Effect of thiamethoxam on growth, biomass of rice varieties and its specialized herbivore, Scirpophaga incertulas Walker.

Not AvailablePesticides employed as seed treatment provides protection to seedlings against insect pests and diseases. Seed treatment of five rice varieties with thiamethoxam, an active ingredient of Actara 25 WG, showed positive effects on seed emergence, plant root and shoot biomass and reduction in dead heart damage under both controlled and greenhouse conditions. Under controlled condition thiamethoxam increased emergence in all of the rice varieties tested. The highest dose i.e., 2.0 g L−1of thiamethoxam had the maximum positive effects. The plant shoot and root characters were also influenced positively by the seed treatment. The total root length was superior with measurements of 38.6, 26.5 and 27.4 cm at 2.0 g L−1 concentration treatment for the rice varieties Ptb 33, AD09219 and AD07073 respectively. Similarly the root shoot ratio also increased positively at the prominent dosage for the varieties Ptb 33, AD07073 and AD09219 showing ratios of 0.402, 0.415 and 0.420 respectively. However, thiamethoxam seed treatment even at 0.50 g/L concentration showed significant difference over the untreated control in all the rice varieties tested. With respect to biomass (fresh and dry root and shoot weight) all the treatment doses of thiamethoxam was superior over the control in which the dose 2.0 g/L showed prominent fresh root and shoot weight in all the three tested varieties. Thus the thiamethoxam seed treatment except at the minimum dose showed increased shoot weight and root weight compared to untreated control. Considering the effect of thiamethoxam on insect pest, the spray application @ 0.2, 0.4, and 0.6 g/L of thiamethoxam 25WG significantly reduced the dead heart damage symptom caused by yellow stem borer in the all the varieties (TN1, Ptb33 and AD09219) tested compared to control treatment. Thus, the present investigation suggests that the bioactivator thiamethoxam when employed as a seed treatment plays a critical role in rice growth and development.Not Availabl

A novel herbal product based on Piper betle and Sphaeranthus indicus essential oils: toxicity, repellent activity and impact on detoxifying enzymes GST and CYP450 of Aedes aegypti Liston (Diptera: Culicidae)

Fresh leaves of Piper betle Linn. (Piperales: Piperaceae) and Sphaeranthus indicus Linn. (Asterales: Asteraceae), commonly known as betel leaves and East Indian globe thistle, respectively, were harvested and steam distilled for the extraction of P. betle and S. indicus crude volatile oils (Pb-CVO and Si-CVO, respectively). LC50 calculated on 3rd instar larvae of dengue mosquito Aedes aegypti Linn. (Diptera: Culicidae) was 42.17 ppm for PbSi-CVO (i.e., herbal formulation based on the EOs of P. betle and S. indicus). The larval and pupal duration were significantly longer post-treatment with 100 ppm of PbSi-CVO, if compared to control. We observed that PbSi-CVO significantly altered the detoxifying enzymes GST and CYP450 compared to the expression of control. Sub-lethal concentrations of PbSi-CVO showed strong repellent properties against dengue mosquitoes, without adverse reactions on the volunteers experiencing the repellent assays. Lastly, the adulticidal activity of PbSi-CVO was studied. Overall, our study outlined that this herbal product represents a promising candidate for the development of botanical based adulticidal agents

Response of Spodoptera litura Fab. (Lepidoptera: Noctuidae) larvae to Citrullus colocynthis L. (Cucurbitales: Cucurbitaceae) chemical constituents: Larval tolerance, food utilization and detoxifying enzyme activities

Not AvailablePest management has increased the alarm across researchers because of the possible risk from harmful insecticides dispersed in the natural environment. Plant derivatives are established from plant extracts and displays latent effects against damaging pests in a multiple ways. Citrullus colocynthis (L.) Schrad, largely dispersed across the world in the warm area. A purified, fractionated ethyl acetate extract of C.colocynthis (bitter apple) has shown 90% lethality toward Spodoptera litura third instar larvae, and slightly lower lethality to the fourth and fifth instars. Based on the food utilization, the mechanism of lethality appears to be reduced digestive enzyme activity. The enzyme analysis of S. litura against fraction F5 demonstrated that the level of ACP, ALP, ATP and LDH decreased significantly based on their concentration. The gut histology of S. litura shows disturbance in the midgut columnar cells against the fraction F5. The fraction F5 was further eluted using column chromatography and the subfraction A3 obtained and it was further characterized using FTIR and NMR. The subfraction A3 exhibits prominent mortality rate with 84% at 100 ppm concentration. The subfraction A3 was characterized and identified as stigmasterol.Not Availabl

Target and non-target response of Swietenia Mahagoni Jacq. chemical constituents against tobacco cutworm Spodoptera litura Fab. and earthworm, Eudrilus eugeniae

Not AvailableToxicological screening of Swietenia mahagoni Jacq. (Meliaceae, West Indies Mahogany) against the lepidopteran pest Spodoptera litura was examined. Phytochemical screening through GC-MS analysis revealed nine peaks with prominent peak area % in Bis (2-ethylhexyl) phthalate (31.5%) was observed. The larvae exposed to discriminating dosage of 100 ppm deliver significant mortality rate compare to other treatment concentrations. The lethal concentrations (LC50 and LC90) was observed at the dosage of 31.04 and 86.82 ppm respectively. Sub-lethal concentrations (30 ppm) showed higher larval and pupal durations. However, pupal weight and mean fecundity rate reduced significantly. Similarly, the adult longevity reduced significantly in dose dependent manner. Midgut histology studies showed that the methanolic extracts significantly disturbs the gut epithelial layer, lumen and brush border membrane compare to the control. The soil assay on a non-target beneficial organism, the soil indicator earthworm Eudrilus eugeniae, with extracts from S. mahagoni (200 mg/kg) showed no toxicity compared to Monocrotophos at the dosage of 10 ppm/kg. Current results suggest that this bio-rational plant product from S. mahagoni displays a significant effect to reduce lepidopteran pests with low toxicity to other beneficial species.Not Availabl