Effectiveness of some botanical extracts on bean aphids attacking yard-long beans

Abstract

The effect of five different botanical extracts-tobacco, neem, garlic, eucalyptus and mehogony-on aphid population on yard long bean was assessed in field, net-house and laboratory conditions at Khulna University, Bangladesh. Aphids were deliberately exposed to the above botanical extracts and then the numbers of live and dead aphids were counted. The botanical extracts showed significant effect on the numbers of live aphids. Tobacco leaf extract had inflicted consistently the maximum level of aphid mortality; about 74-90% of the aphids were killed by the treatment in different conditions. Killing about 53-64% of the aphids on treated plants, the extract of neem followed the extract of tobacco. Garlic extract showed similar performance to that of neem. Eucalyptus and mehogany reduced aphid population but differed among the field, net-house and laboratory conditions. Contrasting to the case with aphid numbers, the botanical extracts did not affect the most common and recognized predators, ladybird beetles in the laboratory. Botanical extracts had significant effects on yield of yard long beans. Tobacco extract treated plants produced the greatest number, amount and biomass of yard-long beans; the treatment was followed by neem and garlic The latter two treatments did not show significant effect. © 2007 Academic Journals.