Efficacy of plant essential oils on black bean aphid (Aphis fabae) and cabbage aphid (Brevicoryne brassicae) under laboratory condition

Abstract

The black bean aphid (Aphis fabae) and cabbage aphid (Brevicoryne brassicae) are the major pest of black bean and cabbage respectively and their control still depends on the use of insecticides. In recent years, application of essential oils derived from aromatic plants has been considered as potential low-risk alternatives. A lab experiment was therefore, performed to study the effects of different essential oils on two different aphid species, at two different concentrations and time duration. The oils used were Citronella (Cymbopogon winterianus), Eucalyptus (Eucalyptus globulus), French Basil (Ocimum basilicum), Juniper berry (Juniperus recurva), Lemon grass (Cymbopogon citratus), Mint (Mentha arvensis) and Palmarosa (Cymbopogon martini) at the concentration of 1% and 2% for contact mortality and 2µl and 4µl for fumigation mortality, with exposure time of 24 and 48 hours. The results revealed that individual mortality percentages generally increased with increasing oil concentrations and exposure time. Among the treatments, Citronella and Lemon grass resulted in highest contact mortality percentage, whereas, Eucalyptus and Juniper berry gave the lowest percentage in both the aphid species. In case of fumigation mortality, Eucalyptus and Juniper berry resulted in highest mortality percentage with Palmarosa giving the lowest percent, in both the aphid species.