Effects of temperature on the development and survival of an endangered butterfly, Shijimiaeoides divinus barine (Leech) (Lepidoptera: Lycaenidae)

The effects of temperature on the development and survival of Shijimiaeoides divinus barine were examined in the laboratory in 2008. The eggs and larvae were reared at temperatures of 15, 17.5, 20, 25, 30 and 35°C with a long-day photoperiod of 16 h light : 8 h dark (16L : 8D). The highest hatchability of eggs was 88.0% at 20°C, but hatchability at high temperatures of 30 and 35°C was 30 and 0%, respectively. The lowest and highest survival rates from the first to third instar were 18.8% at 15°C and 76.9% at 20°C. Few deaths were observed after the fourth instar. The shortest developmental periods of the eggs and larvae were 4.0 and 15.8 days at 30°C, and the durations of the egg and larval stages increased significantly as the temperature decreased. The developmental zero and thermal constants were 9.6°C and 82.6 degree–days for the egg stage, and 10.7°C and 306.8 degree–days for the larval stage. The developmental period of the natural population of S. divinus barine in Azumino City, Nagano Prefecture was calculated using the developmental zero, thermal constants and Azumino City temperature data.     

Sexual dimorphism and the impact of temperature on the pupal and adult stages of Sepedon spinipes spinipes, a potential biological control agent of fascioliasis

The malacophagous feeding behaviour of larvae of members of the family Sciomyzidae makes the group ideal for the selection of potential biological control agents of snail hosts of trematode diseases. The aim of this study was to investigate the effects of temperature (14 °C, 17 °C, 20 °C, 23 °C, and 26 °C) on the pupal and adult stages of Sepedon spinipes spinipes (Scopoli) (Diptera: Sciomyzidae). Larval prey density effects on the pupal stage and the extent of sexual dimorphism within the species are also assessed. Optimum growth conditions for the pupal stage and pre‐oviposition/oviposition periods, and female fecundity are identified for mass culturing purposes. The tendency of mature third instar larvae to engage in wandering behaviour is highlighted, and the biological control implications of such behaviour are discussed. Female puparia were significantly (P<0.001) heavier than males for both larval prey densities. Such sexual dimorphism would enable the prediction of adult sex from puparial weight prior to eclosion, thereby facilitating culture establishment. The effect of three food types [honey/yeast mixture only, crushed Radix balthica (L.) (Gastropoda: Pulmonata: Lymnaeidae) only, and honey/yeast mixture plus a crushed snail] on adult longevity (laboratory conditions) was also determined and the results suggest that adults live longest when provided with a crushed snail and a honey/yeast mixture.     

The effect of temperature on the duration of the egg stage of certain sciomyzid flies which predate Lymnae truncatula

1. 1. The effect of temperature on the duration of the egg stage of 3 species of sciomyzid flies was investigated at 14, 17, 20, 23 and 26°C.

2. 2. Ilione albiseta(Scopoli): the mean duration of the egg stage (m.d.e.s) decreased from 88.53 to 34.05 days as temperature increased up to 26°C. Under changing temperature conditions (14↔20°C) there was a significant retardation in the duration of the egg stage. 50–70% of conditioned embryonated eggs (i.e. eggs maintained on moist filter paper from 10 to 20 days at 23°C) hatched within 24 in a 0.1% solution of ascorbic acid. (Embryonation was judged to have taken place when the cephalopharyngeal skeleton was visible through the chorion and there was evidence of larval movement within the egg.)

3. 3. Limnia unguicornis (Scopoli): the m.d.e.s. at the 5 constant temperatures was very variable but was significantly shorter at 26°C (22.85 days) than at 14 and 17°C (29.8 and 32.48 days respectively).

4. 4. Pherbellia cinerella (Fallén): the m.d.e.s. decreased from 14.73 days at 14°C to 4.42 days to 26°C and percentage hatch was greatest at 14°C.

Bimodal life cycle of the burying beetle Nicrophorus quadripunctatus in relation to its summer reproductive diapause

Abstract 1. Under natural conditions in Kyoto, Japan, the reproductive activities of Nicrophorus quadripunctatus Kraatz (Coleoptera: Silphidae) decreased in summer and the species showed a bimodal life cycle.
2. In the laboratory, most adult pairs raised at 20 °C under a LD 12:12 h regime reproduced when provided with a piece of chicken. In adults raised at 20 °C under a LD 16:8 h regime, however, both reproductive behaviour and ovarian development were reduced. It is concluded that these adults entered a reproductive summer diapause.
3. High temperature (25 °C) also suppressed the reproductive behaviour even under a favourable LD 12:12 h regime. In the field, therefore, adults reduce their reproductive activity in summer because of diapause induced by long-day photoperiods and direct inhibition of reproduction by high temperatures.
4. When the temperature was changed from 20 °C to 25 °C immediately after hatching of larvae, they reached the wandering stage in 95% of adult pairs. When the temperature was changed from 20 °C to 25 °C immediately after oviposition, however, no larvae hatched in 85% of pairs. Egg mortality was significantly higher at 25 °C than at 20 and 22.5 °C; no eggs hatched at 27.5 °C. The physiological mechanisms for reducing reproduction probably prevent the beetles from inefficient oviposition in summer.     

Effects of photoperiod and temperature on the development and diapause of the bark beetle Ips typographus

Abstract:  Diapause was induced in a Central European population of Ips typographus grown at 20°C when the day length decreased below 16 h [50% diapause incidence occurred in the 14.7:9.3 h L:D (light:dark) regime]. The non-diapausing adults fed on days 2–6 and 10–14 after the ecdysis and swarmed after the second feeding bout with chorionated eggs in the ovaries and sperm in the spermiducts. Neither gonads nor the flight muscles matured and no swarming occurred in the diapausing adults. The development from egg to adult took about 34 days in both 18:6 h (no diapause) and 12:12 h L:D (diapause) regimes, but it was extended by up to 30% without diapause induction when only larvae or pupae were exposed to L:D 12:12 h. Diapause was induced in insects reared at L:D 12:12 h through the last larval and the pupal instars and/or in the adult stage. Temperature ≥ 23°C prevented diapause induction at L:D 12:12 h but diapause occurred at L:D 14:10 h associated with 26:6°C thermoperiod. The effect of thermoperiods on the developmental rate requires further research. Exposure of the non-diapausing adults to 5°C for several days blocked feeding and evoked a diapause-like state, whereas diapausing adults fed and their gonads slowly developed at this temperature. Diapausing adults exposed in forest to low night temperatures and transferred in October to 20°C readily reproduced at 18:6, but not 12:12 h L:D photoperiods. After 2-months at 5°C and darkness, they became insensitive to the photoperiod, matured and most of them also swarmed at 20°C in the 12:12 h L:D regime. In a Scandinavian population, diapause occurred at 18:6 h L:D and was terminated either by exposure to 5°C or by very long photoperiod (L:D 20:4 h) combined with high temperature (23°C).     

Effects of temperature of adults and eggs on the induction of embryonic diapause in the band-legged ground cricket, Dianemobius nigrofasciatus

Abstract.  Eggs laid by adult female Dianemobius nigrofasciatus , reared under long-day (LD 16 : 8 h, 25 °C) or short-day (LD 12 : 12 h, 25 °C) conditions from the nymphal stage, are kept at several constant temperatures. At 22.5–30.0 °C, eggs laid by long-day adults show lower incidences of diapause than those laid by short-day adults. In both eggs laid by adults under long-day conditions and those under short-day conditions, the higher the temperature at which the eggs are kept, the lower the incidence of diapause. When eggs of long-day adults are exposed to a low-temperature pulse (10 °C, 24 h) on the day of deposition (day 0), the incidence of diapause increases. The low-temperature pulse on day 1 does not increase the incidence of diapause. By contrast, when the eggs of short-day adults are exposed to a high-temperature pulse (35 °C, 24 h) on day 0 or day 1, the incidence of diapause decreases. The temperature pulses on day 0 are more effective at diapause prevention. Staining of diapause eggs by the Feulgen–Rossenbeck method shows that the eggs enter diapause at the blastoderm stage, which is on day 1 or day 2 at 25 °C. The exposure of adults to long days and higher temperatures prevents the eggs from entering diapause. In D. nigrofasciatus , embryonic diapause is controlled by maternal effects, adult photoperiod and temperature, and egg temperature before or at diapause.     

Comparison of cold tolerance in eggs of two cicadas, Cryptotympana facialis and Graptopsaltria nigrofuscata, in relation to climate warming

The population of the cicada Cryptotympana facialis began to increase in Osaka, Japan, during the late 20th century. Climate warming is considered a major cause, although the relationship between temperature and the cicada population increase remains unclear. By examining cold tolerance in overwintering eggs of C. facialis in relation to another cicada, Graptopsaltria nigrofuscata , whose population has recently decreased in Osaka, we tested the hypothesis that warming has caused the population increase of C. facialis by decreasing egg mortality due to winter temperatures. A short-term (24 h) cold exposure experiment demonstrated that the half-lethal temperatures (LT50) of C. facialis and G. nigrofuscata were −23.3°C and −28.9°C, respectively, although these extreme low temperatures never occurred in Osaka during the 20th century. Prolonged exposure to −5°C for up to 30 days had no harmful effects on the hatching rate in either species. Overwintering mortality was also assessed under naturally fluctuating conditions by transferring eggs to cooler elevated sites that mimicked the environment prior to the current warming. Eggs of C. facialis that overwintered at the cooler site exhibited similar hatching rates to those maintained at the original site. The results of these experiments consistently indicated that overwintering eggs of C. facialis possess adequate tolerance to the low temperatures of the 20th century. Therefore, we rejected our initial hypothesis that recent increases in the C. facialis population have been caused by warming-related reductions in overwintering egg mortality.     

Biological parameters of Thripobius semiluteus Bouček (Hym., Eulophidae), a larval endoparasitoid of Heliothrips haemorrhoidalis (Bouché) (Thysan., Thripidae)

Abstract:  The endoparasitoid Thripobius semiluteus Bouček was recently introduced to Italy from Israel for the biological control of Heliothrips haemorrhoidalis (Bouché). In this study, some aspects of the biology of T. semiluteus were determined in the laboratory. Developmental time (egg to adult), potential fecundity, realized fecundity, progeny, daily rate of deposition of eggs and several demographic growth parameters were evaluated. Studies of the longevity of fed and starved adults at seven temperatures (3, 10, 15, 20, 23, 25 and 30 ± 1°C) showed that fed T. semiluteus lived longest at 15°C (36.45 days) and shortest at 3°C (1.45 days). Longevity was reduced significantly at higher and lower temperatures than 15°C and when honey was not provided. Development time was measured at six temperatures. Pupae did not complete development at 10°C. The lower theoretical temperature threshold was 9.0°C; the optimum developmental temperature and the upper lethal threshold were 28.0°C and 34.1°C respectively. The most rapid development was found at 30°C, but waSPS suffered significantly higher mortality at this temperature than at other temperatures. Ovigeny index showed that T. semiluteus is synovigenic, with a mean realized fecundity of 78.8 eggs per female. The mean progeny was 68.2 adults per female on fed adults.     

Negative relationship between ambient temperature and death-feigning intensity in adult Callosobruchus maculatus and Callosobruchus chinensis

Abstract.  Although the effects of temperature on insect behaviours are studied frequently, few studies report on the relationship between temperature and anti-predator behaviours. A negative relationship between ambient temperature and the intensity of death-feigning is found in adults of two seed beetle species, Callosobruchus maculatus (F.) and C. chinensis (L.) (Coleoptera: Bruchidae). Two traits representing the intensity of immobility, the frequency and the duration of death-feigning, are measured at different temperatures. Almost all adults feign death at 15 °C, but the frequency of death-feigning decreases at higher temperatures in C. maculatus , whereas all C. chinensis adults show this behaviour at 15 and 20 °C and almost all show it at 25 °C, but the frequency of death-feigning decreases at 30 and 35 °C. The difference between the two species might be due to the specific strain of each species used in the experiment. The duration of death-feigning is correlated negatively with the increase in ambient temperature in both species. The frequency at which adults feigned death is higher in females than in males in both species, but the duration of death-feigning is higher in females than in males only in C. maculatus . The relationships between temperature and death-feigning behaviours are discussed from physiological and ecological viewpoints.     

Optimization of fertilization success in Sander vitreus is influenced by the sperm : egg ratio and ova storage

Walleye Sander vitreum eggs could be stored at 7° C for up to 30 h with 60% fertilization rates. Fertilization rates at 1 and 12° C fell to 17 and 5%, respectively. At spermatozoa : egg ratios <25 000 : 1, survival to the eyed stage declined precipitously. Beyond a ratio of 25 000 : 1, survival to the eyed stage did not increase > c . ∼ 70%. Therefore, a standard spermatozoa : egg ratio of 25 000 : 1 was established and is recommended for studies concerning fertilizing success.     

Interspecific and intraspecific variations in egg hatching for British populations of the stoneflies Siphonoperla torrentium and Chloroperia tripunctata (Plecoptera: Chloroperiidae)

SUMMARY 1. The objective was to compare variations in egg hatching between the two species (interspecific variations) and between populations of the same species (intraspecific variations). There were significant interspecific, but not intraspecific, differences in female size, adult life-span, egg production, hatching success, incubation periods and hatching periods.
2. The optimum temperature for hatching success within the range 3.8–22.1°C in the laboratory and the range over which at least 50% of the eggs hatched were lower for Chloroperia tripunctata (Scopoli) (8.5°C, 4.2–17.3°C) than for Siphonoperla torrentium (Pictet) (12.8°C, 6.1–19.4°C). Few eggs hatched at 22.r°C.
3. The relationship between incubation period (d days) and water temperature (T°C) was given by: d=1219/T^1.368 for S. torrentium , d=253/T^0.459 for C. tripunctata . Both equations successfully predicted incubation periods for eggs placed in a stream. The period over which eggs hatched was much longer for C. tripunctata than for S. torrentium at all temperatures.
4. The shorter incubation period (at r>5.6°C) and shorter hatching period for S. torrentium ensure that larvae of this species are already growing when eggs of C. tripunctata start to hatch, but the prolonged hatching period of the latter species ensures a long period of larval recruitment to the population. These differences in egg hatching may reduce competition between the two closely-related species.     

How do the consumption and development rates of the conifer specialist Aphidecta obliterata respond to temperature,and is it better adapted to limited prey than a generalist?

This study aimed to address the effect of temperature on the consumption and development rates of Aphidecta obliterata and to compare the responses of Ap. obliterata (specialist) with that of Adalia bipunctata (generalist) to prey limitation. Temperature had a significant and positive effect on the time to egg hatch of Ap. obliterata . The duration of the larval instars was not affected by prey species at 15°C but was significantly shorter, 12.1 days at 20°C compared with 21.1 days at 15°C. The proportion of time spent in each instar, however, was not affected by temperature or prey species, but the duration of the pupal stage was significantly affected by temperature. The average daily consumption of prey aphids increased with instar and was significantly influenced by temperature. There was a significant difference in the length of the pupal stage between coccinellid species but not that of the larval stage. The duration of the larval period increased under conditions of prey shortage. The pupal period of Ap. obliterata was significantly affected by the food regime but not that of Ad. bipunctata . There was a significant interaction between species and food supply on the length of the pupal stage and the larval stage and the final fresh weight achieved by the newly emerged adults. Male adults weighed significantly less than the females in all regimes. Larvae of Ap. obliterata and Ad. bipunctata did not consume any of the alternative prey (Collembola or Psocoptera) provided. There was no significant difference in the consumption of prey between the two coccinellid species. The results suggest that both of these coccinellids are well adapted to low-density-specific prey. There were no obvious differences between the two, which would tend to favour either species in an environment of limited prey.     

Development of Trichogramma australicum Girault (Hymenoptera: Trichogrammatidae) in Helicoverpa (Lepidoptera: Noctuidae) host eggs

Abstract Morphological studies of development of the egg parasitoid Trichogramma australicum Girault in the cotton bollworm, Helicoverpa armigera (Hübner), were conducted to provide benchmarks for assessing developmental rates in both natural hosts and artificial diets. Observations of living embryos and histological sections show that embryos proceed rapidly through cleavage and blastoderm formation and show a characteristic pinching or rotation 8 h after deposition. Eggs progressively increase in volume, primarily by increasing in diameter at the widest point. At 29 ± 1°C the duration of the egg stage is 22−24 h, the larval stage 27 h, the prepupal stage 50−52 h, and pupa 85 h. Larvae undergo dramatic shape changes as they ingest food but do not show signs of larval moults, reinforcing observations that there is only one larval instar. Criteria for staging the embryonic and postembryonic development in natural hosts will be used for future studies aimed at developing and refining artificial diets for Trichogramma.     

Assessment of temperature effects on the development and fecundity of Pullus mediterraneus (Col., Coccinellidae) and consumption of Saissetia oleae eggs (Hom., Coccoida)

Eggs, larval and nymphal periods and fecundity of Pullus mediterraneus were examined under 16 h light : 8 h dark combined with six constant temperatures: 15, 20, 25, 30, 35 and 40°C. Eggs of Saissetia oleae were used as prey. The developmental time at 15, 20, 25, 30 and 35°C was 17.23, 4.5, 2.64, 1.67, 1.28 days for eggs and 98.47, 68.88, 53.94, 28.96, 36.51 days for larval–pupal duration, respectively. At 7°C no eggs hatched, and at 40°C all the stages died after 36 h of maximum exposure except the three last stages. The fecundity of females rearing at different temperatures ranged between 1.7 eggs at 15°C and 601.86 eggs at 30°C. The pre-oviposition period ranged between 23.75 days at 15°C and 3.47 days at 35°C. The consumption of S. oleae eggs by the larvae reached 597.69 eggs during the pre-imaginal development. Females attacked more eggs than males averaging 77.69 ± 22.34 eggs per 4 day period compared with 46.97 ± 10.12 eggs per 4 day period for males.     

THE EFFECTS OF TEMPERATURE AND HUMIDITY ON THE RATE OF DEVELOPMENT AND THE MORTALITY OF TRIBOLIUM CONFUSUM DUVAL (COLEOPTERA, TENEBRIONIDAE)

The speed of development and the developmental mortality of Tribolium confusum were studied over a series of constant temperatures between 15° and 40° C. at 10, 30, 70 and 90% R.H. using wheatfeed as food.
Eggs did not hatch at 15° or 40° C. at any humidity. At 37.5° C. about 60% of eggs hatched and at all other conditions about 90% hatched. The effect of temperature on the duration of the egg period is shown graphically, the shortest period being at 35° C. Humidity does not affect the egg period.
Larvae failed to develop to pupae at 17.5° C., at 10% R.H. at 20° C, and at 10 and 90% R.H. at 37.5° C. The rate of larval development was affected by both temperature and humidity being quickest at the higher humidities and at about 32.5° C. Larval mortality was less than 16% except at 37.5° C., at 10% R.H. or less, and at 20°C., 90% R.H.
The duration of the pupal period was not affected by humidity and was shortest at 37.5°C. The total developmental period is compared with that of T. castaneum over the range of temperature and humidity conditions in which both species can grow. The optimum for developmental speed and the maximum and the minimum temperatures at which development is possible were all about 2.5°C. lower for T. confusum than for T. castaneum. The developmental periods for the two species were equal at temperatures between 23 and 27°C., depending on humidity. At lower temperatures, T. confusum developed the more quickly and at higher temperatures the more slowly.     

Diapause duration, survival in relation to desiccation and egg-pod morphology of the Senegalese grasshopper, Oedaleus senegalensis

Abstract. The Senegalese grasshopper, Oedaleus senegalensis (Krauss) (Orthoptera: Acrididae), is periodically a devastating pest of subsistence crops in the sahelian zone of West Africa.Egg diapause has been suggested as an important component of the mechanism acting to generate outbreaks and therefore diapause duration, egg survival in relation to desiccation and egg-pod morphology were investigated in this study.
Three months after oviposition, 50% of initially diapausing egg pods maintained in the laboratory exhibited 'partial emergence' and produced hoppers.No difference in diapause duration was evident between egg pods maintained at a constant 30 ± 1°C and those maintained under alternating temperature conditions of 23 ± 1°C and 35 ± 1°C.Laboratory maintained eggs showed significant variation in diapause duration with diapause lasting between 2 months and 4 years.Diapause duration was shorter in the field with only c. 1.4% of eggs remaining in diapause after a single dry season (6–7 months).Survival of eggs in relation to desiccation was high in the field and low in the laboratory, and field eggs lost only c. 20% of their body weight over the dry season.Survival of diapausing and non-diapausing egg pods in the laboratory was similar, indicating that diapause in this species is primarily a mechanism for preventing emergence at an inappropriate time of year, rather than conferring any additional resistance to desiccation.Egg pods oviposited under diapause-inducing conditions (LD 14:10 h, 25°C) were significantly shorter than those laid under non-diapausing conditions (LD 10:14 h, 40°C).These results are discussed both in relation to possible O.senegalensis 'bet-hedging' strategies and to the probable mechanism operating behind major outbreaks of this species.     

Biology of Diaphorina citri (Hem., Psyllidae) on different hosts and at different temperatures

Abstract:  The objective of this work was to study the effect of different hosts and temperatures on Diaphorina citri Kuwayama (Hem., Psyllidae) biology. Citrus limonia (Rangpur lime), Murraya paniculata (orange jessamine) and Citrus sunki (Sunki mandarin) were used as hosts. Measurements included duration and viability of the egg and nymphal stages, sex ratio, fecundity and longevity. In order to verify the effect of temperature on D. citri biology, the duration and viability of its developmental stages and biological cycle were compared at seven different temperature conditions. Durations of the embryonic and nymphal stages were similar for Rangpur lime, orange jessamine and mandarin. However, the nymphal viability obtained on mandarin was lower than the values obtained on the other hosts. Fecundity was higher on orange jessamine and, in all instances, females had greater longevity than males. A fixed number of instars (five) was obtained on the three hosts. Rangpur lime and orange jessamine provided better D. citri development when compared with mandarin. Duration of the egg and nymphal stages varied from 2.6 to 7.7 and from 9.4 to 35.8 days, respectively, at temperatures from 18 to 32°C. Egg viability was higher than 81.6% at the temperature range studied (18–32°C); nymphal viability was higher than 70% at the 18–30°C range, differing from viability at 32°C, which was dramatically reduced. The D. citri lower temperature development threshold (TT) and thermal constant ( K ) values for the egg, nymphal and biological cycle (egg–adult) stages were 12.0°C and 52.6 Degree-Day (DD); 13.9°C and 156.9 DD; and 13.5°C and 210.9 DD respectively.     

Effects of husbandry parameters on the life-history traits of the apple snail, Marisa cornuarietis: effects of temperature, photoperiod, and population density

Abstract. These experiments are part of a larger study designed to investigate the influence of husbandry parameters on the life history of the apple snail, Marisa cornuarietis . The overall objective of the program is to identify suitable husbandry conditions for maintaining multi-generation populations of this species in the laboratory for use in ecotoxicological testing. In this article, we focus on the effects of photoperiod, temperature, and population density on adult fecundity and juvenile growth. Increasing photoperiod from 12 to 16 h of light per day had no effect on adult fecundity or egg hatching and relatively minor effects on juvenile growth and development. Rearing snails at temperatures between 22°C and 28°C did not influence the rates of egg production or egg clutch size. However, the rates of growth and development (of eggs and juveniles) increased with increasing temperature in this range, and when temperatures were reduced to 22°C egg-hatching success was impaired. Juvenile growth and development were more sensitive to rearing density than adult fecundity traits. On the basis of the present results, we conclude that rearing individuals of M. cornuarietis at a temperature of 25°C, a photoperiod of 12L:12D, and a density of <0.8 snails L⁻¹ (with lower densities for juvenile snails) should provide favorable husbandry conditions for maintaining multi-generation populations of this species.     

Effects of photoperiod and temperature on pupal diapause induction of grape berry moth Lobesia botrana

Abstract. The grape berry moth, Lobesia botrana Denn. & Sciff. (Lepidoptera: Tortricidae), one of the most injurious pest of grape berries in Greece, is a multivoltine species that overwinters as diapausing pupae. The effects of several diel and non-diel photoperiods and of temperature, experienced by eggs and larvae, on pupal diapause induction were investigated. The diapause response curve was of Type I (long day type) and the determining factor was the duration of scotophase (> 11 h), regardless of the duration of photophase. However, at very short (< 4 h) photoperiods, the incidence of diapause was also high. Diapause was positively and significantly correlated with the egg-larval developmental time, pupal mortality and the duration of the pupal stage. Eggs and larvae reared under LD 12 : 12 h photoperiod and various temperatures (from 12 to 30 °C) produced diapausing pupae (almost 100%), but the duration of the pupal stage (intensity of diapause) increased with increasing temperature. Under continuous darkness, however, the percentage diapause decreased with increasing temperature. Single and double 1-h light pulses were applied systematically at various times during the scotophase of six diapause-inducing diel photoperiods. Two photosensitive points in time (called A and B) were revealed, during which illumination resulted in a significant decrease of diapause induction. The decrease was much greater during the first sensitive period (early in scotophase) rather than in the second (late in the scotophase).     

Uptake and loss of water in diapause and non-diapause eggs of crickets

ABSTRACT. In laboratory-laid eggs of the striped ground cricket, Allonemobius fasciatus DeGeer (Gryllidae), water absorption occurs at an early stage of embryogenesis (stage II) at 30°C but is delayed until later stages at lower temperatures. This is related to the variation in diapause stage at different temperatures. No egg developed beyond stage VII (the end of anatrepsis) without water absorption.
A. fasciatus shows seasonal variation in the stage of water absorption. At 30°C, eggs collected in August absorb water at the early stage while many of those collected in September avert diapause and absorb water at a later stage.
Diapause also influenced the water absorption of eggs in A. socius Scudder. Eggs of short-day females enter diapause and absorb water at stage II, while those of long-day females develop without diapause and absorb water at a later stage (around stage IV).
The susceptibility to desiccation (r.h. 50%) was examined at 20°C with A. fasciatus eggs. The percentage water loss and mortality of eggs varied with the time and duration of exposure to desiccation. Eggs are most sensitive to desiccation during the first several days after being laid and during the period of water absorption.