A. K. Tripathi

Repellency and toxicity of oil from Artemisia annua to certain stored-product beetles.

Abstract The essential oil of Artemisia annua L. was tested for its toxic repellent and development inhibitory activities against 2 economically important stored product insects: Tribolium castaneum (Herbst) and Callosobruchus maculatus (L.). Adult beetles of T. castaneum were repelled significantly by oil of A. annua at 1% concentration (vol:vol) and above in filter paper arena test. Dose–response relationship of A. annua oil revealed a significant negative correlation between larval survival; pupal survival and adult emergence of T. castaneum (i.e., increase in dose caused decrease in survival and adult emergence). Effective concentration (EC50) to reduce F1 progeny by 50% was calculated to be 2.6 and 4.1 μl/ml solvent against both the insect species, C. maculatus and T. castaneum, respectively. The relationship between bioactivity of oil from A. annua and responses of T. castaneum and C. maculatus is discussed. We found that oil from A. annua was largely responsible for both repellent (behavioral) and toxic (physiological) actions on 2 species of insect tested.

Bioactivities of the Leaf Essential Oil of Curcuma Longa (Var. Ch-66) On Three Species of Stored-Product Beetles (Coleoptera)

Abstract Essential oil extracted from the leaves of turmeric, Curcuma longa L., was investigated for contact and fumigant toxicity and its effect on progeny production in three stored-product beetles, Rhyzopertha dominica F. (lesser grain borer), Sitophilus oryzae L. (rice weevil), and Tribolium castaneum Herbst (red flour beetle). Oviposition-deterrent and ovicidal actions of C. longa leaf oil were also evaluated against T. castaneum. The oil was insecticidal in both contact and fumigant toxicity assays. The adults of R. dominica were highly susceptible to contact action of C. longa leaf oil, with LD50 value of 36.71 μg/mg weight of insect, whereas in the fumigant assay, adults of S. oryzae were highly susceptible with LC50 value of 11.36 mg/liter air. Further, in T. castaneum, the C. longa oil reduced oviposition and egg hatching by 72 and 80%, respectively at the concentration of 5.2 mg/cm2. At the concentration of 40.5 mg/g food, the oil totally suppressed progeny production of all the three test insects. Nutritional indices indicate >81% antifeedant action of the oil against R. dominica, S. oryzae and T. castaneum at the highest concentration tested.

Toxicity, feeding deterrence, and effect of activity of 1,8-Cineole from Artemisia annua on progeny production of Tribolium castanaeum (Coleoptera : Tenebrionidae)

Abstract 1,8-Cineole isolated from Artemisia annua was tested against Tribolium castaneum (Herbst) for contact toxicity, fumigant toxicity, and antifeedant activity. The adults of T. castaneum were more susceptible than larvae to both contact and fumigant toxicity of 1,8-cineole, and LD50 and LC50 values of 108.4 μg/mg body weight of adult insect and 1.52 mg/liter air were found, respectively. Furthermore, 14-d-old T. castaneum larvae were more tolerant than 16- and 18-d-old larvae and adults to the contact toxicity of 1,8-cineole, but the 16- and 18-d-old larvae have similar susceptibility. In contrast, all the larvae (14–18 d old) of T. castaneum were much more tolerant than the adults to the fumigant action, but larvae of different ages had similar susceptibility. The compound 1,8-ciineole applied to filter paper at a concentration of 3.22–16.10 mg/cm2 significantly (P < 0.05) reduced the hatching of T. castaneum eggs and the subsequent survival rate of the larvae. Adult emergence was also reduced by 1,8-cineole. Feeding deterrence of 81.9% was achieved in T. castaneum adults by using a concentration of 121.9 mg/g food, whereas larvae showed 68.8% at the same concentration.

Insecticidal and repellent activities of thymol from the essential oil of Trachyspermum ammi (Linn) Sprague seeds against Anopheles stephensi

Essential oil of seeds of Trachyspermum ammi (Linn.) Sprauge and its pure constituent thymol showed promising results when evaluated for larvicidal, oviposition-deterrent, vapor toxicity, and repellent activity against malarial vector, Anopheles stephensi. Thymol was 1.6-fold more toxic than the oil toward fourth-instar larvae of A. stephensi with LD50 values of 48.88 and 80.77xa0µg/ml, respectively. Egg laying by female adults of A. stephensi was much significantly reduced when exposed to vapors of thymol compared to the oil of T. ammi seeds, and similar effects were recorded for subsequent egg hatching and larval survival. Vapor toxicity assay showed LC50 value of 79.5xa0mg/mat for thymol against adults of A. stephensi, whereas the crude oil exhibited the LC50 value of 185.4xa0mg/mat. Thymol provided complete repellency toward A. stephensi adults at the dose of 25.0xa0mg/mat after 1xa0h duration, whereas same degree of repellency was obtained by the oil at the dose of 55.0xa0mg/mat, indicating its double-fold activity than the oil.

Piperitenone Oxide as Toxic, Repellent, and Reproduction Retardant Toward Malarial Vector Anopheles stephensi (Diptera: Anophelinae)

Abstract Anopheles stephensi (Liston) is a well-known vector of malarial parasite in tropical countries. The developing trend of resistance in mosquitoes toward synthetic mosquitocidal agents makes their management extremely difficult. Effectiveness of essential oils with aroma therapeutic values seems to be an emerging tool to combat this vector. Piperitenone oxide isolated from essential oil of a new genotype, Mentha spicata L. variety viridis, has been evaluated for larvicidal, ovicidal, oviposition-deterrent, developmental toxicity, and repellent properties against various stages of A. stephensi. The results indicated the higher efficacy of piperitenone oxide than the crude essential oil of M. spicata variety viridis in all the bioassay experiments. The lethal response of piperitenone oxide and the oil toward fourth instar larvae showed LD50 values of 61.64 and 82.95 μg/ml, respectively. Female adults of A. stephensi exposed to the oil laid ≈42 times less number of eggs at the dose of 60.0 μg/ml as compared with control, whereas exposure of piperitenone oxide at the same dose completely inhibited the oviposition. Furthermore, piperitenone oxide also completely inhibited egg hatching at the dose of 75.0 μg/ml in ovicidal assay. Developmental toxicity studies showed the significant developmental inhibition potential of the compound and oil. Additionally, piperitenone oxide was found to be highly toxic and repellent toward adults of A. stephensi as compared with oil.

Toxicity of 1,8-cineole towards three species of stored product coleopterans

Abstract1,8-cineole, one of the components of the essential oil of Artemisia annwa, was evaluated for repellency and toxicity against three stored product coleopterans—Callosobruchiis maculatus F. (Coleoptera: Bruchidae), Rhyzopertha dominica F. (Coleoptera: Bostrychidae) and Sitopliilus oryzae L. (Coleoptera: Curculionidae). It was found to be moderately repellent to all three species, with a mean repellency in the range of 65–74% at the highest dose tested (4.0 μl/ml) within 1h. A contact toxicity assay revealed that direct topical application was more effective than using impregnated filter paper. The compound was more effective as a fumigant and gave 93–100% mortality against all the three pest species at the dose of 1.0 μl/l air under empty jar conditions as compared to treatment of jars filled with grain (11–26% mortality). The lethal dose and lethal concentration required to kill 50% of the beetles (LD50 and LC50 respectively) varied with the toxicity assay method. LD50 values of 0.03, 0.04 and 0.04 μl/insect against C. maculatus, R. dominica and S. oryzae respectively were found in the topical application assay while the LC50 in the fumigant assay was 0.28, 0.33 and 0.46 μl/l against C. maculatus, R. dominica and S. oryzae respectively.RésuméL’un des composés de l’huile essentielle d’Artemisia annua, le 1,8-cineole, a été évalué pour sa répulsion et sa toxicité vis à vis de trois coléoptères des denrées stockées, Callosobrnchus maculatus F. (Coleoptera: Bruchidae), Rhyzoperta dominica F. (Coleoptera: Bostrychidae) et Sitopliilus orizae L. (Coleoptera: Curculionidae). Il s’est avéré être modérément répulsif pour les 3 espèces, avec une répulsion moyenne de 65–74% à la plus forte dose testée (4.0 ml/ml) pendant 1 heure. Un essai de toxicité de contact indique qu’une application locale directe est plus efficace que l’utilisation d’un papier filtre imprégné. Le composé est plus efficace en fumigation et provoque 93–100% de mortalité chez les trois espèces de ravageurs à la dose de 1.0 ml/l d’air dans un pot vide par rapport à un pot rempli de grains (11–26% de mortalité). La dose létale et la concentration létale requises pour tuer 50% des scarabées (LD50 et LC50 respectivement) varient avec le type d’essai de toxicité. Des valeurs de LD50 de 0.03, 0.04 et 0.04 ml/insecte pour C. maculatus, R. dominica et S. oryzae respectivement ont été trouvées dans l’essai avec une application locale alors que la LC50 dans l’essai de fumigation était respectivement de 0.28, 0.33 et 0.46ml/l pour C. maculatus, R. dominica et S. oryzae.

Insect feeding deterrent and growth inhibitory activities of scopoletin isolated from Artemisia annua against Spilarctia obliqua (Lepidoptera: Noctuidae)

Abstractu2002 Artemisia annua (Asteraceae) is well known for its antimalarial activities due to presence of the compound artemisinin. We isolated a methoxy coumarin from the stem part of A. annua and confirmed its identity as scopoletin through mass spectral data. The structure was established from 1H‐nuclear magnetic resonance (NMR), 13C‐NMR. The compound scopoletin was evaluated for its feeding deterrence and growth inhibitory potential against a noxious lepidopteran insect, Spilartctia obliqua Walker. Scopoletin gave FD50 (feeding deterrence of 50%) value of 96.7 μg/g diet when mixed into artificial diet. S. obliqua larvae (12‐day‐old) exposed to the highest concentration (250 μg/g diet) of scopoletin showed 77.1% feeding‐deterrence. In a growth inhibitory assay, scopoletin provided 116.9% growth inhibition at the highest dose of 250 μg/g diet with a GI50 (growth inhibition of 50%) value of 20.9 μg/g diet. Statistical analysis showed a concentration‐dependent dose response relationship toward both feeding deterrent and growth inhibitory activities. Artemisinin is found mainly in the leaves of A. annua and not in the stems, which are typically discarded as waste. Therefore identification of scopoletin in stems of A. annua may be important as a source of this material for pest control.

Anti-insect Screening of Medicinal Plants from Kukrail Forest, Lucknow, India

Ten medicinal plants were evaluated at a dose of 10mg/ml for insecticidal, ovicidal, feeding-deterrence, growth inhibition and morphogenetic effects against various life stages of a noxious lepidopteran insect-pest, Spilarctia obliqua Walker. The acetone extract of Ageratum conyzoides, methanol extract of Justicia adhatoda, and chloroform extract of Plumbago zeylanica showed strong feeding-deterrence, growth inhibition and ovicidal effects against eggs and larvae of S. obliqua. In addition, the chloroform extract of P. zeylanica also created strong morphogenetic disorders in treated pupae of S. obliqua. The methanol extracts of Chenopodium ambrosioides and Ailanthus excelsa showed only feeding-deterrence and growth inhibitory effects but no ovicidal effect, whereas all the five extracts (hexane, chloroform, acetone, methanol and water) of Catharanthus roseus exhibited strong growth inhibition towards larvae of S. obliqua. The acetone extract of Vitex negundo was found to exhibit all the activities tested against S. obliqua. Other plants tested, Ajuga remota, Andrographis paniculata and Clerodendrum inermre, were found to have low to moderate effects towards S. obliqua.

Antifeedant and antifungal activity of chromene compounds isolated from Blepharispermum subsessile.

Desmethyl isoencecalin and 5-hydroxy-6-acetyl-2-hydroxymethyl-2-methyl chromene isolated from Blepharispermum subsessile rhizomes were shown to have antifeedant activity against larvae of Spilarctia obliqua and also antifungal activity against Candida albicans and Cryptococcus neoformans (MIC 25-250 microg/ml).

Repellent and insecticidal activities of Hyptis suaveolens (Lamiaceae) leaf essential oil against four stored-grain coleopteran pests

We evaluated the contact toxicity, fumigant toxicity and repellency of the essential oil of Hyptis suaveolens (L.) leaves against adults of four stored-product coleopteran pests, namely Callosobruchus maculatus (Bruchidae), Rhyzopertha dominica (Bostrychidae), Sitophilus oryzae (Curculionidae) and Tribolium castaneum (Tenebrionidae). Four major compounds were identified in the oil by gas chromatography: sabinene (41.0%), terpinen-4-ol (12.31%), β-pinene (10.0%) and β-caryophyllene (8.0%). Oil concentrations of 0.05–2.0% were tested on adult coleopterans for contact toxicity by topical application. Repellency was evaluated at 0.4–18.3 mg/cm2 concentrations using an area preference test, whereas fumigant toxicity of the oil was tested both in air and admixed with grain at 1–50 μ1/l air and 25–100 μ1/l, respectively. Persistence of the oil admixed with grain was tested at 0.1–2.5% concentrations for a period of 40 days. Percentage repellence ranged from 20.0 to 94.7% at 5h against the test insects at the highest dose tested (18.3 mg/cm2). Adults of C. maculatus were the most susceptible in both contact and fumigant toxicity assays, with an LD50 value of 57.0 μg/mg weight of insect and an LC50 value of 4.7mg/l air, respectively. The oil had low persistence. H. suaveolens leaf essential oil may have potential as an alternative to the synthetic pesticides used in the treatment of grain in storage.