Résumé
Callosobruchus chinensis (L.) (Coleoptera: Bruchidae) is one of the major insect pest infesting stored pulses in India. Recourse of synthetic insecticides to protect stored pulses often lead to dangers of the development of resistant strains, toxic residue and users safety. Locally available and less toxic pest management alternatives such as the use of effective botanicals are important. Essential oils of two variants of Cinnamomum verum Presl. Syn. C. zelanicum Blume from North East India (RRL J 1620 and RRL J 1622) were characterized and tested for their biological activity in vapour form against Callosobruchus chinensis (L.). Choice and no-choice tests showed that leaf and bark oil of two variants of C. verum Presl. had significant repellent action and reduced the fecundity and decreased egg hatchability of C. chinenisis (L.). However, leaf oil with higher percentage of eugenol exhibited better activity than the bark oil in both the tests. Hence, the volatile essential oils of both the variants of C. verum Presl. can be used safely as fumigants.
Résumé
The efficacy of neem products like neem oil and commercially available neem formulations viz., Econeem plus®, Neemindia ® and Neemazal ® were evaluated in the laboratory for the control of pulse beetle, C. chinensis in stored bengalgram. These were compared with deltamethrin treatment as a chemical check. The bengalgram seed was treated with the neem formulations and stored under ambient conditions for storability studies. Observations on oviposition, insect damage, germination and seedling vigor index were recorded at three months interval. All the neem formulations were found to be effective against C. chinensis in stored bengalgram up to 12 months of storage. Surprisingly, deltamethrin treatment recorded highest oviposition of pulse beetle and insect damage resulted in poor germination and vigour of stored bengalgram seed. This gives an indication of resistance development in C. chinensis against commonly used synthetic pyrethroid insecticide deltamethrin in bengalgram. Crude neem oil @ 5 ml/ kg seed affected badly the germinability and seedling vigour of bengalgram seed under storage. The results indicated that the neem formulations viz., Neemazal, Econeem plus and Neemindia were found to be very effective against C. chinensis in stored bengalgram and also maintained high viability and vigour of seed up to twelve months of storage. Our results suggest that these neem formulations can be used as safer alternatives to chemicals for long term storage of pulses.
Résumé
Various plant parts of Indigofera tinctoria L. were collected separately at different growth stages and analysed for their rotenoid content. The total rotenoid content decreased with age; among the plant parts, maximum content was in leaves and minimum in stem. The identity of different rotenoids was confirmed by melting point, mixed melting point, UV and infrared spectral studies, and gas-liquid chromatography. Six rotenoids (deguelin, dehydrodeguelin, rotenol, rotenone, tephrosin and sumatrol) were isolated, identified and quantified in vivo. The static cultures of Indigofera tinctoria were established from seeds on RT medium, and maintained for a period of six months by frequent subculturings. Only four rotenoids were present in callus cultures; sumatrol and tephrosin were absent. The maximum content was found in eight week old tissue after fresh subculturings and minimum at 2 weeks. The toxicological studies of in vivo and in vitro extract against the pulse beetle (Callosobruchus chinensis) and mosquito (Anopheles stephensi) larvae, showed that rotenoids were more effective against mosquito larvae than Callosobruchus chinensis. Extracts from callus was more effective against both the test animals than that from plant parts.