Surf Redfish-Based ZnO-NPs and Their Biological Activity with Reference to Their Non-Target Toxicity.

The marine environment is a rich source of bioactive compounds. Therefore, the sea cucumber was isolated from the Red Sea at the Al-Ain Al-Sokhna coast and it was identified as surf redfish (Actinopyga mauritiana). The aqueous extract of the surf redfish was utilized as an ecofriendly, novel and sustainable approach to fabricate zinc oxide nanoparticles (ZnO-NPs). The biosynthesized ZnO-NPs were physico-chemically characterized and evaluated for their possible antibacterial and insecticidal activities. Additionally, their safety in the non-target organism model (Nile tilapia fish) was also investigated. ZnO-NPs were spherical with an average size of 24.69 ± 11.61 nm and had a peak at 350 nm as shown by TEM and UV-Vis, respectively. XRD analysis indicated a crystalline phase of ZnO-NPs with an average size of 21.7 nm. The FTIR pattern showed biological residues from the surf redfish extract, highlighting their potential role in the biosynthesis process. DLS indicated a negative zeta potential (-19.2 mV) of the ZnO-NPs which is a good preliminary indicator for their stability. ZnO-NPs showed larvicidal activity against mosquito Culex pipiens (LC50 = 15.412 ppm and LC90 = 52.745 ppm) and a potent adulticidal effect to the housefly Musca domestica (LD50 = 21.132 ppm and LD90 = 84.930 ppm). Tested concentrations of ZnO-NPs showed strong activity against the 3rd larval instar. Topical assays revealed dose-dependent adulticidal activity against M. domestica after 24 h of treatment with ZnO-NPs. ZnO-NPs presented a wide antibacterial activity against two fish-pathogen bacteria, Pseudomonas aeruginosa and Aeromonas hydrophila. Histopathological and hematological investigations of the non-target organism, Nile tilapia fish exposed to 75-600 ppm ZnO-NPs provide dose-dependent impacts. Overall, data highlighted the potential applications of surf redfish-mediated ZnO-NPs as an effective and safe way to control mosquitoes, houseflies and fish pathogenic bacteria.

Mosquitocidal Activity of the Methanolic Extract of Annickiachlorantha and Its Isolated Compounds against Culex pipiens, and Their Impact on the Non-Target Organism Zebrafish, Danio rerio.

In this study, the crude extract and its isolated compounds from the stem bark of Annickia chlorantha were tested for their larvicidal, developmental, and repellent activity against the mosquito vector, Culex pipiens, besides their toxicity to the non-target aquatic organism, the zebrafish (Danio rerio). The acute larvicidal activity of isolated compounds; namely, palmatine, jatrorrhizine, columbamine, ß-sitosterol, and Annickia chlorantha methanolic extract (AC), was observed. Developmentally, the larval duration was significantly prolonged when palmatine and ß-sitosterol were applied, whereas the pupal duration was significantly prolonged for almost all treatments except palmatine and jatrorrhizine, where it shortened from those in the control. Acetylcholinesterase (AChE) enzyme showed different activity patterns, where it significantly increased in columbamine and ß-sitosterol, and decreased in (AC), palmatine, and jatrorrhizine treatments, whereas glutathione S-transferase (GST) enzyme was significantly increased when AC methanolic extract/isolated compounds were applied, compared to the control. The adult emergence percentages were significantly decreased in all treatments, whereas tested compounds revealed non-significant (p > 0.05) changes in the sex ratio percentages, with a slight female-to-male preference presented in the AC-treated group. Additionally, the tested materials revealed repellence action; interestingly, palmatine and jatrorrhizine recorded higher levels of protection, followed by AC, columbamine, and ß-sitosterol for 7 consecutive hours compared to the negative and positive control groups. The non-target assay confirms that the tested materials have very low toxic activity compared to the reported toxicity against mosquito larvae. A docking simulation was employed to better understand the interaction of the isolated compounds with the enzymes, AChE and GST. Additionally, DFT calculations revealed that the reported larvicidal activity may be due to the differing electron distributions among tested compounds. Overall, this study highlights the potential of A. chlorantha extract and its isolated compounds as effective mosquitocidal agents with a very low toxic effect on non-target organisms.

Impact of paternal transmission of gamma radiation on reproduction, oogenesis, and spermatogenesis of the housefly, Musca domestica L. (Diptera: Muscidae).

PURPOSE: This study aimed to investigate the impact of gamma radiation of Musca domestica males (resulted from irradiated pupae) crossed with unirradiated females on fecundity, egg hatchability, adult emergence, sex ratio, sterility, in addition to reproductive development at the level of oogenesis and spermatogenesis compared to unirradiated group. MATERIAL AND METHODS: The housefly, M. domestica pupae were exposed to three sublethal doses of 5, 10, and 15 Gy. RESULTS: Fecundity was severely reduced particularly in F2 (11.33 ± 1.528; 7.33 ± 1.115 eggs/♀) and F3 (9.0 ± 1.00; 4.67 ± 1.115 eggs/♀) for doses of 10 and 15 Gy, respectively, compared with (52.0 ± 1.4 eggs/♀) for the control. Data revealed latent dose- and generation-dependent reduction in egg hatchability. Hatchability percentages reduced from 93.59 for the control to 10.07 (F1), 8.09 (F2), and 8.34 (F3) when the highest radiation dose 15 Gy was applied. Irradiation induced paternal deleterious substerility effects. Irradiation with 15 Gy induced substerility that reached about 97.0% in F2 and F3 generations. A significant (P < 0.05) reduction of the mean numbers of adult emergence was remarkably detected in the F1, F2, and F3 generations. Applied gamma doses did not affect the male to female ratio in the Parental or F1 generations. However, the F2 and F3 generations did show changes to the sex ratio with males occurring more frequently than females. This trend became more pronounced as dose increased. Ultrastructural examinations exhibited unusual damage and malformation either for males or female reproductive organs. CONCLUSION: The obtained results clearly show that gamma radiation of M. domestica irradiated as pupae induced considerably visible impact on tested biological aspects and reproductive potential.

Impact of gamma irradiation on the development and reproduction of Culex pipiens (Diptera; Culicidae).

PURPOSE: The aim was to evaluate the effects of irradiation of Culex pipiens irradiated as pupae on the larval and pupal mortality percentages, the larval and pupal duration, adult emergence percentages and ovarian development in comparison with the un-irradiated group. MATERIAL AND METHODS: The mosquito, C. pipiens Linnaeus (L) was irradiated as pupae with three gamma doses 40, 60 and 80 Gy. Different biological aspects include the ovarian development of irradiated females tested. RESULTS: Gamma doses used significantly increased the larval and pupal mortality percentages, the larval and pupal duration and significantly decreased the adult emergence percentages. Moreover, fecundity and egg hatchability percentages were severely decreased with increasing gamma doses. While the sterility% was positively correlated with the doses used. Gamma doses caused a dose-dependent decrease in the number of developed eggs, reduction in the number of developed oocytes, signs of degenerative processes in oocytes, yolk mass and egg size decrease. CONCLUSIONS: Results obtained indicated that gamma radiation of C. pipiens induced remarkable effects on the biological, developmental and reproductive activity.

Toxicity of some plant extracts against vector of lymphatic filariasis, Culex pipiens.

Many insecticides are generally used as larvicides to control Culex pipiens, vector of lymphatic filariasis. This study was undertaken to evaluate the larvicidal activity of some potential larvicidal plants extracts against C. pipiens larvae. The toxic effects of both ethanolic and petroleum ether plant extracts were evaluated under laboratory conditions against 3rd instar larvae of C. pipiens. Forty ethanolic and petroleum ether extracts of 10 plants namely Echinochloa stagninum, Phragmites australis, Eichhornia crassipes, Rhizophora mucronata, Cichorium intybus, Ocimum basilicum, Origanum majorana, Azadirachta indica, Rosmarinus officinalis and Nigella sativa. On the basis of LC50, the toxic effect of the plant extracts tested varied depending on the plant species, part, solvent used in extraction and the extract concentrations. The petroleum ether extraction was more effective against mosquito as compared with ethanolic extraction. The most effective plant extract was A. indica followed by Ph. australis, N. sativa, C. intybus, R. officinalis, O. basilicum, O. majorana, E. stagninum, Rh. Mucronata and E. crassipes.

Effects of midgut bacteria and two protease inhibitors on the reproductive potential and midgut enzymes of Culex pipiens infected with Wuchereria bancrofti.

Laboratory investigations were carried out to asses the effect of some proteases inhibitors on the reproductive potential of Culex pipiens females resulted from larvae treated with different protease inhibitors. The fecundity and engorgement of symbiotic and aposymbiotic C. pipiens females were significantly reduced. The blood meal digestion period increased significantly. On the other hand, enzyme band with molecular weight of 40 KDa which may be cysteine protease was detected in untreated symbiotic and aposymbiotic female midguts. The results may explain that the absence of this enzyme bands in treated female midguts may be due to the inhibition caused by (E-64) a cysteine protease inhibitor.

Effects of midgut bacteria and two protease inhibitors on the transmission of Wuchereria bancrofti by the mosquito vector, Culex pipiens.

Laboratory investigations were carried out to study the effect of two protease inhibitors on the transmission of W. bancrofti filarial by Culex pipiens and to study the susceptibility interaction between filaria and protease inhibitors. The results obtained revealed that, infection rates were variable among untreated and treated symbiotic and aposymbiotic Cx. pipiens females resulted from third instar larvae treated with E-64 and EDTA. The survival rate was variable among untreated and treated symbiotic and aposymbiotic females resulted from third instar larvae treated with E-64 and EDTA. Protease inhibitor (E-64) caused inhibition of the parasite development and transmission by means of ceasing catalytic activity- responsible for parasite migration-caused by parasitic larval stages inside the mosquito vector.