Background
The Egyptian cotton leafworm,
Spodoptera littoralis
(Boisd.) (Lepidoptera: Noctuidae) is one of the major insect pests, causing a significant damage on different cultivated agricultural ...crops. Developing an alternative non-chemical tool, an effective and environmentally friendly method to suppress pest's infestation is essentially needed. Therefore, biological control by releasing the egg parasitoids could be the most promising tool for integrated pest management.
Results
This study was designed to evaluate the efficacy of the egg parasitoid,
Trichogrammatoidea bactrae
Nagaraja (Hymenoptera: Trichogrammatidae) as a bio-control agent against
S. littoralis
egg masses with different physical characteristics (number of egg layer and degree of scale density) in a no-choice and choice tests, under laboratory conditions. Also, the parasitoids’ fitness in terms of parasitism percentage, developmental period, adults’ emergence percentage, female offspring percentage, and longevity were investigated. The results revealed that
T. bactrae
wasps had a great ability to parasitize
S. littoralis
egg masses, but with different rates, related to their layers and scales’ thickness in both tests. The highest parasitism percentage was observed on one-layer eggs, followed by two layers. However, 3-layer eggs were the least preferable one. High numbers of adult emergencies (> 80%) were observed in all tested egg masses, except in the case of 3 layers with high scales. Furthermore, female-biased sex ratios were noticed at all examined eggs, with only the exception of high-scaly eggs with a single layer that recorded the lowest rate (≤ 45%). Besides, the survival of adult female parasitoids was not significantly affected in both tests.
Conclusions
T. bactrae
could be used as a bio-control agent against
S. littoralis
egg masses with different physical characteristics based on the achieved results.
Background
The greater wax moth,
Galleria mellonella
(L.) (Lepidoptera: Pyralidae), is the major devastating insect pest of beekeeping industry all over the world; however their larvae were ...valuable to be the most favorable alternative invertebrate model. For this purpose, new-hatched larvae were reared on five different nutritional diets based on: old wax-comb (natural food); wheat flour diet (
Triticum aestivum
L.); soybean diet (
Glycine max
); wheat germ diet; and date syrup diet (
Phoenix dactylifera
L.) till reaching the fully grown 6
th
instars to evaluate their fitness and hemocytic responses.
Results
Fully grown larvae from soybean diet had the highest rates of fresh (280 mg) and dry weights (104 mg), water contents (175.6 mg), carbohydrates (1.97%), total hemocyte count (THC) (4746/mm
3
), total soluble solid (TSS) (21.7%), hemolymph protein concentration (HPC) (1662.5 mg/100 ml), and hemolymph content (density 3.82 mg/µl and volume 70.35 µl/larva), followed by wheat germ diet in comparable to the natural food. All suggested diets considered as rich protein-materials; recording high protein rates on their larvae (39.51–41.87%), with only the exception of old wax-comb had the lowest one (36.63%). Moreover, five types of hemocytes were classified in the larval hemolymph as (prohemocytes (PR), plasmatocytes (PL), granulocytes (GR), oenocytoids (OE) and spherulocytes (SP)), but with different rates related to different diets. Regardless the rearing diets, PR type was the most frequently recorded cell type (73.31%) in hemolymph, followed by PL (8.37%), and the lowest one was OE cells (5.82%).
Conclusions
The suggested diets of soybean and wheat germ recorded the best results than the other diets used almost, and could be recommended as standard diets to mass-produce healthy and high-quality
G. mellonella
for in vivo experimentation and/or microbiological studies.
BACKGROUNDThe goal of the current study was to elucidate the genomic background of biofilm formation in Klebsiella pneumoniae.METHODSClinical isolates were screened for biofilm formation using the ...crystal violet assay. Antimicrobial resistance (AMR) profiles were assessed by disk diffusion and broth microdilution tests. Biofilm formation was correlated to virulence and resistance genes screened by PCR. Draft genomes of three isolates that form strong biofilm were generated by Illumina sequencing.RESULTSOnly the siderophore-coding gene iutA was significantly associated with more pronounced biofilm formation. ST1399-KL43-O1/O2v1 and ST11-KL15-O4 were assigned to the multidrug-resistant strain K21 and the extensively drug-resistant strain K237, respectively. ST1999-KL38-O12 was assigned to K57. Correlated with CRISPR/Cas distribution, more plasmid replicons and prophage sequences were identified in K21 and K237 compared to K57. The acquired AMR genes (blaOXA-48, rmtF, aac(6')-Ib and qnrB) and (blaNDM-1, blaCTX-M, aph(3')-VI, qnrS, and aac(6')-Ib-cr) were found in K237 and K21, respectively. The latter showed a novel ISEcp1-mediated chromosomal integration of replicon type IncM1 plasmid-like structure harboring blaCTX-M-14 and aph(3')-VI that uniquely interrupted rcsC. The plasmid-mediated heavy metal resistance genes merACDEPRT and arsABCDR were spotted in K21, which also exclusively carried the acquired virulence genes mrkABCDF and the hypervirulence-associated genes iucABCD-iutA, and rmpA/A2. Pangenome analysis revealed NTUH-K2044 accessory genes most frequently shared with K21.CONCLUSIONSWhile less virulent to Galleria mellonella than ST1999 (K57), the strong biofilm former, multidrug-resistant, NDM-producer K. pneumoniae K21 (ST1399-KL43-O1/O2v1) carries a novel chromosomally integrated plasmid-like structure and hypervirulence-associated genes and represents a serious threat to countries in the area.
The goal of the current study was to elucidate the genomic background of biofilm formation in
.
Clinical isolates were screened for biofilm formation using the crystal violet assay. Antimicrobial ...resistance (AMR) profiles were assessed by disk diffusion and broth microdilution tests. Biofilm formation was correlated to virulence and resistance genes screened by PCR. Draft genomes of three isolates that form strong biofilm were generated by Illumina sequencing.
Only the siderophore-coding gene
was significantly associated with more pronounced biofilm formation. ST1399-KL43-O1/O2v1 and ST11-KL15-O4 were assigned to the multidrug-resistant strain K21 and the extensively drug-resistant strain K237, respectively. ST1999-KL38-O12 was assigned to K57. Correlated with CRISPR/Cas distribution, more plasmid replicons and prophage sequences were identified in K21 and K237 compared to K57. The acquired AMR genes (
,
,
and
) and (
,
,
,
, and
) were found in K237 and K21, respectively. The latter showed a novel IS
-mediated chromosomal integration of replicon type IncM1 plasmid-like structure harboring
and
that uniquely interrupted
. The plasmid-mediated heavy metal resistance genes
and
were spotted in K21, which also exclusively carried the acquired virulence genes
and the hypervirulence-associated genes
, and
/
. Pangenome analysis revealed NTUH-K2044 accessory genes most frequently shared with K21.
While less virulent to
than ST1999 (K57), the strong biofilm former, multidrug-resistant, NDM-producer
K21 (ST1399-KL43-O1/O2v1) carries a novel chromosomally integrated plasmid-like structure and hypervirulence-associated genes and represents a serious threat to countries in the area.
Background
Fall armyworm (FAW),
Spodoptera frugiperda
(J. E. Smith) (Lepidoptera: Noctuidae), is one of the new alien destructive pests of maize and other 350 economic crops. The majority of farmers ...are still depended upon chemical insecticides to suppress the pest, but
S. frugiperda
has succeeded to develop resistance against most of the chemical families. Improving an effective environmentally-friendly approach is highly recommended. Therefore, the egg parasitoids are the best weapon for managing the FAW in the early egg stage due to the feeding behavior of their larvae. In this regard, the impact of FAW egg mass layers and scale thicknesses, as physical barriers, on the parasitic performance of the egg-parasitoid species,
Trichogrammatoidea bactrae
Nagaraja (Hymenoptera: Trichogrammatidae), in non-choice and choice tests was assessed. Besides, the efficacy of FAW-produced adult wasps on the next generation based on the rates of parasitism, adults' emergence, and female progeny was determined.
Results
Obtained results exhibited that
T. bactrae
was able to parasitize all exposed FAW egg masses but with different rates related to the layers’ number and scales' thicknesses in both tests. One-layer (83.18, 78.24%) and two-layer egg masses (65.99, 76.42%) had significantly the highest parasitism rate, while three layers (42.15, 46.05%) was the least one, in both tests, respectively. All parasitoids emerged after 10–12 days with high rates (~ 88–98%) from all the tested egg masses, and the majority offspring were female-biased in both tests. Furthermore, parasitic performance in F
1
progeny was similar with that recorded in parental generation in terms of parasitism rate, high parasitoid emergency (~ 87–95%), and strongly female-biased (~ 68–76%) in all the exposed egg masses.
Conclusions
The egg parasitoid,
T. bactrae,
could be an efficient and recommended bio-control agent against FAW as its greatest ability to overcome the layers’ number and scales’ thickness.
Abstract
Background
Fall armyworm (FAW),
Spodoptera
frugiperda
(J. E. Smith) (Lepidoptera: Noctuidae) is the new invasive pest of different economic crops, threatening the agricultural economy ...worldwide. Chemical insecticides are the main control management strategy applied by almost farmers. As the adverse effect of these chemicals on the environment and human health, improving alternative environmentally friendly control against this pest is urgently needed. In this response, the pathogenicity bioassays of 2 entomopathogenic nematode species (EPNs),
Steinernema
carpocapsae
(All) and
Heterorhabditis
indica
(EGAZ2), on different FAW larval instars (2nd to 6th instars) were assessed under laboratory conditions.
Results
The results cleared that FAW larval mortality rate was varied significantly related to nematode species, post-exposure times and developmental instar stages.
S.
carpocapsae
application was more virulent and effective against all tested instars larvae, registering 100% mortality after 48–72 h post-exposure at different nematode concentrations (150–2400 IJs). However,
H.
indica
caused 100% mortality in early instars only after 96 h, but late instars required a longer time extending to 120–188 h at tested concentrations. In this context, 2nd and 3rd instars were highly susceptible to
Heterorhabditis
species infection. Lower nematode concentrations (150–300 IJs) caused moderate mortality 33.33–50%, respectively, in 5th and 6th full-developed larvae only. All recovery larvae post-infection died in the pupal stage or adult emerged with wing malformation.
Conclusion
The 2 EPN species were virulent against different FAW larval instars at different concentrations and exposure times. Thereby, they are recommended as biocontrol agents against this invasive pest, particularly
S.
carpocapsae
after low-exposure time. This study provides essential information on EPNs, which will further help in the practical application of biological control against fall armyworm.
Background
Fall armyworm (FAW),
Spodoptera
frugiperda
(J. E. Smith) (Lepidoptera: Noctuidae) is the new invasive pest of different economic crops, threatening the agricultural economy worldwide. ...Chemical insecticides are the main control management strategy applied by almost farmers. As the adverse effect of these chemicals on the environment and human health, improving alternative environmentally friendly control against this pest is urgently needed. In this response, the pathogenicity bioassays of 2 entomopathogenic nematode species (EPNs),
Steinernema
carpocapsae
(All) and
Heterorhabditis
indica
(EGAZ2), on different FAW larval instars (2nd to 6th instars) were assessed under laboratory conditions.
Results
The results cleared that FAW larval mortality rate was varied significantly related to nematode species, post-exposure times and developmental instar stages.
S.
carpocapsae
application was more virulent and effective against all tested instars larvae, registering 100% mortality after 48–72 h post-exposure at different nematode concentrations (150–2400 IJs). However,
H.
indica
caused 100% mortality in early instars only after 96 h, but late instars required a longer time extending to 120–188 h at tested concentrations. In this context, 2nd and 3rd instars were highly susceptible to
Heterorhabditis
species infection. Lower nematode concentrations (150–300 IJs) caused moderate mortality 33.33–50%, respectively, in 5th and 6th full-developed larvae only. All recovery larvae post-infection died in the pupal stage or adult emerged with wing malformation.
Conclusion
The 2 EPN species were virulent against different FAW larval instars at different concentrations and exposure times. Thereby, they are recommended as biocontrol agents against this invasive pest, particularly
S.
carpocapsae
after low-exposure time. This study provides essential information on EPNs, which will further help in the practical application of biological control against fall armyworm.
This study was designed to find out the optimum cold storage temperature (4, 7, and 10 °C) and storage period (1–16 weeks) of 3 different immature developmental stages (2, 4, 6 days post parasitism) ...of the egg parasitoid,
Trichogrammatoidea bactrae
Nagaraja (Hymenoptera: Trichogrammatidae) to produce high-quality individuals to be utilized. Also, the effects of cold storage on parasitoids’ fitness in terms of parasitism percentage, developmental period, adults’ emergence percentage, female percentage, and longevity (fed and un-fed) of parents and F
1
progeny were investigated. The obtained results revealed that
T. bactrae
larvae (2-day post parasitism) could be stored for at least 7 weeks at 10 °C, with least changes in their fitness in both the parents and F
1
progeny, followed by 7 °C, whereas storage at 4 °C was the fatal temperature in this early stage of parasitoid with a maximum mortality rate that extended to the next generation (F
1
). Furthermore, female biased sex ratios were observed at all storage temperatures in the parental and F
1
generations but with different values. After a cold exposure of pre- and pupal stages (4, 6 days post parasitism) of the parasitoid at 7 °C, adults’ emergence percentage in the parents was low, but the biological performance in progeny was great. In addition, these late stages could be stored for a short period up to 4 weeks at 10 °C with highest performances in both generations, followed by 7 °C. Ten degrees Celsius proved to be the most suitable storage temperature at different parasitoid ages (larvae, pre-pupae, and pupae). Only the larval stage could continue up to 16 weeks of cold storage, and hence, it can be recommended for a short- and/or a long-term storage period.
Egypt has a high prevalence of hepatitis C virus (HCV) infection with 92.5% of genotype-4.
This study aimed to clone and express the core gene of HCV genotype-4 for using it to develop a highly ...sensitive, specific, and cost-effective diagnostic assay for detecting HCV infection.
Using synthetic HCV genotype-4 core gene, pET15b as E. coli expression vector, and 1 mM lactose as inducer, the HCV core protein (MW 17 kDa) was expressed in the form of inclusion bodies (IBs) that was purified and solubilized using 8 M guanidinium HCl. The recombinant core protein was in vitro refolded by a rapid dilution method for further purification using weak cation exchange liquid chromatography. The immunogenicity of the purified protein was tested by ELISA using 129 serum samples.
The recombinant core protein was successfully expressed and purified. The results also showed that the in-house anti-HCV core assay is accurate, specific (~96.6%), and highly sensitive (~100%) in accordance with the commercial ELISA kit.
The sensitivity, specificity, and reproducibility of the developed assay were high and promising to be used as a screening assay for detecting HCV infection.
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•HCV Core protein induces cellular and humoral responses, and plays a key role in the pathogenesis of HCV infection.•It potentiates the proangiogenic activity of HCC through various mechanisms to dysregulate the cell signaling pathways.•This study can be a good chance for screening new neutralizing antibodies that hinders the progress of the HCV-induced HCC.•The evaluation of the in-house assay was focused on the availability of ease, specific, and sensitive assay.•The in-house assay was tested on a group of well-characterized samples obtained from diverse regions of Egypt.•The results proved its suitability for manipulation in small laboratories.•An expected drawback of the present assay is that it may not detect HCV infection in the early infected samples.
Antennal morphology and funicular sensillae of male and female peach fruit flies, Bactrocera zonata (Saunders) (Diptera: Tephritidae), were studied with scanning electron microscopy (SEM). This study ...focused on the sensillae found on the antennal segments (scape, pedicel, and flagellum or funiculus that bears the arista) of B. zonata. Antennal segments of females tended to be larger than those of the males. The first two antennal segments, scape and pedicel, were heavily covered with microtrichia and bear bristles. Numerous microtrichia as well as trichoid (I, II), basiconic, clavate, and coeloconic sensillae were observed on the funiculus. SEM studies showed some differences in size and also in position of some sensillae on the antennae of the females of B. zonata. The sensillae found on the funiculus, such as trichoid and basiconic sensillae, were significantly larger in females.
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