The first proof of a possibility of change of temperature norms of insect development as a result of artificial selection for fast or slow development by the example of the red soldier bug <Emphasis Type="Italic">Pyrrhocoris apterus</Emphasis> (Heteroptera,Pyrrhocoridae)

For 3–4 generations, selection of the nymphs most rapidly and slowly developing at 28°C was performed in four families of the red soldier bug Pyrrhocoris apterus L. In each generation, duration of development of nymphs was determined at 5 constant temperatures from 20°C to 28°C. From these data the linear regression coefficient of the development rate against temperature (the development thermolability coefficient) for each generation was calculated. As a result of the selection the average duration of the nymph development was shortened or increased statistically significantly depending on its direction. The artificial selection for the development duration has been established to change not only this parameter, but also the temperature norms of the insect development. At selection for fast development the regression straight line slope (i.e., the regression coefficient value) increased statistically significantly, i.e., development became more dependent on temperature. As a rule, the temperature threshold of development increased. At selection for slow development the values of the regression coefficient and of the threshold decreased, but these differences were not statistically significant. The effect of artificial selection for the development duration on temperature norms of insect development has been revealed for the first time.     

Analysis of pteridines in Pyrrhocoris apterus (L.) (heteroptera,pyrrhocoridae) during development and in body-color mutants

By using thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC), five different pteridines have been quantified in extracts from Pyrrhocoris apterus: neopterin, isoxanthopterin, isoxantholumazine (violapterin), 7-methylxanthopterin, and erythropterin. Biopterin was also detected using HPLC. Pteridines have been analyzed separately in bodies and eyes of the wild type regarding developmental stage and sex. The pteridine content in both bodies and eyes increased from nymphs to 2-day-old adults. After this period, the concentration of pteridines in the eyes of adults remained approximately constant, while in the bodies isoxantholumazine, 7-methylxanthopterin, and isoxanthopterin kept increasing until 20 days. Considering the total amount of pteridines per insect, no qualitative or quantitative differences between males and females have been observed except a lower concentration of erythropterin in female bodies. But when pteridines are analyzed per unit body weight, a lower amount of pteridines is always detected in females due to its bigger size. A new body-color mutant, the yolk body mutant, that goes through developmental colour changes, was also analyzed during development, showing a general deficient accumulation of all pteridines, especially of 7-methylxanthopterin and isoxantholumazine in adult bodies. The effect on pteridine content of three other recessive (white, yellow, mosaic) and two dominant (Pale and Apricot) body-color mutations, has also been studied. A specific pteridine pattern different from the wild type was obtained for each mutant. © 1997 Wiley-Liss, Inc.     

始红蝽越冬聚集行为对其能量代谢的影响

聚集行为是动物适应不良环境的一种生态对策。始红蝽Pyrrhocoris apterus在成虫滞育越冬期间具有显著的聚集行为。采用LI-6400型光合仪测定了5种聚集度(分别用1头、5头、10头、20头和50头的群体大小表示)下始红蝽的呼吸量,通过呼吸量计算得到各聚集度始红蝽的呼吸速率(rate of respiration,Rr)及能量代谢速率(rate of metabolism,Rm),旨在明确聚集行为是否能够对始红蝽越冬时的能量代谢产生影响。结果表明： 不同聚集度间始红蝽的Rm值存在显著性差异; 并且随聚集度的增加,Rm值与聚集度呈显著负相关,Rm值依次为0.052,0.044,0.041,0.037和0.033 W/g。结果说明聚集行为可以有效降低始红蝽新陈代谢速率,有利于种群成功越冬。     

Locomotor activity in adult Pyrrhocoris apterus (Heteroptera) in relation to sex, physiological status and wing dimorphism

The pattern of locomotor (walking) activity was studied in adult males and females of short‐winged (brachypterous) and long‐winged (macropterous) morph of the flightless bug Pyrrhocoris apterus (Linnaeus) (Heteroptera: Pyrrhocoridae) under constant laboratory conditions. Walking activity was measured with a computerized video system and analysed with respect to sex, physiological status (reproduction, diapause and reproductive arrest of non‐diapause type) and wing dimorphism of the bugs. The largest duration was observed in the macropterous females with reproductive arrest of non‐diapause type (average 6 h per day) and the shortest duration in diapausing brachypterous females and males (average less than 2 h per day). This was reflected also in the overall time spent by walking during the first 14 days after imaginal ecdysis. The time spent by walking significantly increased in the macropterous morph as the bugs aged, whereas in diapausing brachypters the time spent by walking decreased with age. No linear relationship between walking activity and age was found in reproductive brachypterous morph. The bugs of all experimental groups moved mostly during the photophase and were almost inactive during the scotophase. Thus, walking activity in P. apterus is diurnal, irrespective of the wing morph, physiological status, sex and age. Contrary to the macropterous morph, where the locomotor activity of females during photophase was significantly higher than in males, no significant differences were found between the locomotor activities of brachypterous males and females. The observed differences in locomotor activity are discussed in relation to different roles of two wing morphs in the life history of this heteropteran.     

Inflexible versus flexible: the influence of temperature and photoperiod on pre‐ and post‐eyespot development time in Libellulidae (Odonata)

Temperature and photoperiod are important environmental parameters for organisms. The present study tests the hypothesis that, during embryogenesis, temperature and photoperiod influence pre ‐ and post ‐ eyespot development time in dragonflies of the family Libellulidae differently. Eggs are used from eight species (five different genera, from Africa/Europe, and lentic/lotic habitat preferences). The eggs are reared under different constant or fluctuating temperature and light conditions. There are no general species‐specific degree‐days for pre ‐ or the post ‐ eyespot development in these species. In all study species, the variance within and between the treatments of the duration in days and the degree‐days of pre ‐ eyespot development is lower than that of post ‐ eyespot development. Pre ‐ eyespot development appears to be less flexible in its reaction to environmental influences. By contrast, post ‐ eyespot development appears to react more flexibly to environmental influences. All eight species show the same pattern. This indicates strongly that this flexibility is a general pattern in Libellulidae that might help the species within this family to cope successfully with variations in environmental conditions. Because eyespot development and katatrepsis occur close to each other, the above‐described pattern might also appear in other odonates and in other insect groups that exhibit katatrepsis. For all of them, it is essential for survival to match the time of hatching with adequate external temperature and photoperiodic conditions.     

Study of intrapopulational variability of duration and temperature norms of development of the linden bug Pyrrhocoris apterus (Heteroptera, Pyrrhocoridae)

The existence of significant variability in duration and temperature norms of development between families within insect populations has been shown for the first time. This variability is inferfamily and therefore has genetic ground. Revealed for the first time is the statistically significant positive correlation between the regression coefficient of the development rate for temperature and the temperature threshold for development of eggs and larvae from different families. The greater the slope of the regression line of the development rate for temperature, the higher the temperature threshold value in this particular family. These results demonstrate for the first time the existence of genetic co-variation between the regression coefficient and the temperature threshold within the insect populations. It is suggested that the source of the interpopulational and interspecies changes in the temperature reaction norms of the insect development might be the intrapopulational hereditary variability of the development duration, regression coefficient, and the development threshold, this variability being an object of natural selection. It was shown that in all studied families and populations the values of the linear regression coefficient of development rates for temperature in eggs of the linden bug Pyrrhocoris apterus were markedly and statistically significantly higher, while the temperature threshold values—lower as compared with the corresponding parameters in larvae. These results obviously are in contradiction with the concept of the “isomorphism of development rates” (Jarosik et al., 2002), according to which the development threshold for all life cycle stages of a species should be the same, whereas only slopes of the regression lines of the development rate for temperature can differ. For the first time the absence of genetic covariation has been shown between the temperature norms of development of different life cycle stages of the species—eggs and larvae. This means that the regression coefficient as well as the sum of the degree-days and the development threshold in eggs and larvae are inherited independently and therefore they can be independently changed in evolution in correspondence with specific environmental conditions, under which these life cycle stages take place.     

Are thermal constants constant? A test using two species of ladybird

There is a controversy about whether the thermal constants, lower developmental threshold, rate of development and corresponding degree days required for development, change when a species is reared under different developmental conditions. We present a more precise way of measuring these constants using the linear relationship between the rate of development and temperature. First we use the equation proposed by Ikemoto and Takai (2000) to determine the linear phase of development and then a generalised linear model having a different variance at low and high temperatures, specific for each condition, to estimate the parameters of the linear relationship. Using this method, we show that providing the difference in food quality is sufficiently great, an aphidophagous ladybird develops significantly faster and starts developing at a significantly lower temperature on a good than on a poor quality diet. Adaptive significance of the thermal constants not remaining constant is discussed in terms of a trade-off between growth and rate of development, when temperature and food quality varies.     

Acclimation of thermal physiology in natural populations of Drosophila melanogaster : a test of an optimality model

Many organisms modify their physiological functions by acclimating to changes in their environment. Recent studies of thermal physiology have been influenced by verbal models that fail to consider the selective advantage of acclimation and thus make no predictions about variation in acclimation capacity. We used a quantitative model of optimal plasticity to generate predictions about the capacity of Drosophila melanogaster to acclimate to developmental temperature. This model predicts that the ability to acclimate thermal sensitivity should evolve when temperature varies greatly among generations. Based on the model, we expected that flies from the highly seasonal environment of New Jersey would acclimate thermal sensitivity more than would flies from the less seasonal environment of Florida. When raised at constant and fluctuating temperatures, flies from these populations failed to adjust their thermal optima in the way predicted by the model, suggesting that current assumptions about functional and genetic constraints should be reconsidered.     

亚洲玉米螟发育速率与温度关系研究

利用１０￣３４℃的９个恒温对亚洲玉米螟Ｏｓｔｒｉｎｉａ ｆｕｒｎａｃａｌｉｓ（Ｇｕｅｎｅｅ）发育与温度的关系进行了研究。亚洲玉米晕除了在１０℃不能发育以外,在其８种恒温中均可发育,但其死亡率在１２０℃和３４℃中较高。从产卵成到虫羽化,卵期占整个发育过程中１７％,幼虫期占５７％,蛹期占２５％。最低发育起点温度卵期为１０．３８℃,幼虫期为１０．０６℃,蛹期为１１．０７℃。高温限制温度卵期为２８．００℃     

Regulation of body size in a heteropteran bug, Pyrrhocoris apterus

The determination of body size (length or weight) of teneral adults of Pyrrhocoris apterus L. was investigated. About 50% of size variation was determined already in the egg stage (average egg weight adult length correlations were 0.67 in males and 0.71 in females). During the larval development, starvation, low temperature, and pollution by excreta combined with crowding reduced adult size and usually increased the development length. The effects were directly proportionate to the length of the stress period, and increased with larval age. Photoperiod or intrinsic variation of development time did not affect adult size. The effects of stress were largely compensated when it was followed by a period of compensation growth at optimum conditions. A dramatic reduction of size appeared when last inster larvae starved and moulted to adults without access to food. Average adult weight was then reduced by up to 48%. Threshold weight for adult moulting was 18 mg, being attained after 1–2 day feeding of the last instar.

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Zusammenfassung Die Körpergrösse bei den Imagines eines Wildstammes der Feuerwanze Pyrrhocoris apterus wurde teilweise durch die Veränderlichkeit der Eigrösse determiniert, teilweise auch durch Hungern der Larven, niedrige Temperatur und metabolischen Produkten beeinflusst. Der Effekt letzterer Faktoren stieg mit deren Dauer und war je grösser desto näher sich die Wirkungsperiode zur Imaginalhäutung befand. Unterschiedliche Photoperioden wirkten auf die Körperlänge nicht. Wurden die Larven zwischen der ungünstigen Periode und der Imaginalhäutung noch den optimalen Bedingungen ausgesetzt, kompensierten sich die negativen Einflüsse weitgehend. Zu einer drastischen Verkleinerung der Imagines kam es nur, wenn das letzte Larven-stadium mit Hunger beeinflusst wurde und bis zur Imaginalhäutung keinen Zutritt zum Futter hatte. Minimales Gewicht, wo die Metamorphose der Larven noch möglich war, wurde zu 18 mg festgestellt.

     

民勤荒漠区16种植物物候持续日数及其积温变化

中国西北荒漠区植物物候随气温变暖表现为提前趋势。本文以甘肃民勤荒漠区16种植物34年的物候观测资料,采用一次趋势线方程研究了荒漠区植物在物候提前的过程中,物候日数变化和物候期积温变化。结果表明,随着气温升高,物候持续日数表现出一定的增长趋势。物候持续期积温增加显著,而且春、秋两季是积温变化较敏感的季节。积温的增减在很大程度上是由物候持续日数增加或减少引起的,其次才是由于气温增高引起的。表明,随着气温的增高或降低,植物的物候持续日数并不能无限制地缩短或延长。