scholarly journals How to escape from insect egg parasitoids: a review of potential factors explaining parasitoid absence across the Insecta

2020 ◽  
Vol 287 (1931) ◽  
pp. 20200344
Author(s):  
N. E. Fatouros ◽  
A. Cusumano ◽  
F. Bin ◽  
A. Polaszek ◽  
J. C. van Lenteren
Keyword(s):  
Egg Size ◽  
Life Stage ◽  
Egg Parasitoids ◽  
Mortality Factors ◽  
Mortality Risks ◽  
Egg Parasitism ◽  
Herbivorous Species ◽  
Potential Factors ◽  
The Many ◽  
Egg Care

The egg is the first life stage directly exposed to the environment in oviparous animals, including many vertebrates and most arthropods. Eggs are vulnerable and prone to mortality risks. In arthropods, one of the most common egg mortality factors is attack from parasitoids. Yet, parasitoids that attack the egg stage are absent in more than half of all insect (sub)orders. In this review, we explore possible causes explaining why eggs of some insect taxa are not parasitized. Many insect (sub)orders that are not attacked by egg parasitoids lack herbivorous species, with some notable exceptions. Factors we consider to have led to escape from egg parasitism are parental egg care, rapid egg development, small egg size, hiding eggs, by e.g. placing them into the soil, applying egg coatings or having thick chorions preventing egg penetration, eusociality, and egg cannibalism. A quantitative network analysis of host–parasitoid associations shows that the five most-speciose genera of egg parasitoids display patterns of specificity with respect to certain insect orders, especially Lepidoptera and Hemiptera, largely including herbivorous species that deposit their eggs on plants. Finally, we discuss the many counteradaptations that particularly herbivorous species have developed to lower the risk of attack by egg parasitoids.

Investigations on Trichogramma lutea, Gir., as a Parasite of the Cotton Bollworm, Heliothis obsoleta, Fabr.

1936 ◽  
Vol 27 (2) ◽  
pp. 219-235 ◽  
Author(s):  
F. S. Parsons ◽  
G. C. Ullyett
Keyword(s):  
Winter Season ◽  
Larval Survival ◽  
Egg Laying ◽  
Mortality Factors ◽  
Cool Season ◽  
Large Numbers ◽  
Typical Experiment ◽  
Egg Parasitism ◽  
Citrus Orchards ◽  
Low Degrees

Some of the problems involved in the estimation of parasitism in populations of Heliothis eggs are discussed:—(a) Effective parasitism of the “active fraction” of eggs as laid in situ is denned.(b) The habits of the egg-laying moth in point of the duration of oviposition on individual crops and diversion of moth activity from one host to another are discussed in relation to releases of Trichogramma lutea. Data are given on the distribution of bollworm eggs in a crop and associated factors.(c) Investigations on the dispersion of liberated parasites are described. Dispersion was found to be rapid and widespread; concerted activity by large numbers in given areas did not apply.Investigations in rain-grown crops are described and results are quoted from a typical experiment in maize, wherein the percentages of parasitism recorded in a large number of equal sections of the crop are regressed on proportionate larval survival. Although the egg parasitism ranged from 21·2 per cent, to 82·3 per cent., differences in larval populations were inappreciable. An explanation for this is offered in an analysis of the effect of various mortality factors.The parasite was relatively ineffective in cotton crops. The low degrees of parasitism found are assigned to the growth-habit of the plant, the scattered manner of egg deposition thereon and the impediment offered to the insect by the dense hair processes of the plant at many sites where eggs are commonly placed.Investigations on irrigated (cool season) market-garden crops and citrus orchards are described. These form the principal breeding sources of summer bollworm. Oviposition is extensive and sustained for three to four months on these crops, thereby affording opportunity for continuous parasite activity and the cumulative participation of progeny bred in the field. In nature Trichogramma lutea does not, however, appear until the latter end of the egg-laying by Heliothis and the authors were unable to establish laboratory-bred representatives at an earlier period.Another egg parasite, Phanurus ullyetti, is prevalent before Trichogramma appears and accomplishes much that was hoped for from the attempted earlier introduction of Trichogramma. In effect, the latter, as seen from diagrams furnished with the paper, becomes substituted for Phanurus toward the close of the winter season. It is probable that temperature is a determining factor in the biology of both parasites, although other causes for the observed relations are suggested.Further investigations are needed on the subject of exploiting T. lutea in the cool season.

Biotic mortality factors affecting emerald ash borer (Agrilus planipennis) are highly dependent on life stage and host tree crown condition

2015 ◽  
Vol 105 (5) ◽  
pp. 598-606 ◽  
Author(s):  
D.E. Jennings ◽  
J.J. Duan ◽  
P.M. Shrewsbury
Keyword(s):  
North America ◽  
Natural Enemies ◽  
Life Stage ◽  
Emerald Ash Borer ◽  
Agrilus Planipennis ◽  
Host Tree ◽  
Tree Crown ◽  
Crown Condition ◽  
Mortality Factors ◽  
Tree Resistance

AbstractEmerald ash borer (EAB), Agrilus planipennis, is a serious invasive forest pest in North America responsible for killing tens to hundreds of millions of ash trees since it was accidentally introduced in the 1990s. Although host-plant resistance and natural enemies are known to be important sources of mortality for EAB in Asia, less is known about the importance of different sources of mortality at recently colonized sites in the invaded range of EAB, and how these relate to host tree crown condition. To further our understanding of EAB population dynamics, we used a large-scale field experiment and life-table analyses to quantify the fates of EAB larvae and the relative importance of different biotic mortality factors at 12 recently colonized sites in Maryland. We found that the fates of larvae were highly dependent on EAB life stage and host tree crown condition. In relatively healthy trees (i.e., with a low EAB infestation) and for early instars, host tree resistance was the most important mortality factor. Conversely, in more unhealthy trees (i.e., with a moderate to high EAB infestation) and for later instars, parasitism and predation were the major sources of mortality. Life-table analyses also indicated how the lack of sufficient levels of host tree resistance and natural enemies contribute to rapid population growth of EAB at recently colonized sites. Our findings provide further evidence of the mechanisms by which EAB has been able to successfully establish and spread in North America.

scholarly journals Genetic architecture of rainbow trout survival from egg to adult

2010 ◽  
Vol 92 (1) ◽  
pp. 1-11 ◽  
Author(s):  
HARRI VEHVILÄINEN ◽  
ANTTI KAUSE ◽  
HEIKKI KOSKINEN ◽  
TUIJA PAANANEN
Keyword(s):  
Life Cycle ◽  
Rainbow Trout ◽  
Genetic Architecture ◽  
Life Stage ◽  
Genetic Correlations ◽  
Early Period ◽  
Mortality Factors ◽  
Time To Death ◽  
Life Cycle Stages ◽  
Binary Character

SummarySurvival from birth to a reproductive adult is a challenge that only robust individuals resistant to a variety of mortality factors will overcome. To assess whether survival traits share genetic architecture throughout the life cycle, we estimated genetic correlations for survival within fingerling stage, and across egg, fingerling and grow-out stages in farmed rainbow trout. Genetic parameters of survival at three life cycle stages were estimated for 249 166 individuals originating from ten year classes of a pedigreed population. Despite being an important fitness component, survival traits harboured significant but modest amount of genetic variation (h2=0·07–0·27). Weak associations between survival during egg-fry and fingerling periods, between early and late fingerling periods (rG=0·30) and generally low genetic correlations between fingerling and grow-out survival (mean rG=0·06) suggested that life-stage specific survival traits are best regarded as separate traits. However, in the sub-set of data with detailed time of death records, positive genetic correlations between early and late fingerling survival (rG=0·89) showed that during certain years the best genotypes in the early period were also among the best in the late period. That survival across fingerling period can be genetically the same, trait was indicated also by only slightly higher heritability (h2=0·15) estimated with the survival analysis of time to death during fingerling period compared to the analysis treating fingerling survival as a binary character (h2=0·11). The results imply that (1) inherited resistance against unknown mortality factors exists, but (2) ranking of genotypes changes across life stages.

Egg mortality of the brown planthopper, Nilaparvata lugens (Homoptera: Delphacidae) and green leafhoppers, Nephotettix spp. (Homoptera: Cicadellidae), on rice in Sri Lanka

1991 ◽  
Vol 81 (2) ◽  
pp. 161-167 ◽  
Author(s):  
S.V. Fowler ◽  
M.F. Claridge ◽  
J.C. Morgan ◽  
I.D.R. Peries ◽  
L. Nugaliyadde
Keyword(s):  
Sri Lanka ◽  
Spatial Scales ◽  
Brown Planthopper ◽  
Nilaparvata Lugens ◽  
Egg Parasitoids ◽  
Dependent Relationship ◽  
Egg Density ◽  
Egg Parasitism ◽  
A Minor

AbstractRice plants, infested with eggs of Nilaparvata lugens (Stål) or Nephotettix spp. in laboratory cultures, were used to trap egg parasitoids in rice fields at two sites over a period of four days in Sri Lanka. Levels of egg parasitism per plant varied from 0 to 54% in N. lugens and 45 to 100% in Nephotettix spp. Egg predation was a minor cause of mortality, but attack by a species of Panstenon (Hymenoptera: Pteromalidae) killed up to 18% Nilaparvata lugens eggs. N. lugens eggs were parasitized by Anagrus sp. nr flaveolus Waterhouse, A. optabilis (Perkins) (Hymenoptera: Mymaridae) and Oligosita sp. (Hymenoptera: Trichogrammatidae). Nephotettix spp. eggs were parasitized by two species of Gonatocerus (Hymenoptera: Mymaridae) and one of Paracentrobia (Hymenoptera: Trichogrammatidae). There was no overlap in field host range between the two parasitoid assemblages. Gonatocerus spp. and Paracentrobia spp. seldom attacked the same Nephotettix sp. egg batch, suggesting the possibility that these species compete in the field. Overall egg parasitism of Nilaparvata lugens was positively related to host egg density at the spatial scale of the rice plant, but unrelated at the tiller or batch scale. Nephotettix spp. egg parasitism showed a negative density dependent relationship at the spatial scales of the tiller and plant and no relationship at the batch level. The potential role of these egg parasitoids in preventing outbreaks of hopper pests in Sri Lanka is discussed.

Does feeding zone influence egg size in slow-breeding seabirds?

2015 ◽  
Vol 93 (8) ◽  
pp. 589-592 ◽  
Author(s):  
F. Stephen Dobson ◽  
Pierre Jouventin
Keyword(s):  
Life History ◽  
Egg Size ◽  
Rapid Development ◽  
Bird Species ◽  
Reproductive Traits ◽  
Positive Association ◽  
Female Body Mass ◽  
Feeding Zone ◽  
Egg Care ◽  
Compensation Hypothesis

In several bird species, mothers that endow their eggs with additional resources benefit from more rapid development and more robust offspring. We examined egg size and associated life-history traits in 44 species of the slow-breeding procellariiform seabirds (albatrosses and petrels). The far distant foraging of some of the species should subject them to difficult ecological conditions and perhaps delays in return to the nest. Such delays might lead to poorer egg care by the remaining parent. To compensate, we predicted a positive association of egg size with foraging zone (offshore, near pelagic, far pelagic), and both with the length of incubation shifts. We tested this hypothesis and also examined egg size and fitness-related reproductive traits. Egg size scaled significantly and tightly with female body mass (β = 0.72, R2 = 0.98). After influences of both size and phylogeny were removed, however, egg size was positively and significantly associated with both mean length of incubation shift and feeding zone (r = 0.45 and 0.46, respectively), perhaps indicating a life-history syndrome of egg size, incubation, and distance that species go to forage during the breeding season, and supporting the compensation hypothesis.

scholarly journals Advice in Defined Contribution Plans

2017 ◽  
Author(s):  
Gordon L. Clark ◽  
Maurizio Fiaschetti ◽  
Peter Tufano
Keyword(s):  
Baby Boomers ◽  
Life Stage ◽  
Retirement Age ◽  
Defined Contribution ◽  
New Wave ◽  
Health Issues ◽  
Family Work ◽  
Average Lifespan ◽  
Defined Contribution Plans ◽  
The Many

As Baby Boomers reach retirement age, they are reshaping the landscape of the retirement phase with a shift in their mindset; they are pursuing old dreams, exploring new opportunities, and thinking about retirement in an entirely new manner. In this chapter the authors examine how Americans are preparing for retirement and analyze the life priorities that are most important to today’s retirees: Health, Home, Family, Work, Giving, Finances, and Leisure. Although there is much optimism and opportunity that comes with this new wave of retirement, there is new concern as well. As the average lifespan increases, health issues are also becoming more prevalent. This chapter explores the many issues, both positive and negative, that both create and are a result of this new take on the retirement life stage.

scholarly journals Parasitism of Locally Recruited Egg Parasitoids of the Fall Armyworm in Africa

Insects ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 430
Author(s):  
Saidou A. Laminou ◽  
Malick Niango Ba ◽  
Laouali Karimoune ◽  
Ali Doumma ◽  
Rangaswamy Muniappan
Keyword(s):  
Fall Armyworm ◽  
Field Testing ◽  
Egg Parasitoids ◽  
Management Approach ◽  
Egg Masses ◽  
Cropping Season ◽  
Egg Parasitism ◽  
Augmentative Releases ◽  
On Farm ◽  
Telenomus Remus

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is an insect native to the tropical and subtropical Americas that has recently spread to Africa, where it predominately attacks maize, sorghum and other plant species. Biological control is an environmentally friendly way of combatting the pest and contributes to an integrated pest management approach. In Africa, several trichogrammatid parasitoids and Telenomus remus Nixon (Hymenoptera: Platygastridae) have been found parasitizing eggs of the FAW. In Niger, the egg parasitoids encountered include Trichogrammatoidea sp. (Hymenoptera: Trichogrammatidae) and Telenomus remus Nixon. Parasitism of the FAW eggs by the two egg parasitoids was assessed in the laboratory, followed by field testing on sentinel eggs. In the laboratory, T. remus parasitized on average 78% of FAW eggs, compared to 25% for Trichogrammatoidea sp. Telenomus remus was able to parasitize egg masses that were fully covered with scales, while Trichogrammatoidea sp. parasitized only uncovered egg masses. On-farm releases of T. remus in sorghum fields caused up to 64% of FAW egg parasitism. Parasitized eggs yielded viable progeny, which can contribute to FAW egg parasitism build-up during the cropping season. Our findings lay the groundwork for the use of T. remus in augmentative releases against FAW in Africa.

scholarly journals Getting the whole story: Integrating patient complaints and staff reports of unsafe care

2021 ◽  
pp. 135581962110293
Author(s):  
Jackie Van Dael ◽  
Alex Gillespie ◽  
Tom Reader ◽  
Katelyn Smalley ◽  
Dimitri Papadimitriou ◽  
...  
Keyword(s):  
Heterogeneous Data ◽  
Incident Reporting ◽  
Patient Complaints ◽  
The United Kingdom ◽  
Incident Reporting Systems ◽  
Level Data ◽  
Incident Reports ◽  
Potential Factors ◽  
The Many ◽  
Reporting Data

Objective It is increasingly recognized that patient safety requires heterogeneous insights from a range of stakeholders, yet incident reporting systems in health care still primarily rely on staff perspectives. This paper examines the potential of combining insights from patient complaints and staff incident reports for a more comprehensive understanding of the causes and severity of harm. Methods Using five years of patient complaints and staff incident reporting data at a large multi-site hospital in London (in the United Kingdom), this study conducted retrospective patient-level data linkage to identify overlapping reports. Using a combination of quantitative coding and in-depth qualitative analysis, we then compared level of harm reported, identified descriptions of adjacent events missed by the other party and examined combined narratives of mutually identified events. Results Incidents where complaints and incident reports overlapped (n = 446, reported in 7.6%’ of all complaints and 0.6% of all incident reports) represented a small but critical area of investigation, with significantly higher rates of Serious Incidents and severe harm. Linked complaints described greater harm from safety incidents in 60% of cases, reported many surrounding safety events missed by staff (n = 582), and provided contesting stories of why problems occurred in 46% cases, and complementary accounts in 26% cases. Conclusions This study demonstrates the value of using patient complaints to supplement, test, and challenge staff reports, including to provide greater insight on the many potential factors that may give rise to unsafe care. Accordingly, we propose that a more holistic analysis of critical safety incidents can be achieved through combining heterogeneous data from different viewpoints, such as through the integration of patient complaints and staff incident reporting data.

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