Entomopathogenic fungi (EPF) are the microorganisms thatspecifically infect and often kill insects and other arthropods. EPF is themost effective biocontrol agent against insects in the natural ...ecosystem whichcould be an effective alternative to chemical insecticides in bio-intensivepest management. Beauveria bassiana, one of the most prevalentsoil-borne entomopathogens, has virulence on insect pests. The present study isaimed to evaluate the pathogenicity of a native isolate of the entomopathogenicfungus B. bassiana isolated from the soil samples of a cotton field(Kuthukkal) in the Tirunelveli district of Tamil Nadu against Dysdercuscingulatus. Bio-efficacy trials were carried out with six differentconcentrations viz., 4.6 × 103,1.5× 104, 5.0 × 105, 2.7 × 106, 3.2 × 107,and 2.8 x 108 (spores/mL) in all the five nymphal instars and theadults of D. cingulatus. A 100% mortality was observed in higherconcentrations 2.8 x 108 (spores/mL) at 120hrs after treatment. The resultsof the present study show that the isolate seems to be highly promising in thepest management of D. cingulatus.
The present study was designed to appraise the insecticidal and antibacterial potential of Clove, Syzygium aromaticum (L.) against some laboratory hosts and Escherichia coli respectively. The ...phytochemicals constituents were extracted with two solvents methanol and acetone. The result of the phytochemical analysis revealed that methanol extract has alkaloids, steroids, tannins, saponins, flavonids, cardiac glycosides, phenolic compounds and aromatic acids but in acetone extract all the constituents are similar as methanolic extract except aromatic acids. Results of the repellent activity observed against Tribolium castaneum and Corcyra cephalonica implies that silver based nanoparticles from methanol extract of 1% concentration showed maximum repellent activity of 71% against T.castaneum. Antibacterial efficacy of clove extracts tested against Gram negative bacterium E. coli revealed that 1% of methanolic extract of clove is found to have maximum growth inhibition (25mm). Results of the larvicidal activity tested against Bombyx mori recorded 100% mortality in 4% acetone extracts of clove. Keywords: Syzygium aromaticum, Tribolium castaneum, Corcyra cephalonica, Bombyx mori, Repellent activity, Larvicidal ac
The polyphagous, ubiquitous, destructive pest, Spodoptera litura(F.) affects 150 host plant species and notably their larval forms arenotorious. Extensive feeding and rapid reproduction cycles led ...the farmers andindustrialists to seek the effective chemical and synthetic pesticides. Randomand inappropriate usages of pesticides imposed a negative impact on non-targetorganisms, environment and abiotic factors and also pest resurgence to theparticular pesticides. To overcome this unnatural incidence, biopesticides arepracticed as an alternative source. Plant botanicals play a huge role as insectgrowth regulators (IGRs) by inhibiting the regular moulting cycle, developmentand survival of insect pests. Also, the silverback fern, Pityrogramma calomelanosare reported with several secondary metabolites which are known for theirpesticidal properties. Hence, the present work was framed to study the dietaryresponses as well as nutritional indices of S. litura treated with crudeextract of P. calomelanos. The treated larvae showed dietary andpost ingestion responses prior to moulting and death. On the 4th day oftreatment, reduction in food intake (522.89 mg), larval weight gain (41.02 mg),ECI (56.25 %), ECD (46.30 %), AD (47.21 %) and RGR (3.06 mg/mg/day) wasobserved as dose dependent manner except the feacal production (378.18 mg) ascompared to control. Therefore, the ethanolic extract of a fern, P. calomelanoscan be recommended as a biopesticides for its post ingestion andanti-nutritional effects on S. litura larvae.
The present experiment was designed to investigate the pesticididal property of the chosen ferns viz., Cyclosorus interruptus (Willd.) H.Itô (Theylepteridaceae), Christella dentata (Willd.) (Forssk.) ...Brownsey et Jermy (Theylepteridaceae), and Nephrolepis cordifolia (L.) Presl. Phytochemical analysis carried out using methanol extracts of the experimental ferns revealed the presence of the secondary metabolites like alkaloids, steroids, tannins, flavonoids, cardiac glycosides and phenolic compounds in methanolic extracts of the experimental ferns. The nano particles of chosen fern extracts synthesized using silver nitrate (AgNO3) showed the characteristic colour change from pale yellow to dark brown indicated the synthesis of silver based nano particles. The UV- Visible spectrum obtained for the silver nanoparticles (AgNPs) of the experimental ferns confirmed the synthesis of nanoparticles (433.50 nm, 447.00 nm and 444.00 nm for C. interruptus, C. dentata and N. cordifolia, respectively). Bioassay on the pesticidal property of the methanol extracts and ferns-AgNP were evaluated against third instar larvae of Spodoptera litura (Fab.) (Lepidoptera: Noctuidae). The results of the bioassay revealed the impact of methanolic extracts and their AgNP particles on the developmental period, pupal weight, percentage of pupation and adult emergence and also caused larval, pupal and adult deformities that confirm the insecticidal activity of the experimental ferns.
Entomopathogenic fungi play an important role in the biological control of the insect pest population in an agroecosystem. Metarhizium anisopliae is one such entomopathogenic fungus, proved to be an ...effective biocontrol agent against different insect pests. However, different strains of entomopathogens show variations in their pathogenicity and host specificity. Hence the present study is aimed to determine the bioefficacy of local isolates of the entomopathogenic fungus M. anisopliae to control Dysdercus cingulatus. Fungal strains were isolated from cotton fields in Tirunelveli, Thoothukudi, Thenkasi, and Viruthunagar districts of Tamil Nadu following standard protocols. Four different isolates were identified and used for the bioassay. Bioefficacy trials were carried out in all the five nymphal instars and the adults of D. cingulatus and were treated with eight different concentrations of M. anisopliae (101,102,103,104,105,106,107and 108 spores/mL). The formulations were evaluated for their pathogenicity and efficiency against D. cingulatusnymphal instars and adults which resulted in 70% to 100% mortality. A 100% mortality rate was observed in four isolates of M. anisopliae at higher concentrations (120 hrs) after treatment. Lethal concentration (LC50) values of M. anisopliae isolates against D. cingulatus were calculated as 5.94×107(ERUM1), 6.09×107(ERUM2), 2.62×107(ERUM3), 2.69×107(ERUM4). Approaching biocontrol agents instead of chemical pesticides seems to be very promising in the march towards more sustainable, eco-friendly agricultural pest management practices and protecting the environment
Marine algae Sargassum wightii Greville ex J.Agardh and Valonopsis pachynema (G. Martens) Borgesen were collected from the coastal area of Tuticorin, Tamil Nadu and subjected to cold striping ...extraction and phytochemical analysis. The preliminary phytochemical analysis identified cardiac glycosides, phenolic compounds, and carbohydrates in both the algal extract, furthermore S. wightii reported to have steroids, tannins, reducing sugar and saponin. Biosynthesis of silver nanoparticles in with methanol extract of S. wightii and V. pachynema was ensured by the change of colour from yellow to dark yellowish brown color. UV–visible spectroscopy and scanning electron microscopy analysis were confirmed the formation of silver nanoparticles (AgNPs). Antibacterial activity of the algal extracts and biosynthesized AgNPs were tested against Micrococcus luteus (Gram positive bacteria) and Serratia marcescens (Gram negative bacteria). The results revealed that, 150 ppm concentration of S. wightii showed maximum antibacterial activity against M. luteus (23.33 ± 2.90 mm) and S. marcescens (14.33 ± 3.05 mm). However, 150 ppm concentration of V. pachynema recorded moderate activity against M. luteus (9.33 ± 0.33 mm) and S. marcescens (8.00 ± 0.58 mm). Whereas, among the AgNPs, 2000 ppm concentration of S. wightii and 1000 ppm concentration of V. pachynema showed maximum antibacterial activity against M. luteus and S. marcescens. In conclusion we could say that, the biosynthesized AgNPs using S. wightii has significant antibacterial potential against Gram positive (25.66 ± 0.87 mm) and Gram negative (24.33 ± 2.18 mm) bacteria. Hence, the biosynthesized AgNPs using S. wightii can be exploited for large scale studies to identify possible designing of novel antimicrobial drugs.
Lepidopteran insect pests voraciously feed the vegetable crops and causes yield loss every year. Chemical insecticides widely used to control the destructive pest incidence which heavily affects the ...beneficial and non-target organisms and in the mean time, pests developed resistance. Biopesticides are being developed to minimize these ill effects. Plants synthesize secondary metabolites to prevent from biotic and abiotic stresses. More than 27 families of pteridophyta (ferns) are reported with phytoecdysteroids (PEs). PEs are analogues of insect moulting hormone and acts as insect growth regulators (IGRs). The present study aimed to isolate the phytoecdysteroid fraction from the fern, Pityrogramma calomelanos, preliminary screening of phytochemicals using standard protocols including UV-Visible spectrophotometric analysis and survival, growth and developmental periods of Spodoptera litura treated with phytoecdysteroid fraction. Steroids and phenolic compounds were present in the fraction and six prominent peaks were recorded between the wavelength of 200-800nm. Spodoptera litura larvae treated with phytoecdysteroid fraction showed maximum larval mortality (68%) in 2000ppm (LC50 = 1473ppm; F = 48.65; p = 0.049). Pupation, pupal weight and adult emergence were decreased in higher concentrations. Pupal mortality was relatively high in treated group than control (2.04%). Larvae treated with minimal concentrations exhibited developmental deformities includes larval - pupal, pupal -adult intermediates, deformed pupae, ecdysial failure, adultoids, early/late developmental periods and it may due to the interaction of phytoecdysteroid fraction to the insect endocrine system. Therefore, phytoecdysteroid mediated biopesticide formulation could be the better alternative to commercial chemical insecticides under IPM programme.
Development of early nymphal instars of a predator bug Rhynocoris albopilosus Signoret 1858 (Reduviidae: Harpactorinae) against first and second instar larvae of eri silkworm, Samiacynthia ricini ...Boisduval 1854 (Lepidoptera: Saturniidae) was investigated under laboratory condition. First-instar R. albopilosus nymphs were provided with larvae of eri silkworm as prey began feeding 6 to 12 hours after hatching and needed 8.67 days to complete their development (range 5-17 days), whereas second and third instar nymphs took 8.00 (range 4-10 days) and 6.67 (range 6-9 days) days respectively to complete their stadium. Observation reveals that first-instar R. albopilosus was not restrained from preying on siblings by kin recognition. Prey consumption was age specific and a higher number of preywas consumed on the fifth day of its first instar, third day in second instar and sixth day in third instar stadium of the predator. Nymphal survival was gradually declined from first instar to the third instar.
Le développement des premiers stades larvaires du prédateur d’insectes Rhynocoris albopilosus Signoret, 1858 (Reduviidae: harpactorinae) se nourrissant avec les premiers et deuxièmes stades larvaires du ver à soie « eri », Samiacynthia ricini Boisduval, 1854 (Lépidoptères: Saturniidae) a été étudié dans des conditions de laboratoire. Les larves de ver à soie « eri » ont été fournies à des larves de premier stade de R. albopilosus qui ont commencé à s’alimenter 6 à 12 heures après l'éclosion. Le premier stade larvaire dure, en moyenne, 8,67, alors que les deuxièmes et troisièmes stades larvaires durent, respectivement, 8,0 et 6,67 jours. L’observation révèle que le premier stade R. albopilosus n’empêche pas la prédation sur les frères et sœurs par reconnaissance familiale. La consommation des proies était spécifique à l'âge et le nombre plus élevé de proies consommées est le cinquième jour de son premier stade, le troisième jour du deuxième stade larvaire et la sixième journée du troisième stade larvaire du prédateur. La survie des nymphesa progressivement diminué, passant du premier au troisième stade larvaire.
