and genetic experiments conducted at a study site near Grant, Michigan, U.S.A., aimed at clarifying the relationship between host specialization and reproductive isolation for these flies. Our findings indicate that apple (Malus pumila) and hawthorn (Crataegus mollis) infesting populations of R. pomonella are partially allochronically isolated. Differences in the timing of adult eclosion account for part of the allochronic divergence, as apple adults emerge approximately ten days earlier than hawthorn flies in the field. Genetic analyses across different life history stages of the fly show that adults do not randomly move between apple and hawthorn trees, but trend to attack the same species of plant that they infested as larvae. Estimates of interhost migration from the allozyme data suggest that from 2.8 to 10% of the apple population is of hawthorn origin and that over 20% of the hawthorn population is of apple origin. The length and quality of the growing season appear to affect the genetic composition of the host races, as allele frequencies in the hawthorn population are correlated with ambient temperature and rainfall during the spring of the preceding year. Finally, allele frequencies for six allozyme loci displaying host associated differentiation also show significant linear regressions with the timing of adult eclosion within both races. These regressions establish a link between allozyme loci displaying inter‐host differentiation and a developmental trait (adult eclosion) responsible for partially isolating the races. The slopes of the regressions are paradoxical, however, as they suggest that apple adults should eclose later, not earlier, than hawthorn flies. We conclude by discussing potential resolutions to the eclosion time paradox.

The place of spinning a cocoon in soil and movement of pupa at the time of adult eclosion by Melittia nipponica (Lepidoptera, Sesiidae)

The place of spinning a cocoon in soil and movement of pupa at the time of adult eclosion by Melittia nipponica (Lepidoptera, Sesiidae)

Seasonal decline in intracolony genetic relatedness in eastern tent caterpillars: implications for social evolution

Genetic relatedness in social insect colonies may vary spatially or temporally as a result of changes in colony membership due to immigration or to variation in patterns of maternity and paternity. We estimated relatedness for eastern tent caterpillars (Malacosoma americanum) in laboratory colonies derived from egg masses using multilocus genotypic data derived from electrophoresis. This estimate is compared with estimates obtained from colony samples taken in the field at four intervals spanning the larval developmental season. We found that average intracolony relatedness is close to 0.5 initially but declines through the developmental season due to colony merging, showing that caterpillars do not discriminate between siblings and nonsiblings in order to preserve colony family structure. Using the intracolony values together with relatedness values for higher levels of population structure, we estimated the effective mean number of simple families represented in single colonies through the season. The overall effective number of families per tent increased from one at the time of eclosion to 1.3 by the end of the season. Average intracolony relatedness remained relatively high despite the occurrence of colony merging, apparently as a result of the low density of tents on most trees, combined with high relatedness within the original colonies. Thus, high intracolony relatedness is maintained in M. americanum populations through the effects of adult dispersal, mating, and oviposition patterns, rather than through behavioral discrimination mechanisms of the larvae. These findings underscore the importance of considering the causes of temporal variation in genetic relatedness as well as the consequences for the indirect component of inclusive fitness.

SIMULATING DEVELOPMENT OF IMMATURE HORN FLIES, HAEMATOB1A IRRITANSIRRITANS (L.) (DIPTERA: MUSCIDAE), IN ALBERTA

AbstractDevelopmental times were determined at constant temperatures for an Alberta population of horn flies, Haematobia irritans irritans (L.). Prepupal (egg and larval) developmental time was determined at seven constant temperatures and ranged from 8.9 days at 20.1°C to 3.5 days at 34.5°C. Prepupal development averaged 44.8% of the preadult (egg, larval, and pupal) developmental time. Preadiilt developmental time was determined at 43 constant temperatures and ranged from 41.6 days at 15°C to 8.4 days at 35°C. The relationship between preadult developmental rate and constant temperature was used in a model to simulate developmental times of horn fly immatures exposed to fluctuating temperatures. The model simulated adult eclosion times well. Deviations of simulated from observed (observed – simulated) mean developmental times averaged 0.4 (SD = 1.3) days, and were less than those found when previously published developmental rate equations were used.

Alternative splicing of fructose 1,6-bisphosphate aldolase transcripts in Drosophila melanogaster predicts three isozymes.

The genes that encode fructose 1,6-bisphosphate aldolase of Drosophila melanogaster have been isolated and characterized. These genes exist in a single copy 8-kilobase pair locus in the Drosophila genome which is located at cytogenetic position 97A-B. The nucleotide sequence and transcript mapping suggest that three overlapping protein isozyme genes may be encoded at this locus. These isozyme genes all share a single promoter, a 5'-untranslated first exon, and two other protein coding exons. The isozyme-specific carboxyl-terminal amino acids are encoded by one of three alternatively utilized fourth exons: 4A, 4B, or 4C by alternative splicing. The transcript containing exon 4C, whose sequence has been reported previously, is abundant throughout development and has a developmental profile similar to other glycolytic gene transcripts; however, it shows developmental specificity in the alternative use of two polyadenylation signals which result in a 2.4-kilobase and a 1.9-kilobase transcript. The transcript containing exon 4B is 1.6 kilobases in size and is most abundant during the larval stages and during the time of eclosion. The transcript containing exon 4A is in low abundance and found only during the adult stage. Sequence comparisons of the alternative fourth exons indicate that the duplication leading to the multiple exons is quite old and preceded the origin of the genus Drosophila.

Ontogenic studies of the neural control of adenohypophyseal hormones in the rat. II. Prolactin.

1. Serum prolactin levels are low during the first 20 days of life and gradually increase toward puberty, in both male and female rats. 2. There is an age-related increase in the cell population engaged in prolactin secretion, as well as an increase in the synthesis of prolactin and of the amount of prolactin secreted from individual lactotropes. 3. The gradual increase in prolactin levels in the third week of life is not related to a decrease in dopaminergic inhibition but to an increase in the efficiency of prolactin releasing factors such as estrogen, serotonin, opiates, and posterior pituitary extracts. 4. Prolactin release induced by physiological factors, such as stress, cervical stimulation, or the expression of spontaneous diurnal and nocturnal surges, requires maturational events within the hypothalamic-pituitary axis which are evident at the end of the third week of life. 5. In the female rat the steadily increasing levels of prolactin are involved in the timing of puberty eclosion acting at the ovary and at the brain. 6. In the prepubertal male rat increasing titers of prolactin may be involved in testicular and accessory organ development and may facilitate the actions of luteinizing hormone, follicle stimulating hormone, and testosterone on male sexual organs.

Selectivity in storage hexamerin clearing demonstrated with hemolymph transfusions between Hyalophora cecropia and Actias luna.

When Hyalophora cecropia hemolymph was injected into wandering Actias luna larvae, a methionine-rich hexamerin was selectively transferred to the host's fat body, and completely cleared from the hemolymph by the time of pupal eclosion. Donor arylphorin was 30-40% removed from the hemolymph, and riboflavin-binding hexamerin was even less completely cleared. During the pupal-adult molt, these rates were reversed: methionine-rich hexamerin disappeared no faster than bovine serum albumin, while riboflavin-binding hexamerin was rapidly and completely cleared from the hemolymph, even though A. luna hemolymph lacks a homologue of this protein; arylphorin, again, was cleared at an intermediate rate. Selective clearing of the three hexamerins occurred at similar stages in H. cecropia, their species of origin. Developmentally programmed clearing, with selectivity at least partially conserved between genera, was also demonstrated with transfused vitellogenin: in A. luna females that were forming yolk, H. cecropia vitellogenin was cleared more rapidly than bovine serum albumin; but in younger females, and in males at all stages of metamorphosis, this Mr 510,000 molecule was instead an indicator of nonselective, large protein clearing. Nonselective clearing was more complete during adult development than during pupation. It also showed signs of being more effective for small than for large proteins, insensitive to carbohydrate conjugates, and unsaturated at the protein levels used.

Structure and expression of the triose phosphate isomerase (Tpi) gene of Drosophila melanogaster

We report the isolation of the genomic sequence that encodes the enzyme triose phosphate isomerase of Drosophila melanogaster. There is a single copy of the Tpi sequence in the genome of Drosophila, as judged by Southern blots and in situ hybridization to salivary gland chromosomes. The sequence of 3414 nucleotides from the Tpi region was determined. The gene has an intron in the 5' untranslated region of the transcript and a second intron in the coding region at an evolutionarily conserved position. Transcripts initiate at a single site which does not have a TATA box in the usual position. Northern blot analysis of RNA prepared from different developmental stages revealed that Tpi mRNA is present in substantial amounts in oocytes, declines in abundance in early embryos, and begins to increase during mid-embryogenesis. Transcript abundance follows a pattern typical of enzymes involved in intermediate metabolism. A peak is found during third instar followed by a decline during pupal stages and then a second rise near the time of eclosion.

Insemination patterns in HawaiianDrosophila species (Diptera: Drosophilidae) correlate with ovarian development

In 35 Hawaiian Drosophilaspecies collected from natural populations, all reproductively mature females were inseminated. Onset of receptivity to insemination broadly correlated with the vitellogenic stage of ovarian development, but species and species groups varied in the exact stage of vitellogenesis at which earliest insemination took place. A striking exception was observed in two picture-winged species of the adiastolasubgroup, which were precociously inseminated in previtellogenesis, close to the time of adult eclosion. For a given species, the range of ovarian stages from earliest receptivity to insemination of all females, termed the “insemination period,” also varied among species. This variability may be due to physiological variation between females in hormonal levels, low population densities, and lek behavior of males, or it may reflect variation in degree of female discrimination toward male courtship attempts. Consideration of the quantities of sperm observed stored in the female sperm storage organs, relative to the numbers of eggs produced, indicates obligatory multiple insemination for some species, notably the fungus breeders. In other species groups, there is no apparent necessity for remating, although it may occur.

Maternal adjustment of sex ratio in response to host size in the aphid parasitoid Ephedrus californicus

It has been suggested that sex ratios dependent on host size are unlikely to evolve in parasitoid wasps developing in growing hosts because future host quality would not be predictable at the time of oviposition by the female. We used logistic regression to estimate the primary sex ratio of a solitary parasitoid of aphid nymphs, using data on offspring sex at the time of adult eclosion. The method corrects for any differential preadult mortality between male and female offspring. Male preadult mortality is estimated separately from data on male-only offspring produced by unmated females. This information is built into the statistical analysis of data on offspring sex at the time of eclosion of progeny of mated females to estimate female preadult mortality and the primary sex ratio. The method was used to demonstrate manipulation of offspring sex by females of the parasitoid Ephedrus californicus parasitizing large (third-instar) and small (first-instar) pea aphids, Acyrthosiphon pisum. Mated E. californicus females fertilized nearly 50% of their eggs laid in large host aphids but only about 20% of those laid in small hosts, the difference being highly significant. Parasitoid survival from oviposition to adult eclosion was about 10% higher in small hosts than in large hosts, but for a given host size, the incidence of survival did not differ significantly between the sexes. Therefore, differential preadult mortality had no effect on modifying the primary sex ratio under the experimental conditions. The results also indicated that female decisions about the sex of offspring were affected by previous experience with the range of host sizes available and were more flexible with large than with small hosts, which were allocated male progeny almost invariably. We discuss the evolution of sex-ratio manipulation in solitary hymenopterous parasitoids of the koinobiotic type, which develop in growing host stages, such as aphid nymphs, as opposed to eggs and pupae. Our data indicate that a growing host can represent a reliable resource that is predictable from its initial size, even though it has not reached its potential size at the time of parasitoid oviposition. At least in species such as E. californicus that attack a range of host instars differing widely in size and thus in potential for parasite growth, the ability to effect sex-ratio adjustments based on host size at the time of oviposition may help to maximize female reproductive success, despite any uncertainty about future host quality.

Activity of Chilo partellus (Lepidoptera: Pyralidae): eclosion, mating and oviposition time

AbstractThe majority of Chilo partellus (Swinhoe) males emerge within the first two hours of scotophase (20.00 to 08.00 h), females five hours later. The asynchrony of eclosion times facilitates mating during the last five hours of scotophase on the night of eclosion. Oviposition occurs during the first six hours of scotophase the following night but the majority of the eggs are deposited during the first two hours. No eggs are laid during photophase. A device for recording the timing of oviposition is described. Previous work is reviewed.

Development of functionally competent cabbage looper moth sex pheromone glands

Unlike some moths, pheromone production in Trichoplusia ni is not regulated by a pheromone activating neuropeptide. Rather, competency to produce pheromone apparently is linked with changes in the ecdysteroid titer that occur late in metamorphosis. In contrast to adult pheromone glands, glands from pharate adults 2 days before eclosion were non-competent, and (1) had undetectable levels of the pheromone, ( Z)-7-dodecenyl acetate, and pheromone-specific intermediates, (2) showed little or no conversion of radiolabeled substrate to product in enzyme assays of fatty acid synthetase, Δ11 desaturase, and acetyltransferase, and (3) failed to incorporate radiolabeled acetate into pheromone in gland culture. Glands 1 day before adult eclosion exhibited low titers of pheromone and the intermediate, ( Z)-11-hexadecenoate, and showed low levels of radiolabeled acetate incorporation into pheromone in gland culture. By the time of adult eclosion, the gland was fully competent. Precocious development of pheromone gland competency was induced by removing the head and thorax from pupae 2 days before adult eclosion. This effect appears to result from the reduction of ecdysteroid, since it was blocked by the administration of 20-hydroxyecdysone. This ability to manipulate the development of the pheromone gland was restricted to a critical period, since removal of head and thorax from younger pupae did not induce pheromone gland competency, and administration of 20-hydroxyecdysone to older pupae did not block its onset. In addition to differences in competency, early pharate and adult glands exhibited dissimilarities with respect to (1) the types of proteins synthesized in gland culture, and (2) the types of proteins translated from mRNA in vitro.

Hormonally regulated expression of arginine kinase in Drosophila melanogaster.

Arginine kinase (AK) is present throughout the life cycle of Drosophila melanogaster, but there is a sharp, transient peak of AK activity during the prepupal period and a second period of elevated activity at the time of eclosion of the adult. Imaginal discs show the greatest increase in AK activity at the prepupal stage of those tissues assayed. The prepupal peak is not seen when the temperature-sensitive ecdysoneless mutant ecd-1 is shifted to 29° C at mid-third instar larval stage. The peak in activity reappears when ecd-1 is either shifted back to 20° C after 60 h at 29° C or is fed 20-hydroxyecdysone. At the restrictive temperature, imaginal discs from ecd-1 larvae progressively lose AK activity, whereas discs from 20-hydroxyecdysone-fed larvae have a marked increase in AK activity at stage P3 of the prepupal period. These data suggest that the prepupal peak is regulated by the hormone 20-hydroxyecdysone.

Semiochemicals of the honeybee queen mandibular glands

The ontogeny of the five queen mandibular gland semiochemicals that initiate and maintain the retinue behavior of worker honeybees was investigated by quantitative splitless capillary gas chromatography. No detectable pheromone is present at the time of eclosion, but decenoic acid levels build up rapidly during the first week of the queen's life. Two aromatic components attain detectable levels later, with the more plentiful methylp-hydroxybenzoate preceding the 4-hydroxy-3-methoxyphenylethanol. Pheromone levels are maximal in mature, mated, laying queens. The ratio of (R,E)-(-)-9-hydroxy-2-decenoic acid to the (S,E)-(+) enantiomer increases with the age of the queen. Pheromone levels in queen mandibular glands are largely unaffected by queen banking, restraint with workers in mailing cages, and limited storage on dry ice. All major body parts of typical queens, especially the head and legs, have sufficient mandibular exudate to be highly attractive to worker bees.