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Summer Diapause (summer + diapause)

Distribution by Scientific Domains

Life Sciences	100%

Selected Abstracts

Control of summer and winter diapause in the leaf-mining fly Pegomyia bicolor Wiedemann (Dipt., Anthomyiidae)

JOURNAL OF APPLIED ENTOMOLOGY, Issue 4 2001

Effects of photoperiod and temperature on diapause induction and termination were investigated in both aestival and hibernal pupae of Pegomyia bicolor Wiedemann under field and laboratory conditions. In the field, summer diapause had occurred already in part of the first pupal population; the proportion of diapause gradually rose as the day length and temperature increased. This fly is a short-day species with a pupal summer and winter diapause. Summer diapause was induced by both long day-lengths and mild temperatures. The whole larval life is sensitive to photoperiod. Winter diapause was induced mainly by low temperatures, especially in the first 10 days after pupation. High temperatures strongly enhanced summer diapause induction regardless of photoperiod. The diapause-averting influence of short photoperiods was fully expressed only at moderately low temperatures. High temperatures delayed diapause development, resulting in a rather long summer diapause; whereas low temperatures hastened it, leading to a short winter diapause and showing a low thermal threshold for diapause development. In the field, the post-diapause development started in January, the coldest month, suggesting that the thermal requirements for post-diapause development is also low. [source]

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

ECOLOGICAL ENTOMOLOGY, Issue 2 2002
Tomoyosi Nisimura
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. [source]

Survival and development of five species of cyclopoid copepods in relation to food supply: experiments with algal food in a flow-through system

FRESHWATER BIOLOGY, Issue 9 2005
ULRICH HOPP
Summary 1. Cyclops spp. generally develop and grow during favourable food conditions in spring and undergo a diapause in summer, while Acanthocyclops robustus, Mesocyclops leuckarti and Thermocyclops crassus develop and grow in summer when they face poorer food conditions and more competition from Cladocera. Since nauplii are the bottleneck in copepod development, we tested the hypothesis that Cyclops abyssorum and C. vicinus nauplii have higher food requirements for survival and development than the nauplii of A. robustus, M. leuckarti and T. crassus. We also tested survivorship and development from hatching to adulthood. 2. Survivorship and development of the copepods was studied in a flow-through system using five concentrations of the phytoflagellate Chlamydomonas reinhardtii in the range from 1 × 104 to 4.5 × 105 cells mL,1 (approximately 0.5,22.5 mg C L,1). 3. Nauplii of both species of Cyclops died at intermediate to low (C. abyssorum) and low (C. vicinus) food concentrations, while nauplii of A. robustus, M. leuckarti and T. crassus survived at all concentrations. 4. The negative effects of low food concentration were also reflected in development. In C. abyssorum and C. vicinus, development duration increased at low food concentration while development was much less affected in A. robustus and T. crassus. Mesocyclops leuckarti was intermediate between Cyclops spp. and A. robustus/T. crassus, with an increase in development duration at the lowest food concentration. 5. Our results support the hypothesis that summer diapause in Cyclops spp. has developed as a strategy to avoid a food bottleneck for nauplii. [source]