Efficacy of different essential oils against aphid (Aphis craccivora) in green gram
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Date
2023
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Abstract
Green gram, Vigna radiata (L) Wilczek is a significant pulse crop in India. It offers a protein-rich diet with 211 calories and 14.2 grams of proteins, along with essential minerals, iron and fiber. However, the crop faces production losses due to insect pests, especially aphids, which hinder its early growth stages by continuously sucking cell sap, leading to leaf drying and hampering vegetative growth. The increasing concern over the adverse environmental impact of chemical pesticides has led to the exploration of alternative and eco-friendly pest control measures. Essential oils are a viable alternative to other botanical extracts used as pesticides due to their widespread availability and relative affordability. In this study, we investigated the efficacy of essential oils derived from neem, clove, mint, garlic, ginger and eucalyptus as potential biopesticides against Aphis craccivora Koch, a destructive pest of green gram. The nymph and adult mortality rates were evaluated at different concentrations (1%, 3%, and 5%) after 4, 12, 24, 48 and 72 hours of treatment. Neem oil exhibited the highest nymph mortality of 96.67%, 100%, 100% at 1%, 3% and 5%, respectively. Mint oil also displayed notable efficacy with mortality rates of 73.33%, 73.33%, and 83.33% at 1%, 3%, and 5% concentrations, respectively after 72 hours of treatment. Clove and garlic oils exhibited moderate nymph mortality while eucalyptus oil showed the lowest impact on nymph mortality. All oils demonstrated significantly higher mortality rates compared to the control group. Similar trends were observed in adult mortality rates, with neem oil demonstrating the highest efficacy (56.67% at 1%, 73.33% at 3%, and 76.66% at 5%). Mint oil also exhibited notable adult mortality rates. Conversely, eucalyptus oil showed the lowest mortality rates among all treatments. Furthermore, treatment with essential oils reduced the total development period of A. craccivora compared to the control group, with neem and mint oils resulting in the shortest development periods. The nymphal duration was significantly shorter in the treatment groups, with clove oil exhibiting the shortest 1st nymphal duration. Neem, mint, and garlic oils also contributed to shorter nymphal periods. Additionally, reproductive performance was affected by the treatments, with mint oil resulting in the shortest reproductive period and neem oil leading to the lowest number of offspring produced by a single female. The total number of offspring was significantly lower in the treatment groups, with the control group having the highest number. The importance of essential oils in pest control lies in their eco-friendly and sustainable attributes, offering effective alternatives to harmful chemical pesticides. As we look to the future, further research and development in harnessing the potential of essential oils hold promise for safer and more environmentally conscious pest management strategies.