Evidence of population expansion and insecticide resistance mechanism in invasive fall armyworm (Spodoptera frugiperda).

BACKGROUND: The invasive and calamitous polyphagous pest Spodoptera frugiperda or commonly known as fall armyworm (FAW) poses serious menace to the global agricultural production. Owing to the revamped invasion of FAW in 2018 in India, present study was undertaken for precise assessment of its genetic identity and pesticide resistance to aid in pest-management strategies. RESULTS: To evaluate the diversity in FAW population across Eastern India, mitochondrial COI sequences were used which revealed a low nucleotide diversity. Analysis of molecular variance indicated significant genetic variation between four global geographical FAW populations with lowest differentiation between India and Africa suggesting a present-day and shared origin of FAW. The study demonstrated existence of two different strains ('R' strain and 'C' strain) based on COI gene marker. However, discrepancies between COI marker and host plant association of FAW was observed. Characterization of Tpi gene revealed abundance of TpiCa1a followed by TpiCa2b and TpiR1a strains respectively. The FAW population showed higher susceptibility towards chlorantraniliprole and spinetoram than cypermethrin. Insecticide resistance genes depicted marked upregulation although with lot of variance. Chlorantraniliprole resistance ratio (RR) exhibited significant correlation with 1950 (Glutathione S-transferase, GST), 9131 (Cytochrome P450, CYP) and 9360 (CYP) genes, while spinetoram and cypermethrin RR was found to correlate with 1950 (GST) and 9360 (CYP) genes. CONCLUSION: This study manifests Indian subcontinent as the potential new hotspot for the growth and distribution of FAW population that can be effectively controlled using chlorantraniliprole and spinetoram. This study also adds novel significant information on FAW population across Eastern India for developing a comprehensive pest management approach for S. frugiperda.

Transcription dynamics of heat-shock proteins (Hsps) and endosymbiont titres in response to thermal stress in whitefly, Bemisia tabaci (Asia-I).

The sweet potato whitefly, Bemisia tabaci (Gennadius), is one of the several species complexes of whitefly that are currently significant agricultural pests. Bemisia tabaci infests more than 600 plant species and thrives under a wide range of temperature conditions. In addition to the direct damage caused by sucking plant sap, it vectors several plant viruses. Heat-shock proteins play a pivotal role in enabling the insect to extend its geographical location, survival, and reproduction under different stress conditions. B. tabaci harbours several endosymbionts under the genera Portiera, Rickettsia, Hamiltonella, Wolbachia, Arsenophonus, Cardinium, and Fritschea that directly or indirectly affect its fitness. By accelerating cuticle biosynthesis and sclerotisation, symbiotic microbes can reduce or enhance tolerance to extreme temperatures and detoxify heavy metals. Thus, symbionts or microbial communities can expand or constrain the abiotic niche space of their host and affect its ability to adapt to changing conditions. The present study delineates the effect of thermal stress on the expression of heat-shock genes and endosymbionts in B. tabaci. Studies of the expression level of heat-shock proteins with the help of quantitative real-time polymerase chain reaction (qRT-PCR) showed that heat- and cold-shock treatment fuels the increased expression of heat-shock proteins (Hsp40 and Hsp70). However, Hsp90 was not induced by a heat- and cold-shock treatment. A significant decrease in the relative titre of secondary endosymbionts, such as Rickettsia, Arsenophonus, and Wolbachia, were recorded in B. tabaci upon heat treatment. However, the titre of the primary symbiont, C. Portiera, was relatively unaffected by both cold and heat treatments. These results are indicative of the fact that Hsp genes and endosymbionts in B. tabaci are modulated in response to thermal stress, and this might be responsible for the adaptation of whitefly under changing climatic scenario.

Chemical and microbial properties of shidal, a traditional fermented fish of Northeast India.

Like Southeast Asian countries fermented fish is a well known strategy of food preservation in the Northeast region of India. Shidals are mostly preferred salt-free fermented fish product amongst all. Chemical and microbial composition, antioxidative potential, fatty acid profile and proteins profile in gel electrophoresis of shidals were studied. pH and total titratable acidity (TTA) have been found as 5.86 ± 0.11, 0.115 ± 0.01 and 6.62 ± 0.07, 0.092 ± 0.01 in punti and phasa shidal respectively. DPPH (·) radical scavenging activity of punti and phasa shidal was determined as 80.15 ± 5.67 and 68.30 ± 3.22 respectively. Presence of eicosapentaenoic, docosahexaenoic, arachidonic, linolenic and linoleic acid indicate the nutritional significance of shidal. However, the result showed that punti shidal was rich in omega-3 but poor in omega-6 fatty acid, whereas, reverse was observed in respect of phasa shidal. Poly acrylamide gel electrophoretic study of protein revealed disappearance of myosin head chain (MHC) in the dry puntius fish (raw material of shidal). Proteins or peptides with low molecular weight between 45 and 29 kDa and between 45 and 66 kDa were noticed in both the shidals and indicative of intensive protein degradation during fermentation. Therefore, fermented fish product, shidal could be used as a potential source of nutrients and natural antioxidants.

Gel properties of sutchi catfish (Pangasius hypophthalmus) surimi as affected by selected washing process and number of washing cycles.

The gel properties of sutchi catfish surimi prepared by conventional washing and alkaline-saline washing method were studied for four washing cycles. Decrease (p < 0.05) in myoglobin content was found in alkaline washing process compared to conventional washing at each washing cycle. The highest hardness, breaking force and deformation was observed in gels prepared from alkaline-saline washing method. Whiteness in conventional washed surimi gels increased non-significantly (p < 0.05) compared to alkaline-saline-washed surimi gels. Protein bands on Sodium dodecyl sulfate polyacrylamide gel electrophoresis indicated that the protein extractability was more in alkaline-saline washing and disappearance of bands in conventional washing method was observed between 116 and 45 kDa indicating less yield of protein.

Effect of garlic extract on physical, oxidative and microbial changes during refrigerated storage of restructured product from Thai pangas (pangasianodon hypophthalmus) surimi.

The effect of garlic's aqueous extract (GAE) during refrigerated storage of the restructured products from Pangasius (Pangasianodon hypophthalmus) was evaluated. Protein and lipid oxidation, protein pattern on SDS-PAGE, TPC as well as WHC, gelling properties, texture profiles and whiteness of the surimi gel was evaluated periodically during a refrigerated storage period of 20 days. Increase of water holding capacity in GAE added gels indicated stronger protein network formation, whereas, decrease of protein solubility suggested formation of protein aggregates during gelation process. Lipid oxidation decreased in treated samples but the rate of increase varied, depending upon the concentration of GAE. Protein carbonyl content increased during storage, but slow increase in treated samples. Gel strength in treated samples increased and accompanied by thickening of myofibrillar head chain. Hardness, adhesiveness and gumminess parameters affected most due to addition of GAE. Sensory analysis revealed that the RP with 1 % GAE preferred most and control was acceptable upto 12 days.

Biochemical and microbial characterization of Ngari and Hentaak - traditional fermented fish products of India.

Ngari and hentaak are the two most preferred traditional salt-free fermented fish products of North-Eastern (NE) states of India. Chemical and microbial composition, antioxidative potential, fatty acid profile and electrophoretic pattern of protein in ngari and hentaak were studied. pH and total titratable acidity (TTA) of the products justified their stability at ambient temperature. Both ngari and hentaak showed higher contents of calcium (362.79 ± 26.89, 472.11 ± 62.7); sodium (199.66 ± 24.92, 94.0 ± 12.78); potassium (58.20 ± 7.36, 75.74 ± 6.62) and magnesium (16.056 ± 3.89, 21.125 ± 3.78) respectively. Iron, copper and zinc were found in lesser amount. DPPH (·) radical scavenging activity was close to 87 % in both the products and the ferric chloride reducing power assay was dose dependent in both the products. Both omega-3 and omega-6 fatty acids were found in ngari; whereas, only omega-3 fatty acids were observed in hentaak. Linoleic acid (11.68 %) and arachidonic acid (0.65 %) were the n-6 PUFA in ngari; while, in hentaak, it was only arachidonic acid (8.54 %). Apart from essential fatty acids, essential amino acids were also found in considerable quantity in both the products. Micrococcus sp. and Staphylococcus sp. were found to be the dominant bacterial genus in both the products; while Ngari also had lactic acid bacteria group. The nutritional properties afforded by these products justify their preference by the population.

Optimization of process conditions for Rohu fish in curry medium in retortable pouches using instrumental and sensory characteristics.

'Kalia', a popular preparation of Rohu fish, packed in four-layered laminated retort pouch was processed in a steam/air mixture over-pressure retort at 121.1 °C to three different F 0 values of 7, 8 and 9 min. Time-temperature data were collected during heat processing using an Ellab Sterilization Monitoring System. Texture profile such as hardness, springiness, gumminess and chewiness decreased as the F 0 value increased. The L* values decreased whereas a* and b* values increased with increasing F 0 value. Based on the commercial sterility, sensory evaluation, colour and texture profile analysis, F 0 value of 8 min and cook value of 66 min, with a total process time of 41.7 min at 121.1 °C was found satisfactory for the preparation of Rohu fish curry (Kalia) in retort pouches.