Potential natural biocontrol agents of Aphrophoridae eggs

Xylella fastidiosa is a phytopathogenic bacterium detected recently in Europe. It causes important economical losses in different crops, mainly in olive, almond and vineyard. Up to now the Aphrophoridae Philaenus spumarius L. (1758) is the main identified vector in Europe. The information about Aphrophoridae biology is insufficient and the knowledge about its natural enemies reduced. Nymphs excrete spumes remaining protected from natural enemies. Therefore, eggs are likely the most vulnerable stage to the natural enemies action. In this work, the potential action of parasitoids, predators and fungi against eggs of Aphrophoridae was studied. For that, at the end of the winter and before the egg hatching, rests of the remaining vegetation in the ground cover, mainly Poaceae, were collected. In the laboratory leaves, particularly the interior part of the blade which is a common oviposition location for spittlebugs, were observed under binocular stereoscope. Viable eggs were introduced in petri dishes until hatching. A total number of eggs of 3841 in 322 eggs laying and with a mean of 12 eggs per egg laying was recorded. From them, 603 eggs were intact and 3238 had sings of natural control agent action. A potential action of predators (in 183 eggs laying), parasitoid (in 198 eggs laying) and entomopathogenic fungi (in 48 eggs laying) was observed. Additionally, 321 parasitoids emerged from 43 of the eggs laying. These results indicate that the eggs mortality due to beneficial organisms, particularly parasitoids, may have a high importance for the control of X. fastidiosa vectorsinfo:eu-repo/semantics/publishedVersio

External control of the Drosophila melanogaster egg to imago development period by specific combinations of 3D low-frequency electric and magnetic fields

We report that the duration of the egg-to-imago development period of the Drosophila melanogaster, and the imago longevity, are both controllable by combinations of external 3-dimensional (3D) low-frequency electric and magnetic fields (LFEMFs). Both these periods may be reduced or increased by applying an appropriate configuration of external 3D LFEMFs. We report that the longevity of D. melanogaster imagoes correlates with the duration of the egg-to-imago development period of the respective eggs. We infer that metabolic processes in both eggs and imago are either accelerated (resulting in reduced time periods) or slowed down (resulting in increased time periods). We propose that external 3D LFEMFs induce electric currents in live systems as well as mechanical vibrations on sub-cell, whole-cell and cell-group levels. These external fields induce media polarization due to ionic motion and orientation of electric dipoles that could moderate the observed effects. We found that the longevity of D. melanogaster imagoes is affected by action of 3D LFEMFs on the respective eggs in the embryonic development period (EDP). We interpret this effect as resulting from changes in the regulation mechanism of metabolic processes in D. melanogaster eggs, inherited by the resulting imagoes. We also tested separate effects of either 3D electric or 3D magnetic fields, which were significantly weaker

The action of certain substituted phenols on marine eggs in relation to their dissociation

It has been shown by Clowes and Krahl (1, 2) that various substituted phenols as well as dinitrophenol increase the respiratory rate of marine eggs. Also, the highly interesting reversible block to cleavage, which they found to occur at the maximum of respiratory stimulation, is likewise exhibited. The different substances (nitro- and halo-phenols and cresols in particular) used were found to be active in different concentrations, and some attempt is made to relate the activity to molecular structure. The degree of dissociation of the phenolic OH is taken to be of no significance in their experiments. There has been some controversy concerning this question. Field, Martin and Field (3, 4) showed that in yeast the amount of respiratory stimulation by 2,4-dinitrophenol and by 4,6-dinitrocresol depends upon the concentration of the undissociated form present, similar calculated concentrations of undissociated DNP giving at different pH's the same stimulation. Citing their own experiments and those of Ehrenfest and Ronzoni (5) on yeast, De Meio and Barron (6), on the other hand, disagree with this conclusion

The Influence of Eggshell Washing on Bacterial Transfer Across the Shell Wall

1. All three methods of washing action (brush, rotary and jet) investigated in this study caused damage to the cuticular surface of the egg shell. 2. The physical trauma to the egg caused by the washing procedure resulted in higher levels of protein in the post wash water. Not all of the protein was derived from the cuticular surface, some was also derived from the contents of broken eggs. 3. The pre wash water in both the brush and jet action machines contained bacteria, highlighting the difficulties associated with plant hygiene. The post water from all three washing machines contained a diverse population of bacteria, several of which were potential food pathogens. 4. The persistence of the bacterial population in the three washing systems, particularly the rotary and jet action machines underlined the inadequacies of the sanitiser regime. Eggs improperly rinsed displayed sanitiser residue on the shell surface. Chlorine from the sanitiser penetrated the thickness of the true shell. 5. In general terms, bacteria translocated across the shell wall of washed eggs more readily than the unwashed group. This trend was independent of the type of wash action although it did appear to be strain related. 6. As the bird aged, shell quality declined with a concomitant increase in bacterial transfer. 7. Infectious Bronchitis was verified during the course of this investigation and observed to have a profound effect on shell structure. This structural deterioration correlated with a rapid increase in bacterial penetration (56% in the unwashed eggs and 66% in the washed eggs). During the recovery phase bacterial penetration decreased

Physiology of fertilization of mammalian eggs

Cell attached patch recordings have been made from zona-free mouse eggs. Potassium channels which show anomalous and delayed rectification have been observed. The conductance of these channels was as high as 160pS. They have been shown to open and shut independently of one another. Another channel with a conductance of about 50pS has been noted and is believed to be a chloride channel. Calcium channels with mean current amplitudes of 1.10 + 0.33pA (mean + SD, n=35) and a conductance in the range 7.5 to 20pS, have also been recorded.Before insemination the membrane potential of zona-free hamster eggs, measured with intracellular electrodes lay in the range -8 to -47mV (whilst bathed in a modified Krebs Ringer solution - called "normal"). In five eggs impaled during this study, the membrane potential was more negative than -61mV. In these eggs calcium action potentials could be evoked by depolarizing pulses. It is suggested that eggs which do not show such action potentials suffer from impalement leaks or have possibly undergone "in vitro deterioration".Inward channel currents have been observed in synchrony with the rising phase of the action potential.Preliminary data are presented on whole cell recording experiments.In zona-free hamster eggs current clamped at potentials more negative than about -80mV, sperm egg fusion was associated with a depolarization, which in some cases elicited an action potential. Such depolarizations or sperm evoked action potentials were also observed in eggs bathed in a solution resembling oviducal fluid, with a potassium concentration of 25mM or in a solution with a sodium concentration of ImM. Such depolarizations were followed by transient recurring depolarizations.During fertilization of eggs with low membrane potentials, no response was observed at the time of sperm fusion, but transient recurring hyperpolarizations were later recorded (as seen by other workers).Similar results were obtained during fertilizations in calcium free solutions containing substituted magnesium and strontium."Action currents" have been measured, during fertilization with cell attached patch pipettes. Results of these experiments reveal the presence of (i) spikes superimposed on the repolarizing phase of transient recurring hyperpolarizations, (ii) the latter are sometimes followed by after depolarizations and (iii) these responses were superimposed on a depolarizing shift.Trinitrotoluene is a nitro explosive belonging to the Benzene Group and is hence a coal tar product, and therefore similar in origin to Aniline, the basis of Aniline Dyes.Toluene is Methyl Benzene C₆H₅(CH)3₆₂₃₄₅₆ and T.N.T. is obtained by nitrating this substance by a mixture of nitric and sulphuric acids.Toluene (sometimes incorrectly called Toluol) is a colourless liquid and is obtained by the fractional distillation of coal tar - a by- product in the manufacture of coal gas.It is lighter than water, having a sp.gr. of .8824 and it boils at 1100 C

Effect of antibiotic materials on rugose spiralling whitefly, Aleurodicus rugioperculatus Martin (Hemiptera: Aleyrodidae) oviposition

The rugose spiralling whitefly is an invasive sucking pest on horticultural crops found in India. Elimination of endomicrobial communities harboured in hosts through antibiotic treatments adversely affects the fitness parameters of rugose spiralling whitefly. Keeping this in view, the present study aimed to evaluate the ovicidal action of antibiotics against rugose spiralling whiteflies reared on four host plants. Antibiotics with varied modes of action were erythromycin, ciprofloxacin, carbenicillin and cefotaxime and were applied to coconut, banana, sapota and guava leaves for whitefly oviposition. Antibiotic treatment, carbenicillin 100 μg/mL + ciprofloxazin 5 μg/mL significantly (p<0.05) reduced the oviposition and % egg hatchability of whiteflies reared in coconut (13 eggs/spiral and 61.54%), banana (15 eggs/spiral and 60.00%), sapota (15 eggs/spiral and 66.67%) and guava (16 eggs/spiral and 56.25%). The reduction in the number of eggs per spiral and hatchability percentage proved that antibiotic treatments significantly (P<0.05) reduced rugose spiralling whitefly fecundity. Antibiotic material affects the fitness parameters of whitefly by disrupting the endomicrobial communities associated with whitefly. Antibacterial materials have a potential plant protection role in the management of whiteflies by reducing population growth

The inactivation of eggs of helminthes under the action of narrowband ultraviolet radiation of excilamps

The inactivation of eggs of Opisthorchis felineus and Diphyllobothrium latum in the water under the action of UV excilamps at 222 and 282 nm in dependence on the surface dose of radiation was studied. It was observed that the water disinfection from eggs of helminthes was more efficient at 222 nm, than at 282 nm. At the surface dose up to 5 mJ/cm2 of UV radiation at 222 nm up to 85 % of Opisthorchis felineus eggs were inactivated. At the comparable surface dose of UV radiation at 222 nm up to 56 % of Diphyllobothrium latum eggs were inactivated

The sensitivity of cells to the lethal action of X-rays

This thesis consists of three papers which record an experimental investigation into the nature of the biological action of X-rays. An introduction has been added in order to correlate the papers with each other and to draw attention to the significance of the experiments described in the papers in relation to the records of work by other investigators.Part I. Introduction. • Part II. The Biological Action of Homogeneous and Heterogeneous X-rays. Proc. Roy. Soc. 1933. B.112, 365. • Part III. The Action of X-rays on the Eggs of Calliphora. Proc. Roy. Soc. B. 1934. In press. • Part IV. The influence of temperature on the sensitivity of calliphorine eggs to X-rays. (This paper is about to be submitted to the Royal Society for publication)

Why cuckoos remove host eggs: Biting eggs facilitates faster parasitic egg‐laying

Brood parasitism by cuckoos relies on manipulating hosts to raise their offspring and has evolved stunning adaptations to aid in their deception. The fact that cuckoos usually but not always, remove one or two host eggs while laying their eggs has been a longstanding focus of intensive research. However, the benefit of this behavior remains elusive. Moreover, the recently proposed help delivery hypothesis, predicting that egg removal by cuckoos may decrease the egg‐laying duration in the parasitism process caused by biting action, lacks experimental verification. Therefore, in this study, we examined the effects of egg removal/biting on the egg‐laying speed in the common cuckoo (Cuculus canorus) to experimentally test this hypothesis. We compared the duration of cuckoo egg‐laying in empty nests, nests with host eggs, and nests with artificial blue stick models to test whether cuckoos biting an egg/stick can significantly hasten the egg‐laying speed than no biting action. Our results showed that biting an egg or an object is associated with cuckoos laying approximately 37% faster than when they do not bite an egg or an object. This study provides the first experimental evidence for the help delivery hypothesis and demonstrates that when cuckoos bite eggs or other objects in the nest, they lay eggs more quickly and thereby avoid suffering the hosts' injurious attack