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1.
Terry F. Branson 《Entomologia Experimentalis et Applicata》1987,43(3):205-208
Laboratory tests with eggs of Diabrotica virgifera virgifera LeConte showed that during a 10-day hatching period, hatch of male eggs predominated on the first and second days, eggs of mixed sex, with ca. 1:1 ratio, hatched on the third and fourth days, and eggs hatching from the fifth to the tenth days were nearly all female. Overall, female eggs hatched a mean of 2.9 days later than male eggs. Not only did female eggs hatch later, but the time for posthatch development to the adult stage was 1.8 days longer for females. The later egg hatch and longer posthatch development for females resulted in female adults emerging a mean of 4.7 days later than male adults. Total adult emergence lasted 14 days; of this, males predominated during the first 5 days, and females predominated during the last 9 days. Males of D. v. virgifera appear to have evolved protandry (the tendency for males to emerge before females) by developing both a postdiapause embryonic stage and a combined larval and pupal stage of shorter duration.
Résumé L'observation, au laboratoire, pendant une période d'éclosion de dix jours, des oeufs de D. v. virgifera LeConte, a montré que les oeufs mâles prédominent les deux premiers jours d'éclosion, que les oeufs des deux sexes, avec des fréquences 0,5/0,5, ont éclos les troisième et quatrième jours, et que les oeufs éclos du cinquième au dixième jour étaient presque tous femelles. Globalement, les oeufs femelles ont éclos en moyenne 2,9 jours plus tard que les oeufs mâles. De plus, la durée du développement post-embryonnaire des femelles a demandé 1,8 jour en plus. Une éclosion plus tardive et un développement post-embryonnaire plus long ont entrainé une émergence des femelles en moyenne 4,7 jours après les mâles. La période d'émergence des adultes s'est étalée sur 14 jours; les mâles ayant dominé pendant les 5 premiers jours et les femelles pendant les 9 derniers. Les mâles de D. v. virgifera semblent avoir évolué vers la protandrie en acquerant, tant une diapause post-embryonnaire que des stades de développements larvaire et nymphal plus brefs.相似文献
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Genetic variation at the Major Histocompatibility Complex locus DQ beta was
analyzed in 233 beluga whales (Delphinapterus leucas) from seven
populations: St. Lawrence Estuary, eastern Beaufort Sea, eastern Chukchi
Sea, western Hudson Bay, eastern Hudson Bay, southeastern Baffin Island,
and High Arctic and in 12 narwhals (Monodon monoceros) sympatric with the
High Arctic beluga population. Variation was assessed by amplification of
the exon coding for the peptide binding region via the polymerase chain
reaction, followed by either cloning and DNA sequencing or single-stranded
conformation polymorphism analysis. Five alleles were found across the
beluga populations and one in the narwhal. Pairwise comparisons of these
alleles showed a 5:1 ratio of nonsynonymous to synonymous substitutions per
site leading to eight amino acid differences, five of which were
nonconservative substitutions, centered around positions previously shown
to be important for peptide binding. Although the amount of allelic
variation is low when compared with terrestrial mammals, the nature of the
substitutions in the peptide binding sites indicates an important role for
the DQ beta locus in the cellular immune response of beluga whales.
Comparisons of allele frequencies among populations show the High Arctic
population to be different (P < or = .005) from the other beluga
populations surveyed. In these other populations an allele, Dele-DQ
beta*0101-2, was found in 98% of the animals, while in the High Arctic it
was found in only 52% of the animals. Two other alleles were found at high
frequencies in the High Arctic population, one being very similar to the
single allele found in narwhal.
相似文献
6.
Under field conditions in eastern South Dakota, USA three different planting dates of corn and three times of egg infestation were used to imposed synchronous and asynchronous timing of corn growth and Diabrotica virgifera virgifera LeConte egg hatch and subsequent development. Median occurrence of each of the three larval stages and of the adult stage for each of the infestation-planting treatments was determined by relating occurrence to thermal units and to days after infestation. No significant differences were found among the treatments for median occurrence of each life stage when the thermal unit approach was used. However, significant differences were found among treatments for median occurrence when the day after infestation approach was used. Consistent parameters are needed for prediction of the occurrence of life stages of this insect. Despite the various imposed conditions, this study indicates that the least variable method of predicting life stage occurrence and adult emergence of D. v. virgifera was the use of thermal unit accumulations (base 11°C).
Résumé Dans les conditions de l'est du Sud Dakota (USA), 3 dates de semailles de maïs et 3 dates de contamination avec des ufs de D. virgifera virgifera LeConte ont servi à imposer ou à empêcher la synchronisation des éclosions des ufs et par conséquent des développements ultérieurs. Les dates médianes d'apparition de chacun des 3 stades larvaires et des imagos ont été déterminées en relation avec les unités de température et le nombre de jours depuis la contamination. Aucune différence significative entre les dates médianes d'apparition n'a été mise en évidence par utilisation des unités de température; par contre, ces différences deviennent significatives lorsque l'on utilise le nombre de jours depuis la contamination. Des paramètres fiables sont nécessaires pour prédire la présence des différentes stades de cet insecte. En dépit des différentes conditions imposées pour cette étude, la méthode la moins capricieuse pour prédire l'apparition d'un stade larvaire et l'émergence des adultes est la somme de températures avec une base de 11°C.相似文献
7.
T. F. Branson 《Entomologia Experimentalis et Applicata》1976,19(2):148-154
A non-diapause strain of Diabrotica virgifera LeConte was selected after nine generations by the technique of mass selection. The passive consequence of chilling the eggs of this species is a synchronization of hatch; the chilling does not break diapause. A hypothetical model (and its mathematical expression) explaining diapause in this species was derived from the data. Initial hatch in the non-diapause strain occurred in 24 days at 20°. In an unchilled-unselected population, the mean minimum period of development to initial hatch (both pre-diapause and post-diapause development) was ca. 24 days, and the duration of the mean dormant period was ca. 78 days. The duration of the dormant period is probably quantitatively inherited since this character appears to have enormous genetic plasticity.
Zusammenfassung Ein Nicht-Diapause-Stamm von Diabrotica virgifera wurde durch Massenselektion nach neun Generationen selektiert. Die passive Folge des Kühlens der Eier dieser Art (was bei normaler Zucht des normalen Stamms geübt wird) ist eine Synchronisation des Schlüpfens; das Kühlen bricht nicht die Diapause. Ein hypothetisches Modell (und sein mathematischer Ausdruck), das die Diapause dieser Art erklärt, wurde von den gewonnenen Daten abgeleitet. Erstes Schlüpfen im Nicht-Diapause-Stamm fand nach 24 d bei 20° statt. In einer nicht gekühlten, nicht selektierten Population war die mittlere Minimalperiode der Entwicklung bis zum ersten Schlüpfen (Prä- und Postdiapause-Entwicklung) ca 24 d, die Dauer der mittleren Dormanzperiode ca 78 d (nach der Formel berechnet). Die Dauer der Dormanzperiode wird wahrscheinlich quantitativ vererbt; denn diese Eigenschaft scheint eine sehr grosse genetische Plastizität zu haben.相似文献
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The efficacy of teflubenzuron (Calicide) for the treatment of farmed Atlantic salmon Salmo salar L. infested with sea lice Lepeophtheirus salmonis (Kr?yer, 1838), was investigated at low water temperatures in 2 commercial salmon farms. Calicide, coated on commercial feed pellets, was administered orally at 10 mg kg(-1) d(-1) for 7 consecutive days. Fish were randomly sampled and lice numbers recorded from both treated and control groups on 3 or 4 sampling occasions post-medication. Statistically significant reductions in the number of L. salmonis per fish were recorded. Maximum efficacy was observed toward chalimus and preadult stages of L. salmonis, and was achieved approximately 26 d post-medication. No adverse drug reactions or palatability problems were associated with the treatments. 相似文献