Assessment of Plants Alkaloids Isolated from Calotropis Procera for Managing Pod Sucking Bug, Clavigralla tomentosicollis Stal (Hemiptera: Coreidae) Infestation on Cowpea

Abstract

Crude plant extracts used to control insect pests are less specific and the active compounds may have antagonistic effects. The trials were thus conducted to assess the effectiveness of alkaloids from Calotropis procera in controlling the pod sucking bug Clavigralla tomentosicollis on cowpea. Three cowpea varieties, Ife brown, IT07K-318-33, and IT07K-292-10, were grown in beds assigned to four treatment groups: 500µg/ml, 250µg/ml, 125µg/ml, and 0µg/ml of the extracts as a control. Each treatment was replicated three times in a randomized complete block design. The findings revealed a significant decrease (p<0.05) in the population of C. tomentosicollis in the treated plots compared to the control. The highest level of protection was observed in plots sprayed with 500µg/ml and 250µg/ml, with no significant difference (p>0.05) between treatment and spray regimes (1-week after spray (1-WAS) and 2-weeks after spray (2-WAS). The average percentage of pod damage was significantly lower at higher treatment concentrations (500µg/ml and 250µg/ml) compared to lower concentrations and the control. There was no significant difference in pod damage among the three cowpea varieties. The relative adult mortality of C. tomentosicollis followed a similar pattern, with higher concentrations (500µg/ml and 250µg/ml) resulting in a significant decrease in ITOK-292-10 compared to other varieties. In the ITOK7-318-33 variety, there was no significant difference in mortality rates between treatments (500µg/ml, 250µg/ml, and 125µg/ml) and spray regimes. This implied that treatment of cowpea ITOK-292-10 with the higher concentration of the Alkaloid (2-piperidinone, N-(4-bromo-n-butyl) would yield an optimum level control of the notorious bug.