The ageing trajectory (trend in ageing) and reproduction-longevity trade-off in both sexes of the ladybird Propylea dissecta were studied. The ageing trajectories of both sexes were investigated in terms of reproductive performance, using initial oviposition (egg laying within 24 h of mating) acting as an indicator of the effect of female age and initial viability (percentage of eggs laid within 24 h of mating that hatched) of the effect of male age. Ageing trends were sex dependent, with reproductive performance declining later in females than in males. Initial oviposition of females was largely age dependent and the initial viability of males was age dependent but less so than for females. There is a strong trade-off between number of matings and longevity. Statistical analyses reveal that this trade-off results from an early onset of mortality rather than an increase in mortality rate. A minimum lifespan was observed in this ladybird beyond which the longevity did not further decline.
Both Scymnus syriacus Mars. and Scymnus levaillanti Muls. are aphidophagous coccinellids. In the laboratory they consumed and successfully reproduced on several species of aphids. Larvae suck the prey contents from aphid appendages, while adults consume the whole aphid, except for parts of the appendages. Extra-oral digestion is practiced during feeding. The mean number of aphids consumed by the larval stage of S. syriacus when reared at 25°C was 95, and 130 aphids at 30°C. For S. levaillanti it was 125 and 139 aphids at 25°C and 30°C, respectively. The mean number of eggs deposited daily by S. syriacus for the first three weeks of adult life was 19.5, with a range of 3-30 eggs at 25°C. Longevity of adults ranged from 3 to 4 months at 25°C and 2.5-3 months at 30°C.
Macropterous individuals of wing polymorphic semiaquatic bugs (Heteroptera: Gerromorpha) usually occur at a high frequency if there is a need to leave an unfavorable habitat or in a generation migrating to/from an overwintering site. Velia caprai (Veliidae) is usually found in unpredictable habitats, but the macropterous morph is rare. Laboratory, mesocosm and field experiments were used to test the hypothesis that individuals of this species migrate by walking rather than by flight. Laboratory experiments that focused on the development of macropterous morph under conditions that usually stimulate the development of this morph in water striders were unsuccessful. A high temperature shortened the duration of nymphal development, but no winged specimens of Velia caprai developed in the laboratory when reared under either high or low temperatures, long or short photoperiods or on the surface of water or wet filter paper. Mesocosm experiments with apterous adults revealed they are able to walk on land. Both the males and females dispersed by walking in semi-natural conditions. Long-term field experiments using mark and recapture confirmed that this species can disperse by walking. Apterous individuals can compensate for downstream drift by upstream terrestrial migration and colonize newly established pools and ditches even several tens of meters from source sites. The development of a macropterous morph in response to environmental factors is replaced by terrestrial dispersal in V. caprai.
Studies of insect population under field conditions to establish survival rates, longevity and dispersal rates are rare in the literature. These types of studies are important and can be used to inform studies of the effects of landscape composition and configuration on levels of biodiversity. Here the Cantharidae beetle, Rhagonycha fulva is studied under field conditions to derive estimates of daily survival rates for both males and females as well as local dispersal rates. Survival was studied at two sites, one in Wales and another in England, whilst dispersal was examined only at the Welsh site. Beetles were marked using different coloured enamel paints at the mid-point of a 200 m linear transect. The beetles were almost exclusively found (and marked) on common hogweed, Heracleum sphondylium. No difference in survival was found between males and females at both of the sites. The survival rates found at the two sites also did not differ. The overall daily survival rate was 0.771 equating with a median longevity of 4.37 days. Casual observations yielded a small number of marked individuals in excess of 400 m away from the point of marking. Movement of males along the transect differed from females. Marked females were never found far from the point of marking whilst males moved further away with time. This difference in behaviour is discussed in terms of hypothesized insect dispersal behaviour following emergence as mobile adults., Laura E. Rodwell, Jennifer J. Day, Christopher W. Foster, Graham J. Holloway., and Obsahuje bibliografii
Stáří a stárnutí jedinců jsou bezpochyby fenomény, které zaujímaly významné místo ve společnosti již v dobách dávno minulých. Během 20. století však nabrala otázka stárnutí nového rozměru, neboť začala nově přesahovat z úrovně individuální na úroveň celospolečenskou. V důsledku zlepšování některých společenských podmínek (např. lékařské péče, životního stylu, hygieny, životní úrovně atd.), jež bylo nastartováno již zhruba na počátku 19. století, dochází k odsouvání úmrtí do vyšších věků, a lidé tak žijí déle. V moderních společnostech je tento jev obvykle doprovázen poklesem porodnosti a plodnosti. Kombinace těchto dvou faktorů pak ve svém konečném důsledku způsobuje proces, který nazýváme demografickým stárnutím. Obecně je tedy třeba rozlišovat dva pohledy na problematiku stárnutí. První pohled se zaměřuje na tzv. stárnutí individuální, druhý přístup se zabývá demografickým stárnutím lidských populací, ovšem je zřejmé, že obě dvě hlediska jsou mezi sebou navzájem provázaná. Podobně tomu bude i v následujícímpříspěvku, jenž se bude zabývat nejen přehledem problematiky demografického stárnutí, ale dotkne se také otázek o dlouhověkosti a kvalitě života, které se dostávají do popředí v souvislosti s tematikou stárnutí jednotlivců., Old age and aging of individuals are phenomenons that took important place in society as early as former times. During twentieth century the question of aging got new meaning, because it newly started to overreach from individual level to all-society. As a result of improvement of some social conditions (f.e. medical care, lifestyle, hygiene, living standard etc.), that was already initiated approximately at the beginning of the nineteenth century, dying started to be moved to higher age and people live longer. In modern societies this event usually goes with decline of natality and fertility. In final effect combination of these two factors causes the process that is known as demographic aging. In general we have to distinction between two views of problems of aging. The first view is focused on individual aging, the second one on demographic aging of human population. But it is clear that both of these views relate to each other. Similarly this article offers the roundup of problems of demographic aging, but also gives a touch of questions about longevity and quality of life, that gain ground in connection with theme of individual aging., Michaela Dimitrová., and Seznam literatury
German cockroaches spend most of the day in aggregations within shelters, which they leave in nocturnal foraging trips; cockroaches are rarely seen outside shelters during daylight hours. However, when population density exceeds shelter availability, diurnal aggregations form in exposed, unsheltered locations. To determine if shelter availability affects fitness of B. germanica, we reared cohorts of nymphs in laboratory arenas with or without shelters, and measured reproduction and longevity of tagged adults. When shelters were available in arenas, nymphs developed faster, adults gained more body mass, and females produced more fertile oothecae than when arenas lacked shelters. Therefore, shelter alone has a significant positive effect on growth and reproduction of B. germanica, and reducing or eliminating shelters should affect population growth of B. germanica in residential and industrial settings. and César Gemeno, Gregory M. Williams, Coby Schal.
The effect of constant temperatures (5, 10, 15, 20, 25 and 30°C) on several biological parameters of Noctua atlantica (Warren), a noctuid endemic to the Azores, was studied using an artificial diet as food. At 5 and 30°C no eggs hatched. Developmental time (egg, larval, pupal and egg-to-adult) differed significantly at each temperature. Pupal weight (males and females) was significantly higher at 10°C and lower at 25°C. Adult longevity and the pre-oviposition period were longer at 10 and 15°C and differed significantly from those observed at higher temperatures. The mean number of eggs laid per female (fecundity) was significantly higher at 15°C, and lower at 25°C. Pupal weight (males and females) was positively correlated with larval, pupal, egg-to-adult developmental times and with adult longevity. Female pupal weight was also positively correlated with the pre-oviposition period and with fecundity. Temperatures ranging from 10 to 20°C are the most suitable for the development of N. atlantica, suggesting that this species is well adapted to the climatic conditions found in their natural habitat. The number of day-degrees required for the development from egg to adult emergence was 1428.57 D°, and 117.79 D° for the pre-oviposition period. Thus, N. atlantica can have two generations per year at high altitudes (550 or 800 m) in the Azores.
A laboratory study was carried out to determine the effects and interactions of temperature, host deprivation and adult feeding on the longevity of the parasitoid Venturia canescens (Gravenhorst) (Hymenoptera: Ichneumonidae). The effect of body size was also examined. Large wasps (hind tibia length > 1.96 mm) lived significantly longer than smaller conspecifics (hind tibia length < 1.89 mm). Adults reared at 15°C lived longer regardless of whether supplied with hosts or food. Correspondingly, adults had a shorter life at 30°C. Honey-fed adults lived significantly longer than starved adults at all temperatures and irrespective of host presence, while access to hosts resulted in a decrease in longevity at all temperatures, regardless of food supply. The Weibull distribution was used to describe the age specific survival, which in V. canescens is of "Type I", as the risk of death increases with age. Despite the significant effect of host presence on survival it was less than either temperature or feeding. The interactions between feeding, host presence and temperature proved to be significant. The objective of the study was to improve the effectiveness of V. canescens as a biological control agent of stored product pests.
The relationship between body size and reproduction was investigated for two laboratory strains of Podisus nigrispinus (Dallas). A strain originating from Surinam and maintained for about 15 years under laboratory conditions, did not demonstrate any significant relationship between body length and fecundity. A second strain originated from Brazil where it had been reared in the laboratory for several generations but under different conditions of climate, food and housing. In the first generation of the Brazilian strain, a significant positive relationship was found between body length and total number of eggs. Results suggest that colonization might act initially in favour of a positive body size/fecundity relationship. In contrast, females of the fifth and tenth generations, like those of the Surinamese strain, showed no significant relationship between body length and reproduction. Fecundity of the tenth generation of the Brazilian strain, with an average of 317 eggs per female, was significantly greater than that or the first and fifth generation, with 220 and 243 eggs per female, respectively. The strain from Surinam, with 545 eggs per female, had a markedly higher reproductive capacity than any generation of the Brazilian strain. Adult body weights of different generations of the Brazilian strain increased consistently from the first to the tenth generation, indicating an adaptation to the new environment. Females and males of the Surinamese strain lived longer than those of the Brazilian one. Besides differences related to the geographical origin of the strains, greater fecundity and longevity in long-term laboratory strains of P. nigrispinus may reflect selective adaptation to food and climatic conditions in the laboratory environment.
In the present study the egg dumping behaviour in short (E)- and long (L)-lived lines of the seed beetle Acanthoscelides obtectus was analyzed. Females of the short-lived E line exhibited substantially higher egg dumping than long-lived L line females. We hypothesize that, since cessation of egg dumping enhances longevity, non-dumping females were selectively favoured in the L regime. Our study also produced evidence that the selection regime affected the male's ability to influence female egg-dumping behaviour. The females mated to males from the lines that were selected for extended longevity and of which the females exhibited little egg-dumping dumped fewer eggs. We suggest that in the L selection regime, where offspring produced at the end of the females' reproductive period were recruited to the next generation, selection operated against those males that stimulated female oviposition in the absence of seeds. This is the first study to provide evidence that selection for long-lived insects results in the reduced potency of male seminal products to stimulate female oviposition.