Control of the Maize Pest Beetle, Anomala denuda (Coleoptera: Scarabaeidae), Using Insecticidal Plants Ricinus communis and Azadirachta indica in a Laboratory Setting

The aim of this study was to identify a natural alternative to synthetic insecticides for controlling the Anomala denuda beetle, a destructive corn pest. The investigation took place at Félix Houphouët-Boigny University's Natural Environments and Biodiversity Conservation Laboratory at a temperature of 17°C. Aqueous extracts of Azadirachta indica leaves and Ricinus communis seed capsules were tested for their effectiveness against the beetle. The reference pesticides, Cypercal 50EC and Viper 42EC, were used as positive control. The tests included three types of toxicity (inhalation, ingestion, and repulsion) with four repetitions each and a four-day exposure period. The ingestion test was the most effective. At 110 g/l, A. indica and R. communis extracts had corrected mortality rates of 87.41 ± 3.21 and 90.28 ± 1.71%, respectively. In the inhalation test, A. indica and R. communis extracts resulted in 80.92 ± 5.88% and 83.14 ± 7.57% mortality rates, respectively, at the same concentration. At the same concentration, R. communis extract repelled 60% of beetles, which was higher than A. indica's 53.3%. The insecticidal effects of the extracts were similar to those of Cypercal in all tests. These results suggest that R. communis and A. indica extracts could be used to control A. denuda pests without relying on synthetic chemical pesticides.