Egg loads and egg masses: Parasitism ofChoristoneura rosaceana eggs by Trichogramma minutum after inundativerelease in a commercial blueberry field

Inundative releases of Trichogramma minutum Riley were made in a commercialblueberry field in British Columbia, Canada, todetermine the extent of dispersal of adult wasps, andto determine whether complete parasitism of eggswithin egg masses of the target host [oblique-bandedleafroller (OBLR), Choristoneura rosaceana(Harris)] occurred. Three weekly releases of waspswere made from a single release point in the center ofeach field during the flight of first generation OBLRadults. Sticky trap, sentinel egg mass andtarget-host egg mass data all indicated only a limitedrange of dispersal of T. minutum within thefield. In addition, only partial parasitism of eggmasses of the target host occurred even in closeproximity to the release point. We discuss theimportance of determining the response of Trichogramma females to previously-parasitized eggswhen using Trichogramma wasps for biologicalcontrol of lepidopterous species that oviposit largeegg masses.     

一种估算草地贪夜蛾卵块中卵粒数量的简易方法

草地贪夜蛾Spodoptera frugiperda (Smith)是2019年发现入侵我国的一种重要的外来害虫,对我国粮食种植业造成严重威胁。明确虫情是做好草地贪夜蛾预测预报和制定科学防控策略基础。在田间调查中需要一种简便、快速估计落卵量的方法,以明确田间虫口数量。本研究在实验室条件下收集草地贪夜蛾雌虫产于玉米叶片上的卵块,记录了每个卵块的长、宽、层数和卵粒数量,获得了卵块面积,建立了卵粒数量与卵块面积的指数函数模型：Y=e(2.1596×0.00832X),并依据该模型提出了根据卵块面积测算卵粒数量的分级表。该方法为田间调查中卵块卵粒数量量的快速估计提供了参考。     

All eggs are made equal: meta‐analysis of egg sexual size dimorphism in birds

Sex‐biased resource allocation in avian eggs has gained increasing interest. The adaptive explanations of such allocation are often related to life‐history strategies of the studied species. In some species, egg sexual size dimorphism (SSD) was suggested to promote future size differences between adults of each sex. In other species, egg SSD was invoked as an adaptive means by which a mother balances sex‐specific nestling mortality. According to the first scenario, mothers should produce bigger eggs for the bigger sex, thus across species, adult SSD should be a significant positive predictor of egg SSD. Under the second scenario, mothers should produce bigger eggs for the smaller sex. If different species use contrasting strategies, then a universal expectation is that there should be a significant relationship between the magnitude of adult SSD and the magnitude of egg SSD, irrespective of the direction of those differences. Our aim was to examine whether the direction of egg SSD is predicted by the direction of adult SSD or whether degree of egg SSD is related to degree of adult SSD. To answer that question, we performed meta‐analysis of 63 studies, which included information on egg SSD of 65 effect sizes from 51 avian species. We found that across species, adult SSD does not predict egg SSD. More importantly, the observed variation in effect sizes in our data set was largely explained by sampling error (variance). Although adult SSD is undoubtedly a prominent feature of birds, there is little evidence for egg SSD across avian species.     

收集甜菜夜蛾卵的简便方法

介绍了一种收集甜菜夜蛾SpodopteraexiguaH櫣ｂｎｅｒ卵的简单而有效的方法 ,收卵率达 90 %以上     

Within clutch co-variation of egg mass and sex in the black-headed gull

Female birds of several species have control over the production of daughters and sons. However, most studies failed to find a relationship between egg size and sex. This is intriguing as adjustment of egg size would constitute a powerful tool for the female to meet different resource demands of the sexes, particularly in size dimorphic species. Our results show that, within clutches of black-headed gulls (Larus ridibundus) the proportion of males was positively associated with egg mass. This applied for all three laying positions, independently of the absolute egg mass. There was a significant relationship between the distribution of the sexes over the laying sequence and the egg mass change. When egg mass decreased over the sequence, first-laid eggs were male biased and last-laid eggs female biased, and vice versa. The potential adaptive value of this allocation strategy is evaluated with regard to male sensitivity to egg quality and competitive differences between the sexes.     

一种采集稻纵卷叶螟卵的高效简便新方法

研究了稻纵卷叶螟Cnaphalocrocis medinalis Guenee的"烧杯+湿纱布"卵收集方法,并与"塑料袋收集法"和"塑料杯收集法"进行了比较。结果表明,"烧杯+湿纱布"卵收集法能显著地延长了稻纵卷叶螟成蛾的寿命、提高单雌产卵量和卵孵化率。采用此法收集稻纵卷叶螟的卵更高效和简便。     

The protective role of endogenous bacterial communities in chironomid egg masses and larvae

Insects of the family Chironomidae, also known as chironomids, are distributed worldwide in a variety of water habitats. These insects display a wide range of tolerance toward metals and organic pollutions. Bacterial species known for their ability to degrade toxicants were identified from chironomid egg masses, leading to the hypothesis that bacteria may contribute to the survival of chironomids in polluted environments. To gain a better understanding of the bacterial communities that inhabit chironomids, the endogenous bacteria of egg masses and larvae were studied by 454-pyrosequencing. The microbial community of the egg masses was distinct from that of the larval stage, most likely due to the presence of one dominant bacterial Firmicutes taxon, which consisted of 28% of the total sequence reads from the larvae. This taxon may be an insect symbiont. The bacterial communities of both the egg masses and the larvae were found to include operational taxonomic units, which were closely related to species known as toxicant degraders. Furthermore, various bacterial species with the ability to detoxify metals were isolated from egg masses and larvae. Koch-like postulates were applied to demonstrate that chironomid endogenous bacterial species protect the insect from toxic heavy metals. We conclude that chironomids, which are considered pollution tolerant, are inhabited by stable endogenous bacterial communities that have a role in protecting their hosts from toxicants. This phenomenon, in which bacteria enable the continued existence of their host in hostile environments, may not be restricted only to chironomids.     

Mediterranean flour moth Ephestia kuehniella eggs and larvae exposed to a static magnetic field and preference by Trichogramma embryophagum

This study investigated the effect of strong magnetic fields as insecticidal activity on Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) larvae and eggs at different stages of development and their preference by the egg parasitoid, Trichogramma embryophagum Hartig (Hymenoptera: Trichogrammatidae). Eggs ranging in age from 24-h to 48-h and 72-h-old and larvae (1 to 2 days) were exposed to 1.4 Tesla (T) magnetic fields from a DC power supply at 50 Hz for different time periods (3, 6, 12, 24, 48 and 72 h). Twelve hours of exposure at 1.4 T was toxic to 24-h-old eggs of E. kuehniella. The 72-h-old host eggs treated with 1.4 T for 6–72 h were not significantly preferred by T. embryophagum. The magnetic field was toxic to 24-h-old eggs of E. kuehniella exposed to 1.4 T for 12. The treatment of magnetic fields on the 72-h-old host egg with 1.4 T at 6–72 h was not significantly preferred by T. embryophagum. Magnetization of 24-h-old eggs of E. kuehniella for 3 h could be effectively used with T. embryophagum as sterilised host eggs. These eggs were markedly preferred by T. embryophagum. The LT₅₀ and LT₉₉ values of magnetic fields at different egg stages of E. kuehniella, and larvae were measured. A level of 1.4 T at 72 h completely prevented the development of the larvae. There was no significant effect on larval survival at 1.4 T at 48 and 72 h. Increasing magnetic fields exposure times for eggs that were 24-h, 48-h and 72-h-old prevented larval emergence and increased their mortality rate. Consequently, magnetic fields could be used in controlling stored-product pest eggs and larvae of E. kuehniella.     

一种采集水稻二化螟卵(块)的高效简便新方法

比较了二化螟Chilosuppressalis卵块的塑料袋收集法和稻株法。结果表明 ,塑料袋法和稻株法收集的卵粒总数及卵孵化率都没有显著的差异 ,均为 2 79粒卵 雌蛾和 95 %。塑料袋法收集的卵块数较稻株法的多 ,但小卵块比例较高 ( <1 0 0粒卵 卵块 )。还讨论了采用塑料袋法收集二化螟及其它昆虫卵的优点。     

Endogenous and exogenous factors affecting parasitism of gypsy moth egg masses by shape Ooencyrtus kuvanae

Factors affecting the orientation, reproduction, and sex ratio of the egg parasitoid Ooencyrtus kuvanae Howard were examined. Adult females were attracted to airborne volatiles from the egg mass and accessory gland of the primary host, the gypsy moth Lymantria dispar L. Visual cues also affected host selection. Background colors against which egg masses were placed affected oviposition preference. In the absence of egg masses, color variation did not affect wasp behavior. Light is required for parasitism by O. kuvanae. The age and density of both the host and parasitoid affected wasp reproduction and sex ratios. Older egg masses issued relatively fewer wasps and higher proportions of males than did young egg masses. Likewise, wasp reproduction and the proportion of females declined with wasp age. Larger egg masses produced more wasps and lower proportions of males than did smaller egg masses. The number of offspring per female, and the proportion of female offspring, were inversely related to wasp density. Implications to biological control of the gypsy moth and parasitoid ecology are discussed.     

A simple tool for calculating egg shape,volume and surface area from digital images

The geometrical properties of eggs – such as volume and surface area – have uses ranging from ecological, physiological and morphological studies in birds, to predictions of chick condition in the poultry industry. Although measurements of an egg's length and breadth can be used to approximate its geometry, the coefficients used in these models are specific to the original test population, and intraspecific variation in egg shape means these methods cannot be used reliably beyond that population. Here I present a novel mathematical formula to describe the curvature of a bird's egg that can be used to calculate the shape, volume and surface area of an egg precisely from digital images. Using data from several species I demonstrate that the model has a greater level of accuracy than length‐ and breadth‐based methods, and release the user‐friendly tool for others to use for measuring eggs from digital images.     

Oviposition behaviour and distribution of egg masses of the European leaf roller,Archips rosanus (L.), on citrus trees

The citrus leaf roller (CLR), Archips rosanus, a threatening pest of leaves and fruitlets on fruit trees, which in recent years has led to considerable damage to different citrus trees in some parts of the Mazandaran province of Iran. Insect activity on citrus trees causes the growth of buds and leaves to stop and foliage to dry. Pest oviposition as egg masses occurs on the host tree’s trunk. Eggs spent a year in the hibernation stage and, in the following spring, hatched the first instar larvae that fed on the opened buds. The distributions of CLR egg masses, deposited in 2015–2016, were evaluated on the Thomson novel cultivar (Citrus sinensis L.) in the northern region of Iran. The results showed that the numbers of egg masses laid on the trees at different height ranges of 0–50, 50–100, 100–150 and 150–200 cm were, respectively, 38.65, 33.78, 18.54 and 9.03%. The mean number of A. rosanus eggs per mass, however, was not significant at different heights of the tree. Also, most of the egg masses were laid in the north and south directions in comparison with the west and east directions, with no significant difference in mean number in different geographical directions.     

Avian eggshell thickness in relation to egg morphometrics,embryonic development,and mercury contamination

Eggshell thickness is important for physiological, ecological, and ecotoxicological studies on birds; however, empirical eggshell thickness measurements for many species and regions are limited. We measured eggshell thickness at the equator and the egg poles for 12 avian species and related eggshell thickness to egg morphometrics, embryonic development, egg status, and mercury contamination. Within an egg, eggshells were approximately 5.1% thicker at the equator than the sharp pole of the egg, although this difference varied among species (0.6%–9.8%). Within Forster's tern (Sterna forsteri), where eggshell thickness was measured at 5 equally spaced positions along the longitude of the egg, eggshell thickness changed more rapidly near the sharp pole of the egg compared to near the blunt pole of the egg. Within species, eggshell thickness was related to egg width and egg volume for six of the 12 species but was not related to egg length for any species. Among species, mean eggshell thickness was strongly related to species mean egg width, egg length, egg volume, and bird body mass, although species mean body mass was the strongest predictor of species mean eggshell thickness. Using three species (American avocet [Recurvirostra americana], black‐necked stilt [Himantopus mexicanus], and Forster's tern), whose nests were carefully monitored, eggshell thickness (including the eggshell membrane) did not differ among viable, naturally abandoned, dead, or failed‐to‐hatch eggs; was not related to total mercury concentrations of the egg content; and did not decrease with embryonic age. Our study also provides a review of all existing eggshell thickness data for these 12 species.     

Transgenic rice plants with a synthetic cry1Ab gene from Bacillus thuringiensis were highly resistant to eight lepidopteran rice pest species

To fully explore the resistance potential of transgenic rice produced by Agrobacterium-mediated transformation, an elite line KMD1 was assessed for its resistance to eight lepidopteran rice pest species. KMD1 contained a synthetic cry1Ab gene from Bacillus thuringiensis under the control of a maize ubiquitin promoter. It was derived from a commercial japonica Chinese rice variety Xiushui 11, and bred true for both agronomic traits and a cry1Ab gene when the bioassays were done in 1998 in the R₅ generation. The eight lepidopteran pest species were: four Pyralidae species: Chilo suppressalis (striped stem borer, SSB), Scirpophaga incertulas (yellow stem borer, YSB), Cnaphalocrocis medinalis (leaf folder), Herpitogramma licarisalis; two Noctuidae: Sesamia inferens (pink stem borer, PSB) and Naranga anescens; one Stayridae: Mycalesis gotama; and one Hesperiidae, Parnara guttata. In laboratory bioassays, 100% mortality was observed in all insect species when their newly hatched or third-instar larvae were fed KMD1 leaf tissues, whereas only 9.65% of the neonates and none of the third-instar larvae died when fed the leaf tissues of non-transgenic control. Moreover, the leaf area of control tissues consumed in four days by stem borers was 20 to 40 times higher than that of KMD1 tissues, and the area of control tissues eaten by leaf-feeding species was 120 to 180 times greater than that of the transgenic tissues. Under natural infestation, no KMD1 plant was visibly damaged by the SSB, YSB and leaf folder in field evaluation. On the other hand, 80, 9.3 and 88.7% of control plants were injured by SSB, YSB, and leaf folder, respectively. These data disclosed that the transgenic line was highly resistant to a broad spectrum of lepidopteran insect species and could be useful in insect resistance breeding programs.     

Sex-related variations of serum immunoglobulins during reproduction in gilthead sea bream and evidence for a transfer from the female to the eggs

A significant elevation of serum immunoglobulin (Ig) concentration occurred in female gilthead sea bream Sparus aurata during spawning. Furthermore, a progressive rise of serum Ig level was observed throughout the process of sexual inversion (from functional male to functional female), suggesting that the synthesis of Ig could be regulated by sex-related factors (probably sexual hormones) involved in the process of oogenesis. The immunoglobulins of eggs were purified by affinity chromatography on protein A-sepharose. SDS-PAGE and Western blot analysis showed reactivity of the antiserum Pab1 with the Ig heavy and light chains, and some degradation products. This purification process yielded detectable amounts of Ig. The sex-related increase of serum Ig during the reproductive period, and the detection of Ig in eggs suggest a transfer of Ig from the blood of the adult female.     

Identification of fish species by an egg identification key: an alternative to the incubation of eggs and rearing of larvae for species recognition

Comparison of the results of two methods for species recognition, an egg identification key and rearing of larvae, showed only small qualitative differences in the identification of fish species present in a stretch of the River Elbe, Germany. Both the identification key and rearing methods complement each other as methods of identification, and the selection of which method to be used should depend primarily on the aim of the investigation.     

A simple method to estimate percentage parasitism when the host and parasitoid phenologies are unknown: A statistical approach

When host and parasitoid phenologies areunknown the estimation of the generationalpercentage parasitism poses severalmethodological problems. We developed a simplemethod, based on a statistical approach, tosolve that problem. An unbiased estimator wasfound, named _CR, of thegenerational percentage parasitism, and itsperformance was tested through the analysis ofdata from two host-parasitoid systems: Phyllonorycter crataegella (Clemens)(Lepidoptera: Gracillariidae) and Sympiesis marylandensis (Girault)(Hymenoptera: Eulophidae), and Pierisrapae L. (Lepidoptera: Pieridae) and Cotesia (Apanteles) glomerata (L)(Hymenoptera: Braconidae). The _CR estimator proved to be a goodapproximation of the generational percentageparasitism, but its 95% confidence intervalwas very wide. The performance of the _CR estimator was improved and the95% confidence interval was smaller when someinformation on host and parasitoid phenologieswas added. The results suggested that thesmaller interval _CR ± onestandard deviation would contain with a greatprobability the generational percentageparasitism.     

Host selection and egg allocation behaviour by Aphytis melinus and A.lingnanensis: comparison of two facultatively gregarious parasitoids

Abstract. 1. The ovipositional and egg allocation behaviour of individual females of Aphytis melinus DeBach and A.lingnunensis Compere were compared.
2. Both Aphytis species exhibit the same behavioural sequence during oviposition.
3. Aphytis melinus laid most of its female eggs on the dorsum of a scale-insect beneath its cover, and most of its male eggs under the scale-insect's body. Aphytis lingnanensis also oviposited both dorsally and ventrally on scale-insect hosts, but female and male progeny arose with equal frequency from eggs laid in both locations.
4. Both A.melinus and A. lingnanensis are facultatively gregarious parasitoids. The degree of gregariousness depends on host size, i.e. the larger the host, the more the Iikelihood that several eggs will be deposited at each visit by the parasitoid.
5. When two eggs were laid during the same host visit, both A.melinus and A.lingnanensis laid one female and one male egg more often than would be expected under an assumption of random allocation of sexes.
6. Because A.melinus successfulIy utilize smaller hosts than A.lingnanensis to produce progeny, these parasitoids should not be considered ecological homo-logues, as suggested by DeBach & Sundby (1963).     

Ca2+ release from intracellular stores by thapsigargin in sea urchin eggs: Relationship to larval development and relevance in egg activation

Thapsigargin (Tg), an inhibitor of microsomal Ca²⁺ ATPase, is used as a tool to study the changes in Ca²⁺ sequestration in sea urchin eggs and their relationship to embryonic development. Micromolar amounts of Tg inhibit ATP-dependent Ca²⁺ sequestration in a dose-dependent and non-reversible manner, depending on the bulk of biological material used. IC_5O values are 1 nmol/L and 1–10μmol/L, respectively, in the cortical Ca²⁺ stores (isolated cortices preparation) and in digitonin-permeabilized eggs, a preparation giving access to the deeper reticulum compartment. Micromolar Tg does not induce Ca²⁺ release from ⁴⁵Ca pre-loaded cortices but leads to a loss of 25% of the total Ca²⁺ content from the cortical area. Using microspectrofluorimetry of fura-2-loaded eggs, we found that 10 μmol/L Tg induced a moderate rise in cytosolic Ca²⁺ activity as compared with the fertilization-induced Ca²⁺ transient whether eggs were fertilized or not. Early events related to fertilization as, for example, elevation of the fertilization envelope, proton excretion and sustained increase of amino acid uptake, are triggered by 10μmol/L Tg but with a delayed onset relative to sperm-induced effects. The present findings indicate that although it triggers most fertilization-related events, Tg cannot be considered as a true mitotic agent in sea urchin eggs. When added after fertilization, Tg affects cleavage and the further embryonic development giving rise to abnormalities comparable to the animalized larvae obtained with other compounds responsible for the inhibition of reticular Ca²⁺ sequestration.     

A method to evaluate relative ovicidal effects of soil microfungi on thick-shelled eggs of animal-parasitic nematodes

Thick-shelled eggs of animal-parasitic ascarid nematodes can survive and remain infective in the environment for years. The present study evaluated a simple in vitro method and evaluation scheme to assess the relative effect of two species of soil microfungi, Pochonia chlamydosporia Biotype 10 and Purpureocillium lilacinum Strain 251 (Ascomycota: Hypocreales), on the development and survival of eggs of faecal origin of three ascarid species, Ascaridia galli (chicken roundworm), Toxocara canis (canine roundworm) and Ascaris suum (pig roundworm). Ascarid eggs were embryonated on water agar with or without a fungus, and the resulting viability of the eggs was evaluated on days 7, 14, 21, 28, 35 and 42 post exposure (pe) by observing eggs in situ. On days 7–42 pe, P. chlamydosporia had reduced the viability of A. galli and T. canis eggs by 64–86% and 26–67%. Corresponding reductions for P. lilacinum Strain 251 were only 15–29% and 4–28%. In contrast, A. suum eggs were extremely resistant to both fungi (2–4% reduction). The differences in results are likely due to different morphologies and chemistry of the egg shell of the three ascarid species. The current in vitro method and evaluation criteria allow for a simple, repeatable and non-invasive evaluation of the ovicidal effects of microfungi. This study demonstrates that P. chlamydosporia Biotype 10 may be utilised as a biocontrol agent to reduce A. galli and T. canis egg contamination of the environment.