Fertility Table Research Articles

Fertility Table and Thermal Requirements for the Development of Callosobruchus maculatus (F) Reared on Different Legume Seeds

Fertility Table and Thermal Requirements for the Development of Callosobruchus maculatus (F) Reared on Different Legume Seeds

Biology, predatory potential and growth parameters of the syrphid fly, Scaeva pyrastri (L.) (Diptera: Syrphidae) feeding on the cabbage aphid, Brevicoryne brassicae (L.)

BackgroundScaeva pyrastri (L.) (Diptera: Syrphidae) is a large-size Palaearctic region syrphid fly. The larval stage of S. pyrastri is aphidophagous in nature, while the adults are efficient pollinators of various crops. Therefore, this study was carried out to investigate the predation efficacy, biology and population growth parameters of S. pyrastri on the cabbage aphid, Brevicoryne brassicae (L.) (Hemiptera: Aphididae) as prey using age–stage-specific two-sex fertility table.ResultsThe results showed that the mean total larval development duration was 8.31 days and the pre-adult stage was 19.82 ± 0.25 days long. In the adult stage, the mean longevity of female (18.57 ± 0.37 days) was longer than that of the male (15.50 ± 0.17 days). The adult pre-ovipositional, ovipositional and post-ovipositional periods were 4.25 ± 0.25, 8.50 ± 0.46 and 3.25 ± 0.31 days, respectively, and the mean female’s fecundity was 37.75 ± 1.16 eggs per female. The two-sex fertility table indicated that the age-specific fecundity (mx) increased gradually peaking at the 27th day of pivotal age (2.71 eggs per day) and decreased thereafter. The life expectancy of female was observed on the 18th (20.25 days) and 19th day (16.44 days) in the female and male flies, respectively. The female attained the maximum reproductive value (vxj) on the 25th day, which was 26.05 eggs needed to produce one individual. The population growth parameters indicated that the population had a net reproduction rate of 15.10 ± 4.19 offspring per individual and a true generation time of 28.86 ± 0.28 days. The intrinsic rate of increase was greater than zero (0.093 ± 0.011) and the finite rate of increase (λ) was greater than one (1.098 ± 0.012), which indicated that B. brassicae was the suitable prey for S. pyrastri. The values related to the number of aphids consumed by the larvae were: a net predation rate (Co) of 377.06 ± 26.54 nymphs and finite predation rate (ω) of 19.58 ± 0.78.ConclusionsScaeva pyrastri had a considerable predatory potential and fitted well for the biological control of aphids, especially B. brassicae. However the field potential is still unknown; thus, this study will be helpful in determining the field efficacy of S. pyrastri against B. brassicae.

A comparative study of unmet information needs of patients with lymphoma and CLL: North America and Europe.

12135 Background: Informed patients are consistently associated with better outcomes and overall patient experiences. However, there are still unknowns about the information needs of patients. This study uses the Lymphoma Coalition (LC) 2020 Global Patient Survey (GPS) on Lymphomas and CLL to describe the differences in the unmet information needs among patients with lymphoma and CLL in North America and Europe. Methods: Globally, 9,179 patients from 90+ countries took part in the LC 2020 GPS. The countries were grouped into regions, and the North American (NA) (n=1543) and European (EU) (n=4343) regions were used for this analysis (Table). The demographics of the regions were examined, and univariate, bivariate and multivariate analyses of questions relating to patients’ information needs, were performed in IBM SPSS v27. Results: When compared, the regions differed significantly in patients’ age distribution, lymphoma subtype, highest educational level completed, and area of residence. The top three areas of unmet information need for patients with lymphoma and CLL in both regions were: diagnosis and what it means, treatment options, and side effects from treatment. Compared to patients in the EU, patients in NA were 27% more likely to need more information about treatment options, 51% more likely to need more information about support for self-care, and 18% less likely to need more information about their diagnosis and what it means. These differences were statistically significant (Table). Patients from NA were 26% more likely to report that they had no informational needs compared to patients from EU (p=0.02) (Table). There was no significant difference between patients in both regions in their need for more information in the following areas: psychological support, support for their families, side effects from treatment and fertility (Table). Conclusions: Regardless of region, patients with lymphoma need more information about certain areas of their care than is currently provided. LC advocates for increased access to appropriate and adequate medical information for patients, and that this information be contextualized to the patient’s needs.[Table: see text]

Host utilization, reproductive biology, and development of the larval parasitoid Tetrastichus planipennisi as influenced by temperature: Implications for biological control of the emerald ash borer in North America

The success of classical biological control programs depends in part on understanding climate effects on introduced agents. Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae), a larval endoparasitoid of emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is being introduced to EAB-invaded regions of the United States (USA) and Canada for biological control. To optimize regional release strategies and increase efficiency of the EAB-biocontrol program, we determined the effects of five constant temperatures from 15 °C to 35 °C on T. planipennisi parasitism rate, development, adult longevity, and fecundity in EAB. Results showed a decrease in parasitoid development time from 139.8 days at 15 °C to 26.3 days at 30 °C, while no parasitoid eggs hatched at 35 °C. Parasitism rates, provisioned with an excess of host larvae throughout their life, increased from 1.4% at 15 °C to 28% at 30 °C then declined to 0.5% at 35 °C. Adult parasitoid longevity declined from 24 weeks at 15 °C to <2 weeks at 35 °C. Fertility table analyses revealed T. planipennisi net reproductive rate was highest at 25 °C, and intrinsic and finite rates of increase were highest at 30 °C, suggesting 25–30 °C as optimal rearing temperatures for this parasitoid. Combining these results with temperature data from climate zones of 3–7 in the USA, we predicted T. planipennisi can complete more than one generation in all locations in these climatic zones, with more generations in warmer climates. Moreover, our findings also suggest that despite the availability of suitable EAB larval stages for parasitism, releases of T. planipennisi in early spring or late fall in cold climate zones may be suboptimal due to low temperatures, as may mid-summer releases in hot climate zones due to high temperatures.

Non‐targeted insecticidal stress in a pest species: insecticides, sexual fitness and hormesis in the Neotropical brown stink bug Euschistus heros

AbstractAn understudied aspect of insecticides is their stress on non‐targeted pest species. Sublethal insecticidal stress may elicit a range of protective and non‐protective responses that may affect behaviour and sexual fitness of the exposed insects, which may lead to negative, neutral or stimulatory (i.e. hormetic) responses. We assessed the behavioural response of the Neotropical brown stink bug, Euschistus heros, a soybean pest in the Neotropical region with increasing pest status, following exposure to chlorantraniliprole, pyriproxyfen and spinosad, insecticides commonly used against soybean caterpillars and whiteflies. Both individuals, or only the male or female of each mating pair, were exposed. Reproductive behaviour and output were measured to determine insecticide‐ and gender‐mediated fitness. We found that treatment scenario significantly affected mating behaviour, and that the duration of some behaviours were significantly affected. Chlorantraniliprole and pyriproxyfen reduced latency to mate, while spinosad increased this behaviour. Insecticide exposure also decreased the interacting time of each couple and male antennation of the female. Fertility table analyses of exposed couples indicated negligible effect of pyriproxyfen exposure, while spinosad extended generation time and reduced net reproductive rate, leading to lower rates of population growth of the brown stink bug. In contrast, chlorantraniliprole led to only a slight extension on the generation time, but enhanced net reproductive rate of the stink bug leading to higher rates of population growth; no effects on sexual fitness were observed, as both compounds exhibited similar effect on females and males. Latency to mate correlated significantly with the population growth rate. The positive response to chlorantraniliprole exposure reinforces the notion that sublethal exposure of the brown stink bug to this insecticide may lead to stimulatory (hormetic) response favouring its outbreaks in soybean fields.

Effect of constant temperature regimes on the biological parameters of an anthocorid predator Orius tantillus (Motsch)

Experiments were conducted to investigate the effect of different temperature regimes (16, 20, 24, 28, 32 and 36±1 ° C) on the biological and fertility table parameters of Orius tantillus (Motsch.), an efficient indigenous predator of various thrips species in India Temperature influenced the development and reproduction of O. tantillus . Based on the biological parameters, viz. longevity, fecundity and fertility parameters, 24 ° C was recorded to be the optimum temperature for rearing O. tantillus . The temperature of 16 ° C had a detrimental effect on nymphal survival, while 36 ° C on fecundity. Thus, 16 and 36 ° C were recorded as unsuitable for rearing O. tantillus . The lower threshold temperatures for development of eggs and nymphs of O. tantillus were 8.66 and 6.92 ° C, respectively, indicating that the eggs are more heat-sensitive than the nymphs. Based on the T 0 values, O. tantillus appears to be less heat sensitive in comparison to other Orius spp. The information generated through this study could be used for further improving the standardized production protocol for O. tantillus and also for planning and timing field releases to target thrips species.

Temperature-Dependent Biological and Demographic Parameters of Coleomegilla maculata (Coleoptera: Coccinellidae).

Knowledge of the most suitable environmental conditions for an organism growth and development is a prerequisite for developing mass rearing technology. The temperature requirements for development and the optimal range of temperatures for growth and reproduction of Coleomegilla maculata De Geer were studied. The development time of individual C. maculata larvae was determined at 18, 21, 24, 27, 30, 33, and 36 °C. Development times were converted to development rates and fitted to a nonlinear temperature-dependent model and to the linear day-degree model. Life and fertility table analysis was used to determine the optimal temperature for population growth within a range of favorable temperatures including 24, 25, 26, 27, and 28 °C. Nonlinear estimates of thermal maximum (TM) for the postembryonic development of C. maculata was 35.09 ± 10.35 °C. Estimation of TM based on pupal development was much lower at 27.23 ± 1.52 °C. Linear and nonlinear estimates of low temperature development threshold were 13.13 ± and 4.77 ± 3.03 °C for the whole postembryonic development and 10.95 and 9.18 ± 1.36 °C for the pupal stage alone, respectively. The most favorable temperature for population growth was 25 °C, where C. maculata showed significantly higher intrinsic rate of increase (rm = 0.066) and significantly lower doubling time (10.57 d) than the other favorable temperatures tested. A negative value of rm was obtained at 28 °C, indicating population decline occurring at this temperature making it unfavorable for C. maculata.

Biology ofDoryctobracon brasiliensisat different temperatures: development of life table and determining thermal requirements

Doryctobracon brasiliensis (Szepligeti) is a parasitoid larval–pupal of fruit flies and has great potential to be used in biological control programmes as it feeds on other Anastrepha species in addition to Anastrepha fraterculus (Wiedemann). This study investigated the biology of D. brasiliensis at different temperatures to design a life fertility table and determine thermal requirements. The parasitoids were multiplied in larvae of A. fraterculus in air-conditioned chambers at 15, 18, 20, 22, 25, 28 and 30°C, 70 ± 20% RH and photophase of 12 h. We determined the number of offspring, sex ratio, longevity of males and females and duration of egg–adult period. The temperature range 18–22°C ensures higher fecundity and at 20°C, and the average number of offspring per female was 152.77 parasitoids. The sex ratio of offspring produced was reduced with increasing temperatures. Longevity of males and females of D. brasiliensis was reduced by increasing temperatures. At 15, 28 and 30°C, there was no development of immature stages. For the temperature range 18–25°C, the duration of egg–adult period of D. brasiliensis was inversely proportional to temperature. At 20 and 22°C, we observed the highest values of net reproduction rate (Ro) and finite reason of increase (λ), meaning that at the estimated optimum temperature (21°C), the population of D. brasiliensis increased 47 times each generation. The lower temperature threshold for development was 10.01°C and the thermal constant (K) 303.21 degree/days. This information confirms that D. brasiliensis is better suited to temperate environments, which implies a significant potential for the use of D. brasiliensis in the control of A. fraterculus, because most areas occupied by this pest are in temperate regions. In addition, D. brasiliensis is useful in mass rearing systems in laboratory.

Temperature-Dependent Fecundity and Life Table of the Fennel Aphid Hyadaphis foeniculi (Passerini) (Hemiptera: Aphididae).

Hyadaphis foeniculi (Passerini) (Hemiptera: Aphididae) is a cosmopolitan species and the main pest of fennel in northeastern Brazil. Understanding the relationship between temperature variations and the population growth rates of H. foeniculi is essential to predict the population dynamics of this aphid in the fennel crop. The aim of this study was to measure the effect of constant temperature on the adult prereproductive period and the life table fertility parameters (infinitesimal increase ratio (rm), gross reproduction rate (GRR), net reproduction rate (R0), finite increase ratio (λ), generation time (GT), the time required for the population to double in the number of individuals (DT), and the reproduction value (RVx)) of the fennel pest H. foeniculi. The values of lx (survival of nymphs at age x) increased as the temperature rose from 15 to 28°C and fell at 30°C, whereas mx (number of nymphs produced by each nymph of age x) increased from 15 to 25°C and fell at 28 and 30°C. The net reproduction rates (R0) of populations of H. foeniculi increased with temperature and ranged from 1.9 at 15°C to 12.23 at 28°C for each generation. The highest population increase occurred with the apterous aphids at 28°C. The rate of population increase per unit time (rm) (day) ranged from 0.0033 (15°C) to 0.1995 (28°C). The highest values of rm were recorded at temperatures of 28°C and 30°C. The rm values were a good fit to the models tested, with R2 > 0.91 and R2 adj > 0.88. The models tested (Davidson, Sharpe and DeMichele modified by Schoolfield et al., Logan et al., Lamb, and Briere et al.) were very good fits for the rm values observed, with R2 > 0.91 and R2 adj > 0.88. The only exception was the Davidson model. Of the parameters studied, the reproductive capacity was higher in the apterous aphids, with the unique exception of daily fecundity at 28°C, which was higher in the alate aphids of H. foeniculi. Parameters relating to the age-specific fertility table for H. foeniculi were heavily influenced by temperature, with the highest biotic potential and population growth capacity found at 34°C. Therefore, the results obtained in this study could be of practical significance for predicting outbreaks of fennel aphids and improving the management of this aphid in fennel crops.

Biologia e tabela de vida de fertilidade de Diabrotica speciosa (Col.: Chrysomelidae) em dieta natural

A vaquinha Diabrotica speciosa é uma importante praga em diversas culturas. O objetivo deste trabalho foi estudar a biologia de adultos de D. speciosa e construir a tabela de vida de fertilidade em dieta natural à base de feijão, e à base de feijão, rodelas de cenoura e solução de mel a 10%. Os parâmetros biológicos avaliados foram: duração dos períodos de pré-oviposição, oviposição e pós-oviposição, fecundidade total, longevidade de adultos e viabilidade dos ovos. Para a tabela de vida de fertilidade, os parâmetros determinados foram: intervalo entre gerações (T), taxa líquida de reprodução (Ro), taxa intrínseca de crescimento (rm) e taxa finita de aumento (λ). A partir dos resultados obtidos, pode-se constatar que houve influência do alimento oferecido aos adultos para os períodos de pré-oviposição e oviposição, e também na fecundidade total e na viabilidade dos ovos. A longevidade dos adultos foi influenciada pela dieta constituída de folíolos de feijão. A dieta constituída de feijão, cenoura e mel propiciou maior longevidade significativa dos machos em relação àqueles alimentados com feijão. Os resultados da tabela de fertilidade indicaram que o potencial de reprodução de D. speciosa aumenta significativamente em duas gerações sucessivas quando as fêmeas são alimentadas com feijão, cenoura e mel, demonstrando que há melhoria na criação massal desse inseto em condições de laboratório.

Biology and life table of Dirphia araucariae (Lepidoptera: Saturniidae): A herbivore of potentially high impact on Araucaria angustifolia

The life-history and biology of Dirphia araucariae Jones, 1908, including its life fertility table, are here described. Moths were reared in the laboratory under controlled conditions on their host plant, Araucaria angustifolia (Bertoloni) O. Kuntze - Araucariaceae. We describe several life-history traits of the species, namely: developmental period, survival rate, growth rate, fertility, fecundity, sex ratio, cephalic capsule width, and pupal weight. Mean duration of life stages were: egg = 26.78 days; larva = 61.78 days; prepupa = 6.85 days; pupa = 62.46 days; adult = 8.37 days. We found statistically significant differences between sexes for adult, larval and pupal stage duration; larval stage was longer in females while pupal stage was longer in males. The survival rate of each life stage was: egg = 96.18%; larva = 95.38%; prepupa = 83.87%; pupa = 100%. The larvae developed through six instars and the mean growth rate was 1.418. The width of male and female cephalic capsules were different in last three instars, even though the total mean width between sexes was not different. Pupal mean weight ranged from 2.40 g to 4.79 g, with females being heavier than males. Fertility ranged from 66.78% to 100%, and the total fecundity was 358.45 eggs/female, including both laid eggs and eggs held in the abdomen. The sex ratio was 0.50 ± 0.05. The estimated biotic potential was 48731.08 specimens/female/year. We found the following values for the fertility life table: (Ro) = 117.21 females; (T) = 162.75 days; (r m) = 0.21; (l) = 1.23. Considering the biological parameters evaluated in this study, we conclude that D. araucariae is not able to cause primary damage in A. angustifolia forests, although further studies are needed to understand the reasons for occasional population outbreaks.

Leaf characteristics, wood anatomy and hydraulic properties in tree species from contrasting habitats within upper Rio Negro forests in the Amazon region

Abstract:Leaf blade physical and chemical characteristics, wood composition and anatomy, as well as long-term water-use efficiency and hydraulic characteristics of leaf-bearing terminal branches were assessed in tree species growing in contrasting forests of the Venezuelan Amazonas: mixed forest on oxisol soil and caatinga on podzol soil. Two upper-canopy tree species were selected in each forest, and three individuals per species were tagged for sampling. Leaf nitrogen isotopic signatures (δ15N) were negative and species-specific, which suggests that in species of both forest the N-cycle is closed, and that tree species can withdraw N from a variety of N-pools. Leaf construction costs, dry mass to leaf area ratio, thickness and sclerophylly index tended to increase in microhabitats with lower fertility and large water table fluctuations. The hydraulic characteristics and long-term water use are species-specific and related to the particular conditions of the habitat at the local scale. Ocotea aciphylla (mixed forest) with a combination of low δ13C and high hydraulic sufficiency may maintain high water loss without risk of xylem embolisms. By contrast, Micranda sprucei (slopes of the caatinga forest), had a combination of relatively high hydraulic sufficiency and the highest long-term water-use efficiency, which suggest that embolism risk would be avoided by water loss restriction. Assuming a warmer and drier climate in the future, the species with more conservative water transport and/or better stomatal control would be at lower risk of mortality.

Fertility life table of Trichogramma pretiosum and Trichogramma acacioi on eggs of Anagasta kuehniella at different temperatures

Species of the Trichogramma genus are among the most important ones for biological control. The objective of this research was to evaluate parasitism potential of two species of Trichogramma on eggs of Anagasta kuheniella through life fertility table, at temperatures between 15ºC and 35ºC. These species were collected in the State of Espírito Santo parasitising eggs of the avocado defoliator Nipteria panacea. Trichogramma pretiosum and T. acacioi showed adequate reproductive potential between 15ºC and 35ºC which indicates possibilities of using them in biological control programs in avocado plantations.

Life history and cost analysis for continuous rearing of Podisus maculiventris (Say) (Heteroptera: Pentatomidae) on a zoophytophagous artificial diet.

The impact of a zoophytophagous, insect-free artificial diet upon the developmental rate, life table parameters, and fertility table parameters was examined over 11 consecutive generations for domesticated and wild colonies of Podisus maculiventris (Say) (Heteroptera: Pentatomidae). This study showed that the developmental time, preoviposition period, fecundity, and nymphal survival improved in the domestic colony when fed an insect-free artificial diet for 11 consecutive generations, but remained relatively constant for the wild colony, as did reproductive rate and intrinsic rate of increase. Although, after 11 generations of adaptation to an artificial diet feeding regime, all reproductive and fertility table parameters were still significantly lower than when fed on T. ni larvae as the natural prey, the realized cost of rearing either colony on the artificial diet approached 1.2 times the cost of rearing these insects on a natural prey. This is a significant achievement in the effort to develop cost-effective artificial diets for the mass-rearing of beneficial pentatomids, and has positive implications for the use of one artificial diet to efficiently rear several beneficial insects.

Life table parameters, reproductive rate, intrinsic rate of increase, and estimated cost of rearing Podisus maculiventris (Heteroptera: Pentatomidae) on an artificial diet.

The impact of an insect-free artificial diet provided at nymphal and/or adult stage upon the developmental rate, life table parameters, and fertility table parameters was examined for Podisus maculiventris (Say). This study showed that when fed an insect-free artificial diet during both the nymphal and adult stage, developmental time was prolonged, preoviposition period was extended, and reproductive rate (R0) and intrinsic rate of increase (r) were significantly lower than when fed larval insect prey at both nymphal and adult stages. Additionally, feeding larval prey to adults reared as nymphs on an artificial diet significantly increased the proportion of fertile females, the number of eggs laid by mated females, the reproductive rate and intrinsic rate of increase, but the mean generation time was not significantly different. Likewise, feeding artificial diet to adults reared on larval prey resulted in a significant reduction in reproductive rate and intrinsic rate of increase. The "realized" cost to rear P. maculiventris on the artificial diet was calculated (as the cost to double the population size) using raw material cost, fertility table parameters and doubling time values. Raw material cost for rearing P. maculiventris colony on Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae) was only 1.4 times higher than the cost of artificial diet raw materials required to rear the same size colony. However, the realized cost of rearing was 3.5 times higher when rearing on artificial diet because of the prolonged developmental time and reduced reproductive output. The cost efficiency of rearing a beneficial insect on an artificial diet that decreases the intrinsic rate of increase of a colony is discussed, as well as the advantages and disadvantages of supplementing adult diets with natural prey at the reproductive stage.

Selection of Azolla forms resistant to the water lily aphid, Rhopalosiphum nymphaeaeLife history of Rhopalosiphum nymphaeae

AbstractThe water lily aphid Rhopalosiphum nymphaeae (L.) (Homoptera: Aphididae) is one of the potential pests of the genus Azolla Lam., an agronomically important aquatic fern used as green manure and as fodder. In this paper its life and fertility table was established by observing 70 virginoparous females individually from birth to death on Azolla microphylla Kaulf. under constant abiotic conditions. A rather short average development time of 6.1 days was observed. The maximum length of survival recorded was 24 days, and a linear relationship was found between age and survival. The fecundity averaged 36.8 larvae/female, but this appeared to be an age‐specific parameter. Life table computation showed a high intrinsic rate of increase (0.315 days−1), meaning that theoretical populations could double every 2.2 days.RésuméLes fougères aquatiques du genre Azolla présentent un grand intérêt en agriculture tropicale et subtropicale, comme engrais vert et comme source de nourriture. Le puceron Rhopalosiphum nymphaeae (L.) est un des insectes déprédateurs susceptibles d'affecter considérablement la productivité d'Azolla Lam.Le but de cette étude était de déterminer les paramètres démographiques et d'établir la table de survie de R. nymphaeae. Pour ce faire, 70 femelles virginopares ont été observées depuis leur naissance jusqu'à leur mort sur Azolla microphylla (souche 69 MI).Le temps de développement moyen enregistré est de 6,1 jour. La survie maximum est de 24 jours et une relation linéaire entre l'âge et le taux de survie a été mise en évidence. La fécondité moyenne totalise 36,8 larves par femelle mais la fécondité journalière montre une évolution clairement âge‐spécifique. Le calcul des paramètres de la table de survie a mis en évidence le haut taux d'accroissement intrinsèque (0,315 par jours), ce qui signifie qu'une population dont la distribution d'âge serait constante dans le temps verrait son effectif doubler tous les 2,2 jours.

Drop-out behaviour and fertility table analysis of pregnancy rates

The life table analysis of infertility study data uses information from patients who drop out and are lost to follow-up. The fact that drop-out patients were not pregnant when last seen has been taken to be useful information that has been entered into the calculation of cumulative pregnancy rates for the population as a whole. However, drop-out patients who subsequently achieve pregnancy have motivations to return to their physician for follow-up, while those who do not become pregnant usually remain lost to follow-up. This can result in a systematic error toward reporting an excess of pregnancies, raising the apparent fecundity rates and plateau values. This study was undertaken to investigate the potential magnitude of these errors. Computer simulations of hypothetical infertility treatments using large cohorts (n = 32 000) were undertaken. Varying assumptions were made regarding post-treatment monthly fecundity rates, 'cure rates', drop-out rates and the percentage of pregnant drop-outs who would return to their physician after achieving pregnancy. Using a range of clinically reasonable assumptions, very large deviations from ideal behaviour were noted in the direction of elevated cumulative pregnancy rates. The non-ideal behaviour was most apparent with lower fecundity rates, lower 'cure rates', higher drop-out rates and higher pregnant drop-out return rates. A change in the method of data collection to minimize the impact of this bias in infertility studies is proposed. This method of active data collection is a departure from that used in classical life table studies and therefore the method is titled the 'fertility table method' in order to avoid confusion.

Recent advances in biosystematics ofTrichogramma andTrichogrammatoidea (Hymenoptera, Trichogrammatidae)

Among the egg parasites used extensively for biological control of various lepidopterous pests all over the world the species ofTrichogramma andTrichogrammatoidea (Hymenoptera, Trichogrammatidae) are the most important. The mode of reproduction of most of these is arrhenotoky while a few inTrichogramma is thelytoky, the later could be facultative with change in temperature, from one mode to the other. Since 1977, a large number of new species were described and studies on different aspects made world over. The studies made include crossing experiments which proved existence in nature of sibling species and other categories of incipient speciation which otherwise are difficult to discern. Studies on isozyme and enzyme analyses showed important differences among species and populations ofTrichogramma, so also response by these to different chemical insecticides. Scanning electron microscopy is yet another important tool to supplement other differentiating factors. Other biological characters aiding systematics include sex ratio, life and fertility table studies showing breeding potential, host preferences, temperature tolerance, etc.

A multiple decrement fertility table based on parity

This paper is a multivariate generalization of the work of Chiang and van den Berg [ Math. Biosci. 62:237-251 (1982)] to model the parity-specific reproductive patterns of female populations using a life table approach. It is also an adaptation of mortality competing risks theory and multiple decrement life tables to the study of parity-specific human fertility. Competing risks in the fertility context are risks of types of reproductive outcome: normal reproductive outcome (type 0); adverse reproductive outcome of type 1; adverse reproductive outcome of type 2; etc. We focus on applicability to studies in demography and reproductive epidemiology involving current populations.

The Construction of a Population Analysis Program Using a Microcomputer Spreadsheet

Abstract This article describes a population analysis program called “HALLEY,” which uses a microcomputer spreadsheet (Lotus 1-2-3). The program calculates a life expectancy table, an age distribution model, a fertility table, and five- and ten-year population projections; the four parts work in sequence. The program is appropriate for analyzing local, regional, state, or national populations and is also useful for teaching the interrelated dynamics of population change. Data for the program are readily available. 1-2-3 can make graphs from the population program, which makes it easy for the user to visualize population changes. The ease of use of such programs can be beneficial in planning analysis, allowing planners, administrators, and the public to examine population models in detail and to test the assumptions on which they are based.