Life cycle and reproductive parameters of Clerada apicicornis signoret (Hemiptera: Lygaeidae) under laboratory conditions

The life cycle of Clerada apicicornis was determined under laboratory conditions. Mean development times in days were: egg 27.2, nymph I 12.5, nymph II 12, nymph III 13.4, nymph IV 16.4, nymph V 26. The life expectancy of adults ranged from 117 to 317 days (mean 196 days). Based on a cohort of 29 females of C. apicicornis, a horizontal life table was constructed. The following predictive parameters were obtained: net rate of reproduction (Ro = 48.31), intrinsic rate of population increase (r(m) = 0.153), generation time (Tc = 28.20 weeks), and finite rate of population increment (lambda = 1.16). The reproductive value (Vx) for each age class of the cohort females was calculated. The following observed parameters were calculated after mortality in each stage: net rate of reproduction (R'o=13.4), intrinsic rate of population increase (r c' =0.09 ), and finite rate of population increment (lambda' =1.1). The generation time (Tc' =27.4) was estimated using the methods of Laughlin and Bengstron. A vertical life table was elaborated and mortality was described for one generation of the cohort.     

New findings on the geographic distribution of the verrucarum group (Diptera: Psychodidae) in Colombia

The incrimination of sand flies belonging to verrucarum species group in the leishmaniasis transmission underscores the need for a detailed information on the geographical distribution of these species. The current listing adds 34 new records that extend significantly the knowledge of the geographical distribution of the verrucarum group in Colombia. The most important new records pertain to Lutzomyia spinicrassa in the tropical dry forest of the Atlantic coast, Lutzomyia ovallesi in the Orinoco and Amazon River watersheds regions of Colombia, and the sympatric occurrence of Lutzomyia spinicrassa and Lutzomyia quasitownsendi in the eastern chain of the Andes mountains. Additionally, the municipal and altitudinal distributions are compiled for 19 new species recorded for Colombia. The series townsendi of the verrucarum group generally restricted to premontane and lower montane zones based on distribution data on Lutzomyia longiflocosa, L. quasitownsendi, Lutzomyia sauroida, L. spinicrassa, Lutzomyia torvida, Lutzomyia townsendi and Lutzomyia youngi. The series verrucarum is distributed from the tropical lowland to the montane zones, and includes species with wide geographical range (Lutzomyia evansi, Lutzomyia columbiana, L. ovallesi, Lutzomyia nuneztovari, Lutzomyia nevesi), and species of highly endemic distribution (Lutzomyia andina, Lutzomyia disiuncta, Lutzomyia moralesi, Lutzomyia antioquiensis). Members of the series pia (Lutzomyia pia, Lutzomyia limafalcaoae) and the series serrana (Lutzomyia serrana) occur from the tropical lowlands to the lower montane zones. The altitudinal divergences may be intrinsically tied to speciation process, especially as it relates to the climatic and geologic events that have affected the flora and fauna of the Andean region.     

Variation in life table characteristics among populations of Phlebotomus papatasi at different altitudes.

Baseline biological growth data were obtained under laboratory conditions for four local populations of the phlebotomine sand fly R papatasi (Scopoli, 1786) (Diptera: Psychodidae) in different eco-regions at altitudes between 368 and 1117 m in the Sanliurfa province of Turkey. The developmental time from egg to adult was found to be significantly different among the populations: 36 days for the AKL population (368 m), 43 days for the HHR population (488 m), 45 days for the HMD population (644 m), and 49 days for the ALT population (1117 m), respectively. Based on cohorts of adults in each population, horizontal life tables were constructed. The average longevity was determined to be in the range of 8.75 +/- 2.39 to 11.60 +/- 3.48 days for adult females, and it was found to be slightly longer for adult males. No significant difference was found in life expectancy at emergence, e(x) when x=1, between females and males in general (P>0.05) in all the populations. While significant differences could be demonstrated among populations for predictive parameters such as net reproductive rate, Ro, and generation time, Tc, no significant differences among the populations were found in terms of intrinsic rate of increase, r(m), finite rate of increase, lambda, birth (b) and death (d) rates (P>0.05). Populations that produced offspring earlier in life also produced more total female offspring, since Tc was negatively correlated with Ro among the populations (r = -0.686, 0.01相似文献   

Comparative demography of the sand fly Phlebotomus papatasi (Diptera: Psychodidae) at constant temperatures.

We measured reproductive and population parameters of adult sand flies, Phlebotomus papatasi (Scopoli, 1786) (Diptera: Psychodidae), in environmental chambers maintained at temperatures of 15, 18, 20, 25, 28, and 32 degrees C. Based on cohorts of adults at each temperature regime, horizontal life tables were constructed using established laboratory colonies initiated from specimens collected in Sanliurfa Province, southeastern Anatolia, Turkey. The fecundity and longevity of the insects were both highly variable, depending on the temperature. At 15 degrees C, all of the cohort females died before laying eggs, so the construction of a life table for this temperature regime was not possible. Within a range of 18 to 32 degrees C, the longevity of adult P. papatasi increased as the temperature decreased; at 15 degrees C, the mean survival times of females and males were 19.04 +/- 6.94 days (9-35) and 17.84 +/- 7.11 days (9-33), respectively. While the highest number of eggs was found in the cohort at 28 degrees C (44.08 +/- 7.79), this was only 3.60 +/- 1.55 in the cohort at 32 degrees C and 2.8 +/- 0.9 in the cohort at 18 degrees C. This result showed that extreme temperatures negatively affect the fecundity of this species. The cohort reared at 28 degrees C exhibited the highest intrinsic rates of population increase (r(m)) for P. papatasi. The r(m) ranged from 0.098 at 28 degrees C to 0.007 at 18 degrees C. The cohort placed at 28 degrees C was found to be significantly different (P < 0.01) from the other cohorts producing the fewest progeny in terms of net reproductive rate, R(0), (15.87). The values for mean generation time (T) were estimated to vary from 36 days to 271 days depending on temperature. Principal Component Analysis (PCA) confirmed results from the previous studies that the cohort at 28 degrees C orientated and clustered as a distinct group along the first two PCs.     

Isolation of Leishmania (Viannia) braziliensis from Lutzomyia spinicrassa (species group Verrucarum) Morales Osorno Mesa, Osorno and Hoyos 1969, in the Venezuelan Andean region

Natural infection with Leishmania spp. in phlebotomine sandflies was searched for during a longitudinal study carried out from July 1997 to July 1998 in the village Catarnica, Municipality Independencia, Táchira State. This hamlet is an old endemic focus of cutaneous leishmaniasis in the Venezuelan Andean region, which lies close to the Colombian border at 1,300 m a.s.l., in an agricultural area mainly used for cultivating coffee. Phlebotomine sandflies were collected using Shannon traps placed in the peridomestic habitat from 19:00 to 21:00 hs. Males were stored in alcohol 70 % while females were kept in Nunc vials with 10 % DMSO and cryopreserved in liquid nitrogen for subsequent dissection and identification. The most abundant anthropophilic species was Lutzomyia spinicrassa with 3,032 males and 4,290 females (85.4%). Among 1,633 (38%) females of Lu. spinicrassa dissected, 26 11.6%) were infected with promastigotes, while no natural infection was found in 209 females of other species. The flagellates were identified as Leishmania braziliensis braziliensis using PCR with species specific primers derived from nuclear DNA and hybridization using species specific probe labelled with digoxigenin. This parasite had been previously isolated from patients with cutaneous leishmaniasis from the same area. These results show Lu. spinicrassa as a new proven vector of Leishmania braziliensis in the Andean region of Venezuela.     

Insecticidal effect on a population of Spilarctia obliqua (Lepidoptera: Arctiidae)

Survivors of Spilarctia obliqua derived from 3^rd instars that had ingested LC₅₀ of imidacloprid (0.025%), dichlorvos (0.014%) and endosulfan (0.012%) were studied through the life table method. Survivorship was reduced in insecticide exposed populations as compared to 45‐day in the control groups. Egg hatching was significantly decreased for the insecticide treated populations. Total larval mortality was the highest for endosulfan (36.76%) as compared to the individuals that died among control groups (14.29%). Life expectancy (e_x) was decreased gradually over time and stage of development for insecticides tested and the control groups. Dichlorvos (0.014%) has caused a significant reduction in the potential fecundity i.e. 315 females/female/generation, while 415 in the unexposed cohorts. Net reproductive rate (R_o) was the lowest in endosulfan (118.47 females/female/generation) treatment followed by dichlorvos (141.97), imidacloprid (144.49) and the control groups (272.42). Similarly, the intrinsic rate of increase (r_m) was substantially decreased after exposure with endosulfan (0.124 females/female/day) as compared to 0.135 in the unexposed cohort. The finite rate of increase (λ) was not significantly different among the insecticide treatments and control groups. Mean generation time was significantly reduced after exposure to dichlorvos (37.19 days). However, 41.34 days were required to complete one generation by S. obliqua in the absence of insecticides. Based on these results, population of S. obliqua would double in 5.19 days under the influence of dichlorvos while requiring 5.13 days for unexposed cohorts.     

Ecology of phlebotomine sand flies (Diptera: Psychodidae) in a focus of Leishmania (Viannia) braziliensis in northeastern Colombia.

The phlebotomine sand fly fauna of two coffee plantations in a Leishmania-endemic area of Norte de Santander, Colombia was studied. Regular insect collections using a variety of methods were made for three and a half years. Information was obtained on diurnal resting sites, host range and seasonal abundance for 17 species, of which five (Lutzomyia spinicrassa, Lu. serrana, Lu. shannoni, Lu. ovallesi and Lu. gomezi) were far more numerous than the others, anthropophilic and present throughout the year. The behaviour of these and the remaining 12 species is discussed in relation to their potential role in transmission of Leishmania (Viannia) braziliensis in the area.     

The natural history of the mud-dauber wasp Sceliphron fistularium (Hymenoptera: Sphecidae) in southeastern Brazil

Nests of Sceliphron fistularium were obtained in Colombia and Moji Gua?u, S?o Paulo, Brazil. Complete nests consisted of 1 to 54 sausage-shaped cells, arranged side by side along a horizontal axis, and found attached to electrical wires (Colombia, n = 7) and walls (Colombia, n = 4 and Moji Gua?u, n = 4). The number of cells per nest ranged from 1 to 54, their length varying from 20.8 to 29.7 mm, and their diameter from 7.6 to 11.7 mm. Brood cells were provisioned with spiders of the family Araneidae. Only Alpaida veniliae was collected in Colombia, whereas the most frequent species found in Moji Gua?u was Micrathena swainsoni (62.0%) followed by M. acuta (23.3%). Adults emerged from June to October. The length and diameter of female and male cells were similar. Nevertheless, females were significantly larger than males. The sex ratio of individuals obtained from nests was 1.16 females: 1 male. A life table was constructed, and details of the life cycle of the wasps and parasitoids are presented. The most common mortality factors were either unknown or due to the parasitoid wasp Melittobia sp.     

Age-dependent fecundity and fertility life tables of the predator Brontocoris tabidus (Heteroptera: Pentatomidae) under field conditions

Reproductive potential, longevity, life expectancy, and fertility life tables of Brontocoris tabidus (Signoret) (Heteroptera: Pentatomidae), a predator of lepidopteran defoliators in eucalyptus (Eucalyptus spp.) plantations, were studied in the field. After a 50-d preoviposition period (emergence of adults to the deposition of the first egg mass), ovipositional activity of B. tabidus continued until females died at 160 d. Females laid an average of 4.2 eggs per day and 601.1 eggs in a lifetime. Gross and net reproductive rates were 216.7 and 75.8 females, respectively. Generation time was 146.1 d, the period for doubling the population was 23.4 d, intrinsic rate was 0.03, and finite population increase was 1.03. Number of females per generation increased at 33.4 times. Results from our field studies indicate that B. tabidus has greater potential reproduction, oviposition period, and longevity than was expected from previous laboratory experiments. This suggests that B. tabidus has potential as a biological control agent to limit economically damaging pests in eucalyptus plantations.     

Geographic differentiation of life table attributes among Anopheles sacharovi (Diptera: Culicidae) populations in Turkey.

Biological data were compared under laboratory conditions for four local populations of the malaria vector, Anopheles sacharovi (Favre, 1903) in different ecological conditions at altitudes between 353 and 1,126 m in the Sanliurfa province of Turkey. No significant differences were found for complete development time from egg to adult among the populations and development times were not correlated with altitude. Based on cohorts of adults in each population, horizontal life tables were constructed. The average longevity was in the range of 15.19 +/- 0.69 to 21.86 +/- 1.04 days for adult females, which was longer than for adult males. No significant difference was found in life expectancy at emergence, e(x) when x = 1, between females and males in general (P > 0.05) in all populations. The net reproductive rate, R(o), was the highest for the SND population, while the rest of the populations showed very low reproductive rates independent of altitudinal effects. Populations that produced offspring earlier in life also produced more total female offspring, since the generation time, T(c), was negatively correlated with R(o) among the populations (r = -0.712, P < 0.05). Important parameters to explain the population growth, the intrinsic rate of increase, r(m) and birth rate, b, were found to be higher in the SND (0.13 and 0.30, respectively). Time required for the population to increase two-fold (doubling time, DT) was also significantly shorter in the SND population. Nineteen parameters in all life stages, both pre-adult and adult features of An. sacharovi, were used as physiological variables and these Operational Taxonomic Units were analyzed using Principal Component Analysis (PCA). Analyses confirmed results from the previous molecular studies that BRC and SND formed a distinct group from the other pair, PMK and GDK, along the first two principal components.     

Laboratory rearing and life history of an emerging grape pest, Xylotrechus arvicola (Coleoptera: Cerambycidae)

Several aspects of the biology of Xylotrechus arvicola (Olivier), an emerging grape pest, were studied under laboratory conditions. Four diets were tested to rear this species in the laboratory. Among them, only one made rearing from larva to adult possible. The highest mortality, in all cases, was recorded during the first days of larval development. Larvae were kept 45 days at 8°C to break diapause in order to reduce the normal field larval developmental time. The species' developmental time was similar between sexes, while pupal developmental time and weight were significantly greater for females than for males. As part of a complementary study, life table parameters of females obtained from the larvae reared on the artificial diet were compared to those of females emerged from field-infested grape root wood. Both laid the majority of eggs in the first two weeks after emergence, and they had a similar pre-laying period. Nevertheless, the females from the diet-reared larvae lived significantly longer, laid eggs over a longer period of time and showed higher fertility than those emerging from infested grape root, suggesting that diet fulfils larval nutritional needs. The species' laboratory-reared population exhibited a low intrinsic growth rate value (rm=0.01) as a result of its long egg-to-adult developmental time and its high larval mortality.     

Population dynamics of a phytophagous lady-beetle,Epilachna vigintioctopunctata (Fabricius), living in spatio-temporally heterogeneous habitats. III. Effects of habitat structure on population dynamics

Temporal changes in the population size of a phytophagous lady-beetle were analyzed to identify mechanisms affecting lady-beetle population dynamics at different spatial scales. The study area (15 ha) included 18 habitat patches. The major host plants were potato for first generation larvae and eggplant for second generation larvae. The habitat patches were classified into three groups according to the major host plants in each patch: P-E patches (both host plants available), P patches (potato only), and E patches (eggplant only). The winter disappearance of adults in the whole study area, and larval mortality in E patches were apparently the most important factors disturbing the overall population density. Density-dependent movement of females appeared to have the greatest stabilizing effect on the yearly fluctuation of population density. Rate of increase of female adults from the first to the second generation,R, was generally higher on eggplants in E patches than in P-E patches because the adult density of the first generation was much higher in P-E patches. The yearly fluctuation of adult density in each generation tended to be less in patches with all habitat components necessary for the full life cycle (P-E patches). However, such patches were not favorable for first generation females, as indicated by the lower rate of increase from the first to the second generation. The density and stability of lady-beetle populations is discussed in relation to habitat structure.     

萼花臂尾轮虫种复合体内三个姐妹种生活史特征的比较研究

应用生命表统计学方法,在13℃、18℃、23℃和28℃下对采自芜湖市莲塘湖和荷花塘水体中的萼花臂尾轮虫三个姐妹种HE1、HE3和LE9的生活史特征进行了比较研究。结果表明,三个姐妹种生命表参数间的差异因温度的不同而异。13℃下,姐妹种LE9的生命期望、平均寿命和世代时间都显著长于姐妹种HE3,LE9的净生殖率和种群内禀增长率均最大,三个姐妹种所产后代中的混交雌体百分率无显著的差异。18℃下,姐妹种LE9的生命期望和平均寿命显著长于姐妹种HE3,姐妹种LE9的世代时间显著长于姐妹种HE1和HE3,姐妹种 HE3的种群内禀增长率显著高于姐妹种LE9,姐妹种HE3所产后代中的混交雌体百分率最高,三个姐妹种的净生殖率无显著的差异。23℃下,姐妹种HE1的生命期望、平均寿命和世代时间均最长,姐妹种HE1所产后代中的混交雌体百分率显著低于HE3,三个姐妹种的净生殖率和种群内禀增长率均无显著的差异。28℃下,三个姐妹种的生命期望、平均寿命、世代时间和种群内禀增长率均无显著的差异;姐妹种HE1的净生殖率最低;姐妹种HE3所产后代中的混交雌体百分率最高。三个姐妹种的生命表参数对升高的温度的响应也不相同。温度、姐妹种及两者间的交互作用对轮虫的世代时间、平均寿命、出生时的生命期望和轮虫所产后代中的混交雌体百分率均有显著的影响;温度和姐妹种对轮虫的净生殖率和种群内禀增长率均有极显著影响,但两者的交互作用对其无显著性影响。     

Impact of inter‐ and intra‐specific competition among larvae on larval,adult, and life‐table traits of Aedes aegypti and Aedes albopictus females

1. Few studies have taken a comprehensive approach of measuring the impact of inter‐ and intra‐specific larval competition on adult mosquito traits. In this study, the impact of competition among Aedes aegypti (L.) and A. albopictus (Skuse) was quantified over the entire life of a cohort. 2. Competitive treatments affected hatch‐to‐adult survivorship and the development time to adulthood of females for both species but affected the median wing length of females only for A. albopictus. Competitive treatments had no significant effect on the median adult female longevity nor were there any effects on other individual traits related to blood feeding and reproductive success. 3. Analysis of life table traits revealed no effect of competitive treatment on the net reproductive rate (R₀) but there were significant effects on the cohort generation time (T_c) and the cohort rate of increase (r) for both species. 4. Inter‐ and intra‐specific competition among Aedes larvae may produce individual and population‐level effects that are manifest in adults; however, benign conditions may enable resulting adults to compensate for some impacts of competition, particularly those affecting blood‐feeding success, fecundity, and the net reproductive rate, R₀. The effect of competition, therefore, affects primarily larva‐to‐adult survivorship and the larval development time, which in turn impacts the cohort generation time, T_c, and ultimately the cohort rate of increase, r. 5. The lack of effects of the larval rearing environment on adult longevity suggests that effects on vectorial capacity owing to longevity may be limited if adults have easy access to sugar and bloodmeals.     

Life table studies on the paddy field population of the green rice leafhopper,Nephotettix cincticeps Uhler (Hemiptera: Cicadellidae), with special reference to the mechanism of population regulation

The population growth of the green rice leafhopper, Nephotettix cincticeps, in the paddy field was analyzed based on the life table data accumulated for six years. The paddy field population, which stems from the invading adults of the first generation (G-I), repeats two complete generations, and the hatchlings of the fourth generation (G-IV) enter diapause and overwinter as the fourth instar nymphs in fallow paddy fields. It was clarified that the density dependent reduction in the mean longevity and oviposition rate of adult females in G-II and III played a primary role in stabilizing the annual population densities. The annual average of the mean longevity of G-II females (3.9 days) was much shorter than that of G-III ones (7.7 days) and thus the density dependent reduction in the mean longevity induced a more prompt regulatory effect on the oviposition of G-II females compared with G-III ones. As the result, two equilibrium densities of eggs were obtained, e.g., ca 100 and 700 eggs per hill in G-III and IV, respectively. Density dependent decrease in the proportion of mature females in the adult population was especially conspicuous in G-II, and this was closely associated with the density dependent reduction in the mean longevity and fecundity. Thus, the density dependent dispersal (emigration) of the adult females by flight in G-II and III was the most convincing factor in the process of population regulation. The density dependent dispersal of the adult females is effective in avoiding the deleterious effects of nymphal crowding in a breeding habitat unit (a paddy field), and may result in a more even distribution of the population over a continuous habitat units in a locality than otherwise.     

Biological studies on Trichogrammatoidea bactrae Nagaraja (Hymenoptera: Trichogrammatidae), egg parasitoid of Tuta absoluta Meyrick (Lepidoptera: Gelechiidae)

The tomato moth, Tuta absoluta Meyrick, is one of the most important tomato pests in South America. In Argentina, management strategies include only chemical control. In this work, the parasitoid wasp Trichogrammatoidea bactrae Nagaraja was evaluated as a potential natural enemy against this pest. Biological and population parameters were estimated by developing a life table under laboratory conditions at 25 ± 1oC, 14:10 photoperiod and 60 ± 10% RH. Three cohorts of 26-30 T. bactrae females each were placed with one of the three following treatments: 1 - Sitotroga cerealella (Olivier) eggs on a piece of cardboard; 2 - S. cerealella eggs on a piece of tomato leaf, and 3- T. absoluta eggs on a piece on tomato leaf. The following parameters were estimated for each cohort: survival (egg to adult), longevity, fecundity and oviposition period of females, sex proportion of the F1, net rate of reproduction (Ro), mean generation time (T) and intrinsic rate of population increase (r m). Survival of the T. bactrae immatures was higher than 90% on both, S. cerealella and T. absoluta eggs. The female survival curves corresponded to type III and showed no significant differences among treatments. The three cohorts did not show significant differences between sex ratio, female longevity, oviposition period, fecundity and the population parameters studied. These results indicate that T. bactrae would be a potential biological control agent of T. absoluta.     

Fertility life table of Aphidius colemani Viereck (Hymenoptera: Braconidae, Aphidiinae) on Aphis gossypii Glover (Hemiptera: Aphididae)

The intrinsic rate of increase of a parasitoid related to its hosts play an important role in biological control programs. In this work, fertility of the parasitoid Aphidius colemani Viereck was evaluated on Aphis gossypii Glover by means of a fertility life table. To determine the immature mortality, the development time and the sex ratio, 12 mated females of A. colemani (24h old), and 240 nymphs of A. gossypii (3 days old) were used. To evaluate fertility 15 mated females (24h old) were used. For each parasitoid female, 300 nymphs were offered in the 1st day, 250 nymphs in the 2nd day, 200 nymphs in the 3rd day, 150 nymphs in the 4th day, 100 nymphs in the 5th day and 50 nymphs in the other days. Immature mortality of A. colemani was 22.1%, development time of males and females were 12.0 and 11.8 days, respectively, and sex ratio was 0.6. The females of A. colemani laid 420 eggs and had longevity of 5.9 days. The net reproduction rate (R(o)) was 194.81 females and the intrinsic rate of increase (r(m)) was 0.384 females/females/day. The finite rate of increase (lambda) was 1.48 females/day, the mean length of a generation (T) was 13.74 days and the time to duplication the population (TD) was 12.60 days. The parasitoid A. colemani had a great potential of population growth on A. gossypii as a host and could be an effective biological control agent of this aphid.     

Population expansion of the poultry fluff louse, Goniocotes gallinae (De Geer, 1778) (Ischnocera, Phthiraptera)

A study was undertaken to determine the rate of population expansion of an ischnoceran Phthiraptera, Goniocotes gallinae (infesting the domestic fowl, Gallus gallus domesticus), on the basis of in vitro and in vivo studies. Data obtained from in vitro rearing were utilized to construct the life history of the louse. The values of the gross reproductive rate (12.49 female eggs/female), net reproductive rate (8.31 female eggs/female), mean length of generation (36.91 days), precise generation time (35.65 days), finite rate of increase (1.06 female/days), and intrinsic rate of natural increase (0.059) of G. gallinae were determined. However, doubling-time values recorded during in vivo studies (14 days) was comparatively higher than those during in vitro rearing (11.73 days).     

An empirical estimate of the generation time of mouse lemurs

The generation time of organisms drives the rate of change in populations and across evolutionary times. In long‐lived species, generation time should also account for overlapping generations, and the average age of parents has been proposed as a best approximation under these conditions. This study uses this definition to estimate the generation time of a widely studied small primate, Microcebus murinus, based on parentage data generated for a free‐living population over a 6‐year period in northwestern Madagascar. The average age of parents was calculated separately for mothers and fathers of three different offspring cohorts that differed in the degree of demographic uncertainty. In addition, adult survival rates were calculated for males and females based on long‐term capture data from the same population to estimate the possible upper limits of generation time. Adult survival was low with only 44% of adult females and 38% of adult males being recaptured at the beginning of their second breeding season. The average age of mothers was 1.56–1.91 years, pointing toward a 2‐year female generation time due to the high proportion of 1‐year old mothers in all three cohorts. Female generation time estimates were fairly stable across the three offspring cohorts. In contrast, the average age of fathers differed by more than 1 year from the first to the third offspring cohort (1.71–2.83 years) pointing toward a 3‐year generation time, but also suggesting a higher degree of demographic uncertainty in the early years of the study. For future modeling purposes, we, therefore, propose to use the average, 2.5 years, of male and female values as new estimate for the generation time of mouse lemurs.     

Growth and fecundity of Daphnia after diapause and their impact on the development of a population

Laboratory and field investigations revealed that the life history traits of exephippial and parthenogenetic generations of Daphnia differ substantially. Daphniids hatching from resting eggs grow faster and their definitive body sizes are bigger than of hatchlings from subitaneous eggs. Size at maturity for exephippial animals is significantly larger. In spite of this, they mature a few days earlier than parthenogenetic females. In this study, the difference was 3–4 days for the laboratory experiments and 1–3 days for the field. Fecundity of the exephippial generation is markedly higher. Here, the clutch size for this generation was up to 3.5–4.0 times as large as for the parthenogenetic generation. Moreover, obtained results suggest that the relationship between clutch size and body length for both generations differ significantly.Estimates of the intrinsic rate of increase for field Daphnia populations demonstrated that life history traits of exephippial animals lead to a two or threefold higher rate of increase in the conditions of invertebrate predation pressure. Under moderate fish pressure, obtained r values for the daphniids hatching from resting eggs were larger than those from subitaneous. High growth rate of exephippial females is disadvantageous only under the conditions of severe pressure by fish. Obtained results suggest that hatchlings from diapausing eggs an acceleration of population increase by several times during the beginning of the development of a population with periodical re-establishment from resting eggs.