Efficacy and side effects of bio-fabricated sardine fish scale silver nanoparticles against malarial vector Anopheles stephensi

Mosquitoes are a great menace for humankind since they transmit pathogenic organisms causing Malaria, Dengue, Chikungunya, Elephantiasis and Japanese encephalitis. There is an urgent need to discover new and novel biological tools to mitigate mosquito-borne diseases. To develop bioinsecticides through newly developed nanotechnology is another option in the present research scenario. In this study we synthesize and characterize sardine fish scales with silver nitrate by adopting various instrumental techniques such as UV- and FTIR-spectroscopy, energy-dispersive X-ray (EDAX), X-ray diffraction analyses (XRD) and scanning electron microscopy (SEM). Toxicity bioassays were conducted with young developmental stages of mosquito vectors. Significant mortality appeared after different life stages of mosquito vectors (young larval and pupal instars were exposed to the nanomaterials). LC50 values were 13.261 ppm for young first instar larvae and 32.182 ppm for pupae. Feeding and predatory potential of G. affinis, before and after exposure to nanoparticles against mosquito larval (I & II) instars of the mosquitoes showed promising results in laboratory experiments. Feeding potential of mosquito fish without nanoparticle treatment was 79.7% and 70.55% for the first and second instar larval populations respectively. At the nanoparticle-exposed situation the predatory efficiency of mosquitofish was 94.15% and 84.3%, respectively. Antioxidant enzymes like (SOD), (CAT), and (LPO) were estimated in the gill region of sardine fish in control and experimental waters. A significant reduction of egg hatchability was evident after nanoparticle application. It became evident from this study that the nano-fabricated materials provide suitable tools to control the malaria vector Anopheles stephensi in the aquatic phase of its life cycle. This finding suggests an effective novel approach to mosquito control.

Stakeholder perceptions and strategies for management of non-native freshwater fishes of Andaman and Nicobar Islands, India

This article examines the non-native fishes in the freshwater bodies of Andaman and Nicobar Islands with a focus on understanding the perception of stakeholders towards providing management solutions. A total of 56 freshwater fish species were reported from Andaman and Nicobar Islands of which 23 species were non-native to the Islands introduced either accidentally or deliberately. Among the 23 fishes introduced, 13 species were found to be transplanted from Indian waters into the Islands and 10 species were non-native to Indian waters. Mosquito Fish (Gambusia affinis), Mozambique Tilapia (Oreochromis mossambicus), Silver Barb (Barbonymus gonionotus), Red Bellied Pacu (Piaractus brachypomus), and Common Carp (Cyprinus carpio) are some of the important invasive species found here. Stakeholder perception studies were undertaken through semi-structured questionnaire and five point likert scale questions. The respondents (N=133) were classified into two groups as a) Fish farmers and b) Research/development personnel. Multinomial logistic regression analysis revealed that the profession of the respondents significantly influenced the awareness about the non-native fishes (p<0.001). Fish farmers (4.04±0.04) and Research/development (4.47±0.21) respondents mutually agreed on the need for awareness and education on the issue of non-native fishes (p<0.01). A management framework is suggested to address the issue of non-native fishes towards effective planning, conservation and management of the fragile Island ecosystems.

Effect of vydate gill histology in female mosquito fish Gambusia affinis (Baird and Girard)

This study aimed to identify the histological changes of mosquito fish (Gambusia affinis) exposed to vydate pesticide. (48) female fishes were collected from local markets and also from the stream that surround Baghdad university campus at Al-jadyria, fishes divided into (4) groups and each group consist of 12 fish: T1(exposed to 0.0000001 mg/L),T2 (exposed to 0.0000002 mg/L ) and T3 (exposed to 0.000001 mg /L) of vydate pesticide for (8) weeks. As well as a control group. Fishes were dissected for histological preparations after each (2,4,6,8) weeks of exposure time. Gills were fixed by Bouin’s fluid and stained with Hematoxylin and eosin. Histological study showed that the structure of gill in a control group consists of primary and secondary gill lamellae appeared parallel and oblique. The secondary gill lamellae lined with squamous epithelial and pillar cells, and each secondary lamellae have capillary derived from blood vessel in primary lamellae, chlorid cells and few mucous cells found between secondary lamellae. The histological alterations in gills included hyperplasia of chloride cells, congestion of blood vessels, lamellar disarray, lifting of epithelial cells, Oedema, fusion of adjacent secondary lamella and Aneurysm. Results concluded that vydate had a vicious effect on gills and caused severe histological alterations such as hyperplasia of chloride cells and simple alterations such as lamellar disarray, and also these histological changes commensurate direct proportion with concentrations were used in this study.