Natural Sex Ratio Research Articles

Can sex differences in spatiotemporal distribution and age composition explain the female-biased sex ratio observed in the catch of butterfly kingfish Gasterochisma melampus?

The catch of butterfly kingfish Gasterochisma melampus, a large pelagic species in southern temperate waters, is strongly biased (73%) towards females. Whether this is caused by differences in sex-specific spatiotemporal distributions or mortality of sexes is investigated herein. Analysis of sex ratios using a generalized additive model (GAM) for year, month, latitude, longitude, sea surface temperature, and fork length from Japanese longline catch data for areas where immature and adult fish occur revealed the influence of space and time on sex ratios to be small, and that of fork length to be large. Based on observation of the increments in vertebrae of immature fish (N = 179), the fork length at the time of increment formation was back-calculated from distances between increments on the anterior and posterior cones, generating 2–8 measurements per vertebra and 865 data points in total. Growth equations were calculated for each sex, with females growing faster. The age composition of males and females in the catch was similar, meaning that the mortality rate in males is unlikely to be higher than that of females. The data suggest that biased sex ratios in catches are representative of the natural sex ratio in a population for fish more than 60 cm in fork length.

Unbalanced sex-ratio in the Neolithic individuals from the Escoural Cave (Montemor-o-Novo, Portugal) revealed by peptide analysis

The sex profile estimation of pre-historic communities is often complicated by the commingled and scattered nature of skeletal assemblages. Demographic profiles are usually lacking and provide very truncated representations of these populations but proteomic analysis of sex-specific amelogenin peptides in tooth enamel brings new promise to these studies. The main objective was to obtain the sex profile of the human assemblage recovered from the Neolithic cave-necropolis of Escoural (Montemor-o-Novo, southern Portugal) through liquid chromatography-mass spectrometry. The secondary objective was to analyse sex-specific linear enamel hypoplasias (LEH), and to test the reliability of canine odontometric sex estimation. Sex estimation through peptide analysis was carried out in 36 left permanent canines which were macroscopically examined for the presence of LEH. The canine buccolingual diameter was used for odontometric sex estimation. The obtained sex ratio (0.5:1, M:F) is biased to female individuals, probably due to cultural factors since the natural sex ratio of the human population falls between 0.95:1 and 1.02:1 (M:F). A high frequency of LEH was observed, but with no significant sexual differences (p = 0.554). The mean LEH age of onset occurred at 3 years of age, with no significant differences between the sexes (p = 0.116), and was possibly related to the weaning process. Odontometric sex estimation revealed a correct classification of 80%, with a high number of males mistakenly attributed to females. This study is one of the largest samples subjected to peptide analysis, and thus demonstrates its usefulness on the research of commingled and scattered skeletal assemblages.

A biotechnological method for silkworm sex regulation

Abstract The aim of this work is to use the biotechnological method of silkworm sex regulation as a breeding method. For this purpose, butterflies were mated immediately after their emergence in a chamber with a constant magnetic field for 4 h. By studying the natural fertilization of the Sheki-2 silkworm in a constant magnetic field, it was possible to change the natural sex ratio of the offspring from 1:1 to 1:3 in favour of males. A direct positive correlation was observed between the magnetic field strength and an increase in the number of males in the offspring, with the maximum number of males observed at a strength of 729.7 kA/m. The developed mathematical model made it possible to calculate the activation coefficient of magnetic fields influencing the cytogenetic process in the silkworm, which was 4.02 × 10−3 kA/m. An attempt was also made to explain the mechanism behind the cytogenetic influence of a constant magnetic field on possible options for obtaining males during the natural fertilization of silkworm females. Implementation of the developed method in the breeding programme will enhance both the quantity and quality of silkworm productivity. This is achieved by increasing silk yield and improvement of the raw materials obtained from the males. If these positive outcomes are consistently observed in other silkworm breeds, this method has the potential to become widely adopted for large-scale breeding of the entire silkworm population in the country.

The effect of pregnancy on metabolic scaling and population energy demand in the viviparous fish Gambusia affinis.

Metabolism is a fundamental attribute of all organisms that influences how species affect and are affected by their natural environment. Differences between sexes in ectothermic species may substantially alter metabolic scaling patterns, particularly in viviparous or live-bearing species where females must support their basal metabolic costs and that of their embryos. Indeed, if pregnancy is associated with marked increases in metabolic demand and alters scaling patterns between sexes, this could in turn interact with natural sex ratio variation in nature to affect population-level energy demand. Here, we aimed to understand how sex and pregnancy influence metabolic scaling and how differences between sexes affect energy demand in Gambusia affinis (Western mosquitofish). Using the same method, we measured routine metabolic rate in the field on reproductively active fish and in the laboratory on virgin fish. Our data suggest that changes in energy expenditure related to pregnancy may lead to steeper scaling coefficients in females (b=0.750) compared to males (b=0.595). In contrast, virgin females and males had similar scaling coefficients, suggesting negligible sex differences in metabolic costs in reproductively inactive fish. Further, our data suggest that incorporating sex differences in allometric scaling may alter population-level energy demand by as much as 20-28%, with the most pronounced changes apparent in male-biased populations due to the lower scaling coefficient of males. Overall, our data suggest that differences in energy investment in reproduction between sexes driven by pregnancy may alter allometric scaling and population-level energy demand.

Addition of 4‐oxoisophorone improves performance of bisexual lure for Autographa gamma (L.) (Lepidoptera: Noctuidae)

AbstractIn field trapping tests the addition of 4‐oxoisophorone (2,6,6‐trimethylcyclohex‐2‐ene‐1,4‐dione) to the known ternary bisexual lure (consisting of phenylacetaldehyde + benzyl acetate + eugenol) significantly increased catches of the silver Y moth Autographa gamma, an important migratory noctuid pest. Both female and male moths were attracted, supposedly in the natural sex ratio of the local population. Traps baited with the quaternary lure caught 27.9% of the number of moths in traps baited with synthetic sex pheromone (all males), and the two types of lures showed similar seasonal trends when following the quantitative changes in moth flight throughout the whole season. This suggests that the improved quaternary bisexual lure could be efficient enough to yield a new tool for detection and monitoring of A. gamma, resulting in more reliable plant protection decisions based on female catches, and can provide data for studies where the catch of females and data on sex ratio are indispensable.

Seasonal variation in the ecology of tropical cavity-nesting Hymenoptera on Mt. Kilimanjaro

Insect communities vary seasonally with changing climatic conditions and related changes in resource availability, strength of competition, or pressure by natural antagonists. But seasonal dynamics, particularly in tropical mountain ecosystems, are not well understood. We monitored cavity-nesting Hymenoptera communities on Mt. Kilimanjaro, Tanzania, to analyse temporal patterns of nest-building activity, ecological rates, and life-history traits in relation to seasonal climatic variation and elevation. We installed trap nests on 25 study sites in natural and disturbed habitat types covering the colline (<1,300 m) and submontane zones (≥1,300 m a.s.l). We analysed patterns of seasonality in the cavity-nesting ecology of Hymenoptera at three different trophic levels –bees, caterpillar-hunting wasps and spider-hunting wasps– over a complete annual period, covering two rainy and two dry seasons. Nest-building activity showed strong seasonal trends in all three investigated trophic levels and peaked at the end of the short rainy season at low elevations. Nest-building activity was considerably higher and seasonal trends were better synchronised between the different trophic levels in the colline zone at low elevations. We also detected seasonal patterns for parasitism and natural mortality rates, sex ratio, and development time, which varied with trophic level and between elevation levels. Climate and flower abundance were important predictors for seasonal patterns in nest-building activity, ecological rates and life-history traits. These results reveal that seasonal trends in nest-building activity of lowland Hymenoptera seem to be linked to changes in climate and resource availability that reflect the seasonal patterns in plant growth and flowering documented in lowland savanna ecosystems. Higher resource availability also increased the sex ratio in bees towards the more costly females and enhanced their survival rates. These spatiotemporal links between climate, resources, ecological rates, and life-history traits indicate high sensitivity of plant-host-antagonist interactions to environmental changes.

Short-term gain, long-term loss: How a widely-used conservation tool could further threaten sea turtles

Sea turtles nest on tropical and subtropical beaches, where developmental success of egg clutches depends on nest temperature. Higher nest temperatures increase embryo and hatchling mortalities and produce female hatchlings. Nest shading has been used on some beaches to reduce nest temperatures, and thereby increase number of hatchlings and reduce female-biased sex ratios. We modeled short- and long-term effects of reducing mean nest temperatures on a leatherback turtle (Dermochelys coriacea) population for which the effect of temperature on sex ratios and emergence success (# hatchlings emerged/ # eggs) is well-established. We simulated mean nest temperature reductions of −0.5 °C, −1 °C, −1.5 °C and −2 °C in relation to current mean (30.4 °C) and projected population responses over 100 years. Additionally, we run climate change simulations of +0.5 °C, +1.0 °C and +2.0 °C to assess if shading could be needed after passing a certain threshold.Emergence success increased with reduced nest temperatures. However, lowering nest temperatures ultimately caused long-term declines in number of nesting females and total population size, because the number of female hatchlings was reduced. Because hatcheries are a widely-used conservation tool, caution must be used to avoid reducing the number of female hatchlings by lowering nest temperatures. Nest cooling may only be needed under critically low hatchling production and extremely biased female sex ratios that we only found at +2.0 °C. If nest shading is to be used, it should be applied strategically to optimize hatchling production with natural sex ratios to achieve both short-term conservation goals and long-term population sustainability.

Sex-reversal and Histopathological Assessment of Potential Endocrine-Disrupting Effects of Graphene Oxide on Japanese medaka (Oryzias latipes) Larvae

Sex-ratio is considered as an end point during endocrine disrupting chemicals (EDCs) evaluation. Many fish species including Japanese medaka have XX/XY sex determination mechanism, however, sex reversal (SR) can be induced by external and genetic factors. SR imposed an imbalance in natural sex ratio of a population living in any ecosystem. Considering SR as an end point, we aimed to investigate the potential EDC effects of graphene oxide (GO), a nanocarbon, using Japanese medaka as a model. One-day post-hatch (dph) medaka fries were exposed to GO (2.5, 5.0, 10.0 and 20 mg/L) for 96 h without food, followed by 6 weeks depuration in a GO-free environment with feeding. Phenotypic sex was determined by gonad histology; genotypic sex by genotyping Y-chromosome-specific male sex determining gene, dmy. Our data indicated testes in both XY and XX genotypes, while ovaries were only in XX females. Histopathology of XY and XX testis showed isogenic spermatocysts with active spermatogenesis. Distribution of spermatocytes (SPTs), not the spermatogonium (SPGs), showed enhancement in XY than XX testis. Female phenotypes had single ovary, either in stage 0 or 1. Ovo-testis/testis-ova were absent in XX or XY gonads. GO (2.5–20 mg/L) had inconsistent concentration-dependent effect in both SPGs and SPTs; however, no effect on ovarian follicles. Despite genotypic differences (XY/XX), in the histopathology/histochemistry of liver and kidneys GO effects was found to be minimum. Taken together, present study showed spontaneous induction of SR in some XX genotypes; however, exposure of fasting fries to GO had no apparent EDC effects.

Trends in missing females at birth in India from 1981 to 2016: analyses of 2·1 million birth histories in nationally representative surveys

Half of the world's missing female births occur in India, due to sex-selective abortion. It is unknown whether selective abortion of female fetuses has changed in recent years across different birth orders. We sought to document the trends in missing female births, particularly among second and third children, at national and state levels. We examined birth histories from five nationally representative household surveys (National Family Health Surveys 1-4 and District Level Household Survey 2) to compute the conditional sex ratio (defined as the number of girls born per 1000 boys depending on previous birth sex) in India during 1981-2016. We estimated decadal variation in conditional sex ratio for 1987-96, 1997-2006, and 2007-16, and quantified trends in the numbers of missing female births for the states constituting >95% of India's population, as well as in 5-year intervals for each survey round. We used multivariate logistic regression to calculate the odds ratio of a second (or third) girl depending on the sex of the earlier child (or children), adjusting for education, wealth, religion, caste, and place of residence. We assessed 2·1 million birth histories across the five surveys. Applying the conditional sex ratios from the surveys to national births, we found that 13·5 million female births were missing during the three decades of observation (1987-2016), on the basis of a natural sex ratio of 950 girls per 1000 boys. Missing female births increased from 3·5 million in 1987-96 to 5·5 million in 2007-16. Contrasting the conditional sex ratio from the first decade of observation (1987-96) to the last (2007-16) showed worsening for the whole of India and almost all states, among both birth orders. Punjab, Haryana, Gujarat, and Rajasthan had the most skewed sex ratios, comprising nearly a third of the national totals of missing second-born and third-born females at birth. From about 1986, the conditional sex ratio for second-order or third-order births after an earlier daughter or daughters diverged notably from that after an earlier son or sons. From 1981 to 2016, the sex ratio for second-born children after an earlier daughter decreased from 930 (99% CI 869-990) to 885 (859-912), and that for third-born children after two earlier daughters decreased from 968 (866-1069) to 788 (746-830). The probability of missing girls was mostly determined by earlier daughters, even after considering wealth quintile and education levels. The conditional sex ratio among the richest and most educated mothers was most distorted compared with lower wealth and education groups, and generally decreased with time, until a modest improvement in 2007-16. In contrast to the substantial improvements in female child mortality in India, missing female births, driven by selective abortion of female fetuses, continues to increase across the states. Inclusion of a question on sex composition of births in the forthcoming census would provide local information on sex-selective abortion in each village and urban area of the country. None. For the Hindi translation of the abstract see Supplementary Materials section.

Effect of natural male and female (sex ratio) on nutmeg (Myristica fragrans) production on Maluku

The composition of males and females is very influential on the productivity of nutmeg plants. This research aimed to get the composition of male, female, and shade types related to the productivity of the nutmeg plant in the center of nutmeg in Maluku. Nested Design Three-Factor. Production centers are divided: Large Island, Medium Island and Small Island, determined as Factor A. Data on the number of trees Ratio male: female as factor B (B1 = ratio <1:10); (B2 = ratio 1:10 - 1:15); and (B3 = ratio> 1:20). Minimum of five female nutmeg samples for observation of production in a layered (Proportional Stratified Random Sample) harvest season in a year as a replication, namely Harvest I; Harvest II; and Harvest III. The results showed that the natural sex ratio of nutmeg was 1:10 in Small Island, Medium Island, and Big Island. The average productivity of nutmeg was 1,494, 1,465, and 1,296 fruit/tree/year, respectively. The farming system in Small Island was a monoculture of 100% shade plants, while in Medium and Big Island, the farming system was 33% - 50% shade plants and 50% - 67% other perennial crops.

Mating Affects Lifespan Differently in Two Strains of Pseudo-female Caenorhabditis elegans

Mating is vital for sexually reproducing species, yet the ideal mating strategy for males and females can differ. The ensuing conflict between the sexes – namely, sexual conflict – results in a decrease in population level fitness. The degree of sexual conflict can be affected by the behavior, physiology, and life history of a population. Previous studies in the nematode Caenorhabditis elegans have shown that mating causes lifespan to decrease in pseudo-females and hermaphrodites, which was interpreted as evidence of sexual conflict. However, it is still an open question whether variations in mating condition and strain type can affect the degree of sexual conflict and lifespan decrease. Here, I investigate whether lifespan is affected by mating in conditions other than sex- skewed individual mating scenarios used in previous work. I conducted population-based mating assays in two different strains of C. elegans using both natural and male-skewed sex ratios. Counter to expectations, I found no effect of mating on lifespan in a wild isolate of C. elegans, while virgins from a canonical laboratory strain had a decreased lifespan relative to their counterparts mated in groups. My data offers a counterpoint to the literature, which agrees that mating universally decreases the lifespan of C. elegans pseudo-females and hermaphrodites. These results highlight the flexibility of reproductive costs and the importance of life histories in experimental populations.

The Coexistence of Oryctes rhinoceros L. and Xylotrupes gideon L. (Coleoptera: Scarabaeidae) on Immature Plant in Oil Palm Plantation

Oryctes rhinoceros L. and Xylotrupes gideon L. (Coleoptera: Scarabaeidae) are known to attack palms. O. rhinoceros is a major pest in oil palm while X. gideon is a minor pest found in certain areas with a relatively few numbers. Collecting these beetles by hand picking and trapping are intended to reduce their population. Objectives of this study were to describe an intimacy of shared existence of O. rhinoceros and X. gideon in the oil palm plantation, and to determine the effect of manual collection of the beetles from the decomposing trunks compared to those that were collected using attractant traps. The study was conducted in Asahan Regency, North Sumatera, in Sei Silau PTPN III oil palm plantation. Five traps (2 Ha/trap) containing the pheromone ethyl-4-methyloctanoate were installed randomly at a replanting area of immature palm. Beetle collection was performed daily for 30 consecutive days using two methods, i.e. (a) hand-picking of beetles on the decomposed trunks at surrounding the trap for 2 hour per day, and (b) using pheromone traps. Simple regression and correlation model was used for data analysis. Results showed that coexistence of O. rhinoceros and X. gideon was observed at the breeding sites of decomposing trunks, but not in the traps, and their coexistence showed a weak relationship (r = 0.12). Number of collected O. rhinoceros (221 beetles) was much more than X. gideon (82 beetles). Natural sex ratio (male: female) was approximately 0.5 for O. rhinoceros and 0.4 for X. gideon. Collection of the beetles in the decomposed trunks showed a moderately positive relationship (r = 0.43) with, and significantly influenced (18.73%) to the collection of beetles using pheromone traps.

Variations in Marriage Squeeze by Region, Religion, and Caste in India

Marriage squeeze is a demographic phenomenon underlining the asymmetry between the availability of potential brides and grooms in a population. Since mate selection is very specific and bound by religion, caste, and region in India, existing demographic and sociocultural variability reflects even more emphatically on marriage squeeze in these subgroups. The last round of the Indian census (2011) was used for this study. To capture the marriage squeeze, the study utilized two methods—Schoen’s method of two-sex life table and the sex ratio method. At present, India is experiencing a marriage squeeze for males in rural as well as urban areas. Differences have been observed in the tightness of marriage squeeze across different subgroups of the population. The tightness of the male marriage squeeze is greater among Hindus than Muslims in the age group 15–45. In terms of caste, the scheduled tribes are experiencing a higher scarcity of brides than “other” castes; conversely, scheduled caste brides are experiencing a scarcity of grooms. Across the states, a higher tightness of marriage squeeze among males is observed in Punjab, Uttar Pradesh, Mizoram, and Haryana compared to the rest of the states. The rapid changes that occurred in the sex ratio in the past few decades are visible in the initial two cohorts of marriageable age. Variations in marriage squeeze across different social groups are mainly driven by alterations in the natural sex ratio and the changing pattern of marriage in India.

Improving Bisexual Lures for the Silver Y Moth Autographa gamma L. and Related Plusiinae (Lepidoptera: Noctuidae)

The addition of synthetic eugenol and benzyl acetate to the known floral chemical and moth attractant phenylacetaldehyde synergized attraction of the silver Y moth Autographa gamma, an important noctuid pest. Traps baited with the ternary blend caught 2 to 6 times more A. gamma moths than traps baited with phenylac-etaldehyde alone. Both female and male moths were attracted, supposedly in the natural sex ratio of the local population. More A. gamma were caught when the blend was formulated in dispenser types with higher release rates. Traps baited with the ternary lure in polyethylene bag dispensers caught 20% to 34% as many moths as were caught in traps baited with synthetic sex pheromone, suggesting that this improved bisexual lure could be efficient enough to yield a new tool for detection and monitoring of female and male A. gamma, for more reliable plant protection decisions. The same ternary lure also improved trap catches of moths over phenylacetaldehyde alone for the plusiinae pests MacDunnoughia confusa (in Europe) and Autographa californica (in North America) and for the Noctuinae cutworm Xestia c-nigrum (in North America).

Short heatwaves during fluctuating incubation regimes produce females under temperature-dependent sex determination with implications for sex ratios in nature

Patterns of temperature fluctuations in nature affect numerous biological processes, yet, empirical studies often utilize constant temperature treatments. This can limit our understanding of how thermally sensitive species respond to ecologically relevant temperatures. Research on turtles with temperature-dependent sex determination (TSD) provides good examples of this, since nest temperatures from many populations rarely exceed those necessary to produce females under constant laboratory conditions. We hypothesized that exposure to brief periods of warm temperatures (i.e., heat waves) are integral to sex determination in species with TSD, which requires tests that move beyond constant temperatures. We exposed Trachemys scripta embryos from multiple populations and across the nesting season to heat waves of variable durations and quantified sex ratios. We found that embryos from all populations were highly sensitive to brief exposures to female producing temperatures; only 7.9 days of exposure produced a 50:50 sex ratio, but the response varied across the nesting season. From these findings, a model was developed to estimate sex ratios from field temperature traces, and this model outperformed traditional methods. Overall, these results enhance our understanding of TSD and emphasize the importance of using biologically relevant temperatures when studying thermally sensitive processes.

Sex Differences and the Heritability of Scute Pattern Abnormalities in the Green Sea Turtle from the Ogasawara Archipelago, Japan.

Although scute pattern abnormalities in sea turtle species are considered to be strongly correlated with survival rate, there is little information available regarding these abnormalities and the primary cause for their development is unclear. For the conservation of sea turtle species, accumulating basic knowledge of scute pattern abnormalities is a fundamental step towards a better understanding of the causes of these abnormalities. In the present study, we counted vertebral and costal scutes from adults hunted for food (male and female) (n = 899), nesting females (n = 155), and hatchlings (n = 44,537) of the green sea turtle (Chelonia mydas) from the Ogasawara Archipelago, Japan. We found that the frequency of turtles with non-modal scute patterns was significantly greater in adult females than that in adult males (P = 0.02). Since females are produced by warmer incubation temperatures, and the period of sex determination coincides with the period of scute pattern determination, high incubation temperatures may be responsible for the induction of scute pattern abnormalities. Moreover, females with non-modal scute patterns produced a higher frequency of hatchlings with non-modal scute patterns than females with modal scute patterns (P < 0.01), indicating that scute abnormality may be heritable. For conservation of this species, our results suggest that decrease of the incubation temperature by cooling methods, such as provision of shade, may minimize the frequency of non-modal scute patterns, with consideration for the natural sex ratio.

An improved female-targeted semiochemical lure for the European corn borer Ostrinia nubilalis Hbn.

The addition of synthetic 4-methoxy-2-phenethyl alcohol to the known attractant phenylacetaldehyde synergized attraction of the European corn borer Ostrinia nubilalis, the blend invariably catching 3 to 5 times more than phenylacetaldehyde on its own. Highest catches were recorded by the 1:1 blend. Both females and males were attracted, supposedly in the natural sex ratio of the local population. This improved bisex O. nubilalis attractant could be more efficient and more suitable for detection and monitoring purposes than previously know lures, making possible to draw more reliable plant protection decisions.

Shading and watering as a tool to mitigate the impacts of climate change in sea turtle nests.

Increasing sand temperatures resulting from climate change may negatively impact sea turtle nests by altering sex ratios and decreasing reproductive output. We analyzed the effect of nest shading and watering on sand temperatures as climate mitigation strategies in a beach hatchery at Playa Grande, Costa Rica. We set up plots and placed thermocouples at depths of 45cm and 75cm. Half of the plots were shaded and half were exposed to the sun. Within these exposure treatments, we applied three watering treatments over one month, replicating local climatic conditions experienced in this area. We also examined gravimetric water content of sand by collecting sand samples the day before watering began, the day after watering was complete, and one month after completion. Shading had the largest impact on sand temperature, followed by watering and depth. All watering treatments lowered sand temperature, but the effect varied with depth. Temperatures in plots that received water returned to control levels within 10 days after watering stopped. Water content increased at both depths in the two highest water treatments, and 30 days after the end of water application remained higher than plots with low water. While the impacts of watering on sand temperature dissipate rapidly after the end of application, the impacts on water content are much more lasting. Although less effective at lowering sand temperatures than shading, watering may benefit sea turtle clutches by offsetting negative impacts of low levels of rain in particularly dry areas. Prior to implementing such strategies, the natural conditions at the location of interest (e.g. clutch depth, environmental conditions, and beach characteristics) and natural hatchling sex ratios should be taken into consideration. These results provide insight into the effectiveness of nest shading and watering as climate mitigation techniques and illustrate important points of consideration in the crafting of such strategies.

Identification of Empoasca onukii (Hemiptera: Cicadellidae) and Monitoring of its Populations in the Tea Plantations of South China.

Tea green leafhoppers (Empoasca spp.) are considered one of the major pests in tea plantations in Asia. They are, however, difficult to monitor due to their size and flying and jumping abilities. In this study, we clarified the identification of the leafhopper species encountered in our study plantations and examined the impacts of sampling methods in estimating population abundance and sex ratio. The natural sex ratio of eggs, nymphs, and adults of tea green leafhopper and the differences between male and female were tested. Despite previous reports that Empoasca vitis (Goethe) was the major leafhopper present in our study area, our results showed that only Empoasca onukii Matsuda was found. Variation in population size over time and bias in sex ratio depending on the sampling methods were found in our monitoring experiments. In general, adult males were more attracted to yellow sticky cards than females. We believe that because female leafhoppers should be the target in pest control, yellow sticky cards may not be the most suitable monitoring or effective control of tea green leafhopper. We demonstrate the importance of understanding the implications of sampling techniques for population estimation and sex ratio bias as well as how temporal variation may affect monitoring results. Precise monitoring should take into consideration the different life histories of male and female.

A Bayesian population model to estimate changes in the stock size in data poor cases using Mediterranean bogue (Boops boops) and picarel (Spicara smaris) as an example

The paper presents an effort to build a biologically realistic, age structured Bayesian model for the stock assessment of data poor fisheries where only aggregated catch data is available. The model is built using prior information from other areas and ecologically or taxonomically similar species. The modeling approach is tested with data poor fisheries on the Cyclades islands in Greek archipelago. The two most important species in the area are selected: bogue (Boops boops) and picarel (Spicara smaris). Both are hermaphroditic. The only data available is the total catch from 1950 to 2010. Information was gathered about natural mortality, recruitment, growth, body size, fecundity, and sex ratio. There were significant problems in finding reliable prior information and a uniform prior was used for fishing mortality. The models at their present stage are not used to give management advice. The biological characteristics of the species in that area should be further studied. However, the posteriors of biological parameters reflect the best available knowledge on these species and they could be used in future studies or in simpler biomass dynamics models as priors.