Egg Distribution Patterns Research Articles

Analysis of Distribution and Consumption Patterns in Pangkalpinang City

The food industry not only fulfils basic human needs for survival, but is also one of the vital economic sectors for a region. It creates jobs, from farmers to distributors, and drives various related industries such as packaging and transportation. Furthermore, the export of food products can be a significant source of foreign exchange. Thus, the healthy and sustainable development of the food industry not only ensures the food security of the community, but also contributes to economic growth and overall regional welfare. The purpose of this study is to analyze distribution and consumption patterns in Pangkalpinang City, using analysis of market structure detection, and analysis of trade and transport margins. The data from this study uses primary data, the results show that the distribution pattern of cooking oil and chicken eggs has the longest path and the pattern of consumption of food commodities contributing to the highest deflation is rice

Modeling weather-driven long-distance dispersal of spruce budworm moths (Choristoneura fumiferana). Part 1: Model description

Long-term studies of insect populations in the North American boreal forest have shown the vital importance of long-distance dispersal to the maintenance and expansion of insect outbreaks. In this work, we extend several concepts established previously in an empirically-based dispersal flight model with recent work on the physiology and behavior of the adult eastern spruce budworm (SBW) moth, Choristoneura fumiferana (Clemens). An outbreak of defoliating SBW in Quebec, ongoing since the mid-2000s, already covers millions of hectares of forests in eastern Canada and threatens to spread into neighboring areas through annual summertime episodes of long-distance dispersal. Such flight events in favorable conditions frequently include billions of SBW moths dispersing in the warm atmospheric boundary layer, typically starting around sunset and often lasting through several hours of wind-driven transport over hundreds of kilometers. Successful SBW dispersal to possibly distant host forest areas depends acutely on the weather. Here we describe the components and results of SBW–pyATM, an open-source individual-based modeling framework developed in Python for the simulation of these weather-driven SBW dispersal events. Using seasonal SBW phenology results from BioSIM at known outbreak locations and high-resolution Weather Research and Forecasting (WRF) model output, we focus on modeling dispersal flights over two successive nights in July 2013 in southern Quebec. Our flight model closely reproduces the SBW spatial patterns and motions observed by weather surveillance radar over the St. Lawrence estuary. With SBW–pyATM we can estimate landing locations for both male and female SBW and the resulting spatial patterns of egg distribution, allowing us eventually to forecast future larval defoliation activity in new locations where immigration could help overcome local limitations on SBW populations. This information could then support forest management decisions where SBW outbreaks threaten valuable resources.

Reproductive traits and spawning activity of striped eel catfish (Plotosidae) in Kolono Bay, Indonesia

Abstract. Asriyana A, Halili H. 2021. Reproductive traits and spawning activity of striped eel catfish (Plotosidae) in Kolono Bay, Indonesia. Biodiversitas 22: 3020-3028. Reproduction is a natural process for a species to ensure its sustainability in nature. This study aimed to investigate the reproductive traits and spawning activity of the striped eel catfish in Kolono Bay, South Konawe District, Southeast Sulawesi, Indonesia. A total of 965 individuals were collected monthly from June 2020 to May 2021 by using bottom experimental gillnets. Spent/spawning stages of the male and female fish were found during the East season (June-August). The proportions of the spent/spawning stages of male and female fish were 60% and 55.56% and the values of the gonadal somatic index were 1.19 ± 0.53 and 2.19 ± 3.47, respectively during the East season, indicate occurring the peak spawning in this season. Females matured gonads more rapidly at 198.3 mm compared to males at 224.5 mm. Female fecundity was 1,730 ± 390 eggs, with an egg diameter of about 0.11-1.35 mm. Striped eel catfish is a total spawner fish that has one mode of egg distribution pattern. During the East season, it needs protection for spawning. The findings will help in designing effective management and developmental strategies to conserve the striped eel catfish population in the future.

Spatial distribution patterns of fish egg and larval assemblages in the lower reach of the Yangtze River: Potential implications for conservation and management

AbstractRiver fish diversity is threatened by anthropogenic environmental alteration to landscapes. The early life‐history stages of fish play an important role in maintaining diversity and population recruitment and can be heavily influenced by landscape patterns. Information on temporal and spatial distribution patterns of fish eggs and larvae is also important for biodiversity conservation and management of fish resources.The Yangtze River possesses a high diversity of fishes, including many commercially important species. The economy along the lower reach of the river is well developed, and most of the area is experiencing high pressure from human impacts. This section of the Yangtze River connects with the largest freshwater lake in China at the upstream end and flows into the estuary at the downstream end. These two landscape features are likely to have a significant impact upon the spatial distributions of fish egg and larval assemblages.Environmental variables, fish eggs, and larval assemblages were sampled in three locations, at Hukou, Anqing, and Jingjiang, in the lower reach of the Yangtze River. The results suggest that the higher number of species and greater abundance in upstream sites reflect the critical function of connectivity of Poyang Lake with the river for fish recruitment in the lower Yangtze. The delayed bloom of larval fish, occurrence of estuarine species, and a lower species number and abundance of freshwater fish downstream reflect the influence of tidal intrusion from the estuary.This study highlights the value of maintaining natural river–lakes connectivity in the Yangtze River as a conservation measure. The connected river–lake system should be designated as a priority area for fish resource protection in the lower reach of the Yangtze River. We recommend further measures to break down barriers between the river and other lakes and to restore the natural lateral connectivity of the floodplain ecosystem.

Host discrimination in the fruit fly parasitoid Diachasmimorpha longicaudata: evidence from virgin female behaviour and egg distribution patterns.

Many parasitoid species discriminate already parasitized hosts, thus avoiding larval competition. However, females incur in superparasitism under certain circumstances. Superparasitism is commonly observed in the artificial rearing of the parasitoid Diachasmimorpha longicaudata, yet host discrimination has been previously suggested in this species. Here, we addressed host discrimination in virgin D. longicaudata females in a comprehensive way by means of direct and indirect methods, using Ceratitis capitata and Anastrepha fraterculus which are major fruit fly pests in South America. Direct methods relied on the description of the foraging behaviour of females in arenas with parasitized and non-parasitized host larvae. In the indirect methods, healthy larvae were offered to single females and the egg distributions were compared to a random distribution. We found that D. longicaudata was able to recognize parasitized host from both host species, taking 24 h since a first parasitization for A. fraterculus and 48 h for C. capitata. Indirect methods showed females with different behaviours for both host species: complete discrimination, non-random (with superparasitism), and random distributions. A larger percentage of females reared and tested on A. fraterculus incurred in superparasitism, probably associated with higher fecundity. In sum, we found strong evidence of host discrimination in D. longicaudata, detecting behavioural variability associated with the host species, the time since the first parasitization and the fecundity of the females.

Pattern of egg distribution by Adzuki bean beetle, Callosobruchus chinensis (L.) (Coleoptera: Chysomelidae) in stored chickpea under natural infestation

Under laboratory experimental condition female Adzuki bean beetles, Callosobruchus chinensis (L.) are known to evenly distribute their eggs over grains available for egg laying. However, currently there are no data on pattern of egg distribution by Adzuki bean beetle in large quantity of chickpea grain stored for extended period of time. The objective of this study was to determine the number and distribution of eggs among grains of chickpea stored in large quantity for 8 months and subjected to natural infestations. The experiment was conducted under room temperature and relative humidity at Debre Zeit Agricultural Research Center. The chickpea cultivars used were Natoli (desi type, 22 g per 100 seeds with Tuberculated seed coat texture) and Arerti (kabuli type, 26 g per 100 seeds with smooth seed coat texture) and for each cultivar there were 21 replicas of bags (40 cm wide and 70 cm high). From each bag, which contains 10 kg each, 25 chickpea grain samples were randomly selected at monthly intervals and examined for the presence or absence of Adzuki bean beetle eggs. Grains with eggs were categorized into frequency classes (i.e. 0, 1, 2, …, n) based on the number of eggs present on them. The variance to mean ratio was used to decide the type of egg dispersion pattern. In all the sampling dates and on both cultivars, the variance to mean ratios were highly significantly greater than one indicating that egg distribution by female Adzuki bean beetles on grains of chickpea was aggregated type. Moreover, further analysis of data had shown that the egg distribution pattern perfectly fits the negative binomial distribution, which confirms that the pattern of egg distribution on chickpea grains was aggregated/clumped type.

Avoidance and aggregation create consistent egg distribution patterns of congeneric caddisflies across spatially variable oviposition landscapes.

Amongst oviparous animals, the spatial distribution of individuals is often set initially by where females lay eggs, with potential implications for populations and species coexistence. Do the spatial arrangements of oviposition sites or female behaviours determine spatial patterns of eggs? The consequences of spatial patterns may be context independent if strong behaviours drive patterns; context dependent if the local environment dominates. We tested these ideas using a guild of stream-dwelling caddisflies that oviposit on emergent rocks, focussing on genera with contrasting behaviours. In naturally occurring oviposition landscapes (riffles with emergent rocks), we surveyed the spatial arrangement and environmental characteristics of all emergent rocks, identified and enumerated egg masses on each. Multiple riffles were surveyed to test for spatially invariant patterns and behaviours. In landscapes, we tested for spatial clumping of oviposition sites exploited by each species and for segregation of congeneric species. At oviposition sites, we characterised the frequency distributions of egg masses and tested for species associations. Genus-specific behaviours produced different spatial patterns of egg masses in the same landscapes. Congregative behaviour of Ulmerochorema spp. at landscape scales and an aggregative response at preferred oviposition sites led to clumped patterns, local aggregation and species overlap. In contrast, avoidance behaviours by congeners of Apsilochorema resulted in no or weak clumping, and species segregation in some landscapes. Spatial patterns were consistent across riffles that varied in area and oviposition site density. These results suggest that quite different oviposition behaviours may be context independent, and the consequences of spatial patterns may be spatially invariant also.

Fish spawning strategies in the northwestern Mediterranean Sea

The Mediterranean is globally considered an oligotrophic sea. However, there are some places or certain seasons in which mechanisms that enhance fertility may occur. These mechanisms, and related processes, are especially relevant in maintaining fish populations when they take place during the period of larval development. This contribution analyzes how environmental conditions occurring in the NW Mediterranean, at local and seasonal scales, determine the temporal and spatial patterns of fish reproductive activity in the region. The structure of the bathymetry, diversity of adult fish habitats and hydrodynamic mechanisms conditioning the primary production of the region (e.g., shelf-slope density front and associated current, continental water inflows, winter mixing, stratification of the water column) determine the location of spawning and the distribution patterns of fish eggs and larvae. A pronounced seasonal variability regarding both the number of species and the number of fish larvae in the plankton can be observed throughout the year. Most NW Mediterranean fish reproduce during the spring–summer stratification period, when the phytoplankton biomass values at the upper layers of the water column are lower than in winter. The development of the Deep Chlorophyll Maximum in this period and the high zooplankton biomass associated to it offers an important food source for the larvae. Additionally, during this period the inputs of continental waters are one of the fertilization mechanisms of surface waters and some species, as anchovy, takes advantage of this situation. Autumn–winter is the period with lower ichthyoplankton diversity, being dominated by sardine. Vertical mixing during winter is one of the mechanisms that enhance productivity. Overall, fish species show reproductive strategies and larval fish behavior that allow them to take advantage of the available resources throughout the seasonal cycle. These strategies, together with the high ecological efficiency of oligotrophic systems, contribute to the relatively high yield of Mediterranean fisheries. In a context of global change, understanding of the mechanisms relating environmental changes to the extent of spatial and temporal location of suitable spawning habitats of fish is a key first step to predicting and projecting such future changes, and thereby adapting to these changes.

Efek Pemuasaan pada Masa Dara terhadap Pola Produksi Telur dan Distribusi Waktu Oviposisi pada Burung Puyuh

The research is aimed to investigate the effect of fasting at grower period (3 to 6 week of age) on pattern of egg production and distribution of oviposition time in Japanese quail. Three hundreds and forty female of Japanese quails at 3 week of age were used in this research. The treatments were (1) without fasting or control, (2) skip-a-day fasting, (3) nighttime fasting: 18.00 p.m to 06.00 a.m.; and (4) daytime fasting: 06.00 a.m to 18.00 p.m. Data collected were age of the onset of laying (sexual maturity) until 12 weeks of age. The results showed that (1) the peak of egg production of control group was faster (10 weeks of age) and higher (89,3%) than the quails of groups fasting at grower period, but the peak of egg production was maintained longger than control group; (2) there was a fact that the egg production compensation was happened in fasting groups at grower period; (2) in quails group of daytime fasting at was grower period the distribution of oviposition time was relative smoother between periode observed: 12.00 – 18.00 p.m., 18.00 – 24.00 p.m. and 00.00 – 06.00 a.m., than other treatments. Key words: japanese quail, fasting, egg production, oviposition time

DNA barcoding technology to identity spawn from the Jiangmen marine environment in summer

PDF HTML阅读 XML下载 导出引用 引用提醒 基于DNA条形码技术对江门沿岸海域夏季鱼卵的鉴定 DOI: 作者: 作者单位: 1. 中国水产科学研究院南海水产研究所, 农业农村部南海渔业资源开发利用重点实验室, 广东 广州 510300;2. 上海海洋大学 水产与生命学院, 上海 201306 作者简介: 张楠(1987-),男,助理研究员,从事水产种质资源研究.E-mail:zhangnhs@163.com 通讯作者: 中图分类号: S917 基金项目: 科技部科技基础性工作专项（2013FY110700）；中国水产科学研究院中央级公益性科研院所基本科研业务费专项（2013A11）；农业部重大财政专项（NFZX2013）；国家科技基础条件平台建设运行项目（2017DKA30470）. DNA barcoding technology to identity spawn from the Jiangmen marine environment in summer Author: Affiliation: 1. Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture and Rural Affairs;South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, China;2. College of Aqua-life Science and Technology, Shanghai Ocean University, Shanghai 201306, China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以江门沿岸海域夏季采集到的鱼卵研究对象，利用DNA条形码技术分析鉴定鱼卵种类。本研究获得鱼卵个体有效线粒体COI序列信息217个，测序成功率为68.5%。经BOLD数据库比对分析，成功鉴定鱼卵5目14科19属20种（未知种2种）；种内遗传距离为0~0.006，平均遗传距离为0.002，种间遗传距离为0.149~0.325，平均遗传距离为0.255，种间遗传距离为种内遗传的128倍；鱼卵样品以鲈形目数量最多，占51.8%；鲱形目次之，占24.8%；其中鱼卵优势种为黄斑鲾（Megalaspis cordyla）、粗鳞鮻（Harpadon nehereus）、亚洲鱚（）。本次调查川山群岛东部海域获得鱼卵数量、鱼卵种类数均最多，是江门沿岸海域日本鳀、龙头鱼的主要产卵场；黄茅海、镇海湾西部水域均未获得鱼卵，可能与水域环境变化及陆源污染导致产卵环境破坏、亲体量减少有关。该研究结果揭示了江门沿岸海域夏季鱼卵分布格局，为其制定有效的产卵场保护措施提供依据，同时表明DNA条形码技术能有效地对鱼卵进行种类鉴定，可被广泛地应用于我国沿海海域鱼卵鉴定工作。 Abstract:The main purpose of this study was to analyze and identify the species of fish eggs from the Jiangmen marine environment in summer, based on DNA barcoding technology. In the present study, we acquired a total of 217 effective mitochondrial COI sequences from fish eggs, and the success rate of sequencing was up to 68.5%. After the alignment of the BOLD database, we found that besides 2 species, a total of 5 orders, 14 families, 19 genera, and 20 species were identified. Statistical analyses showed that the interspecific genetic distances were 0~0.006, and mean interspecific genetic distance was 0.002, whereas the intraspecific genetic distances were 0.149~0.325, and mean intraspecific genetic distance was 0.255, which was 128-fold higher than the former. Among the fish eggs, the most abundant order was Perciformes (51.8%), followed by Clupeiformes (24.8%); the most abundant species was Megalaspis cordyla, , and . In this investigation, the most abundant fish eggs were found in eastern Chuanshan Archipelago, both in numbers and species. The Chuanshan Archipelago is also known as the main spawning site of . However, nearly no fish eggs were found in the Huangmao Bay area or western Zhenhai Bay, possibly owing to environmental disruption and a decrease of effective parent number, triggered by environmental variation and contamination from land-sourced pollutants. In general, we revealed the distribution pattern of fish eggs from the Jiangmen marine environment in summer, which provided a theoretical basis for developing effective protective measures for spawning sites. Meanwhile, the results also showed that DNA barcoding technology could be effective and broadly applied to identify the species of fish eggs in the marine habitats of our country. 参考文献 相似文献 引证文献

Linking spawning ground extent to environmental factors — patterns and dispersal during the egg phase of four North Sea fishes

Previous studies have shown that four commercially important demersal species, namely Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), whiting (Merlangius merlangus), and European plaice (Pleuronectes platessa), spawn in distinct areas across the North Sea. Based on two comprehensive ichthyoplankton surveys in 2004 and 2009, the present study uses generalized additive mixed models to delimit these spawning grounds using the distribution of recently spawned eggs, investigates their relationship to specific environmental conditions, and examines egg dispersal during their development. Results indicate that presence–absence of early stage eggs is more related to temporal and topographic variables, while egg densities are closely linked with hydrography. Egg distribution patterns were relatively consistent during development and only changed near hatching. Compared with historic observations, the location of the spawning grounds appeared stable on the broad scale but centres of egg abundance varied between the surveyed years. Potential effects of long-term climate change and anthropogenic short-term disturbances, such as seismic surveys, on fish reproduction are discussed, pointing out the demand for multispecies studies on these issues.

Spatial distribution of eggs and larvae of Engraulis anchoita (Hubbs & Marini, 1935) in the southern brazilian shelf

This paper describes the horizontal distribution patterns of eggs and larvae of the anchovy, Engraulis anchoita, at two distinct oceanographic regions in the Southern Brazilian Shelf (SBS). Santa Marta Cape (SMC; 28°30’) is characterized by upwelling, while Albardão (33º) is influenced by Plata Plume Waters (PPW) and the Subtropical Shelf Front (SSF). Ichthyoplankton was sampled during winter 2005 and summer 2007 in SMC and Albardão during darkness and daytime with a Multinet. Three 330μm mesh-nets results were combined to express the horizontal distribution of anchovy early stages. Maps of salinity, temperature, fish eggs and larvae were made to evaluate spatial distributional patterns. Temperature-Salinity-Icthyoplankton (TSI) diagrams were used to infer fish larvae distribution with respect to water mass composition. Mean larvae and eggs abundance during winter was greater than summer, and SMC had higher ichthyoplankton abundance than Albardão. In both seasons the largest concentration of anchovy eggs and larvae were found in coastal areas with low salinity. Eggs and larvae were usually present in cold waters during winter and summer. According TSI diagrams, PPW was found in both regions and was positively associated with ichthyoplankton abundance.

Leafminer egg distribution at decreasing leaf availability levels: do females avoid intraspecific competition?

AbstractFemale oviposition choices are expected to maximize offspring fitness. Leafminers often lay their eggs in an aggregated fashion, leading to exploitative or interference competition among larvae. However, few studies have explored whether egg distribution patterns vary with leaf availability and whether these changes are an attempt to reduce competition effects on offspring fitness. Here, we evaluated the egg distribution patterns of the specialist leafminer Liriomyza commelinae Frost (Diptera: Agromyzidae) for decreasing levels of leaf availability of their host plant Commelina erecta L. (Commelinaceae). Competition effects on insect performance were evaluated at various leaf larval densities in the laboratory and egg distribution was investigated for a wide range of leaf availability levels, both in the laboratory and in the field. Liriomyza commelinae performance indicated that larvae competed for resources (exploitative competition), with a negative impact on survival and adult size at emergence when four or more larvae shared a leaf. The distribution of the immature stages of the leafminer was aggregated in both the laboratory and in the field. As this pattern did not change with leaf availability, increasing levels of larval competition occurred when available leaves were scarce. Moreover, the proportion of total individuals subjected to the strongest competition level (six or more larvae per leaf) increased exponentially at the lower levels of leaf availability. Competition was found to be irrelevant as a selective force in shaping L. commelinae oviposition decisions, as egg distribution was aggregated and did not vary with leaf availability, leading to relatively strong levels of competition. The egg distribution patterns observed in L. commelinae may have resulted from trade‐offs between competition and factors such as enemy‐free space and leaf quality.

Egg laying pattern of Sesamia inferens on maize (Zea mays)

To study the egg laying pattern of Sesamia inferens (Walker) on maize (Zea mays L.), a set of variable number of 12-day old plants, i e 1, 2, 3 and 4 plants in each set of resistant cultivar HQPM 1 and susceptible cultivar, Basi Local were offered to a single pair of adult S. inferens in versatile insect rearing cage. The number of eggs laid on HQPM 1 was 47.7 % more than the number of eggs laid on Basi Local. When only one plant was available for oviposition, the female laid 84% of its eggs complement on it both in case of HQPM 1 and Basi Local. The number of eggs was divided unequally when two plants were made available with the first plant receiving 60-70% of the eggs. The maximum number of plants utilized for depositing the eggs was four out of ten plants offered to the female, although at times, the female oviposited six plants as well but the total number of eggs did not increase when the number of plants exceeded more than four, on contrary, it got reduced. The distribution pattern of eggs on plants resulted in the decline in number of eggs per plant with increase of every additional plant. The egg distribution within a plant showed significantly more percentage (58.57) of eggs on first leaf sheath followed by second leaf sheath (27.19) and least number on basal leaf sheath (14.24). The total oviposition period was observed to be seven days with average fecundity as 405 and maximum number of eggs (174) obtained on second day of emergence of adults.

Insights into spatial distribution patterns of early stages of the Antarctic silverfish, Pleuragramma antarctica, in the platelet ice of Terra Nova Bay, Antarctica

The Antarctic silverfish, Pleuragramma antarctica, is ecologically important for connecting lower and upper trophic levels within the coastal marine Antarctic food web. In recent decades, populations of silverfish have exhibited a declining trend in some regions of the Antarctic, in particular the western Antarctic Peninsula. It is of paramount importance to elucidate its life history and to characterize the areas that are crucial for the reproduction of the species: spawning, hatching and nursery areas. Presently, the overall available knowledge is scant and spatially restricted. In this study, we assessed the spatial scales of variation in the distribution patterns of eggs and newly hatched larvae, and their vertical distribution within the platelet ice layer underlying fast ice at Terra Nova Bay. We found that (1) distribution patterns of eggs and larvae abundance significantly changed at a spatial scale of kilometers, while they did not at scale of tens of kilometers and hundreds/tens meters, and (2) eggs were not homogeneously distributed under the solid ice; in particular, the egg abundance was highest at −2.5 m within the platelet ice and dramatically declined more in depth. This study thus allowed shed light on distribution patterns of eggs and early-hatched larvae of the Antarctic silverfish. Such information will be useful to better understand the ecological processes possibly producing the patterns we have observed and then identify further reproduction and nursery areas around the Antarctic continent.

Distribution patterns of Macrodasyceras hirsutum (Hymenoptera: Torymidae) eggs among Ilex integra (Aquifoliaceae) seeds and berries

AbstractPreference-performance hypothesis in host selection by herbivorous insects predicts selective oviposition on plant on which the offspring maximise fitness. The seed parasitoid wasp, Macrodasyceras hirsutum Kamijo (Hymenoptera: Torymidae) selectively lays the eggs into the fertilised seeds of Ilex integra Thunberg (Aquifoliaceae). Only one larva develops in a seed. Therefore, the hypothesis predicts a uniform distribution pattern of wasp eggs among fertilised seeds. Dissection of 531 berries showed that M. hirsutum deposited one to five eggs into a fertilised seed. Iwao's patchiness regression suggested a uniform distribution pattern of M. hirsutum eggs among fertilised seeds at the scales of tree and berry and their random distribution pattern among berries at the tree scale. Destroying the connection of seeds within berries revealed that female wasps randomly selected berries for oviposition in most trees. Generalised linear mixed models showed that the number of fertilised seeds in a berry could not explain the number of eggs in a seed but could explain the number of eggs in a berry. Therefore, this study shows that the wasp females do not distinguish between berries with different numbers of fertilised seeds but distinguish between seeds harbouring different numbers of eggs, which supports the hypothesis.

How Mosquito Age and the Type and Color of Oviposition Sites Modify Skip-Oviposition Behavior in Aedes aegypti (Diptera: Culicidae)?

To address how physiological age, container type and the number of substrates affect Aedes aegypti skip-oviposition behavior, we examined egg distribution by individual females across consecutive gonotrophic cycles. We found no support for the effect of age on egg distribution. However, the hypothesis that both the variety and color of the container would influence skip-oviposition behavior was confirmed. Skip-oviposition behavior remained unchanged throughout the female’s life. The egg distribution pattern was characterized by a significantly higher oviposition rate in one site, with residual eggs distributed in groups of 1–30 eggs. Regardless type, most eggs were registered in dark containers. These data suggest that females contribute equally to population dynamics throughout their lifespan and illustrates the impact of color on egg dispersion.

Spawning site selection by European anchovy (Engraulis encrasicolus) in relation to oceanographic conditions in the Strait of Sicily

AbstractEuropean anchovy egg occurrence and density data from summer surveys (1998–2007) and oceanographic data were examined to study the mechanisms that control the spatial distribution of anchovy spawning habitat in the Strait of Sicily. Quotient analysis indicated habitat preference for temperature (18–19°C), bottom depth (50–100 m), water column stability (13–14 cycle h−1), fluorescence (0.10–0.15 μg m−3 Chl a), salinity (37.5–37.6 PSU), current speed (0.20–0.25 m s−1) and density (26.7–26.8 kg m−3, σt). Canonical discriminant analysis identified temperature, column stability and fluorescence as major drivers of anchovy spawning habitat. Three of the 4 years which had lower egg abundance were warmer years, with low values of primary productivity. A geostrophic current flowing through the Strait (the Atlantic Ionic Stream, AIS) was confirmed as the main source of environmental variability in structuring the anchovy spawning ground by its influence on both the oceanography and distribution of anchovy eggs. This 10‐yr data series demonstrates recurrent but also variable patterns of oceanographic flows and egg distribution. A lack of freshwater flow in this area appears to depress productivity in the region, but certain and variable combinations of environmental conditions can elevate production in some sub‐areas in most years or other sub‐areas in fewer years. These temporal and spatial patterns are consistent with an ocean triad theory postulating that processes of oceanographic enrichment, concentration, and retention may help predict fishery yields.

Environmental factors associated with the distribution of floodwater mosquito eggs in irrigated fields in Wrocław, Poland

A survey of distribution patterns of floodwater mosquito eggs related to environmental conditions such as moisture and plant associations was conducted by using soil samples from irrigated fields in Wrocław, Poland. Mosquito egg distribution was determined by repeatedly flooding the soil samples with aerated water at a temperature of 25° C. Under laboratory conditions, hatching in installments of Aedes caspius (Pallas) and Aedes vexans (Meigen) were commonly observed. The results show that ∼75% of the larvae of Ae. caspius and Ae. vexans hatched after the first flooding under summer-like conditions, whereas, following the second and third flooding, the numbers of hatched larvae were significantly lower. In our study, within one intermediate flooded field, a total of 66 plant species was identified and classified into six communities. All vegetation types were associated by varied egg densities and showed differences both in richness and Shannon-Wiener diversity index as well as in ecological indices for moisture, soil reaction, and nutrient level. Small changes in elevation along the slope within the study area showed a large difference in the distribution of mosquito eggs. The highest average egg density was observed in zones with high occurrence of Phalaris arundinacea, usually prevalent in intermediate flooded and fertile areas. Knowledge of the indicators for the distribution of floodwater mosquito eggs in temporary breeding sites may be essential for organizing a successful, integrated mosquito control program with special regard to microbial control agents.

Plant-mediated decisions by an herbivore affect oviposition pattern and subsequent egg parasitism

Natural enemies are important mortality factors for herbivores and thus may influence herbivore population dynamics. In response to natural enemy pressure, herbivores can alter life history decisions, such as oviposition behavior, so that offspring are protected from natural enemies. One such strategy is to deposit eggs into structures where vulnerability to natural enemies is reduced or eliminated, i.e., use enemy-free space. The plant bug, Lygus lineolaris (Palisot de Beauvois), is native to North America and has a broad host range (>350 plant species), including crops. This bug’s eggs are attacked by a native parasitoid, Anaphes iole Girault, and parasitism levels vary greatly among host plant species. Weed hosts are critical to contemporary L. lineolaris life history because they serve as an ecological bridge from one crop growing season to the next. We investigated the egg distribution pattern of L. lineolaris on 11 host plant species (nine weeds and two crops), and parasitism by A. iole, to determine whether oviposition choices by L. lineolaris females protect their eggs from parasitism and to demonstrate the mechanism of this protection. Our results indicate that the reproductive structures of Erigeron annuus, as well as those of several other host plant species, provide a refuge from parasitism for most L. lineolaris eggs. This refuge is due to the deposition of host eggs deeper in plant tissue than the length of the ovipositor of A. iole. Also, overall parasitism levels were greater on non-Asteraceae host plant species compared with host plant species belonging to Asteraceae. Oviposition site choice by female bugs appears to be a selective strategy to take advantage of enemy-free space.