scholarly journals Defense of Milkweed Bugs (Heteroptera: Lygaeinae) against Predatory Lacewing Larvae Depends on Structural Differences of Sequestered Cardenolides

Insects ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 485
Author(s):  
Prayan Pokharel ◽  
Marlon Sippel ◽  
Andreas Vilcinskas ◽  
Georg Petschenka
Keyword(s):  
Defense Mechanisms ◽  
Insect Species ◽  
Predator Prey ◽  
Plant Toxins ◽  
Structural Differences ◽  
Insect Populations ◽  
Context Specific ◽  
Plant Choice ◽  
Full Factorial ◽  
Lygaeus Equestris

Predators and parasitoids regulate insect populations and select defense mechanisms such as the sequestration of plant toxins. Sequestration is common among herbivorous insects, yet how the structural variation of plant toxins affects defenses against predators remains largely unknown. The palearctic milkweed bug Lygaeus equestris (Heteroptera: Lygaeinae) was recently shown to sequester cardenolides from Adonis vernalis (Ranunculaceae), while its relative Horvathiolus superbus also obtains cardenolides but from Digitalis purpurea (Plantaginaceae). Remarkably, toxin sequestration protects both species against insectivorous birds, but only H. superbus gains protection against predatory lacewing larvae. Here, we used a full factorial design to test whether this difference was mediated by the differences in plant chemistry or by the insect species. We raised both species of milkweed bugs on seeds from both species of host plants and carried out predation assays using the larvae of the lacewing Chrysoperla carnea. In addition, we analyzed the toxins sequestered by the bugs via liquid chromatography (HPLC). We found that both insect species gained protection by sequestering cardenolides from D. purpurea but not from A. vernalis. Since the total amount of toxins stored was not different between the plant species in H. superbus and even lower in L. equestris from D. purpurea compared to A. vernalis, the effect is most likely mediated by structural differences of the sequestered toxins. Our findings indicate that predator–prey interactions are highly context-specific and that the host plant choice can affect the levels of protection to various predator types based on structural differences within the same class of chemical compounds.

EFFECT OF KAIROMONE ON PREDATOR–PREY DYNAMICS — A DELAY MODEL

2013 ◽  
Vol 06 (05) ◽  
pp. 1350035 ◽  
Author(s):  
SUDIP SAMANTA ◽  
JOYDEV CHATTOPADHYAY
Keyword(s):  
Vertical Migration ◽  
Defense Mechanisms ◽  
Multiple Delays ◽  
Predator Population ◽  
Delay Model ◽  
Refuge Use ◽  
Predator Prey ◽  
Interior Equilibrium ◽  
Fish Kairomone ◽  
The Stability

In most of the predator–prey systems, prey individuals make transitions between vulnerable and invulnerable states or locations. This transition is regulated by various inducible defense mechanisms. Diel vertical migration (DVM) in zooplankton is the most effective and instantaneous defense observed in zooplankton population. Zooplankton shows downward vertical migration in the daytime in the presence of predators (or predator kairomones) to avoid predation (i.e. refuge use), and it enters into the surface water again at night to graze phytoplankton. The dynamics of the planktonic ecosystem under DVM of zooplankton along with fish kairomone and the multiple delays due to migration for vulnerable and invulnerable prey and reproduction in the predator population is of considerable interest both in theoretical and experimental ecologists. By developing mathematical model, we analyze such a system. The conditions for which the system enters into Hopf-bifurcation are obtained. Moreover, the conditions for which the bifurcating branches are supercritical are also derived. Our results indicate that DVM along with the effect of kairomone and multiple delays with a certain range are responsible to enhance the stability of the system around the positive interior equilibrium point.

scholarly journals Pine Pitch Canker and Insects: Regional Risks, Environmental Regulation, and Practical Management Options

Forests ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 649 ◽  
Author(s):  
Mercedes Fernández-Fernández ◽  
Pedro Naves ◽  
Dmitry L. Musolin ◽  
Andrey V. Selikhovkin ◽  
Michelle Cleary ◽  
...  
Keyword(s):  
Forest Management ◽  
Management Practices ◽  
Environmental Control ◽  
Pathogenic Fungus ◽  
Insect Species ◽  
Pitch Canker ◽  
Management Options ◽  
Pine Trees ◽  
Insect Populations ◽  
The Impact

Pine pitch canker (PPC), caused by the pathogenic fungus Fusarium circinatum (Nirenberg and O’ Donnell), is a serious threat to pine forests globally. The recent introduction of the pathogen to Southern Europe and its spread in Mediterranean region is alarming considering the immense ecological and economic importance of pines in the region. Pines in forests and nurseries can be infected, resulting in severe growth losses and mortality. The pathogen is known to spread in plants for planting and in seeds, and results from recent studies have indicated that F. circinatum may also spread through phoretic associations with certain insects. With this review, we aim to expand the current understanding of the risk of insect-mediated spread of PPC in different parts of Europe. Through the joint action of a multinational researcher team, we collate the existing information about the insect species spectrum in different biogeographic conditions and scrutinize the potential of these insects to transmit F. circinatum spores in forests and nurseries. We also discuss the impact of environmental factors and forest management in this context. We present evidence for the existence of a high diversity of insects with potential to weaken pines and disseminate PPC in Europe, including several common beetle species. In many parts of Europe, temperatures are projected to rise, which may promote the activity of several insect species, supporting multivoltinism and thus, further amplifying the risk of insect-mediated dissemination of PPC. Integrated pest management (IPM) solutions that comply with forest management practices need to be developed to reduce this risk. We recommend careful monitoring of insect populations as the basis for successful IPM. Improved understanding of environmental control of the interaction between insects, the pathogen, and host trees is needed in order to support development of bio-rational strategies to safeguard European pine trees and forests against F. circinatum in future.

scholarly journals THE EFFECTS OF INVASIVE EPIBIONTS ON CRAB–MUSSEL COMMUNITIES: A THEORETICAL APPROACH TO UNDERSTAND MUSSEL POPULATION DECLINE

2020 ◽  
Vol 28 (01) ◽  
pp. 127-166 ◽  
Author(s):  
JINGJING LYU ◽  
LINDA A. AUKER ◽  
ANUPAM PRIYADARSHI ◽  
RANA D. PARSHAD
Keyword(s):  
Indirect Effects ◽  
Defense Mechanisms ◽  
Gulf Of Maine ◽  
Population Decline ◽  
Keystone Species ◽  
Optimal Foraging Theory ◽  
Dynamical Analysis ◽  
Didemnum Vexillum ◽  
Predator Prey ◽  
Global Boundedness

Blue mussels (Mytilus edulis) are important keystone species that have been declining in the Gulf of Maine. This could be attributed to a variety of complex factors such as indirect effects due to invasion by epibionts, which remains unexplored mathematically. Based on classical optimal foraging theory (OFT) and anti-fouling defense mechanisms of mussels, we derive an ODE model for crab–mussel interactions in the presence of an invasive epibiont, Didemnum vexillum. The dynamical analysis leads to results on stability, global boundedness and bifurcations of the model. Next, via optimal control methods, we predict various ecological outcomes. Our results have key implications for preserving mussel populations in the advent of invasion by non-native epibionts. In particular, they help us understand the changing popluation dynamics of local predator–prey communities, due to indirect effects that epibionts confer.

Response of Limnetic Insect Populations of Two Acidic, Fishless Lakes to Liming and Brook Trout (Salvelinus fontinalis)

1989 ◽  
Vol 46 (2) ◽  
pp. 342-351 ◽  
Author(s):  
Richard A. Evans
Keyword(s):  
New York ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Rapid Reduction ◽  
Density Estimates ◽  
Predator Prey ◽  
Fishless Lakes ◽  
Lower Sign ◽  
Insect Populations ◽  
Seasonal Population

Seasonal population density estimates of limnetic insects in two Adirondack (New York) lakes were obtained from horizontal and vertical net tows and benthic sweep net samples over a 3-yr period; 1 yr while the lakes were acidic and fishless, and 2 yr following addition of (calcium carbonate) CaCO3 and the introduction of brook trout (Salvelinus fontinalis). Before treatment, the limnetic insect assemblages in the study lakes resembled those reported from acidic and/or fishless lakes in Sweden and Canada. Maximum densities of dominant taxa were: Notonectidae; 1.5∙m−3; Corixidae; 1.1∙m−3, Graphoderus (Dytiscidae) larvae; 0.27∙m−3; and Chaoborus americanus; 400∙m−3. Within 3 mo after treatment, all limnetic populations were near or below the detection limit (0.01∙m−3). Limnetic densities of notonectids, corixids, and C. americanus were significantly lower (Mann–Whitney U-tests), and benthic densities of Hemiptera and Coleoptera tended to be lower (sign tests) the summer after treatment than the previous summer. Calculated trout predation levels on Hemiptera and C. americanus, and evidence from the literature, strongly suggest that predation was the major cause of reduced limnetic insect populations. The rapid reduction or elimination of these populations indicates considerable instability of the predator–prey relationships of acidic lakes which have been recently limed and stocked with fish.

scholarly journals Chemical food safety hazards of insects reared for food and feed

2021 ◽  
pp. 1-10
Author(s):  
A.M. Meyer ◽  
N. Meijer ◽  
E.F. Hoek-van den Hil ◽  
H.J. van der Fels-Klerx
Keyword(s):  
Heavy Metals ◽  
Food Safety ◽  
Polychlorinated Biphenyls ◽  
Life Stage ◽  
Veterinary Drugs ◽  
Insect Species ◽  
Safety Hazards ◽  
Chemical Safety ◽  
Plant Toxins ◽  
Food And Feed

Insects are a promising future source of sustainable proteins within a circular economy. Proving the safety of insects for food and feed is necessary prior to supplying them to the market. This literature review provides a state-of-the-art overview of the chemical food safety hazards for insects reared for food and feed, focusing mainly on transfer of contaminants from the substrate. Contaminants covered are: heavy metals, dioxins and polychlorinated biphenyls, polyaromatic hydrocarbons, pesticides, veterinary drugs, mycotoxins, and plant toxins. The twelve insect species reported as having the largest potential as feed and food in the EU are included. Transfer and bioaccumulation of contaminants depend on the chemical, insect species, life stage, and source of contaminant (spiked vs natural), as well as the particular substrate and rearing conditions. The heavy metals lead, arsenic, mercury, and cadmium can accumulate, whereas mycotoxins and polycyclic aromatic hydrocarbons (PAHs) seem not to accumulate. Mycotoxins and veterinary drugs could be degraded by insects; their metabolic routes need to be further investigated. Data are generally limited, but in particular for PAHs, plant toxins, and dioxins and dioxin-like polychlorinated biphenyls. Further research on chemical safety of different edible insects is therefore warranted.

scholarly journals Olfactory conditioning in a parasitic insect and its relation to the problem of host selection

1937 ◽  
Vol 124 (834) ◽  
pp. 56-81 ◽  
Keyword(s):  
Host Selection ◽  
Insect Species ◽  
Olfactory Conditioning ◽  
Selection Principle ◽  
Structural Differences ◽  
Long Time ◽  
Biological Characters ◽  
Inheritance Of Acquired Characters ◽  
Polyphagous Insect ◽  
Acquired Characters

It has often been stated that insect species which breed on two or more hosts tend to become split into biological races, each of which is attached to a particular food-plant or host as the case may be. But although the fact of the existence of biological races is well known, their mode of origin is, in most cases, in dispute. It is not known how far the biological characters of such races are germinally fixed, and it has been suggested that in many cases a group of individuals may become restricted to certain host species not by any germinal change, but by a kind of conditioning, as a result of which the adult female is attracted for oviposition to the particular species on which she had fed as a larva. This is the idea behind the so-called "Host Selection Principle" of Walsh, and it is a possibility which must be care­fully considered when assessing the value of experiments attempting to establish the inheritance of acquired characters. It is obvious that if a conditioning of this sort was actually occurring, a polyphagous insect species might rapidly become split into two or more populations each attached to a given species of host (plant or animal as the case may be). The barrier thus created might persist for a very long time without any hereditary specialization taking place. It is known, however, that the characters which distinguish biological races are in fact often germinally fixed, and in some instances it has been shown that even though all structural differences are absent there may be repugnance for cross­breeding between two biological races of the same species (Thorpe 1930 b ). It is nevertheless often difficult to visualize the means by which such germinal differences could become established without the aid of the eco­logical separation which such host conditioning might provide.

New Ultrastructural Observations on Injury and Regeneration of Cilia in Mammalian Conducting Airway Epithelium

1981 ◽  
Vol 39 ◽  
pp. 624-625
Author(s):  
J.L. Carson ◽  
A.M. Collier
Keyword(s):  
Respiratory Tract ◽  
Airway Epithelium ◽  
Defense Mechanisms ◽  
Normal Growth ◽  
Fetal Lung ◽  
Secretory Cells ◽  
Airway Epithelial ◽  
Ciliated Cells ◽  
Conducting Airway ◽  
Conducting Airways

The ciliated cells lining the conducting airways of mammals are integral to the defense mechanisms of the respiratory tract, functioning in coordination with secretory cells in the removal of inhaled and cellular debris. The effects of various infectious and toxic agents on the structure and function of airway epithelial cell cilia have been studied in our laboratory, both of which have been shown to affect ciliary ultrastructure.These observations have led to questions about ciliary regeneration as well as the possible induction of ciliogenesis in response to cellular injury. Classical models of ciliogenesis in the conducting airway epithelium of the mammalian respiratory tract have been based primarily on observations of the developing fetal lung. These observations provide a plausible explanation for the embryological generation of ciliary beds lining the conducting airways but do little to account for subsequent differentiation of ciliated cells and ciliogenesis during normal growth and development.

High Resolution Observations of Ion-Milling Induced Transformation in Synthetic Hollandses

1981 ◽  
Vol 39 ◽  
pp. 114-115 ◽  
Author(s):  
T. J. Headley
Keyword(s):  
High Resolution ◽  
Radioactive Waste Disposal ◽  
Ion Milling ◽  
Minor Elements ◽  
Waste Forms ◽  
Carbon Substrates ◽  
Structural Differences ◽  
Oxide Phases ◽  
Argon Ions ◽  
High Resolution Microscopy

Oxide phases having the hollandite structure have been identified in multiphase ceramic waste forms being developed for radioactive waste disposal. High resolution studies of phases in the waste forms described in Ref. [2] were initiated to examine them for fine scale structural differences compared to natural mineral analogs. Two hollandites were studied: a (Ba,Cs,K)-titan-ate with minor elements in solution that is produced in the waste forms, and a synthesized BaAl2Ti6O16 phase containing ∼ 4.7 wt% Cs2O. Both materials were consolidated by hot pressing at temperatures above 1100°C. Samples for high resolution microscopy were prepared both by ion-milling (7kV argon ions) and by crushing and dispersing the fragments on holey carbon substrates. The high resolution studies were performed in a JEM 200CX/SEG operating at 200kV.

Parasite defense mechanisms in bees: behavior, immunity, antimicrobials, and symbionts

2019 ◽  
Vol 4 (1) ◽  
pp. 59-76 ◽  
Author(s):  
Alison E. Fowler ◽  
Rebecca E. Irwin ◽  
Lynn S. Adler
Keyword(s):  
Defense Mechanisms ◽  
Poor Quality ◽  
Future Research ◽  
Immune Priming ◽  
Social Bees ◽  
Bee Health ◽  
Landscape Scales ◽  
And Function ◽  
Solitary Species

Parasites are linked to the decline of some bee populations; thus, understanding defense mechanisms has important implications for bee health. Recent advances have improved our understanding of factors mediating bee health ranging from molecular to landscape scales, but often as disparate literatures. Here, we bring together these fields and summarize our current understanding of bee defense mechanisms including immunity, immunization, and transgenerational immune priming in social and solitary species. Additionally, the characterization of microbial diversity and function in some bee taxa has shed light on the importance of microbes for bee health, but we lack information that links microbial communities to parasite infection in most bee species. Studies are beginning to identify how bee defense mechanisms are affected by stressors such as poor-quality diets and pesticides, but further research on this topic is needed. We discuss how integrating research on host traits, microbial partners, and nutrition, as well as improving our knowledge base on wild and semi-social bees, will help inform future research, conservation efforts, and management.

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