Comparative evaluation of insecticidal properties of essential oils of some selected botanicals as bio-pesticides against Cowpea bruchid, Callosobruchus maculatus (Fabricius) [Coleoptera: Chrysomelidae]

Abstract

Background: The insecticidal activities of essential oils from seeds of five botanicals Tetrapleura tetraptera, Annona muricata, and Aframomum melegueta and leaves of Eucalyptus globulus and Ficus exasperata were evaluated as biopesticides against the storage pest of cowpea Callosobruchus maculatus (Fabricius). The oils were applied at the concentration of 1 ml/kg, 3 ml/kg, and 5 ml/kg of cowpea seeds mixed evenly. The experiment was laid out in a completely randomized design. The parameters assessed include the percentage of mortality, oviposition, adult emergence, seeds damaged, weight loss, and germinability capacity of the protected seeds. Results: The results from the study showed that the effectiveness of the essential oils was dependent on application rates and time of exposure. In the treated cowpea seeds, A. melegueta essential oil was the most effective with 50% lethal concentration (LC50) value of 2.42 ml/kg and 95% lethal concentration (LC95) value of 4.86 ml/kg when compared to the other treatments as indicated by the application rate which caused 50% and 95% mortality of cowpea beetles. A. melegueta essential oil at the concentration of 5 ml/kg achieved 100% mortality of C. maculatus at 48 h of application. Cowpea seeds treated with 5 ml/kg of E. globulus essential oil significantly reduced (P < 0.05) oviposition compared to the other treatments. Cowpea seeds treated with 5 ml/kg of A. muricata essential oil reduced adult emergence (3.67) and weight loss (0.59). The cowpea seeds treated with essential oils at different concentrations had no significant (P > 0.05) adverse effect on seed germination after 120 days of storage. Conclusion: Based on the findings of this study, the essential oils could be explored as an alternative bio-pesticide to synthetic insecticide in the protection of stored cowpea against C. maculatus.

Management of stored grain pest with special reference to Callosobruchus maculatus, a major pest of cowpea: A review

“…These extracts reduce fecundity, hatching and adult emergence ( Ofuya and Akhidue, 2005 ; Adenekan et al., 2013 ). Idoko and Ileke (2020) studied insecticidal property of five botanical seed oil used against C. maculatus and essential oil from Aframomum melegueta was found most effective. Various nanoparticles were synthesized from the extracts of different plant parts (bark, leaves, flowers, stems, roots etc.).…”

Entomotoxicity of some agro-wastes against cowpea bruchid, Callosobruchus maculatus (Fab.) [Coleoptera: Chrysomelidae] infesting cowpea seeds in storage

“…To obviate the problem of chemical insecticides, different control methods have been advocated across the globe. However, botanical insecticides are gaining more attention than other control measures because of availability and ease of application compared to other control measures ( Ashamo et al., 2013 ; Idoko and Ileke 2020 ; Obembe et al., 2020 ). However, despite several researches on the use of botanical insecticides, very few are useful because the researchers failed to consider the availability of the botanicals to resource-poor farmers who have little knowledge of how to extract oils and active compounds from pesticidal plants.…”

“…Adeyemo et al (2013) opined that the backwardness in the agricultural sector of any country amounts to backwardness in the economic growth of such a country. Despite its relevance to human life, it has been facing a lot of challenges among which the infestation of its products by weevils and moths appears most prominent (Obembe and Ogungbite 2016;Idoko and Ileke 2020;Ileke et al, 2020b;Obembe et al, 2020). The menace of these insect pests inhibits the agricultural growth of some developing countries where insect pest management practices and government intervention in terms of efficient storage facilities are still low (Ashamo and Ogungbite 2014;Ileke et al, 2021).…”

“…Cowpea, V. unguiculata is one of the most popular agricultural products known as poor man's meat among Africans because it is very cheap and affordable (Ileke 2014(Ileke , 2019Idoko and Ileke 2020;Obembe et al, 2020). The crop plays an integral role in reducing food insecurity in many developing countries (Ileke and Olotuah 2012;Ashamo et al, 2013;Oyeniyi et al, 2015;Idoko and Ileke 2020). Despite the importance of this crop, infestation by C. maculatus has been a major constraint hindering its large-scale production and storage.…”

“…The damage due to insect infestation is not only restricted to the field but also extended to the storage where they can cause more than 60% seed damage (Oni 2014;Ileke 2015Ileke , 2019Ileke et al, 2021). The multivoltine type of reproduction of the insect is a factor that compounds the problem of its infestation compared to other insect pests of cowpea (Obembe and Ogungbite 2016;Idoko and Ileke, 2020;Ileke et al, 2020b;Obembe et al, 2020).…”