生物因子对寄生蜂滞育的影响

在影响寄生蜂滞育的生物因子中,寄主及亲代是主要影响因子。寄主可以从种类、类型、生理状态及丰富度等方面影响寄生蜂的滞育:寄生不同种类的寄主,寄生蜂的滞育反应、滞育进度、滞育比例以及光周期反应表现等均有不同;寄主类型的影响在蚜茧蜂类群中表现最为突出,不同寄主类型能对蚜茧蜂的滞育诱导产生不同影响;此外,寄主生理状态和寄主丰富度也是影响寄生蜂滞育的重要因子。亲代对寄生蜂滞育的影响则通过其所经历的环境条件以及自身因素等方面来表现:亲代经历的光周期和温度等能显著影响子代的滞育,甚至起完全决定作用;在亲代自身因素的影响中,亲代虫龄差异是主要因素。本文同时对寄生蜂滞育的研究及应用前景也一并作了展望。     

Photoperiodic and temperature control of diapause induction and colour change in the southern green stink bug Nezara viridula

Abstract. The effect of photoperiod and temperature on the duration of the nymphal period, diapause induction and colour change in adults of Nezara viridula (L.) (Heteroptera: Pentatomidae) from Japan was studied in the laboratory. At 20 °C, the developmental period for nymphs was significantly shorter under LD 10 : 14 h (short day) and LD 16 : 8 h (long day) than under intermediate photoperiods, whereas at 25 °C it was slightly shorter under intermediate than short- and long-day conditions. It is assumed that photoperiod-mediated acceleration of nymphal growth takes place in autumn when day-length is short and it is unlikely that nymphal development is affected by day-length under summer long-day and hot conditions. Nezara viridula has an adult diapause controlled by a long-day photoperiodic response. At 20 °C and 25 °C in both sexes, photoperiodic responses were similar and had thresholds close to 12.5 h, thus suggesting that the response is thermostable within this range of temperatures and day-length plays a leading role in diapause induction. Precopulation and preoviposition periods were significantly longer under near-critical regimes than under long-day ones. Short-day and near-critical photoperiods induced a gradual change of adult colour from green to brown/russet. The rate of colour change was significantly higher under LD 10 : 14 h than under LD 13 : 11 h, suggesting that the colour change is strongly associated with diapause induction. The incidences of diapause or dark colour did not vary among genetically determined colour morphs, indicating that these morphs have a similar tendency to enter diapause and change colour in response to short-day conditions.     

Insect photoperiodic calendar and circadian clock: independence, cooperation, or unity?

The photoperiodic calendar is a seasonal time measurement system which allows insects to cope with annual cycles of environmental conditions. Seasonal timing of entry into diapause is the most often studied photoperiodic response of insects. Research on insect photoperiodism has an approximately 80-year-old tradition. Despite that long history, the physiological mechanisms underlying functionality of the photoperiodic calendar remain poorly understood. Thus far, a consensus has not been reached on the role of another time measurement system, the biological circadian clock, in the photoperiodic calendar. Are the two systems physically separated and functionally independent, or do they cooperate, or is it a single system with dual output? The relationship between calendar and clock functions are the focus of this review, with particular emphasis on the potential roles of circadian clock genes, and the circadian clock system as a whole, in the transduction pathway for photoperiodic token stimulus to the overt expression of facultative diapause.     

Diapause in the seasonal cycle of stink bugs (Heteroptera,Pentatomidae) from the Temperate Zone

The paper reviews the data on diapause and related phenomena in stink bugs (Heteroptera: Pentatomidae). Using stink bugs as examples, the consecutive stages of the complex dynamic process of diapause (such as diapause preparation, induction, initiation, maintenance, termination, post-diapause quiescence, and resumption of direct development) are described and discussed. Out of 43 pentatomid species studied in relation to diapause in the Temperate Zone up to date, the majority (38 species) overwinter as adults, two species—as eggs, and another two species—as nymphs. Pentatoma rufipes is believed to be able to overwinter at different stages of its life cycle. Less than 5 % of pentatomid species are probably able to overwinter twice. Only five species have obligate diapause, others have the facultative one. Day-length and temperature are the main diapause inducing factors in the majority of species. The role of food in the control of seasonal development is essential in the pentatomid species feeding on plant seeds. In different species, different stages are sensitive to day-length. Some pentatomids retain sensitivity to photoperiod even after diapause, others lose it and become photo-refractory (temporarily or permanently). In Pentatomidae, such seasonal adaptations as photoperiodic control of nymphal growth rates, seasonal body colour change, migrations, and summer diapause (aestivation) are widely represented, whereas wing and/or wing muscle polymorphism has not been reported yet. In the subfamily Podopinae, induction of facultative reproductive winter diapause is under the control of photoperiod and temperature. All species feed on seeds and their seasonal development to a great extent reflects availability of food. However, the same food preferences and pattern of seasonal development are also characteristic to many species from the subfamily Pentatominae. All species of the subfamily Asopinae are predators. Among them, Picromerus bidens and Apateticus cynicus have obligate embryonic winter diapause, which is rear among true bugs. At the same time, A. cynicus and Podisus maculiventris belong to the same tribe but have different types of diapause: obligate embryonic diapause in A. cynicus and facultative adult diapause in P. maculiventris. Other Asopinae species studied up to date have facultative adult diapause controlled by photoperiod and temperature with probably only one exception: in Andrallus spinidens, adult diapause is controlled by temperature, and photoperiod plays only a secondary role. Thus, in spite of the similar habits and feeding types among Asopinae, the species of this subfamily have different types of diapause and the latter is controlled by different factors. In the subfamily Pentatominae, most species overwinter as adults and induction of their diapause is controlled by the long-day type photoperiodic response, in spite of the differences in their feeding preferences (within phytophagy). However, there are some exceptions in this subfamily, too: Palomena prasina, P. angulosa and Menida scotti have obligate diapause, which conditions univoltinism in these pentatomids. In M. scotti, only females have obligate adult diapause, whereas males remain physiologically active through the whole winter, this pattern being unusual for Heteroptera. The univoltine seasonal cycle of this species with summer diapause (aestivation) and apparent migrations is similar to that of shield bugs (Scutelleridae). According to the analysis of seasonal development, the evolution of seasonal adaptations in Pentatomidae does not directly reflect their phylogeny. However, individual genera, small tribes or even subfamilies have similar complexes of seasonal adaptations. At the same time, Pentatominae is a large and apparently collected taxon, but most of species in this subfamily have the same facultative adult diapause.     

Insect photoperiodism — the clock and the counter: a review

ABSTRACT. Insect photoperiodic responses are complex and variable, but all involve a 'clock' which is used to determine the qualitative difference between long and short nights, and a 'counter' mechanism which accumulates successive long (or short) nights quantitatively up to an internal threshold at which induction (of diapause, seasonal morphs, etc.) is 'complete'. The clock is circadianbased in at least seven species; in others a non-oscillatory 'hour-glass' device is indicated, but negative 'resonance' experiments may not necessarily rule out a circadian involvement in time measurement. The counter is temperature-compensated. In some species it adds up long nights, in some short nights, and in others long and short nights. The proportion of the population entering diapause is dependent on an interaction between the temperature-compensated counter and temperature-dependent rates of development; this interaction explains many of the known effects of temperature, diet, and latitude in insect photoperiodic responses. In formal terms, the accumulation of long nights is seen as an increase in a 'diapause titre' which is compared with an individual internal threshold. In concrete terms, this 'titre', and the counter mechanism, might be represented by the accumulation of neurosecretory granules within the neuro-endocrine system.     

Photoperiodic induction of prepupal diapause and its role in synchronization with host phenology in the hibiscus caterpillar,Xanthodes transversa

The hibiscus caterpillar, Xanthodes transversa (Lepidoptera: Noctuidae), is a multivoltine insect that is an important pest of Malvaceae plants such as the okra, Abelmoschus esculentus, and the common rose mallow, Hibiscus mutabilis, in Japan. In the present study, the effects of photoperiod and temperature on the induction of prepupal diapause and the adaptive significance of this diapause were examined in a local population of X. transversa in Miyazaki, Kyushu, southwestern Japan. Larvae showed a long‐day photoperiodic response for controlling the induction of prepupal diapause with a critical day length between 13 and 14 h at 20 to 25°C. Under long‐day conditions larvae rapidly pupated from the sixth instar, but under short‐day conditions they entered diapause in the prepupal stage. Diapause occurrence in the field increased in late September, which was consistent with the laboratory results in terms of the photoperiodic response. Non‐diapause development after this time is maladaptive because most larvae of the next generation could not reach the critical stage (prepupae) before winter and died during early winter in outdoor experiments. Larvae suffered from a high rate of mortality when fed leaves collected late in autumn. The photoperiodic response for controlling the induction of diapause in this insect may play an important role in synchronizing the life cycle with the seasonal changes in food and temperature conditions.     

Temperature and photoperiodic control of diapase induction in the ant <Emphasis Type="Italic">Lepisiota semenovi</Emphasis> (Hymenoptera,formicidae) from Turkmenistan

The ants L. semenovi has been found to belong to species with endogenous-heterodynamic seasonal life cycles with the obligate diapause induced predominantly by factors internal for a colony, whereas external ecological factors (photoperiods and temperature) produce merely modifying effects by accelerating or delaying the diapause onset. The photoperiodic and temperature regulation of diapause induction in larvae and queens is shown. Under effect of short days and low temperature the periods of larval pupation and queen oviposition in a colony are shortened markedly, i.e., the diapause of larvae and queens occurs earlier. The daily rhythms of temperature 15/25°C and particularly 20/30°C as compared with constant temperatures 20 and 25°C that correspond to the mean circadian temperatures of the thermorhythm, inhibit manifestations of the short day effects by stimulating the non-diapause development and increasing duration of the seasonal development cycle of ant colonies. The L. semenovi photoperiodic reaction is quantitative, as development and pupation of larvae and egg-laying of queens cease sooner or later under both the short and the long days, but in the latter case significantly later. Thus L. semenovi is one more example among very rare ant species that are revealed to have the photoperiodic regulation of the colony development seasonal cycle.     

Role of photoperiod and temperature in seasonal morph determination of the butterfly Eurema hecabe

ABSTRACT. Environmental cues affecting seasonal morph determination of the pierid butterfly Eurema hecabe L. were examined in laboratory experiments and in the field. A sexual difference exists in the photoperiodic response for seasonal morph determination: in short days at 25C the proportion of the autumn morph is higher in females than in males, and as the rearing temperature is decreased the proportion of autumn morphs increases in both sexes. A 5C drop in temperature during the final larval stadium induces 100% autumn morph production in short-day animals. This increase in autumn morph production induced by temperature decrease explains the seasonal morph change of this butterfly occurring in early autumn in the field. The role of this sex-linked photoperiodic response is discussed as a seasonal strategy of reproduction.     

Photoperiodism and seasonality in neotropical population of Plutella xylostella L. (Lepidoptera: Yponomeutidae)

Neotropical populations of the diamondback moth Plutella xylostella L. have seasonal cycles of growth and decrease, and moth migration plays a fundamental role in generating such population dynamics. Since the oscillation of these populations is predictable, photoperiod might operate as a signal that triggers the migratory behaviour of the insect. Migration in insects is usually preceded by reproductive diapause, a photoperiodic response that can be characterised by morphological, physiological and behavioural alterations that permit to discriminate between migratory and non-migratory forms. In this study, I tested whether the pre-imaginal and reproductive development of P. xylostella from Minas Gerais (Brazil) is affected by artificial day-lengths that are equivalent to the periods of natural population growth or decrease. No evidence of photoperiodic response was found for the insect reared in laboratory on five different constant photoperiods, from 8h to 16h of light per day. There was no significant variation in survival and duration of egg, larva, and pupa stages or in pupal weight, adult size (forewing length), fecundity, and longevity. Although some species have geographically distinct photoperiodic responses, previous assumptions that cosmopolitan P. xylostella responds to photoperiod in temperate regions was questioned. Migratory and population seasonality among neotropical populations of P. xylostella certainly occurs independently of the photoperiodic announcement of seasonal changes in habitat quality.     

Color polymorphism,development, and reproductive diapause of the multicolored Asian ladybird <Emphasis Type="Italic">Harmonia axyridis</Emphasis> (Pallas) (Coleoptera,Coccinellidae) females

Preimaginal development and maturation of females of two laboratory strains originated from two populations of the multicolored Asian ladybird Harmonia axyridis were investigated under laboratory conditions. Females of the autochthonous population from Irkutsk (Siberia) enter diapause under the short day conditions, whereas in females of the invasive population from Sochi (the Caucasus) photoperiodic induction of diapause is weak. The two populations also differ in the proportions of morphs: the population from Sochi is represented only by the morph succinea, whereas the population from Irkutsk is represented by the morphs succinea и axyridis with the predominance of the last one, which in our study was separated into two phenotypes, differed in the degree of melanization. Rearing of adults under the short day (12 h) conditions induced reproductive diapause in females of all the studied morphs and phenotypes of the Irkutsk population, whereas under the long day (18 h) conditions females of the morph succinea showed a slightly lower tendency to diapause. Evidently, the interpopulation differences in the responses regulating the seasonal cycle of the multicolored Asian ladybird are determined by genes that are not involved (or almost not involved) in the determination of the color polymorphism. The interpopulation differences in size and weight were quite substantial, whereas the differences between morphs and phenotypes were statistically significant in only some of our experiments. In combination with the literature data, these results suggest that the genes determining the color polymorphism in H. axyridis may have a pleiotropic effect on other traits including important eco-physiological parameters but this effect is relatively weak and manifests itself only against a particular genetic background and / or under particular environmental conditions.     

Adaptive latitudinal cline of photoperiodic diapause induction in the parasitoid Nasonia vitripennis in Europe

Living in seasonally changing environments requires adaptation to seasonal cycles. Many insects use the change in day length as a reliable cue for upcoming winter and respond to shortened photoperiod through diapause. In this study, we report the clinal variation in photoperiodic diapause induction in populations of the parasitoid wasp Nasonia vitripennis collected along a latitudinal gradient in Europe. In this species, diapause occurs in the larval stage and is maternally induced. Adult Nasonia females were exposed to different photoperiodic cycles and lifetime production of diapausing offspring was scored. Females switched to the production of diapausing offspring after exposure to a threshold number of photoperiodic cycles. A latitudinal cline was found in the proportion of diapausing offspring, the switch point for diapause induction measured as the maternal age at which the female starts to produce diapausing larvae, and the critical photoperiod for diapause induction. Populations at northern latitudes show an earlier switch point, higher proportions of diapausing individuals and longer critical photoperiods. Since the photoperiodic response was measured under the same laboratory conditions, the observed differences between populations most likely reflect genetic differences in sensitivity to photoperiodic cues, resulting from local adaptation to environmental cycles. The observed variability in diapause response combined with the availability of genomic tools for N. vitripennis represent a good opportunity to further investigate the genetic basis of this adaptive trait.     

Association between circadian clock genes and diapause incidence in Drosophila triauraria

Diapause is an adaptive response triggered by seasonal photoperiodicity to overcome unfavorable seasons. The photoperiodic clock is a system that controls seasonal physiological processes, but our knowledge about its physiological mechanisms and genetic architecture remains incomplete. The circadian clock is another system that controls daily rhythmic physiological phenomena. It has been argued that there is a connection between the two clocks. To examine the genetic connection between them, we analyzed the associations of five circadian clock genes (period, timeless, Clock, cycle and cryptochrome) with the occurrence of diapause in Drosophila triauraria, which shows a robust reproductive diapause with clear photoperiodicity. Non-diapause strains found in low latitudes were compared in genetic crosses with the diapause strain, in which the diapause trait is clearly dominant. Single nucleotide polymorphism and deletion analyses of the five circadian clock genes in backcross progeny revealed that allelic differences in timeless and cryptochrome between the strains were additively associated with the differences in the incidence of diapause. This suggests that there is a molecular link between certain circadian clock genes and the occurrence of diapause.     

Quantitative trait loci associated with photoperiodic response and stage of diapause in the pitcher-plant mosquito, Wyeomyia smithii

A wide variety of temperate animals rely on length of day (photoperiodism) to anticipate and prepare for changing seasons by regulating the timing of development, reproduction, dormancy, and migration. Although the molecular basis of circadian rhythms regulating daily activities is well defined, the molecular basis for the photoperiodic regulation of seasonal activities is largely unknown. We use geographic variation in the photoperiodic control of diapause in the pitcher-plant mosquito Wyeomyia smithii to create the first QTL map of photoperiodism in any animal. For critical photoperiod (CPP), we detect QTL that are unique, a QTL that is sex linked, QTL that overlap with QTL for stage of diapause (SOD), and a QTL that interacts epistatically with the circadian rhythm gene, timeless. Results presented here confirm earlier studies concluding that CPP is under directional selection over the climatic gradient of North America and that the evolution of CPP is genetically correlated with SOD. Despite epistasis between timeless and a QTL for CPP, timeless is not located within any detectable QTL, indicating that it plays an ancillary role in the evolution of photoperiodism in W. smithii. Finally, we highlight one region of the genome that includes loci contributing to CPP, SOD, and hormonal regulation of development.     

Experimental investigation of the seasonal aspect of the relationship between blowflies and their parasites

It has been shown experimentally that the diapause in the life cycles of blowflies Parasarcophaga similis, P. argyrostoma, Bellieria melanura, Calliphora vicina and their parasites Aphaereta minuta and Alysia manducator is induced by the seasonal shortening of the daylength. The host species modifies the photoperiodic reaction of the A. minuta parasite. In A. manducator, there is intraspecific geographical variability of the photoperiodic reaction. In certain conditions, diapause induction in this parasite depends on the physiological state of the host. The parasite's influence on the host's development: parasitization by A. minuta terminates the diapause and induces the premature pupation of Lucilia illustris larvae.     

Diapause and seasonal life cycle strategy in the house spider, Achaearanea tepidariorum (Araneae, Theridiidae)

Abstract In order to elucidate the mechanism regulating its seasonal life cycle, the photoperiodic response of Achaearanea tepidariorum has been analysed. Nymphal development was faster in long-day and slower in short-day photoperiods. The combined action of low temperature, poor food supply and short daylength induced diapause at an earlier developmental stage than short days alone. Thus, photoperiod is a primary factor inducing nymphal diapause, but the diapausing instar is influenced by both temperature and food supply. Hibernating nymphs became unresponsive to photoperiod in late December. After hibernation, however, sensitivity was restored and the nymphs remained sensitive to photoperiod throughout their life. This spider could also enter an imaginal or reproductive diapause. Photoperiod was again a primary inducing factor and temperature modified the photoperiodic response to some extent. The induction of the reproductive diapause was almost temperature-compensated whereas development was not. So the involvement of a photoperiodic counter system was suggested. Irrespective of whether the nymph had experienced diapause or not, the imaginal diapause was induced in response to a short-day photoperiod after adult moult. Based on these observations, the seasonal life cycle and the adaptive significance of nymphal and imaginal diapause are discussed.     

Sex‐linked inheritance of diapause induction in the butterfly Pieris napi

Many temperate insects survive harsh environmental conditions, such as winter, by entering a state of developmental arrest. This diapause state is predominantly induced by photoperiod. The photoperiod varies with latitude and has led to local adaptation in the photoperiodic induction of diapause in many insects. To understand the rapid evolution of the photoperiodic threshold, it is important to investigate and understand the underlying genetic mechanisms. In the present study, the genetic basis of photoperiodic diapause induction is investigated in the green‐veined white butterfly Pieris napi (Lepidoptera, Pieridae) by assaying diapause induction in a range of conditions for a Swedish and Spanish population. Furthermore, the inheritance of diapause induction is assessed in reciprocal F1 hybrids and backcrosses between the two populations. The southern population shows a clear photoperiodic threshold determining diapause or direct development, whereas the northern populations show a high incidence of diapause, regardless of photoperiod. The hybrid crosses reveal that the inheritance of diapause induction is strongly sex‐linked, and that diapause incidence in the genetic crosses is highly dependent on photoperiod. This emphasizes the importance of assaying a range of conditions in diapause inheritance studies. The results indicate a strongly heritable diapause induction with a major component on the Z‐chromosome, as well as a minor effect of the autosomal background.     

Inheritance of the photoperiodic response controlling imaginal summer diapause in the cabbage beetle, Colaphellus bowringi

Adults of the cabbage beetle Colaphellus bowringi display a summer diapause in response to the exposure of their larvae to long photoperiods. In the present study, the inheritance of the photoperiodic response controlling summer diapause in C. bowringi by crossing a high diapause strain (D strain) with a laboratory selected nondiapause strain (N strain) was investigated under different photoperiods at 22, 25 and 28 °C. The beetles in both reciprocal crosses and backcrosses showed a clear short-day response for the induction of diapause at all temperatures, similar to that of the D strain, suggesting that photoperiodic response of this beetle is heritable. The diapause incidences in the progeny from all the crosses under LD 15:9 or LD 12:12 at 25 °C suggest that genetic and genetic-environmental interactions are involved in diapause induction. The incidence of diapauses in F₁ progeny was significantly lower than that in the D × D strain but significantly higher than that in the N × N strain, indicating that the diapause capability is inherited in an incomplete dominant manner. The incidence of diapause was greater among the offspring of hybrid females when those females had a D strain mother or grandmother rather than a N strain mother or grandmother, indicating that maternal effects on diapause induction are stronger than paternal effects. The laboratory selected nondiapause strain also showed a short-day photoperiodic response at a low temperature of 22 °C, indicating that the photoperiodic photoreceptor and photoperiodic clock still function in the nondiapause strain.     

Photoperiodic Control of Pre-Adult Development and Adult Diapause Induction in Zoophytophagous Bug Dicyphus errans (Wolff) (Heteroptera,Miridae)

Zoophytophagous plant bugs (Heteroptera, Miridae) increasingly attract interest as agents of biological plant protection. In the laboratory experiment, the effects of the day length and temperature on the duration of the pre-adult period and on induction of facultative winter adult diapause were studied in Dicyphus errans (Wolff, 1804) collected in Italy. The experiment demonstrated that at 20°C the duration of the pre-adult period of D. errans significantly depended on the day length. On average, females developed 1.3 days longer than males and, at the same time, the day length equally influenced the duration of the pre-adult period in both sexes. The pre-adult period was the shortest under short-day conditions (10 to 12 h of light per day), reached its maximum at day length of 14 h, but then decreased at 15 h, and at day length of 16 h it was as short as under short-day conditions. Also, a pronounced long-day type photoperiodic response of adult diapause induction was recorded in females of D. errans at 20°C: under short-day conditions (10 to 14 h of light per day) almost all females entered diapause, whereas under long-day conditions (15 and 16 h of light per day) about 90% of females were mature. The threshold of this photoperiodic response was close to 14 h 30 min. The mean (± S.D.) egg load of mature females was 6.3 ± 4.0 eggs per female and did not depend on the day length at which the female was reared before and after the final molt. When photoperiodic response of adult diapause induction was observed at two constant temperatures (20 and 25°C), the proportion of mature females depended significantly on the day length but not on the temperature: the shapes of the photoperiodic response curves of diapause induction were almost the same within the near-threshold zone at 20 and 25°C, i.e., the photoperiodic response was thermostable. The set of two photoperiodic responses manifested at different stages of the species’ life cycle has an obvious adaptive significance. In Central Europe, D. errans has 2 or 3 generations per year and hibernates at the adult stage. Due to the thermostable photoperiodic response, females enter diapause always at the same time at the end of summer, regardless of the weather conditions of a particular year. When oviposition and pre-adult development are extended over a prolonged period in summer, nymphs from the later eggs might not be able to molt to adults in due time and then fully prepare for stable winter diapause. Under such circumstances, the photoperiodic response controlling the rates of pre-adult development acquires apparent adaptive meaning: with an autumnal shortening of the day length to 10–12 h, even under conditions of seasonal decrease in temperature, the rates of nymphal development increase and, thus, the chances of nymphs from the later eggs to molt to adults and properly prepare for overwintering also increase. The new data should be taken into account when analyzing the seasonal cycle of D. errans and developing the programs of mass rearing of this zoophytophagous mirid as an agent of biological plant protection.