The Effect of <i>Aphthona whitfieldi</i> (Coleoptera: Chrysomelidae) Populations’ Density on the Growth of <i>Jatropha curcas</i> in Burkina Faso

Abstract

Aphthona whitfieldi Bryant (Coleoptera: Chrysomelidae) is a major insect pest of Jatropha curcas L. in Burkina Faso. This study aimed at evaluating the effect of the insect pest populations’ density on the growth of the plant. To achieve this purpose, 90-day aged single plants were caged in a randomized complete block design experiment with 5 treatments and 5 replicates. The treatments consisted of increasing numbers of adults of A. whitfieldi used to infest the caged plants: T0 (0 adult = check), T1 (100 adults), T2 (200 adults), T3 (300 adults), T4 (400 adults). All caged plants were infested 21 days after transplantation and the evaluation started 14 days later one on every 2-week basis from September 18, 2014 to February 19, 2015. The growth parameters of the plant were assessed. The results showed that the intensity of damage caused by A. whitfieldi on the growth of young plants of J. curcas varied according to the treatment (i.e., according to the number of adult individuals infesting the plant at the beginning). The higher the number, the heavier the level of damage caused by the pest. So, the growth of the J. curcas plant was inversely proportional to the number of A. whitfieldi infesting individuals. There was also a positive linear correlation between the defoliation rate and the height of the seedlings. The status of this insect pest was confirmed by the results of this study.