Sibling and non-sibling cannibalism by larvae of a lady beetleHarmonia axyridisPallas (Coleoptera: Coccinellidae) in the field

Summary Sibling (cannibalism among siblings) and non-sibling cannibalism (cannibalism among non-siblings) were studied in a natural population of a lady beetle,Harmonia axyridis Pallas. Of all the eggs laid (n=2269), 24.76% (n=562) were killed by sibling cannibalism and 36.10% (n=819) were killed by non-sibling cannibalism. Sibling cannibalism occurred constantly and intensively in most egg batches throughout the entire oviposition period. On the other hand, non-sibling cannibalism was more intense in the middle and late oviposition periods, and when the egg batches were close to an aphid colony. This may be due to the high density ofH. axyridis larvae relative to aphid density in the middle and late oviposition periods and also the larvae searching intensively near an aphid colony.     

Stimuli governing intraspecific egg predation in the flour beetles,Tribolium confusum andT. castaneum

Summary The present research has not identified all of the factors that interact to produce the observed egg cannibalism rates inTribolium. It has, however, shown that some physical and chemical properties of the egg and environment play an important role in determining cannibalistic activity in a population. Of general interest is the observation that cannibalism is not solely the result of the biological characteristics of the cannibal. While it is generally acknowledged that the quality and quantity of food may influence the intensity of cannibalism, it is not generally recognized that the environment can affect cannibalism in as complex a manner as is suggested by the current research. That two such closely related species, and even two life-stages of the same species, may respond so differently to the same environmental cues is impressive. Predicting the intensity and hence the importance of cannibalism in natural populations may be difficult without detailed empirical studies.     

Possible influences of habitat characteristics on the evolution of semelparity and cannibalism in the hump earwigAnechura harmandi

The possible influences of life history and habitat characteristics on the evolution of semelparity and cannibalism in the hump earwigAnechura harmandi were studied. This species is univoltine and overwinters as an adult. Females laid single egg-batches during winter in nests under stones at a riverside in a valley. They took care of the eggs which hatched in early spring and the offspring ate their mother before dispersing. The valley was sometimes flooded in summer. Nymphs emerged as adults and dispersed to elsewhere before the rainy season arrived. They returned to the riverside after the rainy season. The flooding and/or summer heat seemed to be the selective force for the evolution of dispersal behavior and semelparity in this species. The cannibalism of the female parent by her offspring seemed to have readily evolved after the evolution of semelparity. The unfavorable environmental conditions seemed to have a large effect on the evolution of semelparity and cannibalism in this species.     

How an ant decides to prey on or to attend aphids

The following results on the behavior decision making of the antLasius niger toward two species of myrmecophilous aphidsLachnus tropicalis andMyzocallis kuricola on chestnut trees have been found. (1) An individual worker consistently attended only one aphid species, even if her nestmates attended other aphid species on the same tree. (2) The ants preyed less on the aphid species which they attended than on other myrmecophilous aphid species. (3) The ants preyed less on the aphids which had been attended by their nestmates, even if both aphids were the same species. (4) The ants preyed less on aphids which had provided honeydew to their nestmates. (5) The increased aphid density per ant led to an increase in the rate of predation on the introduced aphids by the ants. These results suggest that each worker ofL. niger chooses aphid species to attend from her experience. In addition, the workers can recognize whether an aphid has been attended by their nestmates and whether an aphid has given their nestmates honeydew. Through these processes, each worker decides to attend or to prey on the aphid. As a result, they may realize efficient collective foraging dependent on aphid density per worker.     

Perceived Sibling Relationships of Sexual Minority Youth

The purpose of this study was to examine the relationships of sexual minority youth and their siblings. The participants were 56 lesbian, gay, bisexual, or transgender individuals ranging in age from 18 to 24 years, who reported information about a total of 107 siblings. Respondents completed a demographic data questionnaire as well as adapted versions of the Sibling Closeness Scale (SCS) and the Sibling Approval of Sexual Behavior Scale (SASBS) to describe their relationship with each of their siblings. Analyses examined birth order and gender in relation to outness to siblings as well as sibling closeness and approval. Results provide information about disclosure of LGBT status to siblings, elements of closeness and acceptance in sibling relationships of sexual minority youth, and the significance of gender and birth order in these sibling relationships.     

Family size,schooling and child labor in Peru -- an empirical analysis

This paper analyzes the effects of being indigenous, number of siblings, sibling activities and sibling age structure on child schooling progress and child non-school activity. The analysis is based on the Peru 1991 Living Standards Survey. The analysis shows that family size is important. However, the analysis also demonstrates the importance of taking into consideration the activities of siblings. The number of siblings not entrolled in school proves to be an important control variable in at least one specification of the empirical model. However, more research is needed on the interactions between siblings, their activities and their age structure. In other words, an attempt must be made to find ways of taking into account the “life cycle effects” of one‘s siblings on their schooling performance and labor force activity. The analysis also shows that the age structure of siblings is important, but in conjunction with their activities. That is, having a greater number of younger siblings implies less schooling, more age-grade distortion in the classroom and more child labor. JEL classification: J22, J23, I21 Received August 1, 1996 / Accepted February 21, 1997     

Sisters in Later Life: Changes in Contact and Availability

SUMMARY

The strongest of sibling bonds is the relationship between sisters. However, researchers know little about how these relationships change over lime. This study presents a longitudinal examination of structural and contact features of older, rural women's (N = 82) sibling networks. Also, sibling network variables were correlated with measures of subjective well-being. Significant loss of siblings occurred over 12 years. After controlling for proximity, frequency of contact between siblings did not change. Although sisters predominated in sibling networks, proximate brothers were slightly more prevalent and had more frequent contact with the respondents. Associations between sibling variables and subjective well-being were not found. Siblings remain active in the kin networks of women into late old age.     

Factors affecting oviposition rate in the flour beetleTribolium castaneum and the origin of the population regulation mechanism

Summary The effects of egg cannibalism, conditioned medium and the presence of quinone secretions on oviposition rate were studied using single pairs of adults to eliminate any direct crowding effects. Most measurements were made on beetles confined to the surface of the flour medium in plastic towers. Oviposition rate was decreased by about 58% when pairs were transferred from fresh to conditioned medium; lowered about 25% when only quinones were present and the medium was still fresh; and enhanced 35% in dry conditions when beetles were provided with eggs to eat. Both the lowered oviposition rate in confined cultures and egg-eating may be explained by natural selection at the individual level. Cannibalizing eggs boosts a female's oviposition rate. The presence of quinones or conditioned medium indicates high population densities and acts as a signal for ceasing oviposition and dispersing to avoid high egg mortality. In confined populations, this results in population regulation, while in open populations, this strategy is a mechanism to avoid competition. It implies that the resource shortages normally experienced by such organisms are relative, not absolute.     

Understanding the effects of siblings on child mortality: evidence from India

Given the intrinsically sequential nature of childbirth, timing of a child’s birth has consequences not only for itself but also for its older and younger siblings. The paper argues that prior spacing and posterior spacing between consecutive siblings are thus important measures of intensity of sibling competition for limited parental resources. While the available estimates of child mortality tend to ignore the endogeneity of sibling composition, we use a correlated recursive model of prior and posterior spacing and child mortality to correct it. There is evidence that uncorrected estimates under-estimate the effects of prior and posterior spacing on child mortality.

Siblings and the Coming-Out Process: A Comparative Case Study

Siblings play a key, supportive role in the lives of many lesbian and gay adults. Yet siblings are rarely considered in the literature regarding the coming-out process (D’Augelli et al., 1998; Hilton & Szymanski, 2011; LaSala, 2010; Savin-Williams & Dubé, 1998). To fill this gap in the research literature, we carried out a comparative case study in the country of Belgium between two sets of siblings—three Romani brothers with one sibling identifying as a gay male and three White sisters with one sibling identifying as a lesbian. These two cases were pulled from a larger qualitative study (Haxhe & D’Amore, 2014) of 102 native French-speaking Belgian participants. Findings of the present study revealed that siblings offered critical socio-emotional support in the coming out of their lesbian and gay sibling, particularly with disclosing to parents and with fostering self-acceptance.     

Living same-name siblings and British historical demography

This article examines the extent to which living siblings were given identical first names. Whilst the practice of sibling name-sharing appeared to have died out in England during the eighteenth century, in northern Scotland it persisted at least until the end of the nineteenth century. Previously it has not been possible to provide quantitative evidence of this phenomenon, but an analysis of the rich census and vital registration data for the Isle of Skye reveals that this practice was widespread, with over a third of eligible families recording same-name siblings. Our results suggest that further research should focus on regional variations in sibling name-sharing and the extent to which this northern pattern occurred in other parts of Britain.     

Unhealthy Weight in Indian Families: The Role of the Family Environment in the Context of the Nutrition Transition

India faces a dual burden of increasing obesity and persistent underweight as it experiences the nutrition transition—the dietary and lifestyle changes that accompany globalization, economic development, and technological change. Yet, the nutrition transition is not solely a top-down process; rather, global forces converge with local practices at multiple levels of the social ecology. The family environment, a key site for the transmission of local customs and norms, remains largely unexplored in India. We examined the extent to which opposite-gender siblings and mother–child pairs were concordant or discordant in body weight, and whether domains of the family environment, specifically, food practices, food-related gender norms, and household resources, were associated with patterns of unhealthy weight within and between families. Multilevel dyadic analysis and logistic regression were conducted using survey data from a representative sample of 400 families in a Southern Indian city. We identified substantial clustering of weight among opposite-gender sibling pairs (ICC = 0.43) and mother–child pairs, as well as important patterns of discordance, including 11% of families experiencing a dual burden of underweight and overweight. Household resources, including mother’s education and income, were salient in explaining the distribution of body weight within and between families. Importantly, less examined domains of the family environment were also relevant, including food practices (e.g., grocery shopping frequency), and food-related gender norms (e.g., mother’s control of food served at home). Continued exploration of how global and local practices converge in households will be necessary to develop programming that effectively addresses India’s dual burden of unhealthy weight.     

A galling aphid with extra life-cycle complexity: Population ecology and evolutionary considerations

Summary In most gall-forming aphids, only the fundatrix is able to induce a gall on the host plant. InSmynthurodes betae Westw. (and a few other species), F₂ descendants emerge from the mother gall and induce their own, morphologically different galls. This constitutes an added complexity to the already very complex life cycle of gall-forming aphids. We investigated the ecology ofS. betae on marked trees and shoots at four sites in Israel. Gall initiation, gall distribution and density, and temporal changes in clone size within the galls were investigated during two consecutive years. We discuss the possibility that the two-gall life cycle evolved from the typical one-gall system of most gall aphids, and the possible selective advantage of this added complexity in the life-history strategy of gall aphids. Although the total reproductive output ofS. betae is not higher than in related species with a single gall per life cycle, there seems to be an advantage in the subdivision of each aphid clone into several galls, thus reducing the risk of the accidental extinction of the clone (genotype) by environmental factors, including parasites and predators.     

Siblings, child labor, and schooling in Nicaragua and Guatemala

This paper explores empirically within-household gender and sibling differences in child labor, domestic work, and schooling of Guatemalan and Nicaraguan children. The main results show that older boys spend more time engaged in market and domestic work, whereas older girls spend more time in domestic work than their younger siblings. These results are independent of whether the younger sibling is a boy or a girl, which suggests that there is no substitution within the household of younger for older siblings in market and domestic work. This paper’s findings show the relevance of domestic work and gender differentials in children’s allocation of time in developing countries.     

Intergenerational earnings mobility and divorce

This paper examines the potential effect of marital disruption on intergenerational earnings mobility. We observe the earnings of children born in 1960 and 1970 along with their biological fathers and mothers. The earnings mobility between sons and daughters relative to the earnings of their mothers and fathers is estimated. Our results suggest that divorce is associated with increased mobility, except between mothers’ and daughters’ earnings. Transition matrices reveal that the direction of the mobility is negative; children of divorced parents tend to move downward in the earnings distribution compared to children from intact families. Finally, we utilize information on the earnings mobility of siblings in dissolved families who grew up when the family was intact. The difference between pre- and post-divorce siblings is in turn compared with sibling differences in intact families.     

The linked survival prospects of siblings: Evidence for the Indian states

This paper reports an analysis of micro-data for India that shows a high correlation in infant mortality among siblings. In 13 of 15 states, we identify a causal effect of infant death on the risk of infant death of the subsequent sibling (a scarring effect), after controlling for mother-level heterogeneity. The scarring effects are large, the only other covariate with a similarly large effect being mother's (secondary or higher) education. The two states in which evidence of scarring is weak are Punjab, the richest, and Kerala, the socially most progressive. The size of the scarring effect depends upon the sex of the previous child in three states, in a direction consistent with son-preference. Evidence of scarring implies that policies targeted at reducing infant mortality will have social multiplier effects by helping avoid the death of subsequent siblings. Comparison of other covariate effects across the states offers some interesting new insights.     

Re-Conceptualizing Gaps by Socioeconomic Status in Parental Time with Children

Differences in the total time that parents spend with their children by socioeconomic status (SES) are well documented. However, the qualitative aspects of such gaps are potentially important, yet relatively understudied. The current study analyzes time-use data for a nationally representative sample of married households with at least two children, one of whom is under 13 (N = 21,016), from the American Time Use Survey to provide a more nuanced analysis of previously documented differences in the time parents spend with children by SES. Specifically, two understudied aspects of family time are considered, both of which are distinct from other types of parent–child time and are potentially particularly developmentally beneficial: shared time when both parents are present with a child and individual child time when no siblings are present. We find that shared time when both parents are simultaneously present with a child often comprises a substantial portion of the total gap in parental time spent with children between college-educated parents and parents who did not complete high school. Similarly, college-educated parents spend more time with children in the absence of the child’s siblings than do less-educated parents. Gaps in this time classification are often found within enriching time, which is likely especially developmentally beneficial, potentially amplifying the effects of these gaps on child development. Generally, these results suggest that gaps in parental time with children by SES are more nuanced than previous research has recognized.     

Adolescent sexual activity in the family context: The impact of older siblings

Using approximately 2,000 sibling pairs from the National Longitudinal Survey of Labor Market Experience of Youth, we examine the influence of an older sibling's age at first sexual intercourse on the sexual initiation of a younger sibling. Hypotheses about differences by gender composition of the pair are tested, using a framework derived from social comparison theory and a two-stage failure-time model. Results provide evidence of a direct but modest-sized older sibling effect for white but not black youth. This effect is approximately equal in magnitude for same- and opposite-sex siblings. Little support is offered for the greater salience and association of sexual activity for brother-brother as compared with sister-sister pairs.     

Education Gains Attributable to Fertility Decline: Patterns by Gender,Period, and Country in Latin America and Asia

We investigate the heterogeneity across countries and time in the relationship between mother’s fertility and children’s educational attainment—the quantity-quality (Q-Q) trade-off—by using census data from 17 countries in Asia and Latin America, with data from each country spanning multiple census years. For each country-year, we estimate micro-level instrumental variables models predicting secondary school attainment using number of siblings of the child, instrumented by the sex composition of the first two births in the family. We then analyze correlates of Q-Q trade-off patterns across countries. On average, one additional sibling in the family reduces the probability of secondary education by 6 percentage points for girls and 4 percentage points for boys. This Q-Q trade-off is significantly associated with the level of son preference, slightly decreasing over time and with fertility, but it does not significantly differ by educational level of the country.